U.S. patent application number 17/129226 was filed with the patent office on 2021-05-20 for realizing mobile relays for device-to-device (d2d) communications.
The applicant listed for this patent is InterDigital Patent Holdings, Inc.. Invention is credited to Martino M. Freda, Paul Marinier, Diana Pani, Benoit Pelletier.
Application Number | 20210153094 17/129226 |
Document ID | / |
Family ID | 1000005359243 |
Filed Date | 2021-05-20 |
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United States Patent
Application |
20210153094 |
Kind Code |
A1 |
Freda; Martino M. ; et
al. |
May 20, 2021 |
REALIZING MOBILE RELAYS FOR DEVICE-TO-DEVICE (D2D)
COMMUNICATIONS
Abstract
Systems, methods, and instrumentalities are disclosed for a WTRU
to act as a mobile relay, the method comprising the WTRU connecting
to the network, the WTRU receiving a message from the network
indicating that the WTRU is to act as a mobile relay for one or
more devices outside of the coverage of the network, the WTRU
discovering one or more devices outside of the coverage of the
network, and the WTRU receiving a message from the out-of-coverage
device that indicates that the out-of-coverage device has selected
the WTRU to act as a mobile relay.
Inventors: |
Freda; Martino M.; (Laval,
CA) ; Pani; Diana; (Montreal, CA) ; Pelletier;
Benoit; (Roxboro, CA) ; Marinier; Paul;
(Brossard, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
InterDigital Patent Holdings, Inc. |
Wilmington |
DE |
US |
|
|
Family ID: |
1000005359243 |
Appl. No.: |
17/129226 |
Filed: |
December 21, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16414549 |
May 16, 2019 |
10912007 |
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17129226 |
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15565088 |
Oct 6, 2017 |
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PCT/US2016/026765 |
Apr 8, 2016 |
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16414549 |
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62144667 |
Apr 8, 2015 |
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62161145 |
May 13, 2015 |
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62201184 |
Aug 5, 2015 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04B 7/155 20130101;
H04W 88/04 20130101; H04B 7/15528 20130101; H04W 76/14 20180201;
H04W 76/23 20180201; H04W 36/36 20130101 |
International
Class: |
H04W 36/36 20060101
H04W036/36; H04W 76/23 20060101 H04W076/23; H04W 76/14 20060101
H04W076/14; H04W 88/04 20060101 H04W088/04; H04B 7/155 20060101
H04B007/155 |
Claims
1-32. (canceled)
33. A method of allocating resources to a group, the group
including one or more mobile Wireless Transmit/Receive Units
(WTRUs) and a supervising mobile (SM) WTRU, as group members; the
method comprising: receiving, by the SMWTRU, configuration
information indicating one or more resource allocations to be used
by the group members; and sending, by the SMWTRU to other group
members in accordance with the received configuration information,
resource information associated with any of: one or more pooled
resource allocations and/or one or more individual resource
allocations.
34. The method of claim 33, wherein the sending of the resource
information includes sending, for the one or more pooled resource
allocations, by the SMWTRU to the other group members, the resource
information for establishment of communication between or among the
group members.
35. The method of claim 33, wherein the sending of the resource
information includes sending, for the individual resource
allocations, by the SMWTRU to one or more other group members, the
resource information for establishment of communication between or
among any of subsets of group members.
36. The method of claim 33, further comprising: communicating
between or among the SMWTRU, as a first vehicle, and any of the one
or more other group members, as further vehicles, using a group
identifier associated with a first pooled resource allocation of
the one or more pooled resource allocations.
37. The method of claim 33, wherein the sending of the resource
information is via a PC5 message for vehicle communication.
38. The method of claim 33, further comprising establishing
pre-configured resource allocations for communications between or
among the group members, prior to the SMWTRU sending the resource
information.
39. The method of claim 33, further comprising: receiving, by a
first mobile WTRU of the group from a network entity, an indication
that the first mobile WTRU is to act as the SMWTRU for the group;
and configuring, by the first mobile WTRU, the first mobile WTRU to
act as the SMWTRU.
40. The method of claim 39, further comprising performing by the
configured SMWTRU both relaying operations and operations, as a
member of the group.
41. The method of claim 39, further comprising: sending, by the
first mobile WTRU to the network entity prior the SMWTRU being
configured, capability information associated with the first mobile
WTRU, wherein the receiving of the indication that the first mobile
WTRU is to act as the SMWTRU is based on the first mobile WTRU
having capabilities to support an SMWTRU operation.
42. The method of claim 41, wherein the capability information
includes any of: (1) operating frequency information of the first
mobile WTRU; (2) operational information regarding one or more
radios of the first mobile WTRU; (3) an indication of whether the
first mobile WTRU supports relaying operations; and/or (4) location
information of the first mobile WTRU.
43. A first Wireless Transmit/Receive Unit (WTRU) configured to
allocate resources to a group, the group including one or more
other mobile WTRUs and the first WTRU, as group members,
comprising: a transmit/receive unit configured to: receive
configuration information indicating one or more resource
allocations to be used by the group members; and send, to other
group members in accordance with the received configuration
information, resource information associated with any of: one or
more pooled resource allocations and/or one or more individual
resource allocations.
44. The first WTRU of claim 43, wherein the transmit/receive unit
is configured to send, for the one or more pooled resource
allocations to the other group members, the resource information
for establishment of communication between or among the group
members.
45. The first WTRU of claim 43, wherein the transmit/receive unit
is configured to send, for the one or more individual resource
allocations to one or more other group members, the resource
information for establishment of communication between or among any
of subsets of group members.
46. The first WTRU of claim 43, wherein the transmit/receive unit
is configured to communicate between or among the first WTRU, as a
first vehicle, and any of the other group members, as further
vehicles, using a group identifier associated with a first pooled
resource allocation of the one or more pooled resource
allocations.
47. The first WTRU of claim 43, wherein the transmit/receive unit
is configured to send the resource information via a PC5 message
for vehicle communication.
48. The first WTRU of claim 43, wherein the first WTRU includes
pre-configured resource allocations for communication between or
among the group members, prior to the resource information being
sent by the first WTRU.
49. The first WTRU of claim 43, wherein the transmit/receive unit
is configured to receive from a network entity an indication that
the first WTRU is to act as a supervising mobile (SM) WTRU for the
members of the group; and a processor configured to configure the
first WTRU to act as the SMWTRU.
50. The first WTRU of claim 49, wherein the configured SMWTRU is
configured to perform both relaying operations and operations, as a
member of the group.
51. The first WTRU of claim 49, wherein: the transmit/receive unit
is configured to send to the network entity capability information
associated with the first WTRU; and the indication to act as the
configured SMWTRU is based on the first WTRU having capabilities to
support a SMWTRU operation.
52. The first WTRU of claim 51, wherein the capability information
includes any of: (1) operating frequency information of the first
WTRU; (2) operational information regarding one or more radios of
the first WTRU; (3) an indication of whether the first WTRU
supports relaying operations; and/or (4) location information of
the first WTRU.
Description
BACKGROUND
[0001] Major standardization bodies for wireless communication
protocols (for example, the institute of electrical and electronics
engineers (IEEE), third generation partner project (3GPP), etc.)
are currently studying support direct device-to-device (D2D)
communications. For example, for 3GPP and long term evolution (LTE)
based radio access systems, support for D2D communications may
allow cost-efficient and high-capability communications using radio
waveforms that are similar to LTE cellular transmissions.
Utilization of LTE-like transmissions for both network-based and
D2D communication may assist in harmonizing radio access technology
across jurisdictions in order to lower the capital expenditure
(CAPEX) and operational expenditure (OPEX) of radio-access
technology available for the use.
[0002] For example, D2D communications may be utilized to support
public safety (PS) type applications. Examples of PS applications
may include applications that allow first responders to communicate
with each other and other users in an area with or without network
coverage. Some PS communications may require higher reliability
transmissions than other types of services.
[0003] Additionally, PS applications may require support for radio
communications in areas that are often not under radio coverage of
an LTE network. For example, the goal may be to ensure support for
D2D communications in areas with limited network coverage such as
in tunnels, in deep basements, or following catastrophic system
outages. Thus, D2D protocols may be defined to support D2D
communications for in the absence of any operating network (or, for
example, prior to the arrival of AdHoc deployed radio
infrastructure).
[0004] D2D communications may also be designed to support
commercial applications. For example, as the number of connected
devices increases, it may be more efficient from the perspective of
the mobile network to allow some communications for commercial and
other user data to be exchanged as D2D communications rather than
or in addition to routing the communications through the mobile
network. D2D communications may also facilitate the communication
of data that has stringent quality of service (QoS) requirements
(e.g., low latency, high reliability, etc.). One example use case
would be for commercial wearable devices (e.g., watches, glasses,
etc.) that are configured to communicate wireless with other
devices (e.g., phones, tablets, computers, mobile networks,
etc.).
[0005] D2D communication protocols may be defined in a flexible
manner in order to support one or more of PS and commercial
applications.
SUMMARY
[0006] Systems, methods, and instrumentalities are disclosed for a
WTRU to act as a mobile relay and/or to connect to a mobile relay,
for example by performing D2D communications and procedures. For
example, a WTRU that is to connect to a mobile relay (e.g., a
remote WTRU) may receive transmissions from multiple mobile relays.
The remote WTRU may determine channel quality based on the
transmissions. The remote WTRU may determine whether channel
quality for a mobile relay exceeds a configured threshold. The
configured threshold may be based on a required channel quality
corresponding to application layer data to be transmitted from the
remote WTRU via the mobile relays. The remote WTRU may rank the
mobile relays. The remote WTRU may select a highest ranked mobile
relay that supports a service associated with the application layer
data. The remote WTRU may send a request to connect with the
highest ranked mobile relay. The remote WTRU may connect with the
highest ranked mobile relay.
[0007] The remote WTRU may periodically measure channel quality.
The remote WTRU may determine whether the channel quality for
transmission from the mobile relay to which the remote WTRU is
connected exceeds the configured threshold. If transmission from
the mobile relay to which the remote WTRU is connected no longer
exceeds the configured threshold, the remote WTRU may reselect
another mobile relay. The channel quality for transmission from the
reselected mobile relay may exceed the configured threshold. The
channel quality for transmission from the reselected mobile relay
may become the highest ranked. The remote WTRU may decide whether
the re-selected mobile relay supports the service associated with
the application layer data. The remote WTRU may disconnect with the
previously selected mobile relay and connect with the reselected
mobile relay.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1A is a system diagram of an example communications
system in which one or more disclosed embodiments may be
implemented.
[0009] FIG. 1B is a system diagram of an example wireless
transmit/receive unit (WTRU) that may be used within the
communications system illustrated in FIG. 1A.
[0010] FIG. 1C is a system diagram of an example radio access
network and an example core network that may be used within the
communications system illustrated in FIG. 1A.
[0011] FIG. 1D is a system diagram of another example radio access
network and another example core network that may be used within
the communications system illustrated in FIG. 1A.
[0012] FIG. 1E is a system diagram of another example radio access
network and another example core network that may be used within
the communications system illustrated in FIG. 1A.
[0013] FIG. 2 is a diagram of an example WTRU-to-Network Mobile
relay function.
[0014] FIG. 3 is a diagram of an example WTRU-to-Network Mobile
relay function.
[0015] FIG. 4 is a diagram of an example WTRU-to-Network Mobile
relay function.
[0016] FIG. 5 is a diagram of an example of public safety discovery
according to Model A.
[0017] FIG. 6 is a diagram of an example of public safety discovery
according to Model B.
[0018] FIG. 7 is a diagram of an example of selection of a mobile
relay WTRU.
[0019] FIG. 8 is a diagram of an example of pre-selection of a
mobile relay WTRU based on location.
[0020] FIG. 9 is a diagram of an example of a selection/connection
establishment.
[0021] FIG. 10 is a diagram of an example of resource
reconfiguration.
DETAILED DESCRIPTION
[0022] A detailed description of illustrative embodiments will now
be described with reference to the various figures. Although this
description provides a detailed example of possible
implementations, it should be noted that the details are intended
to be exemplary and in no way limit the scope of the application.
In addition, the figures may illustrate one or more message charts,
which are meant to be exemplary. Other embodiments may be used. The
order of the messages may be varied where appropriate. Messages may
be omitted if not needed, and, additional messages may be
added.
[0023] FIG. 1A is a diagram of an example communications system 100
in which one or more disclosed embodiments may be implemented. The
communications system 100 may be a multiple access system that
provides content, such as voice, data, video, messaging, broadcast,
etc., to multiple wireless users. The communications system 100 may
enable multiple wireless users to access such content through the
sharing of system resources, including wireless bandwidth. For
example, the communications systems 100 may employ one or more
channel access methods, such as code division multiple access
(CDMA), time division multiple access (TDMA), frequency division
multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrier
FDMA (SC-FDMA), and/or the like.
[0024] As shown in FIG. 1A, the communications system 100 may
include wireless transmit/receive units (WTRUs) 102a, 102b, 102c,
and/or 102d (which generally or collectively may be referred to as
WTRU 102), a radio access network (RAN) 103/104/105, a core network
106/107/109, a public switched telephone network (PSTN) 108, the
Internet 110, and other networks 112, though it will be appreciated
that the disclosed embodiments contemplate any number of WTRUs,
base stations, networks, and/or network elements. Each of the WTRUs
102a, 102b, 102c, 102d may be any type of device configured to
operate and/or communicate in a wireless environment. By way of
example, the WTRUs 102a, 102b, 102c, 102d may be configured to
transmit and/or receive wireless signals and may include user
equipment (UE), a mobile station, a fixed or mobile subscriber
unit, a pager, a cellular telephone, a personal digital assistant
(PDA), a smartphone, a laptop, a netbook, a personal computer, a
wireless sensor, consumer electronics, and/or the like.
[0025] The communications systems 100 may also include a base
station 114a and a base station 114b. Each of the base stations
114a, 114b may be any type of device configured to wirelessly
interface with one or more of the WTRUs 102a, 102b, 102c, 102d to
facilitate access to one or more communication networks, such as
the core network 106/107/109, the Internet 110, and/or the networks
112. By way of example, the base stations 114a, 114b may be a base
transceiver station (BTS), a Node-B, an eNode B, a Home Node B, a
Home eNode B, a site controller, an access point (AP), a wireless
router, and/or the like. While the base stations 114a, 114b are
each depicted as a single element, it will be appreciated that the
base stations 114a, 114b may include any number of interconnected
base stations and/or network elements.
[0026] The base station 114a may be part of the RAN 103/104/105,
which may also include other base stations and/or network elements
(not shown), such as a base station controller (BSC), a radio
network controller (RNC), relay nodes, etc. The base station 114a
and/or the base station 114b may be configured to transmit and/or
receive wireless signals within a particular geographic region,
which may be referred to as a cell (not shown). The cell may
further be divided into cell sectors. For example, the cell
associated with the base station 114a may be divided into three
sectors. Thus, in one embodiment, the base station 114a may include
three transceivers, i.e., one for each sector of the cell. In
another embodiment, the base station 114a may employ multiple-input
multiple output (MIMO) technology and, therefore, may utilize
multiple transceivers for each sector of the cell.
[0027] The base stations 114a, 114b may communicate with one or
more of the WTRUs 102a, 102b, 102c, 102d over an air interface
115/116/117, which may be any suitable wireless communication link
(e.g., radio frequency (RF), microwave, infrared (IR), ultraviolet
(UV), visible light, etc.). The air interface 115/116/117 may be
established using any suitable radio access technology (RAT).
[0028] More specifically, as noted above, the communications system
100 may be a multiple access system and may employ one or more
channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA,
and/or the like. For example, the base station 114a in the RAN
103/104/105 and the WTRUs 102a, 102b, 102c may implement a radio
technology such as Universal Mobile Telecommunications System
(UMTS) Terrestrial Radio Access (UTRA), which may establish the air
interface 115/116/117 using wideband CDMA (WCDMA). WCDMA may
include communication protocols such as High-Speed Packet Access
(HSPA) and/or Evolved HSPA (HSPA+). HSPA may include High-Speed
Downlink Packet Access (HSDPA) and/or High-Speed Uplink Packet
Access (HSUPA).
[0029] In another embodiment, the base station 114a and the WTRUs
102a, 102b, 102c may implement a radio technology such as Evolved
UMTS Terrestrial Radio Access (E-UTRA), which may establish the air
interface 115/116/117 using Long Term Evolution (LTE) and/or
LTE-Advanced (LTE-A).
[0030] In other embodiments, the base station 114a and the WTRUs
102a, 102b, 102c may implement radio technologies such as IEEE
802.16 (i.e., Worldwide Interoperability for Microwave Access
(WiMAX)), CDMA2000, CDMA2000 1.times., CDMA2000 EV-DO, Interim
Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim
Standard 856 (IS-856), Global System for Mobile communications
(GSM), Enhanced Data rates for GSM Evolution (EDGE), GSM EDGE
(GERAN), and/or the like.
[0031] The base station 114b in FIG. 1A may be a wireless router,
Home Node B, Home eNode B, or access point, for example, and may
utilize any suitable RAT for facilitating wireless connectivity in
a localized area, such as a place of business, a home, a vehicle, a
campus, and/or the like. In one embodiment, the base station 114b
and the WTRUs 102c, 102d may implement a radio technology such as
IEEE 802.11 to establish a wireless local area network (WLAN). In
another embodiment, the base station 114b and the WTRUs 102c, 102d
may implement a radio technology such as IEEE 802.15 to establish a
wireless personal area network (WPAN). In yet another embodiment,
the base station 114b and the WTRUs 102c, 102d may utilize a
cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, etc.)
to establish a picocell or femtocell. As shown in FIG. 1A, the base
station 114b may have a direct connection to the Internet 110.
Thus, the base station 114b may not be required to access the
Internet 110 via the core network 106/107/109.
[0032] The RAN 103/104/105 may be in communication with the core
network 106/107/109, which may be any type of network configured to
provide voice, data, applications, and/or voice over internet
protocol (VoIP) services to one or more of the WTRUs 102a, 102b,
102c, 102d. For example, the core network 106/107/109 may provide
call control, billing services, mobile location-based services,
pre-paid calling, Internet connectivity, video distribution, etc.,
and/or perform high-level security functions, such as user
authentication. Although not shown in FIG. 1A, it will be
appreciated that the RAN 103/104/105 and/or the core network
106/107/109 may be in direct or indirect communication with other
RANs that employ the same RAT as the RAN 103/104/105 or a different
RAT. For example, in addition to being connected to the RAN
103/104/105, which may be utilizing an E-UTRA radio technology, the
core network 106/107/109 may also be in communication with another
RAN (not shown) employing a GSM radio technology.
[0033] The core network 106/107/109 may also serve as a gateway for
the WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the
Internet 110, and/or other networks 112. The PSTN 108 may include
circuit-switched telephone networks that provide plain old
telephone service (POTS). The Internet 110 may include a global
system of interconnected computer networks and devices that use
common communication protocols, such as the transmission control
protocol (TCP), user datagram protocol (UDP) and the internet
protocol (IP) in the TCP/IP internet protocol suite. The networks
112 may include wired or wireless communications networks owned
and/or operated by other service providers. For example, the
networks 112 may include another core network connected to one or
more RANs, which may employ the same RAT as the RAN 103/104/105 or
a different RAT.
[0034] Some or all of the WTRUs 102a, 102b, 102c, 102d in the
communications system 100 may include multi-mode capabilities,
i.e., the WTRUs 102a, 102b, 102c, 102d may include multiple
transceivers for communicating with different wireless networks
over different wireless links. For example, the WTRU 102c shown in
FIG. 1A may be configured to communicate with the base station
114a, which may employ a cellular-based radio technology, and with
the base station 114b, which may employ an IEEE 802 radio
technology.
[0035] FIG. 1B is a system diagram of an example WTRU 102. As shown
in FIG. 1B, the WTRU 102 may include a processor 118, a transceiver
120, a transmit/receive element 122, a speaker/microphone 124, a
keypad 126, a display/touchpad 128, non-removable memory 130,
removable memory 132, a power source 134, a global positioning
system (GPS) chipset 136, and other peripherals 138. It will be
appreciated that the WTRU 102 may include any sub-combination of
the foregoing elements while remaining consistent with an
embodiment. Also, embodiments contemplate that the base stations
114a and 114b, and/or the nodes that base stations 114a and 114b
may represent, such as but not limited to transceiver station
(BTS), a Node-B, a site controller, an access point (AP), a home
node-B, an evolved home node-B (eNodeB), a home evolved node-B
(HeNB or HeNodeB), a home evolved node-B gateway, and proxy nodes,
among others, may include some or all of the elements depicted in
FIG. 1B and described herein.
[0036] The processor 118 may be a general purpose processor, a
special purpose processor, a conventional processor, a digital
signal processor (DSP), a plurality of microprocessors, one or more
microprocessors in association with a DSP core, a controller, a
microcontroller, Application Specific Integrated Circuits (ASICs),
Field Programmable Gate Array (FPGAs) circuits, any other type of
integrated circuit (IC), a state machine, and/or the like. The
processor 118 may perform signal coding, data processing, power
control, input/output processing, and/or any other functionality
that enables the WTRU 102 to operate in a wireless environment. The
processor 118 may be coupled to the transceiver 120, which may be
coupled to the transmit/receive element 122. While FIG. 1B depicts
the processor 118 and the transceiver 120 as separate components,
it will be appreciated that the processor 118 and the transceiver
120 may be integrated together in an electronic package or
chip.
[0037] The transmit/receive element 122 may be configured to
transmit signals to, or receive signals from, a base station (e.g.,
the base station 114a) over the air interface 115/116/117. For
example, in one embodiment, the transmit/receive element 122 may be
an antenna configured to transmit and/or receive RF signals. In
another embodiment, the transmit/receive element 122 may be an
emitter/detector configured to transmit and/or receive IR, UV, or
visible light signals, for example. In yet another embodiment, the
transmit/receive element 122 may be configured to transmit and
receive both RF and light signals. It will be appreciated that the
transmit/receive element 122 may be configured to transmit and/or
receive any combination of wireless signals.
[0038] In addition, although the transmit/receive element 122 is
depicted in FIG. 1B as a single element, the WTRU 102 may include
any number of transmit/receive elements 122. More specifically, the
WTRU 102 may employ MIMO technology. Thus, in one embodiment, the
WTRU 102 may include two or more transmit/receive elements 122
(e.g., multiple antennas) for transmitting and receiving wireless
signals over the air interface 115/116/117.
[0039] The transceiver 120 may be configured to modulate the
signals that are to be transmitted by the transmit/receive element
122 and to demodulate the signals that are received by the
transmit/receive element 122. As noted above, the WTRU 102 may have
multi-mode capabilities. Thus, the transceiver 120 may include
multiple transceivers for enabling the WTRU 102 to communicate via
multiple RATs, such as UTRA and IEEE 802.11, for example.
[0040] The processor 118 of the WTRU 102 may be coupled to, and may
receive user input data from, the speaker/microphone 124, the
keypad 126, and/or the display/touchpad 128 (e.g., a liquid crystal
display (LCD) display unit or organic light-emitting diode (OLED)
display unit). The processor 118 may also output user data to the
speaker/microphone 124, the keypad 126, and/or the display/touchpad
128. In addition, the processor 118 may access information from,
and store data in, any type of suitable memory, such as the
non-removable memory 130 and/or the removable memory 132. The
non-removable memory 130 may include random-access memory (RAM),
read-only memory (ROM), a hard disk, or any other type of memory
storage device. The removable memory 132 may include a subscriber
identity module (SIM) card, a memory stick, a secure digital (SD)
memory card, and/or the like. In other embodiments, the processor
118 may access information from, and store data in, memory that is
not physically located on the WTRU 102, such as on a server or a
home computer (not shown).
[0041] The processor 118 may receive power from the power source
134, and may be configured to distribute and/or control the power
to the other components in the WTRU 102. The power source 134 may
be any suitable device for powering the WTRU 102. For example, the
power source 134 may include one or more dry cell batteries (e.g.,
nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel metal hydride
(NiMH), lithium-ion (Li-ion), etc.), solar cells, fuel cells,
and/or the like.
[0042] The processor 118 may also be coupled to the GPS chipset
136, which may be configured to provide location information (e.g.,
longitude and latitude) regarding the current location of the WTRU
102. In addition to, or in lieu of, the information from the GPS
chipset 136, the WTRU 102 may receive location information over the
air interface 115/116/117 from a base station (e.g., base stations
114a, 114b) and/or determine its location based on the timing of
the signals being received from two or more nearby base stations.
It will be appreciated that the WTRU 102 may acquire location
information by way of any suitable location-determination
implementation while remaining consistent with an embodiment.
[0043] The processor 118 may further be coupled to other
peripherals 138, which may include one or more software and/or
hardware modules that provide additional features, functionality
and/or wired or wireless connectivity. For example, the peripherals
138 may include an accelerometer, an e-compass, a satellite
transceiver, a digital camera (for photographs or video), a
universal serial bus (USB) port, a vibration device, a television
transceiver, a hands free headset, a Bluetooth@ module, a frequency
modulated (FM) radio unit, a digital music player, a media player,
a video game player module, an Internet browser, and/or the
like.
[0044] FIG. 1C is a system diagram of the RAN 103 and the core
network 106 according to an embodiment. As noted above, the RAN 103
may employ a UTRA radio technology to communicate with the WTRUs
102a, 102b, 102c over the air interface 115. The RAN 103 may also
be in communication with the core network 106. As shown in FIG. 1C,
the RAN 103 may include Node-Bs 140a, 140b, 140c, which may each
include one or more transceivers for communicating with the WTRUs
102a, 102b, 102c over the air interface 115. The Node-Bs 140a,
140b, 140c may each be associated with a particular cell (not
shown) within the RAN 103. The RAN 103 may also include RNCs 142a,
142b. It will be appreciated that the RAN 103 may include any
number of Node-Bs and RNCs while remaining consistent with an
embodiment.
[0045] As shown in FIG. 1C, the Node-Bs 140a, 140b may be in
communication with the RNC 142a. Additionally, the Node-B 140c may
be in communication with the RNC 142b. The Node-Bs 140a, 140b, 140c
may communicate with the respective RNCs 142a, 142b via an Iub
interface. The RNCs 142a, 142b may be in communication with one
another via an Iur interface. Each of the RNCs 142a, 142b may be
configured to control the respective Node-Bs 140a, 140b, 140c to
which it is connected. In addition, each of the RNCs 142a, 142b may
be configured to carry out or support other functionality, such as
outer loop power control, load control, admission control, packet
scheduling, handover control, macrodiversity, security functions,
data encryption, and/or the like.
[0046] The core network 106 shown in FIG. 1C may include a media
gateway (MGW) 144, a mobile switching center (MSC) 146, a serving
GPRS support node (SGSN) 148, and/or a gateway GPRS support node
(GGSN) 150. While each of the foregoing elements are depicted as
part of the core network 106, it will be appreciated that any one
of these elements may be owned and/or operated by an entity other
than the core network operator.
[0047] The RNC 142a in the RAN 103 may be connected to the MSC 146
in the core network 106 via an IuCS interface. The MSC 146 may be
connected to the MGW 144. The MSC 146 and the MGW 144 may provide
the WTRUs 102a, 102b, 102c with access to circuit-switched
networks, such as the PSTN 108, to facilitate communications
between the WTRUs 102a, 102b, 102c and traditional land-line
communications devices.
[0048] The RNC 142a in the RAN 103 may also be connected to the
SGSN 148 in the core network 106 via an IuPS interface. The SGSN
148 may be connected to the GGSN 150. The SGSN 148 and the GGSN 150
may provide the WTRUs 102a, 102b, 102c with access to
packet-switched networks, such as the Internet 110, to facilitate
communications between and the WTRUs 102a, 102b, 102c and
IP-enabled devices.
[0049] As noted above, the core network 106 may also be connected
to the networks 112, which may include other wired or wireless
networks that are owned and/or operated by other service
providers.
[0050] FIG. 1D is a system diagram of the RAN 104 and the core
network 107 according to an embodiment. As noted above, the RAN 104
may employ an E-UTRA radio technology to communicate with the WTRUs
102a, 102b, 102c over the air interface 116. The RAN 104 may also
be in communication with the core network 107.
[0051] The RAN 104 may include eNode-Bs 160a, 160b, 160c, though it
will be appreciated that the RAN 104 may include any number of
eNode-Bs while remaining consistent with an embodiment. The
eNode-Bs 160a, 160b, 160c may each include one or more transceivers
for communicating with the WTRUs 102a, 102b, 102c over the air
interface 116. In one embodiment, the eNode-Bs 160a, 160b, 160c may
implement MIMO technology. Thus, the eNode-B 160a, for example, may
use multiple antennas to transmit wireless signals to, and receive
wireless signals from, the WTRU 102a.
[0052] Each of the eNode-Bs 160a, 160b, 160c may be associated with
a particular cell (not shown) and may be configured to handle radio
resource management decisions, handover decisions, scheduling of
users in the uplink and/or downlink, and/or the like. As shown in
FIG. 1D, the eNode-Bs 160a, 160b, 160c may communicate with one
another over an X2 interface.
[0053] The core network 107 shown in FIG. 1D may include a mobility
management gateway (MME) 162, a serving gateway 164, and a packet
data network (PDN) gateway 166. While each of the foregoing
elements are depicted as part of the core network 107, it will be
appreciated that any one of these elements may be owned and/or
operated by an entity other than the core network operator.
[0054] The MME 162 may be connected to each of the eNode-Bs 160a,
160b, 160c in the RAN 104 via an S1 interface and may serve as a
control node. For example, the MME 162 may be responsible for
authenticating users of the WTRUs 102a, 102b, 102c, bearer
activation/deactivation, selecting a particular serving gateway
during an initial attach of the WTRUs 102a, 102b, 102c, and/or the
like. The MME 162 may also provide a control plane function for
switching between the RAN 104 and other RANs (not shown) that
employ other radio technologies, such as GSM or WCDMA.
[0055] The serving gateway 164 may be connected to each of the
eNode-Bs 160a, 160b, 160c in the RAN 104 via the S1 interface. The
serving gateway 164 may generally route and forward user data
packets to/from the WTRUs 102a, 102b, 102c. The serving gateway 164
may also perform other functions, such as anchoring user planes
during inter-eNode B handovers, triggering paging when downlink
data is available for the WTRUs 102a, 102b, 102c, managing and
storing contexts of the WTRUs 102a, 102b, 102c, and/or the
like.
[0056] The serving gateway 164 may also be connected to the PDN
gateway 166, which may provide the WTRUs 102a, 102b, 102c with
access to packet-switched networks, such as the Internet 110, to
facilitate communications between the WTRUs 102a, 102b, 102c and
IP-enabled devices.
[0057] The core network 107 may facilitate communications with
other networks. For example, the core network 107 may provide the
WTRUs 102a, 102b, 102c with access to circuit-switched networks,
such as the PSTN 108, to facilitate communications between the
WTRUs 102a, 102b, 102c and traditional land-line communications
devices. For example, the core network 107 may include, or may
communicate with, an IP gateway (e.g., an IP multimedia subsystem
(IMS) server) that serves as an interface between the core network
107 and the PSTN 108. In addition, the core network 107 may provide
the WTRUs 102a, 102b, 102c with access to the networks 112, which
may include other wired or wireless networks that are owned and/or
operated by other service providers.
[0058] FIG. 1E is a system diagram of the RAN 105 and the core
network 109 according to an embodiment. The RAN 105 may be an
access service network (ASN) that employs IEEE 802.16 radio
technology to communicate with the WTRUs 102a, 102b, 102c over the
air interface 117. As will be further discussed below, the
communication links between the different functional entities of
the WTRUs 102a, 102b, 102c, the RAN 105, and the core network 109
may be defined as reference points.
[0059] As shown in FIG. 1E, the RAN 105 may include base stations
180a, 180b, 180c, and an ASN gateway 182, though it will be
appreciated that the RAN 105 may include any number of base
stations and ASN gateways while remaining consistent with an
embodiment. The base stations 180a, 180b, 180c may each be
associated with a particular cell (not shown) in the RAN 105 and
may each include one or more transceivers for communicating with
the WTRUs 102a, 102b, 102c over the air interface 117. In one
embodiment, the base stations 180a, 180b, 180c may implement MIMO
technology. Thus, the base station 180a, for example, may use
multiple antennas to transmit wireless signals to, and receive
wireless signals from, the WTRU 102a. The base stations 180a, 180b,
180c may also provide mobility management functions, such as
handoff triggering, tunnel establishment, radio resource
management, traffic classification, quality of service (QoS) policy
enforcement, and/or the like. The ASN gateway 182 may serve as a
traffic aggregation point and may be responsible for paging,
caching of subscriber profiles, routing to the core network 109,
and/or the like.
[0060] The air interface 117 between the WTRUs 102a, 102b, 102c and
the RAN 105 may be defined as an R1 reference point that implements
the IEEE 802.16 specification. In addition, each of the WTRUs 102a,
102b, 102c may establish a logical interface (not shown) with the
core network 109. The logical interface between the WTRUs 102a,
102b, 102c and the core network 109 may be defined as an R2
reference point, which may be used for authentication,
authorization, IP host configuration management, and/or mobility
management.
[0061] The communication link between each of the base stations
180a, 180b, 180c may be defined as an R8 reference point that
includes protocols for facilitating WTRU handovers and the transfer
of data between base stations. The communication link between the
base stations 180a, 180b, 180c and the ASN gateway 182 may be
defined as an R6 reference point. The R6 reference point may
include protocols for facilitating mobility management based on
mobility events associated with each of the WTRUs 102a, 102b,
102c.
[0062] As shown in FIG. 1E, the RAN 105 may be connected to the
core network 109. The communication link between the RAN 105 and
the core network 109 may defined as an R3 reference point that
includes protocols for facilitating data transfer and mobility
management capabilities, for example. The core network 109 may
include a mobile IP home agent (MIP-HA) 184, an authentication,
authorization, accounting (AAA) server 186, and a gateway 188.
While each of the foregoing elements are depicted as part of the
core network 109, it will be appreciated that any one of these
elements may be owned and/or operated by an entity other than the
core network operator.
[0063] The MIP-HA may be responsible for IP address management, and
may enable the WTRUs 102a, 102b, 102c to roam between different
ASNs and/or different core networks. The MIP-HA 184 may provide the
WTRUs 102a, 102b, 102c with access to packet-switched networks,
such as the Internet 110, to facilitate communications between the
WTRUs 102a, 102b, 102c and IP-enabled devices. The AAA server 186
may be responsible for user authentication and for supporting user
services. The gateway 188 may facilitate interworking with other
networks. For example, the gateway 188 may provide the WTRUs 102a,
102b, 102c with access to circuit-switched networks, such as the
PSTN 108, to facilitate communications between the WTRUs 102a,
102b, 102c and traditional land-line communications devices. In
addition, the gateway 188 may provide the WTRUs 102a, 102b, 102c
with access to the networks 112, which may include other wired or
wireless networks that are owned and/or operated by other service
providers.
[0064] Although not shown in FIG. 1E, it will be appreciated that
the RAN 105 may be connected to other ASNs and the core network 109
may be connected to other core networks. The communication link
between the RAN 105 the other ASNs may be defined as an R4
reference point, which may include protocols for coordinating the
mobility of the WTRUs 102a, 102b, 102c between the RAN 105 and the
other ASNs. The communication link between the core network 109 and
the other core networks may be defined as an R5 reference, which
may include protocols for facilitating interworking between home
core networks and visited core networks.
[0065] Public safety (PS) types of applications (e.g., between
first responders) may include direct push-to-talk speech services
using one or multiple talk groups. PS types of applications may
utilize capabilities an LTE broadband radio, for example, services
such as video push or download.
[0066] Once deployed, D2D communications may be available for PS
types of applications, and for commercial use cases. One example
commercial use case may be the case of utility companies which
require support for 2-way radio communications in areas not covered
by network infrastructure. D2D services, such as D2D discovery
procedures, may be defined to include suitable signaling mechanisms
to allow for proximity-based services and/or traffic offload using
LTE based radio access in commercial use cases.
[0067] Examples of commercial use cases may include wearables use
cases, Internet of Things (IoT) use cases, and/or machine type
communication (MTC) use cases. For example, a user may use a
handheld device (e.g., a smartphone) as a mobile relay for traffic
for one or more wearable devices (e.g., a watch, glasses, etc.).
The wearable devices may be in relatively close proximity to the
mobile relay device. The wearable devices may be configured to
communicate with the network and/or other devices in an energy
efficient manner. The wearable devices may communicate through the
handheld device such as a WTRU. The handheld device/WTRU may act as
a unidirectional mobile relay and/or a bidirectional mobile relay.
For example, if the WTRU is acting as a unidirectional mobile
relay, the wearable devices may receive downlink communication
directly from the eNB and/or other mobile network nodes. The
wearable devices may transmit uplink via the unidirectional mobile
relay/WTRU. By communicating via the mobile relay in the uplink,
power for transmissions may be saved since the mobile relay is
likely closer in proximity to the wearable device than the mobile
network node. Wearable devices may communicate with the network via
the mobile relay at an edge of an eNB coverage. Wearable devices
may comprise radios that may or may not be designed with the same
sensitivity as the mobile relay's radio.
[0068] Signaling mechanisms may be used to allow multiple remote
WTRUs to communicate via a mobile relay WTRU such that the mobile
relay may efficiently communicate with multiple wearables. The
mobile relay WTRU may manage multiple wearables. The wearables may
be a smart watch along with other smart devices. For example, the
smart devices may be google glasses, hands-free headset, handheld
game console, and/or the like.
[0069] In examples of IoT or MTC use cases, millions of (or more)
devices may be connected with a network. Some or all of the devices
in IoT or MTC use cases may be relatively low-cost and/or limited
capability devices. The devices may be configured to communicate in
an energy efficient manner. The devices may attempt to connect to
the network simultaneously, which could cause congestion. A
connection through a mobile relay device may avoid some issues
associated with simultaneous connection with the network. The
mobile relay device may comprise a mobile relay WTRU. Some or all
of the devices may have little or no coverage of an eNB. Some or
all of the devices may be in proximity of a WTRU. For example, the
WTRU may act as a mobile relay, for example to extend network
coverage.
[0070] Signaling mechanisms may be used to allow one or multiple
remote WTRUs to communicate via a mobile relay WTRU. In the
examples of IoT or MTC use cases, the number of remote WTRUs may be
expected to be great. The remote WTRUs may connect to the mobile
relay such that direction connections of devices with the network
may be reduced. Efficient association/re-association may designed
to attempt to provide a relatively equal distribution of remote
WTRUs to mobile relays. That WTRUs are configured unnecessarily as
mobile relays may be avoided. Proper service continuity to the
network and/or between mobile relays may be maintained.
[0071] The mobile relay WTRU may communicate with the remote WTRUs
using a 3GPP RAT and/or non-3GPP RATs (e.g., WiFi, Bluetooth,
and/or the like). The link between the mobile relay WTRU and the
remote WTRU may be PC5. A communication may be via D2D. A D2D may
be through PC5 interface. A communication may be over a D2D made to
support vehicle to vehicle (V2V), low cost wearables, and/or the
like. A narrow band IOT (NB-IOT) waveform, RAT and/or the like may
be used to support low-cost or low power devices. The low-cost or
low power devices may communicate over a non-3GPP RAT. The PC5 link
may be over licensed or unlicensed spectrum.
[0072] The link between the mobile relay WTRU and the eNB may be
Uu. The link may comprise LTE Uu RAT. The link may be over a 3GPP
RAT, such as NB-IoT, eMTC, future 5G (NR), and/or the like. The
link may be over a non-3GPP RAT such as WiFi. The Uu link may be
over licensed or unlicensed spectrum.
[0073] The mobile relay WTRU may implement functionality at a layer
of protocol stack. The mobile relay may be an layer 2 (L2) relay,
implemented at MAC, RLC, or PDCP layers. The mobile relay may be an
IP relay or above IP relay.
[0074] A standardization of D2D communications by 3GPP was
completed in Release 12 (R12) of the LTE standard. For example, the
R12 standardization efforts focused on direct communications
between WTRUs and open discovery procedures for Proximity-Based
Services (ProSe). Use of D2D communications for mobile relays may
be studied to enhance to allow WTRUs to act as a mobile relay for a
WTRU which is out of coverage. As an example, consider two types of
mobile relays: 1) WTRU-to-Network mobile relays, and 2)
WTRU-to-WTRU mobile relays. A mobile relay WTRU may be considered a
WTRU-to-Network mobile relay by being configured to act as a mobile
relay between the eNB (e.g., and/or any other mobile network
infrastructure node, other RAN nodes, etc.) and a remote WTRU. The
remote WTRU may or may not be out of coverage of the eNB and/or
other network infrastructure. A mobile relay WTRU may be considered
a WTRU-to-WTRU mobile relay by being configured to facilitate
communication among two or more remote WTRUs. The multiple remote
WTRUs may communicate with each other in D2D when they are out of
range/proximity of each other.
[0075] FIG. 2 illustrates an exemplary WTRU-to-Network mobile relay
(e.g., mobile relay) deployment. The function may include support
for the mobile relay of unicast traffic (e.g., uplink (UL) and
downlink (DL)) between remote WTRUs that are not served by evolved
universal terrestrial radio access network (E-UTRAN) and the
network and/or support bi-directional traffic. For example, the
WTRU-to-Network Mobile relay 202 (e.g., mobile relay) may provide a
Layer 3 (L3) forwarding function that may relay some types and/or
any types of IP traffic that is relevant for public safety and/or
commercial communication. The WTRU-to-Network Mobile relay 202
(e.g., a mobile relay) may provide other types communications
between eNB 204 and remote WTRU 210. The WTRU-to-Network Mobile
relay 202 may provide a layer 2 (L2) relay forwarding function, and
forward packets at a layer of communications between eNB 204 and
remote WTRU 210. For example, WTRU-to-Network Mobile relay 202 may
communicate with eNB 204 to send data to and/or receive data from
Application Service (AS) 208 (e.g., via EPC 206). The data may be
forwarded to and/or communicated on behalf of remote WTRU 210
(e.g., which may be out-of-network coverage). the WTRU-to-Network
Mobile relay 202 may communicate with WTRU 210 (e.g., a remote
WTRU) via a PC5 interface. The WTRU-to-Network Mobile relay 202 may
communicate with eNB 204 via a Uu interface. EPC 206 may
communicate with AS 208 (e.g., AS for public safety and/or
commercial communication) via a SGi interface. The example
illustrated in FIG. 2 may involve a public safety and/or commercial
communication application server.
[0076] FIG. 3 illustrates an exemplary WTRU-to-network mobile relay
communication exchange. For example, the mobile relay WTRU 302 may
attach to the network at 304, if mobile mobile relay WTRU 302 is
not already attached to the network. The mobile relay WTRU 302 may
establish a PDN connection at 304. The packet data network (PDN)
connection may be used for communication of traffic to/from remote
WTRUs 316. For example, appropriate PDN connection for mobile
relays may not yet exist/be configured for the remote WTRU(s) 316.
For IPv6, the mobile relay WTRU 302 may obtain an IPv6 prefix, such
as via a prefix delegation function from the network (e.g., as
defined in 3GPP technical specification (TS) 23.401).
[0077] Remote WTRU(s) 316 may perform discovery of a mobile relay
WTRU 302 using a discovery procedure, for example, model A and/or
model B discovery at 306. For example, a model A discovery may
include an announcement, and a model B discovery may include a
solicitation and a response. A Remote WTRU 316 may select a mobile
relay 302 and establish a connection for one-to-one communication
with the mobile relay 302 at 308. The establishment of connection
for one-to-one communication may be with or without EPC
involvement, as determined by SA3 at 314. The EPC involvement may
comprise MME 318 or home subscriber server (HSS) 320.
[0078] For IPv6, on PC5, the Remote WTRU 316 may perform IPv6
stateless address auto-configuration at 310. A Remote WTRU 316 may
send a Router Solicitation (RS) message to the network using the
Layer-2 ID of the Mobile relay as Destination Layer-2 ID at 310. A
Remote WTRU 316 may solicit a router advertisement (RA) message
(e.g., as specified in with internet engineering task force reason
for collaboration (IETF RFC) 4862) at 310. A RA message may include
an assigned IPv6 prefix. After the Remote WTRU 316 receives the RA
message, it may construct a full IPv6 address via IPv6 stateless
address auto-configuration (e.g., in accordance IETF RFC 4862) at
310.
[0079] For IPv4, on PC5, the Remote WTRU 316 may use dynamic host
configuration protocol (DHCP)v4. A Remote WTRU 316 may send a
DHCPv4 discovery message using the layer-2 ID of the Mobile relay
as destination layer-2 ID at 312. The mobile relay WTRU 302 may act
as a DHCPv4 server, sending a DHCPv4 Offer with the assigned remote
WTRU IPv4 address at 312. When the Remote WTRU 316 receives the
lease offer, it may send a DHCP REQUEST message containing the
received IPv4 address at 312. The mobile relay WTRU 302 acting as
DHCPv4 server may send a DHCP ACK message to the remote WTRU 316
including the lease duration (e.g., configuration information that
a client may have requested). On receiving the DHCP ACK message at
312, the Remote WTRU 316 may complete a TCP/IP configuration
process.
[0080] FIG. 4 illustrates an exemplary WTRU-to-Network mobile relay
procedure. The procedure may be used by a ProSe-enabled WTRU (e.g.,
remote WTRU 420) to request a mobile relay 402 to start monitoring
the availability of a temporary mobile group identity (TMGI). The
mobile relay 402 may broadcast the TMGI on a broadcast channel, for
example, when it is detected on the multicast control channel
(MCCH) of the serving cell (e.g., a cell of Network 420). The eMBMS
traffic related to this TMGI, if available, may also be forwarded
to the remote WTRUs 420 served by the mobile relay 402 over a
one-to-many link (e.g., identified by a specific Layer-2 Group ID
provided by the ProSe mobile relay 402 when the procedure is
executed).
[0081] If a remote WTRU 420 has successfully discovered the mobile
relay 402 and has obtained (e.g., after a one to one communication
sessions with the mobile relay 401) from a group communication
application a TMGI, the WTRU may use the TMGI to receive related
broadcast (e.g., eMBMS) content at 404. The related broadcast
content may be available (e.g., in a eNB). The WTRU may obtain the
TMGI it is interested in by static configuration or by interaction
with the group communication application. This interaction may
happen before or after the WTRU has joined the mobile relay
402.
[0082] The WTRU may send to the mobile relay 402 a TMGI monitoring
request at 406 where TMGI is the value obtained herein. The mobile
relay 402 may acknowledge reception of the request herein with a
TMGI monitoring response (e.g., layer 2 group ID_traffic,
TMGI_Monitoring_Refresh Timer, and/or the like) at 408. The layer 2
group ID_traffic may be used to forward to remote WTRUs the eMBMS
content related to the TMGI value received herein. The
TMGI_Monitoring_Refresh Timer may be configurable in the mobile
relay 402. The TMGI_Monitoring_Refresh Timer may be provided to the
WTRU at 408 so that when the timer elapses the WTRU may execute the
TMGI monitoring request procedure (e.g., if it is still configured
to monitor the TMGI). If a remote WTRU 420 does not execute the
TMGI Monitoring Request procedure when the TMGI_Monitoring_Refresh
Timer expires in the mobile relay 402 at 408, and no other WTRU
executes the refresh procedure for the TMGI, when the
TMGI_Monitoring_Refresh Timer for the TMGI expires in the mobile
relay 402, the mobile relay 402 may stop monitoring the TMGI and/or
may stop forwarding related content.
[0083] The ProSe mobile relay 402 may detect the TMGI it has been
requested to monitor at 410. Upon detection of the TMGI at 410, the
mobile relay 402 may broadcast availability of the TMGI by sending
a TMGI announcement message over a broadcast channel at 412. The
mobile relay 402 may broadcast availability of the TMGI by sending
a TMGI announcement message over a broadcast channel at 412 (e.g.,
repeatly with a configurable repetition interval). The repetition
interval may be shorter than the TMGI_Monitoring_Refresh Timer. The
value of the TMGI may be used by devices discovering the mobile
relay 402 as a preference criterion for mobile relay selection
(e.g., if they are interested in the TMGI the mobile relay 402 is
advertising).
[0084] A WTRU may detect a TMGI announcement and may start to
receive the broadcast content on the PC5 one-to-many link
associated to the layer-2 group ID_traffic, and may release a
unicast distribution leg if a unicast distribution leg was being
used at 414. Upon detection of loss of TMGI, the mobile relay 402
may stop broadcasting availability of the TMGI at 416. The ProSe
mobile relay 402 may send a positive indication of loss of TMGI to
accelerate loss of TMGI detection in the WTRU. A WTRU may request a
unicast distribution leg from the group communication AS at 416.
The group communication may include a public safety or commercial
communication. A WTRU may stop receiving the broadcast content on
the PC5 one-to-many signaling link associated to the group layer-2
ID_traffic at 418.
[0085] FIG. 5 illustrates an exemplary public safety discovery
according to Model A. In FIG. 5, the type may be an announcement.
The discovery type may be mobile relay discovery. Announcing WTRU-1
502 may send a message to monitoring WTRUs at 504-510. The message
sent at 502 may comprise information such as type, discovery type,
PLMN ID, connection information, ProSe mobile relay WTRU ID,
status, group Information, and/or the like. Some of all of the
monitoring WTRUs at 504-510 may receive messages 512-518. For
example, WTRU-2 504 may receive message 1 512.
[0086] FIG. 6 illustrates an exemplary public safety discovery
according to Model B. Discover WTRU-1 at 602 may send a message to
discoveree WTRUs at 604-610. The messages 1-4 sent at 612-618 may
comprise information type, discovery type, PLMN ID, connection
information, ProSe mobile relay WTRU ID, status, group information,
and/or the like. In FIG. 6, the type may be a solicitation. The
discovery type may be mobile relay discovery. Some of all of the
discoverees at 604-610 may send the messages back to the discoverer
WTRU-1 at 602. For example, in FIG. 6, the dicoveree at 604 and
discoveree at 606 may send a message back to the discoverer at 602.
The messages 5-6 sent at 620-622 may comprise information type,
discovery type, PLMN ID, connection information, proSe mobile relay
WTRU ID, status, group information, and/or the like. In the
messages 5-6 sent at 620-622, the type may be a response. The
discovery type may be a mobile relay discovery.
[0087] The following parameters may be used for WTRU-to-Network
Mobile relay Discovery in the example shown in FIG. 6. A mobile
relay WTRU ID may be a link layer identifier. The link layer
identifier may be used for direct communication. The link layer
identifier may be associated with a PDN connection that the mobile
relay has established. A public land mobile network (PLMN) ID may
identify the PLMN to which radio frequencies used on the link to
which the Remote WTRU belongs. The radio frequencies may be shared
between multiple PLMNs. The radio frequencies may or may not be
allocated to a PLMN. The selection of PLMN ID may be configured by
the Home PLMN (HPLMN). Connectivity information may comprise a
parameter identifying a connectivity that the mobile relay provides
(e.g., including APN information). Status/maintenance flags may be
used to indicate whether the mobile relay is temporarily without
connectivity and/or battery running low (e.g., so the Remote WTRUs
can seek/reselect another mobile relay). Group Information may
comprise information about the group(s) that the mobile relay is
relaying for.
[0088] Several complications/difficulties may be associated with
using D2D communication to realize a mobile relay function (e.g.,
for one or both of WTRU-Network and/or WTRU-WTRU mobile relays).
For example, a remote WTRU may be served by a mobile relay (e.g., a
mobile relay WTRU). The remote WTRU may be unknown to an eNB that
serves the mobile relay. The remote WTRU may be unable to receive
system information from the eNB. The remote WTRU may be unable to
properly select the mobile relay WTRU and/or an optimal mobile
relay WTRU (e.g., from the device and/or the network perspective).
The mobile relay WTRU may be able to serve the remote WTRU. For
example, proper selection of the mobile relay WTRU may be related
to a lower-layer signal quality and/or application-layer service.
The mobile relay WTRU and/or remote WTRU may be mobile. The remote
WTRU may be capable of reselecting a different mobile relay WTRU
when the mobile relay WTRU to which the remote WTRU connected
becomes unsuitable to serve as its mobile relay.
[0089] In addition to mobile relay selection/reselection, current
resource assignment rules developed for D2D (e.g., in R12) may be
inappropriate and/or sub-optimal for mobile relays. For example,
the remote WTRU may be out-of-coverage, and the remote WTRU may be
configured to use pre-configured resources for direct communication
when out-of-coverage. The usage of the pre-configured resources for
direct communication may result in over-use of the pre-configured
resources when multiple remote WTRUs and mobile relay WTRUs are
co-located in an area (e.g., in an out-of-coverage area).
[0090] The resource usage rules defined for direct D2D
communication may be inefficient for mobile relay scenarios. An eNB
may not be able to control the resources that may be used by the
remote WTRUs when R12 rules are applied. For example, R12 rules may
lack support for service continuity for scenarios involving mobile
relays (e.g., mobile relay mobility and/or remote WTRU mobility
between mobile relays). For example, a remote WTRU may enter and/or
leave an area that is covered by an eNB, which may affect resource
utilization for D2D communications. R12 rules do not provide ways
in which the switching of the remote WTRU between areas covered by
an eNB and areas not covered by eNB is transparent to the
application layer. A mobile relay WTRU may lose coverage with the
eNB, and the remote WTRUs that are served by the mobile relay WTRU
may or may not be able to maintain service upon the loss of
connection.
[0091] A WTRU that is attempting to connect to a mobile relay may
perform one or more autonomously determined actions to select a
mobile relay and/or receive instructions from a network entity to
select a mobile relay. For example, a remote WTRU may be configured
to perform procedures for selection and reselection of a mobile
relay WTRU and configured to perform measurements that may be used
to support these selection/reselection procedures. The remote WTRU,
the mobile relay WTRU, and/or an eNB may perform procedures
associated with initiation of a mobile relay based on the control
of the associated eNB. The mobile relay WTRU, the remote WTRU,
and/or the eNB may perform procedures for assigning resources for
communication between the mobile relay WTRU and the remote WTRU.
The mobile relay WTRU, the remote WTRU, and/or the eNB may perform
procedures for handling service continuity, for example during
remote WTRU mobility between mobile relays and/or between mobile
relay mobility between eNBs.
[0092] A WTRU may perform a mobile relay selection/re-selection
process to select the mobile relay to connect to for services
(e.g., one-to-one communication, eMBMS, etc.), and may perform
associated measurements that may be provided to the upper layers to
perform the mobile relay selection/re-selection process. The
process may apply if the WTRU is out-of-coverage and/or
in-coverage. The processes may apply if the WTRU is transitioning
from being in-coverage to being out-of-coverage. For example,
initial mobile relay selection may be performed in the application
layer with assistance information by the lower layer (e.g.,
measurements). Examples described herein may use the term remote
WTRU to refer to a WTRU that is connected to and/or attempted to
connect to a mobile relay. The mobile relay may be referred to as a
mobile relay WTRU.
[0093] The lower layers (e.g., physical (PHY), medium access
control (MAC), or radio resource control (RRC)) may report
measurements taken on mobile relay transmission to higher layers.
The measurements may be made on one or more of the following:
demodulation reference signal (DMRS) on the sidelink
synchronization channel (SL-SCH), DMRS on the physical sidelink
broadcast channel (PSBCH), the device to device synchronization
signal (D2DSS), discovery resources, and/or the like.
[0094] The lower layers in the remote WTRU may report a measurement
for a transport block received. For example, the lower layers in
the WTRU may report a measurement for a transport block received.
The lower layers in the WTRU may report a list of some or all
measurements taken. The lower layers may report an averaged
measurement report made on multiple transport blocks over a given
period of time. The measurements may be sent periodically to the
upper layers, or may be provided to the upper layers when requested
by the upper layers.
[0095] The measurements reported to higher layers may contain one
or more of: channel quality measurements (e.g., reference signal
received power (RSRP)) and/or mobile relay ID. The mobile relay ID
may correspond to an ID retrieved from PSBCH. The mobile relay ID
may correspond to the Layer 1 ID decoded in the system aspects
(SA). The mobile relay ID may correspond to the L2 WTRU ID. The
mobile relay ID may correspond to the ID decoded in MAC header. For
example, the mobile relay ID may correspond to the ID decoded in
MAC header if measurements are taken from data packets. The
measurements may allow the association of a channel quality
measurement to the mobile relay ID corresponding to a given mobile
relay.
[0096] A mobile relay may be selected based on selection criterion
and other information. The selection criteria of the mobile relay
may include one or more of: services (e.g., connection info)
announced, PLMN ID announced, TMGI, and mobile relay specific
information. Mobile relay selection may employ the measurements
provided by lower layers and/or one or more thresholds associated
with the measurements. The associated thresholds may be provided in
the application layer and/or by lower layers. The associated
thresholds may be provided as part of a RRC configuration. FIG. 7
is a diagram of an example of selection of a mobile relay WTRU.
[0097] A remote WTRU may receive a Model A mobile relay
announcement and/or a Model B response from one or more mobile
relay WTRUs. For example, as illustrated in FIG. 7, the remote WTRU
718 receives a mobile relay announcement from mobile relay WTRU1
702 at 704. The remote WTRU 718 receives a mobile relay
announcement from mobile relay WTRU2 720 at 706. The mobile relay
announcement at 704 and at 706 may be a Model A mobile relay
announcement and/or a Model B response. The mobile relay
announcements may include an indication of services provided by or
supported by the mobile relay WTRUs. For example, the mobile relay
announcements may include an indication that the mobile relays
WTRUs support one or more services requested by the remote WTRU
718. The mobile relay announcements may include an indication of a
PLMN that serves the mobile relay WTRUs. For example, the mobile
relay announcements may include an indication that the mobile
relays WTRUs are associated with one or more PLMNs that the remote
WTRU 718 is allowed to connect to.
[0098] The application layer associated with the remote WTRU may
filter the responses which include the services to be used by the
remote WTRU at 708. The application layer associated with the
remote WTRU may filter the responses in which the remote WTRU may
be allowed on the PLMN at 708. The remote WTRU may filter mobile
relay candidates according to a configured threshold(s) at 708. The
remote WTRU may compare measurements from the mobile relay
announcements to one or more configured thresholds. The remote WTRU
may rank the mobile relays whose channel quality exceed the
configured threshold(s) according to measurements and/or qualities
(e.g., channel qualities) at 708. The rankings may be based on
mobile relay WTRUs that support the service to be used by the WTRU
and that have signal qualities that exceed the configured
threshold. The remote WTRU 718 may select a mobile relay at 708.
For example, the remote WTRU may select a ranked mobile relay that
supports certain service and meets certain quality criteria. The
ranked mobile relay may be a highest ranked mobile relay. The
rankings may be based on received signal strength and/or signal
quality (e.g., with the highest strength and/or signal qualities
ranked the highest). The remote WTRU may initiate a connection
establishment to a selected mobile relay. The remote WTRU may send
a connection request to the selected mobile relay at 710. The
selected mobile relay may send the mobile relay request at 712 to
the eNB 722. The eNB may send the mobile relay accept at 714 to the
selected mobile relay 702. The selected mobile relay 702 may send a
connection accept at 716 to the remote WTRU 718.
[0099] A connection failure may occur. If a connection failure
occurs, the remote WTRU may select the next ranked mobile relay and
attempt a connection establishment process. A failure to establish
a mobile relay connection may occur. A failure to establish a
mobile relay connection may occur when the secure link with the
mobile relay WTRU may not be established due to failure of the
authentication and/or security association. A failure to establish
a mobile relay connection may occur when a valid TMGI for broadcast
may not be successfully obtained. A failure to establish a mobile
relay connection may occur when the remote WTRU may be unable to
receive the broadcast for the TMGI. For example, the remote WTRU
may be unable to receive the broadcast for the TMGI due to
authentication and/or permission reasons. A failure to establish a
mobile relay connection may occur when the eNB may reject the
connection of the remote WTRU with the mobile relay. For example,
the eNB may reject the connection of the remote WTRU with the
mobile relay due to inability of the mobile relay to support the
resources for the requested services. The eNB may reject the
connection of the remote WTRU with the mobile relay due to
availability of other mobile relays. The eNB may reject the
connection and provide a redirection message. The rejection may be
sent by the eNB to the remote WTRU via the mobile relay when the
connection is rejected by the eNB. For example, the Uu connection
may be used to send the rejection first to the mobile relay WTRU.
The mobile relay WTRU may forward the rejection to the remote WTRU.
The rejection may be sent by the eNB directly to the remote WTRU
over the Uu interface. For example, the rejection may be sent by
the eNB directly to the remote WTRU over the Uu interface when the
remote WTRU is potentially in coverage of the eNB. A connection
acceptance may be sent by the eNB directly to the remote WTRU over
the Uu interface when the remote WTRU is potentially in coverage of
the eNB or confirmed by the eNB.
[0100] The remote WTRU may perform a mobile relay reselection
procedure. The remote WTRU may perform autonomous
selection/reselection. To perform autonomous mobile relay
reselection, the remote WTRU may periodically perform evaluation of
signal quality of the mobile relay WTRU to which the remote WTRU is
connected. The remote WTRU may start a reselection procedure when
one or more of certain conditions are met. The remote WTRU may
start a reselection procedure when the signal quality of the mobile
relay WTRU to which the remote WTRU is connected is below the
configured threshold. For example, the remote WTRU may start a
reselection procedure when the WTRU no longer detects the mobile
relay. The signal quality of the mobile relay WTRU to which the
remote WTRU is connected may be determined using one or more of the
measurements described herein.
[0101] The remote WTRU may measure signal qualities of the mobile
relay WTRU to which the remote WTRU is connected based on Model A
or Model B discovery messages. For example, the remote WTRU may
measure the signal quality of the mobile relay WTRU to which the
remote WTRU is connected based on Model A or Model B discovery
messages. The remote WTRU may measure the signal quality by
triggering Model B response messages. The remote WTRU may be
configured to periodically transmit Model B solicitation to trigger
Model B response messages from the serving mobile relay. For
example, the remote WTRU may derive measurements of the signal
quality from Model B response messages from the serving mobile
relay. The remote WTRU may obtain its measurements of the signal
quality directly from SL-SCH or SL-BCH of the mobile relay
WTRU.
[0102] The remote WTRU may initiate a reselection procedure when
the mobile relay WTRU is not announcing the service to be use by
the WTRU and/or requested by the WTRU. The remote WTRU may start a
reselection procedure when one or more other candidate mobile relay
WTRUs are announcing the service utilized by the remote WTRU. The
remote WTRU may start a reselection procedure when measurements of
signal quality of the other candidate mobile relays is above a
configured threshold. The remote WTRU may start a reselection
procedure when measurements of signal quality of the other
candidate mobile relays are better than the measurements of the
signal quality of the mobile relay WTRU to which the remote WTRU is
connected. For example, the remote WTRU may perform reselection
when the signal quality of one or more candidate mobile relays may
be better than the measurements of the signal quality of the
current mobile relay WTRU by a given offset. The remote WTRU may
perform reselection when the signal quality of one or more
candidate mobile relays may be better than the measurements of the
signal quality of the mobile relay WTRU for a given period of time.
The remote WTRU may perform reselection when the signal quality of
one or more candidate mobile relays may be better than the
measurements of the signal quality of the mobile relay WTRU by a
given offset for a given period of time. The remote WTRU may start
a reselection procedure when a mobile relay redirection message is
received.
[0103] Autonomous mobile relay selection/reselection may comprise
one or more actions. When one or more of the conditions that
trigger the remote WTRU to start a reselection procedure are met
and/or other triggers are met, the remote WTRU may trigger higher
layers to perform one or more of certain actions. The remote WTRU
may trigger higher layers to initiate discovery monitoring process
if the discovery monitoring process had been stopped. The discovery
monitoring process may be a Model A or Model B. The remote WTRU may
trigger higher layers to initiate the remote WTRU to send a new
Model B solicitation message. For example, the remote WTRU may
trigger higher layers to initiate the remote WTRU to send a new
Model B solicitation message to discover other mobile relays that
are capable of supporting the required services. The remote WTRU
may trigger higher layers to initiate the lower layers to perform
updated measurements/quality associated with a potential mobile
relay WTRU that has been detected. The remote WTRU may send to
higher layers updated measurements/quality associated with a
potential mobile relay WTRU. For example, measurements may be taken
on one or more of the channels or signals described herein. The
remote WTRU may trigger higher layers to perform mobile relay
selection procedure based on provided measurements and services
advertised for the given mobile relay. The remote WTRU may trigger
the lower layers to perform targeted measurements of the mobile
relays that initially responded to the Model B solicitation message
or for which Model A messages for given mobile relays were received
if the lower layer supports the targeted measurements. The remote
WTRU may trigger the lower layers to perform targeted measurements
through the application layer. The list of mobile relay WTRUs may
be provided to the lower layers. For example, the list of mobile
relay WTRUs may be provided to the lower layers as a list of L2
IDs. The lower layers may return with corresponding measurements
for one or more of the identified WTRUs.
[0104] Autonomous mobile relay selection/reselection may comprise
various further actions. A selection or reselection of a mobile
relay WTRU may or may not be successful. For example, if mobile
relay reselection is unsuccessful, a mobile relay redirection
message may be received. The WTRU may perform one or more actions
upon receiving a mobile relay redirection message. For example, the
remote WTRU may perform one or more of the certain actions prior to
moving to a new mobile relay upon receiving a mobile relay
redirection action.
[0105] For example, upon receiving a mobile relay redirection
action the remote WTRU may verify that a suggested mobile relay is
part of the ranked list of mobile relays. The WTRU may verify that
a suggested mobile relay meets the selection criterion (e.g.,
supports the service requested by the WTRU and/or has a channel
quality that exceeds as threshold). For example, if a suggested
mobile relay is not part of the ranked list of mobile relays, the
remote WTRU may stay connected to its current mobile relay. If a
suggested mobile relay is part of the ranked list of mobile relays
and meets the selection criterion, the remote WTRU may initiate
mobile relay selection to the suggested mobile relay. The remote
WTRU may perform a connection establishment procedure with the
suggested mobile relay.
[0106] Upon determining to reselect to a candidate mobile relay,
the remote WTRU may perform one or more actions. For example, upon
determining to reselect to a candidate mobile relay, the remote
WTRU may tear down the connection with the mobile relay to which
the remote WTRU is currently connected. Upon determining to
reselect to a candidate mobile relay, the remote WTRU may initiate
a connection establishment to the reselected candidate mobile
relay.
[0107] In an example, rather than tearing down the connection to
the current mobile relay, upon determining to reselect to a
candidate mobile relay, the remote WTRU may keep the connection to
the current mobile relay while attempt a connection establishment
procedure with the reselected candidate mobile relay. The remote
WTRU may tear down the connection to the mobile relay to which the
remote WTRU is connected when it has successfully established a
connection with the reselected candidate mobile relay. The
connection to the mobile relay to which the remote WTRU is
connecting may be tom down, after the remote WTRU has ensured that
the remote WTRU has started to receive services from the reselected
candidate mobile relay. For example, the services may be via
eMBMS.
[0108] Autonomous mobile relay selection/reselection may be
supported. Reselection may be supported by various layers. For
example, reselection may be supported by the remote WTRU upper
layers (e.g., Application layer). As an example, the WTRU may be
configured to continuously (e.g., regularly or relatively
continuously, at set intervals, etc.) perform measurements of the
mobile relay to which the remote WTRU is connected. For example,
the remote WTRU upper layers may configure continuous measurements
of the mobile relay to which the remote WTRU is connecting. The
upper layer may request the lower layers to send measurements
associated with the currently connected mobile relay and/or mobile
relays that transmitting measurable signals. Upper layers may
configured the lower layers to measure one or more other mobile
relays, which may be identified by a mobile relay ID. When the
remote WTRU has been successfully connected to a mobile relay WTRU,
the upper layers in the remote WTRU may configure measurements to
be performed by the lower layers on the mobile relay. When
requested by the upper layers, the lower layers may stop collecting
measurements on the SL-SCH for the specific mobile relay ID. For
example, the upper layers may request the lower layer to stop
collecting measurements on the SL-SCH for the mobile relay ID when
the remote WTRU terminates a connection to the mobile relay.
[0109] For autonomous mobile relay selection/reselection, the
remote WTRU may inform the eNB of the identity of a selected mobile
relay. For example, a mobile relay selection/reselection may occur
while the remote WTRU is still in coverage of the eNB. The
selection/reselection may occur autonomously. The WTRU may inform
the eNB the identity of the selected mobile relay. The WTRU may
inform the eNB of relevant information about the selected mobile
relay. Relevant information about the selected mobile relay may
include one or more of mobile relay identification information
(e.g., Mobile relay L2 ID, PHY layer ID, and/or the like), the
identity of the eNB to which the mobile relay is connected,
measured signal quality (e.g., PC5 measurements) of the mobile
relay, access point name (APN) or connectivity information
broadcast by the mobile relay, and/or the signal quality of the Uu
link between the mobile relay and the eNB. Informing the eNB may
occur through Uu and/or via a mobile relay.
[0110] A reselection of a mobile relay may be indicated to the eNB
to inform the eNB of the reselected mobile relay. Indication of the
reselection and the reselected mobile relay may occur periodically.
Indication of the reselection and the reselected mobile relay may
occur when the measured PC5 link quality with the selected mobile
relay deteriorates. A WTRU may inform the eNB of the reselection
and the reselected mobile relay (e.g., information of the
reselected mobile relay) at connection establishment with the
mobile relay.
[0111] Reselection to a new mobile relay may be triggered by the
eNB. Reselection may be triggered by the eNB based on measurements,
for example measurements that are reported by the remote WTRU.
Measurements of the remote WTRU by the mobile relay WTRU may be
performed and be sent to the eNB in order to facilitate eNB-based
mobile relay reselection. The remote WTRU may take measurements of
the PC5 link and send the measurements of the PC5 link to the eNB
via the mobile relay WTRU. The remote WTRU may take measurements of
the PC5 link and send the measurements of the PC5 link directly to
the eNB when connection between the remote WTRU and the eNB is
available (e.g., the remote WTRU is in coverage). The remote WTRU
may indicate to the mobile relay WTRU that the measurements should
be sent to the eNB (e.g., via the mobile relay WTRU) using an
indication that indicates to the mobile relay WTRU that the
measurements are intended to be sent to the eNB. For example,
measurements that are intended for the eNB may be sent to the
mobile relay WTRU using a dedicated message that that indicates
that the measurements are meant for the eNB. The mobile relay WTRU
may take measurements of the PC5 link between the mobile relay and
the remote WTRU and send the measurements of the PC5 link between
the mobile relay and the remote WTRU to the eNB.
[0112] The eNB or the mobile relay WTRU may send a configuration to
the remote WTRU. The configuration may include indication to the
remote WTRU to enable measurements, indication to the remote WTRU
to send measurements, criterion that may be used by the remote WTRU
to determine when a measurement report may be triggered from
transmission to the eNB, and/or an allowable list of mobile relays
which may be measured.
[0113] For example, the configuration may be broadcast by the
mobile relay WTRU to some or all remote WTRUs connected to the
mobile relay WTRU. A broadcast mechanism discussed herein may be
used. The configuration for the remote WTRU may be derived from the
same or a different measurement configuration for the mobile relay
WTRU. The configuration for the mobile relay WTRU may be sent by
the eNB to the mobile relay WTRU over the Uu link. For example, the
configuration for the mobile relay WTRU may be sent using system
information block (SIB) signaling or RRC signaling.
[0114] Based on the configuration, the remote WTRU may enable
measurements over the PC5 link of mobile relay WTRUs which are
transmitting discovery messages within the communication range of
the remote WTRU. The allowable list of mobile relays which may be
measured may be sent by the eNB to the remote WTRU. The allowable
list of mobile relays which may be measured may be sent by the eNB
to the remote WTRU as part of the configuration. The allowable list
of mobile relays to which the remote WTRU is allowed to reselect
may be sent by the eNB to the remote WTRU as part of the
configuration.
[0115] The remote WTRU may receive a configuration indicating that
the remote WTRU may send measurements to the eNB via the mobile
relay WTRU and may use an indication in a measurement report that
indicates to the mobile relay WTRU that the measurements are meant
for the eNB. The remote WTRU may compile a list of measurements and
transmit the list of measurements to the mobile relay WTRU using an
indication that the measurements are meant for the eNB. The
indication and the measurements may include a list of one or more
mobile relay WTRUs, the signal qualities for the one or more mobile
relay WTRUs, and/or quality measurements for some or all mobile
relay WTRUs that are reported. The indication and the measurements
may be sent using a MAC CE over PC5.
[0116] The configuration may include criterion that may be used by
the remote WTRU to determine when a measurement report may be
triggered from transmission to the eNB. The WTRU may trigger a
report to the eNB when one or more of the configured criterion is
met and when one or more of the criterion described herein as part
of WTRU autonomous reselection are met. Example criterion for
triggering a measurement report to the eNB may include information
that the signal quality for the mobile relay to which the remote
WTRU is connected may be below a threshold for a given time period.
Example criterion for triggering a measurement report to the eNB
may include information that the mobile relay to which the remote
WTRU was connecting may no longer be detected. Example criterion
for triggering a measurement report to the eNB may include
information that a different candidate mobile relay WTRU may be
detected. The WTRU may trigger a report to the eNB when one or more
of the configured criterion is met and when one or more of the
criterion described herein as part of WTRU autonomous reselection
are met.
[0117] For example, a different candidate mobile relay WTRU may be
detected when a candidate mobile relay WTRU meets the higher layer
configured connection criterion. The remote WTRU may select the
candidate mobile relay when the signal quality of the different
candidate mobile relay WTRU may be above a threshold for a period
of time. The remote WTRU may select the candidate mobile relay when
the signal quality of the different candidate mobile relay WTRU may
be better than the mobile relay to which the remote WTRU was
connecting by a threshold for a period of time.
[0118] The mobile relay WTRU may send the measurements over the Uu
interface to the eNB. For example, the mobile relay WTRU may send
the measurements over the Uu interface to the eNB when receiving a
measurement packet (e.g., a MAC CE or a RRC-like message) over the
PC5 interface from the remote WTRU. This measurement report may be
sent using RRC signaling and/or MAC CE. The measurement report may
contain identification of the remote WTRU making the measurements.
The identification may include L2 ID, physical layer ID, and/or the
like. The measurement report may contain a list of measured mobile
relay WTRUs. The list of measure mobile relay WTRUs may be reported
in terms of L2 ID or physical layer ID. The measurement report may
contain associated measurements for a mobile relay. The measurement
report may contain the measurement quality of the mobile relay to
which the remote WTRU is connecting. The measurement report may
contain type of service requested by the WTRU.
[0119] The list of mobile relay WTRUs that the remote WTRU may
report to the eNB may be filtered at the application layer based on
application-layer services of application layer information sent in
the discovery message. A mobile relay may or may not serve the
purposes of a remote WTRU. When a mobile relay does not serve the
purposes of a remote WTRU, the remote WTRU may or may not send
measurements to the eNB for the mobile relay. A mobile relay may or
may not offer the services. When a mobile relay does not offer the
services, the remote WTRU may or may not send measurements to the
eNB for the mobile relay. A mobile relay may be on a non allowed or
unauthorized PLMN. When a mobile relay is on a non allowed or
unauthorized PLMN, the remote WTRU may or may not send measurements
to the eNB for the mobile relay. The eNB may control reselection
based on the list of mobile relays that may serve the remote
WTRU.
[0120] The remote WTRU may receive a command to perform a
reselection to a mobile relay that is measured and reported to the
eNB. The remote WTRU may receive a command to perform a reselection
to a mobile relay that is measured and reported to the eNB at a
time of the mobile relay selection/reselection procedure. The eNB
may send the information to the mobile relay WTRU using RRC
message. The mobile relay WTRU may send a RRC message to the remote
WTRU over the PC5 interface. The RRC message that is sent from the
mobile relay WTRU to the remote WTRU may be similar to the RRC
message that is sent from the eNB to the mobile relay WTRU. A MAC
CE may be used to transfer a reselection command.
[0121] Upon determining a reselection of a candidate mobile relay,
the remote WTRU may perform one or more of certain actions. Upon
determining a reselection of a candidate mobile relay, the remote
WTRU may tear down the connection with the mobile relay to which
the remote WTRU is connecting. Upon determining a reselection of a
candidate mobile relay, the remote WTRU may initiate a connection
establishment to the reselected candidate mobile relay. Upon
determining a reselection of a candidate mobile relay, the remote
WTRU may keep the connection to the mobile relay to which the
remote WTRU is connecting and attempt a connection establishment
with the reselected candidate mobile relay. The remote WTRU may
tear down the connection to the mobile relay to which the remote
WTRU is connecting when it has successfully established connection
with the reselected candidate mobile relay. The connection to the
mobile relay to which the remote WTRU is connecting may be tom
down, after the remote WTRU has ensured that the remote WTRU has
started to receive services from the reselected candidate mobile
relay. For example, the services may be eMBMS.
[0122] Selection/reselection of a mobile relay may be triggered by
a combination of one or more of autonomous triggers and/or eNB
triggers. The configuration received by the remote WTRU may control
the reselection behavior of the remote WTRU. The behavior of the
remote WTRU may depend on the measured signal strength of the
mobile relay to which the remote WTRU is communicating. How
reselection is performed may depend on the measured signal strength
of the mobile relay to which the remote WTRU is communicating. This
may allow the remote WTRU to have flexibility to perform mobile
relay reselection on its own when the quality of the PC5 link
and/or Uu link is degrading. The remote WTRU may or may not be able
to successfully transmit the measurements to the mobile relay. The
remote WTRU may be able to successfully transmit the measurements
to the eNB.
[0123] The combination of autonomous and eNB triggers may be
controlled by certain rules related to the Uu link quality. The
combination of autonomous and eNB triggers may be controlled by
certain rules related to the link state between the remote WTRU and
the eNB, when the WTRU performs mobile relay selection/reselection
in the coverage of the eNB.
[0124] If certain quality criteria for the Uu link between the eNB
and the mobile relay WTRU are met, the remote WTRU may or may not
perform mobile relay selection/reselection. For example, the remote
WTRU may hold or delay the selection/reselection if under eNB
coverage. The remote WTRU may wait to receive the choice of the
mobile relay WTRU from the eNB. If the quality criteria of the Uu
link is no longer met, the remote WTRU may autonomously trigger
selection/reselection on its own. If the quality criteria of the Uu
link is no longer met, the remote WTRU may autonomously select the
mobile relay WTRU for connection. For example, the determination
that the quality of the Uu link is low enough to merit autonomous
selection/reselection may be related to a measured RSRP of the eNB.
The determination that the quality of the Uu link is low enough to
merit autonomous selection/reselection may be related to
measurements made by the WTRU on the Uu link that are below a
configured threshold for a configured period of time. A
determination that the quality of the Uu link is low enough to
merit autonomous selection/reselection may be based on the state of
the RRC connection on the Uu link. For example, the state of the
RRC connection on the Uu link following radio link failure (RLF)
and/or the state of the RRC connection on the Uu link following an
unsuccessful RRC connection re-establishment may be used.
[0125] For example, the remote WTRU may receive two thresholds as
part of the configuration (e.g., thresh1>thresh2). If the
measurements of the mobile relay WTRU to which the remote WTRU is
connected is below thresh1, but still above thresh2, the remote
WTRU may be triggered to start performing measurements of other
mobile relay WTRUs. The remote WTRU may be triggered to start
sending these measurements to the eNB. The mechanism discussed for
eNB-triggered reselection may be used, for example while the mobile
relay WTRU to which the remote WTRU is connected is below thresh,
but still above thresh2. If the measurements of the mobile relay
WTRU to which the remote WTRU is connected are below thresh2, the
mobile relay WTRU may initiate a mobile relay reselection
procedure. For example, the mobile relay reselection procedure may
be as described for remote-WTRU autonomous reselection based on the
mobile relay signal quality falling below thresh2. The WTRU may
perform autonomous reselection, and upon reselection criteria being
triggered, the WTRU may notify the eNB of the reselection
decision.
[0126] Upon reselecting a mobile relay, the WTRU may autonomously
initiate a connection establishment procedure to the reselected
candidate mobile relay. In an example, the remote WTRU may wait for
an explicit indication from the eNB, and for example the explicit
indication may inform the remote WTRU whether to initiate the
connection establishment to the reselected mobile relay WTRU. The
eNB may proactively stop the establishment of a connection to the
reselected mobile relay. Upon reselection to the mobile relay, the
WTRU may indicate to the reselected mobile relay the identity of
the mobile relay to which the remote WTRU is connecting. Indicating
to the reselected mobile relay the identity of the mobile relay to
which the remote WTRU is connecting may occur in the establishment
request or over a new PC5 message.
[0127] An internal state or condition within the WTRU, the eNB,
and/or combination of the two, may affect how reselection is
performed. For example, in the case of a remote WTRU starting from
in-coverage and moving out of coverage of an eNB, how the
reselection is performed when the remote WTRU is in RRC_CONNECTED
may be different from when the WTRU is in RRC_IDLE. For example, in
the RRC_CONNECTED state, reselection may be eNB controlled. The eNB
may be allowed make a decision about which mobile relay the WTRU
may be connected to. The remote WTRU may use transmission resources
when the remote WTRU is connected to the mobile relay. The remote
WTRU was previously actively transmitting with the eNB in connected
mode. If the remote WTRU is in RRC_IDLE, the remote WTRU may
perform a WTRU-autonomous mobile relay selection. The remote WTRU
may potentially receive eMBMS traffic from the eNB. The remote WTRU
may expect to receive eMBMS from a mobile relay WTRU.
[0128] Lower layer measurements may be used to support the
selection/reselection procedures. The upper layer may configure the
measurements of the lower layers. The upper layer may enable the
measurements at different times or continuously on relays including
the relay to which the remote WTRU is connected.
[0129] Enhancements to R12 discovery/communication and measurement
procedures may be introduced to provide a measurement quality of
the mobile relay WTRU as seen by the remote WTRU. An indication of
the quality of a mobile relay WTRU from the remote WTRU may be
provided. An indication of the quality of a mobile relay WTRU from
the remote WTRU may be provided to the higher layer.
[0130] Measurement configuration of the lower layers (e.g.,
PHY/MAC/RRC) may be done by the upper layers. The upper layers may
configure the lower layers to report measurements associated with
transport blocks coming from a source. The transport blocks may
come from a specific source or from any number of sources
identified as mobile relays. The source or sources may be
identified as the source WTRU ID. The source or sources may found
in the MAC header of the SL-SCH. The source or sources may found in
the layer 1 ID decoded in the SA. The source or sources may be
found in the ID retrieved from the PSBCH. The source or sources may
be received from a resource reserved for sending messages or
signals.
[0131] Measurements may be enabled by the upper layers (e.g.,
higher layer) at different times. The measurements may be enabled
during the period of time when the upper layer is expecting a Model
B response message and/or a Model A announcement message. The Model
B response message and/or the Model A announcement message may be
transmitted by a potential mobile relay. The measurements may be
disabled by the upper layers of the remote WTRU. The measurements
may be disabled by the upper layers of the remote WTRU when some or
all expected discovery messages are received. Some or all expected
discovery messages may be received after the expiry of a timer.
[0132] The measurements may be enabled continuously to allow for
measurements of mobile relay WTRUs on a continual basis.
Measurements may be enabled continuously on the mobile relay to
which the remote WTRU is connecting. The measurements on other
mobile relays may be started and/or stopped. Measurements may be
enabled continuously based on the value of the measurements. For
example, if the measurements on the mobile relay to which the
remote WTRU is connecting go below a specific threshold, the upper
layers may enable measurements on the other mobile relays that were
ranked and measured. If the measurements on the mobile relay to
which the remote WTRU is connecting go below a specific threshold,
the upper layers may perform measurements on some or all mobile
relays sending announcements. The threshold may be configured in
the remote WTRU by the upper layers or by the mobile relay WTRU or
eNB. The threshold may be sent to the remote WTRU from the mobile
relay WTRU or the eNB during the establishment of the secure link
with the remote WTRU.
[0133] To support measurements of a mobile relay WTRU, the PSBCH
may be transmitted by a WTRU that acts as a mobile relay at a given
time. The upper layers of the mobile relay WTRU may enable the
transmission of the PSBCH whenever a mobile relay connection is
made to the mobile relay, and/or disabled whenever the WTRU no
longer has mobile relay connections to it.
[0134] The remote WTRU may perform measurements of the sidelink
broadcast channel SL-BCH (sidelink broadcast channel) and/or
sidelink shared channel (SL-SCH).
[0135] The remote WTRU may perform measurements on DMRS that is
transmitted by the mobile relay WTRU on the SL-SCH. This may be
done, for example, where the Model B discovery response or Model A
mobile relay announcements are sent by the remote WTRU through D2D
communications (e.g., on SL-SCH).
[0136] The measurements/quality of the mobile relay WTRU may be
based on measurements made by the remote WTRU of the DMRS
transmitted in the PSBCH. To allow measurement procedures (e.g.,
measurements of SL-SCH), the R12 PSBCH may be enhanced to include,
in the payload, the L2 WTRU ID of the WTRU transmitting the PSBCH.
To allow measurements during the Model B response or Model A
announcement when the response is transmitted using D2D discovery,
D2D discovery may be enhanced so that the PSBCH is transmitted
during D2D discovery. For example, the upper layers in the mobile
relay WTRU may configure the lower layers to transmit PSBCH using
the D2D discovery to send the Model B response.
[0137] Radio access network level relay control may comprise
operations and procedures to preselect relays and/or initiate
relays at various stages including relay discovery, relay
connection request, request to receive broadcast from a TMGI,
and/or the like.
[0138] Mobile relay operation may be controlled by the eNB. The eNB
may perform resource allocation for mobile relay operation. For
example, the eNB may specify which resources should be used by a
mobile relay WTRU for communicating with a remote WTRU (e.g.,
and/or vice versa). The eNB may allow/reject mobile relay operation
depending on available resources, optimized resource, and WTRU to
mobile relay grouping. The eNB may interact with higher layer
following certain procedures. For example, the mobile relay may
send a request and/or report to the eNB.
[0139] To enable RAN control of mobile relay operation, the mobile
relay WTRU may initiate a transmission of a report and/or a request
to the eNB. The mobile relay WTRU may send the request according to
one or more of the following triggers. The triggers may include
pre-selection occurring prior to a higher-layer mobile relay
discovery operation. The triggers may include initiation of model A
discovery for a mobile relay. The triggers may include initiation
of Model B discovery for a mobile relay when the mobile relay is in
monitoring mode. The triggers may include initiation of Model B
discovery for a mobile relay when the mobile relay wants to
initiate the transmission of the solicitation message. The triggers
may include reception of a solicitation message (e.g., from Model
B) for which the WTRU is allowed to send a response message. The
solicitation message may be from Model B discovery. The triggers
may include request by the remote WTRU to establish a one-to-one
connection. The triggers may include successful connection
completion as determined by higher layers. The triggers may include
request by a remote WTRU to receive broadcast messages for a
specific TMGI. The triggers may include detection of TMGI that it
has been requested to monitor a WTRU requested TMGI from the eNB.
The triggers may include request by the remote WTRU to change the
type of service. For example, changing the service may include
starting a different video call over the same mobile relay link.
Changing the service may include dropping an existing service.
Changing the service may include stopping the link to a
service.
[0140] The request/report may contain certain information. The
request/report may contain type of discovery. The type of discovery
may be mobile relay, group member, or the like. The request/report
may contain discovery model type. The discovery mode type may be
Model A or Model B. The type of discovery may contain stage of
Model B. The state of Model B may include monitoring for
solicitation message, transmission of solicitation message,
solicitation message received and trigger of response required, or
the like. The request/report may contain connection information.
The connection information may be to help the eNB determine whether
the eNB supports a service. The connection information may be to
help the eNB determine whether the mobile relay may act as a mobile
relay. The request/report may contain measurement report indicating
the signal strength with respect to the eNB. The request/report may
contain ID of the remote WTRU. The request/report may contain ID of
a detected mobile relay announcing mobile relay operation or
announcing a service. The request/report may contain TMGI requested
by the WTRU(s). The request/report may contain TMGI detecting that
the mobile relay has been requested to monitor. The request/report
may contain measurements of the selected mobile relay and/or other
mobile relays. The measurements may be made by a remote WTRU and/or
by the mobile relay WTRU. The request/report may contain an
indication of services and/or resources needed by the remote
WTRU.
[0141] The request message may be MOBILE RELAY_REQUEST_MESSAGE.
Depending on which stage the request message is sent in, the
response from the eNB may configure different behavior in the WTRU.
The MOBILE RELAY_REQUEST_MESSAGE may be sent to the eNB through RRC
or MAC CE. The MOBILE RELAY_REQUEST_MESSAGE may trigger the
assignment of resources by the eNB to be used by the mobile relay.
The MOBILE RELAY_REQUEST_MESSAGE may trigger outright rejection of
the request by the eNB.
[0142] A WTRU may be configured to act as a mobile relay and/or
reject mobile relay-related operations before and/or after
initialization of mobile relay related procedures. The mobile relay
related procedures may include discovery, establishment of
connection, TMGI request, and/or the like.
[0143] A WTRU may be configured to act as a mobile relay during
pre-selection processes based on the WTRU's capability to act as a
mobile relay, the number of remote WTRUs that the WTRU may be able
to serve as determined by a prediscovery procedure, and/or the
location of the WTRU. The pre-selection may occur before the WTRU
receives higher-layer requests for operation as a mobile relay. A
process of pre-selection of mobile relay WTRUs may be performed so
that in-coverage WTRUs are selected to serve as mobile relay WTRUs
in an intelligent manner. When information may be communicated by a
mobile relay WTRU, multiple WTRUs mobile communicating the same
information may be avoided by performing the pre-selection process.
Pre-selection of mobile relay WTRUs may be performed by the eNB
and/or the network. Pre-selection of mobile relay WTRUs may be
performed by the eNB and the network acting in coordination. The
network, the application/function, or a combination of the network,
the application/function may be involved in the pre-selection
(e.g., by the eNB).
[0144] The eNB may configure a WTRU to act as a mobile relay based
on the WTRU's capability. The WTRU may register with the eNB and
provide its capabilities to the eNB and/or the network. The WTRU
may provide information about whether it is capable of operating as
a mobile relay. The WTRU may provide information about its mobile
relay properties. For example, the mobile relay properties may
include whether the WTRU may operate using one or more separate
radios, separate operating frequencies/bands, and/or the like.
[0145] A pre-selection of a mobile relay may be made based on the
location of the mobile relay. The eNB may configure the WTRU to
operate as a mobile relay and allow it to participate in mobile
relay discovery based on the location of the WTRU and/or the
capability of the WTRU to act as a mobile relay. FIG. 8 illustrates
an exemplary pre-selection based on location. The WTRU may connect
to the eNB and/or send its mobile relay capability information to
the eNB at 802. The capability information may include frequencies
on which the WTRU may operate. The capability information may
include ability to operate with separate radios. The capability
information may include ability to release support. For example,
the ability to release support may include whether the WTRU
supports mobile relay operation. The eNB may determine the location
of the WTRU at 804. The eNB may use channel quality measurements.
The eNB may use specific functions for localization. Specific
functions for localization may be obtained from higher layers.
[0146] The eNB may decide whether or not to allow the WTRU to
function as a mobile relay at 806. The eNB may use the eNB'ss
knowledge of the WTRU's location relative to the eNB. For example,
the eNB may decide to configure a WTRU as a mobile relay if the
WTRU is close to the coverage edge of the eNB at 806. The WTRU that
is close to the coverage edge of the eNB may serve a maximum number
of potential remote WTRUs which are outside the coverage area of
the eNB. WTRUs which are known by the eNB to be relatively close to
the eNB may or may not be configured by the eNB as a mobile relay
at 806. For example, if other options exist, WTRUs which are known
by the eNB to be relatively close to the eNB may not be configured
by the eNB as a mobile relay. The other options may include a
mobile relay WTRU at the edge of the coverage area of the eNB. The
eNB may or may not advertise the WTRUs which are known by the eNB
to be relatively close to the eNB to WTRUs that are searching for a
mobile relay. The preselection process may end.
[0147] The eNB may send a message to the WTRU to configure the WTRU
to participate in mobile relay discovery or to disable mobile relay
discovery at 808. If the WTRU is allowed to operate as a mobile
relay, the eNB may assign discovery or communication resources to
the mobile relay. The eNB may send an RRC message to
configure/reconfigure the mobile relay D2D resources. For example,
the eNB may configure the higher layers in the mobile relay to
listen to a solicitation message and/or to send the Model A
announcement message. The WTRU may receive a positive indication to
behave as a mobile relay. The WTRU may indicate to the higher
layers that it is able to accept mobile relay solicitation
messages. The WTRU may start transmission of Model A discovery
announcement message at 810. The WTRU may receive a negative
indication. The negative indication may indicate that the WTRU may
not act as a mobile relay. The WTRU may trigger the notification to
upper layers. The notification may notify the upper layers not to
transmit Model A announcement or not to respond to Model B
solicitation messages. The eNB may or may not configure discovery
resources for the WTRU if the WTRU may not act as a mobile
relay.
[0148] If mobile relay operation is accepted, the eNB and/or the
mobile relay may initiate reconfiguration of the mobile relay
resources at 808. The resources may be used for discovery at 810.
The discovery may include Model A and/or Model B discovery. For
example, for Model A discovery, mobile relay WTRU may transmit
discovery announcement for mobile relay discovery. The WTRU may
request additional mobile relay resources based on the results of
the relay initiation during relay discovery and/or relay initiation
during request to receive broadcast from TMGI.
[0149] Pre-selection based on location may be performed through
signaling. The eNB may use signaling to provide the WTRU with
acceptable locations for mobile relay operation. The signaling may
include broadcast or dedicated RRC signaling. For example, the eNB
may signal the allowable location(s) for mobile relay operation via
broadcast signaling. The WTRU may perform its own determination of
whether the WTRU's location may be within the acceptable locations
for mobile relay operation. The WTRU may perform its own
determination of whether the WTRU's location may satisfy the
location requirements of the eNB and/or whether the WTRU's location
may satisfy other requirements. If the WTRU determines that the
WTRU's location satisfies the location requirements of the eNB and
other requirements, the WTRU may operate as a mobile relay. The
WTRU may utilize resources assigned by the eNB to perform
discovery. The eNB may have assigned resources through dedicated
and/or broadcast signaling.
[0150] A pre-selection of a mobile relay may be made based on
pre-discovery of WTRUs that may act as remote WTRUs. An
eNB/Network/function may initiate a pre-discovery procedure to
determine which WTRUs may be configured as mobile relays for which
potential remote WTRUs. The pre-discovery procedure may use R12 D2D
discovery to determine which WTRUs are in proximity of each other.
The pre-discovery procedure may use R12 D2D discovery to determine
which WTRUs are capable of mobile relay operation. The
pre-discovery procedure may use R12 D2D discovery to determine
which WTRUs may serve the maximum number of remote WTRUs.
[0151] For example, an eNB may perform the pre-discovery procedure.
The eNB may perform the pre-discovery procedure periodically. The
eNB may use the pre-discovery procedure eNB to designate potential
mobile relay WTRUs within the eNB coverage. The eNB may initiate
the procedure when a number of WTRUs are already operating as
mobile relays. The eNB may use the pre-discovery procedure eNB to
have mobile relay WTRUs cease operation as mobile relay WTRUs.
[0152] The pre-discovery procedure may comprise one or more of the
following steps in any order. In the pre-discovery procedure, the
eNB may configure some or all D2D capable WTRUs within its coverage
which have registered with the network to listen for discovery
messages on a pre-configured discovery resource pool. In the
pre-discovery procedure, a remote WTRU may perform a self-initiated
discovery message to find D2D WTRUs which may serve as mobile
relays. The remote WTRU may perform a self-initiated discovery
message when it is turned on without coverage of an eNB. The remote
WTRU may perform a self-initiated discovery message when it moves
to an out-of-coverage scenario. A code for the self-initiated
discovery message may be hard-coded or otherwise preconfigured in
the WTRU. A default value may be used for Mobile relay Search. The
discovery message may contain "Mobile relay Search" code. The
discovery message may contain an identifier for the WTRU. The
identifier for the WTRU may be used to identify which WTRUs sent
the discovery message. The identifier for the WTRU may be used to
identify which WTRUs are searching for a mobile relay. The
identifier may be part of the application code within the discovery
message. A remote WTRU that is out of coverage of an eNB may use
pre-configured discovery resources as defined in R12.
Out-of-coverage WTRUs which are already being served by a mobile
relay may or may not send the discovery message.
[0153] In the pre-discovery procedure, some or all D2D WTRUs that
successfully receive the discovery message with the application
code of "Mobile relay Search" may report the reception of the
discovery message to the eNB/Network. The report may be performed
via RRC message, MAC CE, and/or application message. The report may
contain the identity of the remote WTRU. The D2D capable WTRUs may
be responsible for sending the report. The D2D capable WTRUs may
compile a report containing some or all remote WTRUs for which it
received a discovery message with the code of "Mobile relay Search"
for a certain period of time.
[0154] In the pre-discovery procedure, the eNB may collect some or
all reports from the various D2D capable WTRUs within its coverage.
The eNB may designate a set of WTRUs which are in coverage to act
as mobile relays. The eNB may designate the set of WTRUs based on
the reported remote WTRUs. The eNB may designate the set of WTRUs
based on which WTRUs that are in the coverage reported the remote
WTRUs for multiple times. In the pre-discovery procedure, the eNB
may indicate to core network that a WTRU or a set of WTRUs may be
configured as WTRU-Network mobile relays. In the pre-discovery
procedure, the selected coverage WTRUs may be configured as mobile
relays. The selected mobile relay WTRUs may perform a mobile relay
discovery operation. The mobile relay discovery operation may be
based on Model A and/or Model B.
[0155] A WTRU may be configured to act as a mobile relay and/or
reject mobile relay-related operations after initialization of
mobile relay related procedures. Mobile relay initiation may occur
at various stages. Mobile relay initiation may occur during mobile
relay discovery. If the eNB and WTRU support mobile relay
operation, higher layers associated with the WTRU may initiate
mobile relay related procedures. The WTRU may trigger a report or
request to the eNB. The mobile relay related procedures may include
Model A, Model B, mobile relay announcement, WTRU to mobile relay
establishment success, TMGI request, and/or the like.
[0156] The WTRU may trigger a report to the eNB when Model A
discovery procedure is triggered in the WTRU by higher layers. The
WTRU may trigger a report to the eNB when Model B solicitation
request is received and the mobile relay WTRU may send a response.
The response may be sent according to higher layers.
[0157] Certain information may be provided to the eNB. The report
may contain the information. The information may include discovery
type. The discovery type may include mobile relay discovery (e.g.,
WTRU-to-network discovery), group member discovery, or WTRU-to-WTRU
mobile relay discovery. The information may include type of
message. The types of message may include announcement,
solicitation, and/or response. The information may include
connection information. The connection information may include what
the mobile relay WTRU intends to announce. The connection
information may include what the mobile relay WTRU intends to send
in the response message. The information may include the received
WTRU ID and/or the group of the received WTRU IDs in the
solicitation message if the discovery is model B response type. The
information may include WTRU ID or mobile relay ID of the WTRU that
is sending the report to the eNB. The information may include
channel quality measurement of the WTRU that is sending the message
or location information of the WTRU that is sending the message.
The channel quality measurement may be for the eNB, for detected
mobile relay WTRUs, and/or for remote WTRUs.
[0158] The eNB may take certain actions. The eNB may receive a
request (e.g., a request for a mobile relay WTRU). The eNB may
determine whether to allocate resources to the potential candidate
mobile relays WTRUs for the requested services. The eNB may
determine whether to allow the operation of the WTRU as a mobile
relay. To allow the operation of the WTRU as a mobile relay, the
eNB may allow the initiation of the transmission of discovery
messages, announcement, and/or WTRU response.
[0159] The eNB may determine whether to allow mobile relay
operation of the potential candidate WTRU based on the reports sent
by the WTRU. The eNB may determine whether to allow mobile relay
operation of the potential candidate WTRU based on certain
information. The eNB may determine whether to allow mobile relay
operation of the potential candidate WTRU based on reported remote
WTRUs and/or the number of mobile relay WTRUs that indicate
solicitation requests and/or mobile relay establishment from the
reported remote WTRUs. The eNB may determine whether to allow
mobile relay operation of the potential candidate WTRU based on
service requested by the remote or mobile relay WTRU, if the
network supports that type of service. The eNB may determine
whether to allow mobile relay operation of the potential candidate
WTRU based on the location of the WTRU with respect to the eNB. The
location of the WTRU with respect to the eNB may be determined
based on measurement received. The eNB may determine whether to
allow mobile relay operation of the potential candidate WTRU based
on candidate mobile relay WTRUs detected in the proximity of the
potential candidate mobile relay WTRU that is requesting to become
a mobile relay. Based on the reports sent by the WTRU and the
information, the eNB may determine whether to allow mobile relay
operation and may respond to the potential candidate WTRU by
allocating resources, if resources are not already available in the
WTRU. The eNB may send an explicit message indicating that mobile
relay operation is allowed.
[0160] The potential candidate mobile relay WTRU may take certain
actions. The WTRU may initiate the transmission of higher layer
message and/or reconfiguration of the mobile relay resources when
the potential candidate mobile relay WTRU receives a message
providing resources for the requested service. The WTRU may
initiate the transmission of higher layer message and/or
reconfiguration of the mobile relay resources when the potential
candidate mobile relay WTRU receives an explicit approval of mobile
relay operation. The WTRU may initiate the transmission of higher
layer message and/or reconfiguration of the mobile relay resources
when the WTRU determines that the criterion to become a mobile
relay has been met. The criterion may be configured by the eNB.
Mobile relay operation discovery transmission may be rejected. When
mobile relay operation discovery transmission may be rejected, the
higher layers may stop the discovery message transmission.
[0161] Mobile relay initiation may occur during a Mobile relay
Connection Request. A mobile relay WTRU may send a report to the
eNB when a connection with a remote WTRU has been requested to be
established. A mobile relay WTRU may send a report to the eNB when
a connection with a remote WTRU has been established.
[0162] Mobile relay initiation may occur during mobile relay
connection request. The mobile relay WTRU may be triggered to send
a report and/or request to the network when certain events occur.
The triggering events may be that the mobile relay WTRU has
established a successful connection with a remote WTRU. The higher
layers may determine whether the mobile relay WTRU has established
a successful connection with a remote WTRU. A successful connection
may be established with additional remote WTRUs. The triggering
event may be that the mobile relay WTRU has established a
successful connection with an additional remote WTRU. The
triggering event may be that the mobile relay WTRU has established
a successful connection with a remote WTRU that belongs to a group
different from a group for the remote WTRU. The triggering event
may be that the mobile relay WTRU has established a successful
connection with a remote WTRU that may request a type of service
different from the services requested by the remote WTRU. The
triggering event may be that the mobile relay WTRU receives a
connection establishment message from an additional remote WTRU.
The triggering event may be that the remote WTRU requests
additional or different services. The triggering event may be that
the remote WTRU disconnects from a mobile relay WTRU. The
triggering event may be that a TMGI request is not renewed by the
remote WTRU, indicating that the remote WTRU may or may not use the
services of the mobile relay.
[0163] A report may comprise identifications of remote WTRU or
potential remote WTRUs and/or service related information. The
report may be the same report that was sent when the triggering
events occur. The information in the report may include the remote
WTRU identity (e.g., WTRU ID), a list of WTRUs with which the
remote WTRU is connected, and/or the WTRU ID(s) of the remote WTRUs
that request connection establishment or have requested connection
establishment. The information in the report may include the
service or any other service-related information. The service
information may include connection info and/or group info. Service
related information may include connection information. Connection
may be for requesting a list of available TMGIs. For example,
connection may be for requesting to connect to a broadcast service.
Connection may be for one-to-one communication. The one-to-one
communication may include file download from a server. The
information in the report may include measurements with respect to
the eNB.
[0164] The eNB may accept or reject the request and or report to
connect, and/or the eNB may initiate a redirection process as
described herein. The eNB may decide to not provide resources for
mobile relay communication, to reject the connection to the remote
WTRU, or to redirect. The determination may be based on the
information that the eNB received. The received information may
include services provided, TMGI requested, measurements, and/or
methods described herein. The initiation of a mobile relay may be
rejected by the eNB for various reasons. For example, the eNB may
not be able to provide communication resources that is used for the
mobile relay connection (e.g., even though the mobile relay WTRU
may be able to be configured using discovery resources). Other
mobile relays in the system may be present that can offer the
services of the remote WTRU.
[0165] The mobile relay WTRU may forward the rejection to the
higher layers. Reception of the rejection by the higher layers may
trigger the higher layer to initiate a procedure to break and/or
reject the connection with the remote WTRU. For example, the mobile
relay WTRU may reject a connection by not continuing the connection
establishment procedure with the higher layers and/or by sending a
connections establishment failure message to the remote WTRU. A
report provided herein may be sent to the eNB prior to the
connection between the mobile relay WTRU and the remote WTRU is
fully approved by the function. For example, a report provided
herein may be sent to the eNB when the connection establishment
procedure from a remote WTRU to a mobile relay WTRU is initiated.
Forward the rejection to the higher layers may initiate the
breaking or stopping of the connection between the remote WTRU and
the mobile relay WTRU such that the remote WTRU may find another
candidate mobile relay WTRU.
[0166] Mobile relay initiation may occur during a request to
receive broadcast from a TMGI. The eNB may reject a request that
comes from a remote WTRU asking to receive eMBMS broadcast from a
mobile relay. An eNB may reject the initiation of a mobile relay or
the connection of the remote WTRU to the mobile relay during a
request to receive broadcast from a TMGI for various reasons. For
example, the eNB may or may not be able to provide sufficient
resources to the mobile relay to broadcast traffic for the
associated TMGI. An eNB may reject initiation of the mobile relay
to remote WTRU connection such that the remote WTRU may connect to
another mobile relay that may be broadcasting the requested TMGI.
An eNB may or may not have resources to assign to the mobile relay
WTRU. The mobile relay WTRU may be operating as a mobile relay for
other remote WTRUs.
[0167] A potential rejection of mobile relay connection by the eNB
during the request to receive broadcast from a TMGI may be
supplemented by identifying one or more alternative mobile relay
WTRUs to which the remote WTRU may connect to obtain the services.
Identifying one or more alternative mobile relay WTRUs to which the
remote WTRU may connect to obtain the services may allow the eNB to
control which mobile relay WTRUs may forward broadcast services
related to a specific TMGI. Being able to control which mobile
relay WTRUs may forward broadcast services related to a specific
TMGI may avoid a scenario where different mobile relay WTRUs may be
transmitting broadcast services associated with the same TMGI to
different remote WTRUs. Services associated with the same TMGI may
be broadcasted by a mobile relay WTRU to different remote WTRUs.
Multiple remote WTRUs may be connect to the same mobile relay
WTRU.
[0168] An eMBMS broadcast that is sent by a mobile relay WTRU may
be controlled by the eNB through the transmission of a request. For
example, the request may be BROADCAST_MOBILE RELAY_REQUEST_MESSAGE
from the mobile relay WTRU to the eNB. The upper layers may trigger
the lower layers of the mobile relay WTRU to send the
BROADCAST_MOBILE RELAY_REQUEST_MESSAGE to the eNB in one or more of
the following scenarios. The upper layers may trigger the lower
layers of the mobile relay WTRU to send the BROADCAST_MOBILE
RELAY_REQUEST_MESSAGE to the eNB when the upper layers of the
mobile relay WTRU receives a request from a remote WTRU to monitor
a specific TMGI. The upper layers may trigger the lower layers of
the mobile relay WTRU to send the BROADCAST_MOBILE
RELAY_REQUEST_MESSAGE to the eNB when the upper layers of the
mobile relay WTRU detects that a remote WTRU stops monitoring a
specific TMGI that the remote WTRU is requesting. The upper layers
of the mobile relay WTRU may receive a direct message that is sent
from the remote WTRU to the mobile relay WTRU. The direct message
may indicate that the upper layers of the mobile relay WTRU may
stop monitoring a specific TMGI that the remote WTRU is requesting.
The upper layers of the mobile relay WTRU may detect that the
remote WTRU stops re-requesting the same TMGI after a certain
predefined time period. The upper layers may trigger the lower
layers of the mobile relay WTRU to send the BROADCAST_MOBILE
RELAY_REQUEST_MESSAGE to the eNB when the upper layers of the
mobile relay WTRU receive a request from a remote WTRU to monitor a
TMGI which does not correspond to TMGIs that are monitored by the
mobile relay WTRU. For example, the TMGI which does not correspond
to TMGIs that are monitored by the mobile relay WTRU may include a
new TMGI. Some or all broadcast messages associated with a TMGI may
be sent over PC5 by the mobile relay using the same D2D resources.
The upper layers may trigger the lower layers of the mobile relay
WTRU to send the BROADCAST_MOBILE RELAY_REQUEST_MESSAGE to the eNB
when the mobile relay WTRU stops monitoring a TMGI for WTRUs. The
upper layers may trigger the lower layers of the mobile relay WTRU
to send the BROADCAST_MOBILE RELAY_REQUEST_MESSAGE to the eNB when
a mobile relay WTRU may periodically send the BROADCAST_MOBILE
RELAY_REQUEST message to the eNB with the required information.
[0169] The BROADCAST_MOBILE RELAY_REQUEST message may contain
certain information. The BROADCAST_MOBILE RELAY_REQUEST message may
contain an indication of a cause(s) for sending the
BROADCAST_MOBILE RELAY_REQUEST message. Exemplar causes may include
a new WTRU requesting a TMGI to be monitored, a WTRU no longer
monitoring a TMGI, a periodic report or the like. The
BROADCAST_MOBILE RELAY_REQUEST message may contain the TMGI that is
requested to be monitored and communicated. The BROADCAST_MOBILE
RELAY_REQUEST message may contain the WTRU ID of the remote WTRU
that is requesting the TMGI and/or the WTRU ID of the remote WTRU
that has stopped requesting the reception of a TMGI. The WTRU ID
may be L2 WTRU ID, the physical layer ID of the WTRU, or the like.
The BROADCAST_MOBILE RELAY_REQUEST message may contain the
connection information associated with a connection that the remote
WTRU has established with the mobile relay WTRU. The
BROADCAST_MOBILE RELAY_REQUEST message may contain information
related to the service. The information related to the service may
identify the amount of resources that may be used to forward the
broadcast traffic over PC5. The BROADCAST_MOBILE RELAY_REQUEST
message may contain the information described herein including
TMGI, WTRU ID, connection information, additional service
information for a remote WTRU that is listening to the mobile relay
ID for eMBMS broadcast. The BROADCAST_MOBILE RELAY_REQUEST message
may contain measurements from remote WTRU of other mobile relay
WTRUs detected in the vicinity that may offer the services. The
BROADCAST_MOBILE RELAY_REQUEST message may contain indication of
presence of other mobile relay WTRUs detected in the vicinity that
may offer the services.
[0170] The BROADCAST_MOBILE RELAY_REQUEST message may be sent using
MAC CE or RRC message, for example. The BROADCAST_MOBILE
RELAY_REQUEST message is used as an example. A message described
herein may be used to send such a request and/or information that
is contained in the BROADCAST_MOBILE RELAY_REQUEST message. A WTRU
Information message may be used to send such a request and/or
information that is contained in the BROADCAST_MOBILE RELAY_REQUEST
message. The request and/or information may be one of more of
information described herein.
[0171] The eNB may not respond to the BROADCAST_MOBILE
RELAY_REQUEST message. For example, the eNB may not respond to the
BROADCAST_MOBILE RELAY_REQUEST message when a periodic
BROADCAST_MOBILE RELAY_REQUEST message serves an indication.
[0172] The eNB may respond to the BROADCAST_MOBILE RELAY_REQUEST
message in various ways. The eNB may reconfigure the D2D resources
required by the mobile relay. The eNB may respond to the
BROADCAST_MOBILE RELAY_REQUEST through an RRC message, a MAC CE or
the like. The response may be forwarded by the mobile relay WTRU to
its upper layers.
[0173] The eNB's response may include accepting the request. For
example, the eNB's acceptance may cause the upper layers in the
remote WTRU to respond to the request. For example, if the request
was sent as a result of a remote WTRU's requesting to monitor a
TMGI, the acceptance may cause the upper layers in the remote WTRU
to accept the TMGI monitoring request from the remote WTRU and to
provide information associated with the TMGI monitoring
request.
[0174] The eNB's response may include rejecting the request. For
example, the eNB may reject the request of the mobile relay WTRU to
monitor or mobile relay a TMGI. The mobile relay WTRU may forward
the rejection to the higher layers. The higher layers may trigger
the mobile relay WTRU to send a rejection message to the remote
WTRU. The rejection message may indicate the mobile relay WTRU's
rejection the mobile relaying of a TMGI. The connection between the
remote WTRU and the mobile relay WTRU may break. The disconnection
may be initiated upon the reception of the rejection message by the
remote WTRU. The remote WTRU may find a different candidate mobile
relay WTRU.
[0175] The eNB's response may include sending to the mobile relay
WTRU identifications of one or more mobile relay WTRUs (e.g., L2 ID
of the mobile relay) that provide connection to the service that
the rejected mobile relay WTRU may offer, along with the rejection
of the request. The identification may be sent to the upper layers.
The upper layers may provide a re-direction message. The
redirection message may prompt the remote WTRU to act in various
manner. In some instances, the redirection message may suggest the
remote WTRU to act in certain manner. In some instances, the
redirection message may force the remote WTRU to act in certain
manner.
[0176] The redirection message may prompt the remote WTRU to
tear-down the connection with the mobile relay to which the remote
WTRU is connecting. The mobile relay to which the remote WTRU is
connecting may not be tasked with communicating the broadcast
traffic associated with the requested TMGI.
[0177] The redirection message may prompt the remote WTRU to
initiate a mobile relay reselection process to find candidate
mobile relays that may offer the service that the rejected mobile
relay WTRU may offer.
[0178] The redirection message may prompt the remote WTRU to
initiate a connection with a candidate mobile relay WTRU that may
be included in the re-direction message. The remote WTRU may ignore
the prompt or act accordingly. For example, the remote WTRU may not
hear the candidate mobile relay that is suggested by the eNB. An
example, the candidate mobile relay may not have responded to a
Model B discovery when the remote WTRU initiated the Model B
discovery. The remote WTRU may ignore the suggestion of the
candidate mobile relay and continue to operate on the mobile relay
to which the remote WTRU is connecting.
[0179] The remote WTRU may act accordingly when the redirection
message may prompt the remote WTRU to initiate a connection with a
candidate mobile relay WTRU. The remote WTRU may hear the candidate
mobile relay suggested by the eNB. An example, the candidate mobile
relay may have responded to a Model B discovery when the remote
WTRU initiated the Model B discovery. The remote WTRU may tear down
the connection with the mobile relay to which the remote WTRU is
connecting. The remote WTRU may initiate a connection with the
candidate mobile relay suggested by the eNB. The remote WTRU may
request broadcasting of a TMGI. It is possible that the candidate
mobile relay may be already broadcasting the same TMGI.
[0180] FIG. 9 is example of a selection/connection establishment.
The remote WTRU 920 and mobile relay WTRU 922 may engage in
discovery at 902 (e.g., public safety or commercial communication
discovery). The mobile relay WTRU 922 may have been previously
initiated by the eNB 924 using criterion described herein. The
remote WTRU 920 may perform measurements of potential candidate
mobile relays in the vicinity at 902. The remote WTRU 920 may use
signals in the discovery messages transmitted by the mobile relay
WTRU 922. The remote WTRU 920 may select a mobile relay WTRU that
has acceptable measurements and whose upper layer information
(e.g., services, PLMN ID) meets the service requirements of the
remote WTRU 920. The remote WTRU 920 may send a one-to-one
connection request to the mobile relay WTRU 922 at 904. The
one-to-one connection request may include identification and
measurements of selected and other mobile relays, required service,
and/or the like. The remote WTRU 920 may send identification of the
mobile relay WTRU 922 and the identifications of candidate mobile
relays at 904. The remote WTRU 920 may send the service
requirements at 904. The remote WTRU 920 may send a list of mobile
relay WTRUs that may satisfy the requirements of the remote WTRU
920, and measured qualities of the mobile relay WTRUs at 904. The
mobile relay WTRU 922 may send a mobile relay request to the eNB
924 at 906. The request may include identification and measurements
of selected and other mobile relays, required service, and/or the
like. The mobile relay request may include identification of the
mobile relay WTRU 922 and the identifications of candidate mobile
relays, a list of mobile relay WTRUs that may satisfy the
requirements of the remote WTRU 920 and measured qualities of the
mobile relay WTRUs, and/or service requirements of the remote WTRU
920. The mobile relay request may include the number of WTRUs that
are connected to mobile relay WTRU 922. The mobile relay WTRU 922
may forward the measurements sent by the remote WTRU 920 to the eNB
924 at 906. At 908, the eNB 924 may respond to the request that was
forwarded at 906. The eNB 924 may accept the request, reject the
request, and/or provide an candidate mobile relay from the list of
mobile relays that was provided at 906 and given by the remote WTRU
920 at 908. The eNB 924 may reconfigure the D2D resources at 908.
For example, the eNB 924 may reconfigure the D2D resources at 908
if additional resources are to be allocated to support the
transmission. Secure link establishment may occur at 910. The
remote WTRU 920, during connection with the mobile relay WTRU 922,
may indicate to the mobile relay WTRU 922 a request to change the
service at 912. The change of services at 912 may be based on an
additional bearer that is established to the network, starting an
additional/different video connection, ceasing to use the mobile
relay WTRU 922 or other mobile relays, and/or the like. The mobile
relay WTRU 922 may send a different mobile relay request at 914,
indicating a change in service for the remote WTRU 920. The
different mobile relay request at 914 may include identification of
the mobile relay WTRU 922, identification of a candidate mobile
relay that may be selected, and the identifications of candidate
mobile relays. The different mobile relay request at 914 may
include a list of mobile relay WTRUs that may satisfy the change of
the service request of the remote WTRU 920 and measured qualities
of the mobile relay WTRUs in the list, and/or service requirements
of the remote WTRU 920. The mobile relay request may include the
number of WTRUs that are connected to mobile relay WTRU 922 and/or
the candidate mobile relay that may be selected at 914. At 916, the
eNB 924 may respond to the request that was sent at 914. The eNB
924 may accept the request, reject the request, or provide a
candidate mobile relay from the list of mobile relays that was
provided at 914. The eNB 924 may reconfigure the D2D resources at
916. The response by the eNB 924 may trigger the tear-down of the
link to the mobile relay WTRU 922 at 918. The response by the eNB
924 may trigger a reconfiguration of the resources used on the PC5
interface at 918.
[0181] Resource may be allocated or assigned for mobile relay WTRUs
and/or for D2D communications. Resource assignment including
scheduling of resources may be performed by the eNB or mobile
relays. Assignment of resources to mobile relay WTRUs may be
performed based on various requirements including estimation of
services that may be offered to the remote WTRUs. Assignment of
resources to D2D communications including scheduling of resources
may be achieved by various approaches. Certain approaches may
comprise an eNB that configures a resource pool and WTRUs that
schedule resources among resource pools. Certain approaches may
comprise an eNB that configures a resource pool and WTRUs that
segregate resources and assigned segregated resources to remote
WTRUs or groups of remote WTRUs. Certain approaches may comprise an
eNB that directly schedules resource among resource pools. For
example, an eNB may directly schedule a resource pool for mobile
relay WTRUs, and WTRUs may schedule resources among resource pools
for other WTRUs.
[0182] A mobile relay WTRU may be configured with a pool(s) of
resources. For example, the eNB may allocate a set of resources or
resource pool(s) to be used for mobile relays. The pool of
resources may dedicated for mobile relays. The dedicated mobile
relay resources may be a subset of the D2D communication resources
which may be used by the mobile relay WTRU. The dedicated mobile
relay resources may be separate resources from the resources that
the mobile relay may use for D2D communications. The eNB may
re-configure the dedicated mobile relay WTRU resources. RRC
configuration message may be used to re-configure the dedicated
mobile relay WTRU resources. The eNB may re-configure the dedicated
mobile relay WTRU resources when the eNB receives an update from
the mobile relay WTRU. The update may be related to the change of
the number of remote WTRUs that are managed by the mobile relay
WTRU. For example, the number of remote WTRUs may change with the
addition/removal of a remote WTRU to/from the remote WTRUs that are
managed by the mobile relay WTRU. Resource pool(s) dedicated to a
mobile relay WTRU may be modified/re-configured dynamically when
the number of services requested by remote WTRU is changes.
Resource pool(s) dedicated to a mobile relay WTRU may be
modified/re-configured dynamically when the estimated traffic for
the mobile relay WTRUs changes. Changes and/or reallocation of
resources may be performed through various approaches.
[0183] Resource assignments for mobile relay WTRUs may be achieved
by estimating the services provided by a mobile relay WTRU. Upon
connection of a remote WTRU to a mobile relay WTRU, the amount of
resources that may be used to serve the remote WTRU may be
estimated. The mobile relay WTRU and/or the eNB may estimate the
amount of resources that may be used to serve the remote WTRU. For
example, the remote WTRU may request the communication of eMBMS
traffic which the mobile relay WTRU is already transmitting over
the PC5 interface to a different remote WTRU. The estimation may be
made that the amount of resources that are used by the remote WTRU
may not be changed significantly to meet the request of the remote
WTRU. The eNB may make the estimation.
[0184] The estimate of these resources may be based on an
assumption that the resources to be used may be near a maximum
needed for a given service or set of service requirements. For
example, an estimation may be made such that the maximum amount of
resource for the given service may be added to available resources
when the given service starts. The mobile relay WTRU may send an
indication of increase in the amount of resources when the mobile
relay WTRU is connected with an additional remote WTRU. The mobile
relay WTRU may send an indication of the set of additional services
that concern the additional remote WTRU. The estimate of the
resources may take into account all possible services that may be
used by the additional remote WTRU. The mobile relay WTRU may use
the estimation of the resources to define the resource pool
configuration for the mobile relay WTRU. The mobile relay WTRU may
take into account of the number of remote WTRUs that the mobile
relay WTRU serves. The mobile relay WTRU may send to the eNB via
RRC signaling the indication of increase in the amount of resources
when the mobile relay WTRU is connected with an additional remote
WTRU and/or the indication of the set of additional services that
concern the additional remote WTRU. The indications may be sent by
the mobile relay WTRU to the eNB via a MAC CE.
[0185] The indications may contain various information. The
indications may include the number of remote WTRUs that the mobile
relay WTRU serves. The indications may include the amount of
resources that may be used. The amount of resources that may be
used may be based on the amount of additional resources that may be
used as a result of an additional remote WTRU(s) becomes connected
with the mobile relay WTRU and/or the amount of resources that are
used by some or all of the remote WTRUs that are connected with the
mobile relay WTRU. The indications may include the loading of
resource pools that the mobile relay WTRU is experiencing. The
loading of resource pools that the mobile relay WTRU is
experiencing may be based on the mobile relay WTRU's knowledge of
scheduling resources when the mobile relay WTRU uses Mode 2. The
indications may include the additional services requested by the
additional/or a remote WTRU that is connected to the mobile relay
WTRU.
[0186] The mobile relay WTRU may report the amount of resources
and/or the services that may be used to serve remote WTRUs. In the
report, the mobile relay WTRU may indicate the number of
independent streams or destinations that it serves. The mobile
relay WTRU may indicate the data rate requested for some or all of
independent streams. The mobile relay WTRU may or may not have the
capability to transmit to multiple destination and/or independent
streams simultaneously. The eNB may use the report to provide
sufficient time-resources to the mobile relay WTRU.
[0187] Scheduling resources for D2D communications may be achieved
by various modes. The modes may include mode 1, mode 2, or enhanced
modes. In mode 1, the eNB may directly schedule the resources among
the resource pool to be used for transmission. The scheduling of
the resources may be communicated via the SA. In mode 2, the eNB
configures a resource pool. The transmitting WTRU may autonomously
decide the resources to be used for a scheduling period. Enhanced
modes may be based on and improved on mode 1 and/or mode 2. The
remote WTRU may be out-of-coverage, and may or may not receive the
pool configuration from system information. Mode 1 and/or mode 2
may be enhanced in the context of mobile relay WTRUs and scheduling
resources to be used by the remote WTRU.
[0188] Scheduling resources for D2D communications may be achieved
through various approaches that may be based enhanced modes.
Certain approaches may comprise an eNB that configures a resource
pool and WTRUs that schedule resources among resource pools.
Certain approaches may comprise an eNB that configures a resource
pool and WTRUs that segregate resources and assigned segregated
resources to remote WTRUs or groups of remote WTRUs. Certain
approaches may comprise an eNB that directly schedules resource
among resource pools. For example, an eNB may directly schedule a
resource pool for mobile relay WTRUs, and WTRUs may schedule
resources among resource pools for other WTRUs.
[0189] Certain approaches may comprise an eNB that configures a
resource pool and WTRUs that schedule resources among resource
pools. A WTRU may transmit D2D discovery or communication using
pre-configured pools and/or using pools signaled by the eNB. The
pre-configured pools may include configured pools in the device
and/or configured pools by the layer. For example, pre-configured
pools may be used when the WTRU is out-of-coverage. eNB signaled
pools may be used when the WTRU is in coverage. To allow a WTRU
(e.g., a WTRU that is out of coverage of the eNB) to communicate
with a mobile relay WTRU (e.g., a WTRU that is in coverage of the
eNB), the transmitter (TX) pool of a WTRU may reside within the
receiver (RX) pool of a different WTRU. Making the TX pool of a
WTRU reside within the RX pool of a different WTRU may be achieved
through various approaches.
[0190] The various approaches for making the TX pool of a WTRU
reside within the RX pool of a different WTRU may include a mobile
relay WTRU indicating to the eNB its own pre-configured resources
and/or the pre-configured resources of the remote WTRU. The mobile
relay WTRU may indicate to the eNB its own pre-configured resources
and/or the pre-configured resources of the remote WTRU via RRC
signaling. The mobile relay WTRU may indicate to the eNB its own
pre-configured resources when its own pre-configured resources
match the pre-configured resources of the remote WTRU. The remote
WTRU may send its preconfigured resources to the mobile relay WTRU
during connection establishment with the mobile relay WTRU. The eNB
may configure resources for the mobile relay WTRU based on the
knowledge of the pre-configured resources.
[0191] The various approaches for making the TX pool of a WTRU
reside within the RX pool of a different WTRU may include the eNB
receiving the pre-configured resources to be used by a certain
mobile relay WTRU(s) from the network and/or from the function. The
eNB may configure the pools to be used by the mobile relay WTRU
based on the information received from the network and/or the
function. The pre-configured pools may be specifically related to a
remote WTRU. If the pre-configured pools are specifically related
to a remote WTRU, the eNB may use the identification of the remote
WTRU to determine the pools to be used by the mobile relay WTRU for
communicating with the remote WTRU. The eNB may receive from the
mobile relay WTRU the identification of the remote WTRU (e.g., by
means described herein).
[0192] The resource pool configuration may be communicated to
mobile relay WTRUs and/or remote WTRUs. The eNB may determine the
resource pool(s) to be used by the mobile relay and remote WTRUs as
discussed herein. The eNB may configure the mobile relay WTRU with
the resource pool configuration. The eNB may use a R12 mechanism of
RRC signaling to configure the mobile relay WTRU. The mobile relay
WTRU may forward the resource pool configuration to remote WTRUs. A
control D2D communication message may be used to forward the
resource pool configuration to remote WTRUs. For example, the D2D
control message used to forward the resource pool configuration to
the remote WTRUs may be referred to as a D2D mobile relay resource
pool control message. The D2D mobile relay resource pool control
message may be destined for example to the RRC layer of a remote
WTRU. The D2D mobile relay resource pool control message may inform
the remote WTRU of the resource pool(s) to be utilized for future
D2D communications. The control D2D message may be identified
through a number of different ways.
[0193] The D2D mobile relay resource pool control message may be
identified through a certain SCI format (e.g., SCI format 1). The
SCI format may be used to transmit the D2D mobile relay resource
pool control message. The remote WTRU may identify data
corresponding to the D2D mobile relay resource pool control
message. The data may be forwarded to radio resource control
(RRC).
[0194] The D2D mobile relay resource pool control message may be
identified through a certain group destination ID (e.g., L2 ID).
The group destination ID may be used for the D2D mobile relay
resource pool control message. The group destination ID may be
indicated in a SCI format. For example, the SCI format may be the
SCI format 0. The SCI format 0 may schedule resource blocks to be
received/decoded on the SL-SCH. The group destination ID may allow
some or all remote WTRUs to receive a control message. For example,
the mobile relay WTRU may transmit a message to some or all remote
WTRUs that the mobile relay WTRU serves.
[0195] The D2D mobile relay resource pool control message may be
identified through a certain field or indicator in the packet data
convergence protocol (PDCP) packet header. The field and/or
indicator may indicate that a certain type of PDCP packet may be
destined for RRC control. The field and/or indicator may indicate
that the type of PDCP packet is not to be forwarded to the
application layer (e.g., but rather to a RRC layer).
[0196] The D2D mobile relay resource pool control message may be
identified through a method utilized for sending broadcast
messaging. The D2D mobile relay resource pool control message may
be identified through RRC signaling directly from the eNB. The
remote WTRU may be in coverage of the eNB when the resources for
D2D are being configured.
[0197] The remote WTRU may be signaled via the D2D mobile relay
resource pool control message to use the pre-configured resources.
The remote WTRU may be signaled prior to initial configuration.
When the D2D mobile relay resource pool control message is received
and resource pool(s) for the remote WTRU reconfigured, the remote
WTRU may listen to reconfigured pool(s). The remote WTRU may
transmit on the new pool(s) to communicate with the mobile relay. A
subsequent reconfiguration may take place in a manner discussed
herein.
[0198] Resource pool reconfiguration may include various types of
reconfiguration. The remote WTRU may be reconfigured to monitor
additional RX discovery and/or communication pools in addition to
the pre-configured RX pools. The remote WTRU may use the
pre-configured TX pools to transmit. The remote WTRU may be
reconfigured by the eNB (e.g., via the mobile relay) to monitor a
certain set of RX pools. The remote WTRU may transmit using a
certain set of TX pools for discovery and/or communication. The
mobile relay WTRU may be reconfigured to monitor a certain set of
RX pools. The mobile relay WTRU may be reconfigured by the eNB or
the function. The set of RX pools may include the pre-configured TX
pools of the remote WTRU. The mobile relay WTRU may use the initial
eNB configured TX pools to transmit.
[0199] Resource pool reconfiguration may be useful for
out-of-coverage WTRUs. Out-of-coverage WTRUs may be reached through
the use of pre-configured resources. For example, some or all
mobile relays may use pre-configured resources for initial
communication with the remote WTRUs. Pre-configured resources may
allow some or all mobile relays to establish the connection with
the remote WTRUs. Mobile relay communication may use a large amount
of resources. The eNB may control the large amount of resources
without defining the pre-configured pools to ensure the sufficient
bandwidth for mobile relay operation. The eNB may control the
resources for efficient resource management.
[0200] Resource pool reconfiguration may occur in various manners.
Resource pool reconfiguration may occur during connection
establishment. The remote WTRU may use pre-configured discovery
and/or communication resource pools to perform mobile relay
discovery and/or connection establishment. During connection
establishment, the remote WTRU may be reconfigured to use a
reconfigured set of resource pools for further communication over
the mobile relay link following reception of the reconfiguration
message. The remote WTRU may be reconfigured, at the end of the
connection establishment procedure, to use a reconfigured set of
resource pools for some or all further communication over the
mobile relay link following reception of the reconfiguration
message. The remote WTRU may be reconfigured when D2D communication
for the connection establishment procedure completes.
[0201] FIG. 10 is a diagram of an example of resource
reconfiguration. The remote WTRU 1010 may send a connection
establishment request message using pre-configured D2D
communication resources at 1002. The mobile relay WTRU 1012 may
check with the eNB 1014 to authorize the use of resources for the
remote WTRU 1010. The mobile relay WTRU 1012 may receive the
resource pools to be used by the mobile relay WTRU 1012 and remote
WTRU 1010 with the eNB authorization at 1004. The mobile relay WTRU
1012 may have received the resource pools to be used by the mobile
relay WTRU 1012 earlier. For example, the mobile relay WTRU 1012
may have received the resource pools to be used by the mobile relay
WTRU 1012 when the mobile relay WTRU 1012 was set up to operate as
a mobile relay. The mobile relay WTRU 1012 may send the connection
establishment complete message at 1006. The connection
establishment complete message may include new resource pools to be
used (e.g., the reconfigured resource). Following reception of the
connection establishment complete message, the remote WTRU 1010 may
monitor RX pools and use TX pools as specified in the resource
reconfiguration at 1008.
[0202] Resource pool reconfiguration may be accomplished through
mobile relay discovery. For example, the mobile relay WTRU may
embed the resource reconfiguration within the mobile relay
discovery message. When a remote WTRU attempts to establish a
connection with a mobile relay, the remote WTRU may transmit the
connection request using the reconfigured pools received in the
discovery announcement/response from the mobile relay.
[0203] Resource pool reconfiguration may occur during one-to-one
communication between the mobile relay WTRU and remote WTRU. The
mobile relay WTRU may send resource reconfiguration message during
a one-to-one communication between the mobile relay WTRU and remote
WTRU. The mobile relay WTRU may use the preconfigured resources
and/or resources which are previously reconfigured by the mobile
relay WTRU to send resource reconfiguration. At the reception of
the resource reconfiguration message, the remote WTRU may start to
transmit and monitor using the reconfigured pools.
[0204] Resource pool reconfiguration may occur when a remote WTRU
is in-coverage of an eNB and/or may potentially connect to a mobile
relay. For example, the remote WTRU may be moving out of the
coverage of an eNB. Some of the remote WTRU's traffic (e.g., public
safety traffic) may be moved to a mobile relay. The resource pool
reconfiguration may be received through dedicated RRC signaling to
the remote WTRU and/or through broadcast signaling (e.g., system
information block (SIB)).
[0205] The resource reconfiguration message may contain one or more
of the following: description of the TX/RX discovery/communication
pool, time validity for using the pool, and/or eNB identifier.
[0206] A remote WTRU may store a resource reconfiguration that the
remote WTRU received from an eNB and/or a mobile relay. The
resource reconfiguration may correspond to the last resource
reconfiguration received from an eNB and/or a mobile relay by the
remote WTRU. The remote WTRU may store the resource reconfiguration
in the remote WTRU's memory. If a previous resource pool
configuration exists in the remote WTRU's memory, the remote WTRU
may attempt to communicate with the mobile relay the previous pool
configuration. For example, the remote WTRU may search for
discovery signals using the previously pre-configured pools. The
remote WTRU may try to perform mobile relay connection
establishment using the previously pre-configured pools from
memory. If a connection establishment fails, another connection
establishment may be retried using the previously pre-configured
pools. If connection establishment using the previously
pre-configured pools from memory fails, the remote WTRU may delete
the previously pre-configured pools from the remote WTRU's
memory.
[0207] Scheduling resources for D2D communications may be achieved
through resource pool configuration with segregation of resource
pools (e.g., mode 2 with segregation of resource pools). The mobile
relay WTRU may receive Mode 2 resource pools from the eNB. The
mobile relay WTRU may segregate the resource pools to different
remote WTRUs or groups of remote WTRUs. The mobile relay WTRU may
autonomously select several sub-pools from the pool(s) configured
by the eNB. The mobile relay WTRU may configure different remote
WTRUs separately with the sub-pools that the mobile relay WTRU
selected from the pool(s) configured by the eNB. The mobile relay
WTRU may configure different subgroups of remote WTRUs separately
with the sub-pools that the mobile relay WTRU selected from the
pool(s) configured by the eNB. The mobile relay WTRU may determine
the amount of resources to allocate to a different remote WTRU. The
determination of the amount of resources to allocate to a different
remote WTRU may be based on expected traffic from the remote
WTRU.
[0208] The eNB and/or the network may select how the resource pools
are segregated among the mobile relay WTRU and some or all remote
WTRUs. The eNB may configure transmit resource pools for the remote
WTRUs and for the mobile relay WTRU to avoid resource collision
between and/or among transmissions. For example, the transmit
resource pools for a remote WTRU and transmit resource pools for a
mobile relay WTRU may be configured to be orthogonal to avoid
resource collision.
[0209] A number of remote WTRUs may be assigned to the same
transmit resource pool if they are known to have no risk of
interference. For example, they may not transmit simultaneously.
Their relative location may be such that there is no risk of
interference.
[0210] The eNB may assign resource pools according to potentially
static priorities associated with a WTRU. For example, the mobile
relay WTRU may have higher potentially static priorities than the
remote WTRUs. The eNB may signal to the mobile relay WTRU the
resource pool(s) to be used by the mobile relay WTRU. The eNB may
then signal the resource pool(s) to be used by a remote WTRU. The
eNB may signal the resource pool(s) to be used by a group of remote
WTRUs.
[0211] The eNB may send a number of resource pools which may be
used for mobile relay to remote WTRU communication. The mobile
relay WTRU may determine how to subdivide the resource pools among
the remote WTRUs. The mobile relay WTRU may send a pool
configuration for a remote WTRU to determine which transmission
pool that remote WTRU may use. The mobile relay WTRU may send a
pool configuration for a remote WTRU to determine which reception
pools that remote WTRU may listen to.
[0212] A remote WTRU may be configured with a selected
transmission/receive pool, and the selected resource pool may allow
it to receive transmissions from the mobile relay WTRU (e.g., based
on the mobile relay WTRUs transmission pool). For example, the eNB
may configure four transmit pools (e.g., for SA and data) to the
mobile relay WTRU to be used for mobile relay communication. The
mobile relay WTRU may decide to use one of the transmit pools for
transmission of its own communication towards the remote WTRUs. The
remaining transmit pools may then be used for the transmission of
the remote WTRUs. Some or a group of remote WTRUs may be selected
for a remaining pool. In another example, the mobile relay WTRU may
use all four pools for its transmission and configure each remote
WTRU with a single receive pool. The mobile relay WTRU may then
select the transmission pool to use for a remote WTRU that is
intended recipient of the transmission.
[0213] If the number of remote WTRUs is larger than number of
pools, the selection may be performed based on certain assignments.
The assignments may be random assignment of a number of WTRUs to
each remaining pool to ensure that approximately the same number of
remote WTRUs are assigned to each remaining pool. The priorities
may be based on the expected loading of the transmissions for a
remote and/or mobile relay WTRU. The expected loading of the
transmissions for a remote and/or mobile relay WTRU may be obtained
from the eNB and/or from the layer in the mobile relay WTRU. A
relatively equal amount of traffic transmission load may be
assigned to a transmit pool. For example, a WTRU that has a large
traffic expectation may be in a pool alone. A set of multiple WTRUs
having lesser traffic expectation may be assigned to another
pool.
[0214] The eNB may send one or more pools to the mobile relay WTRU.
A single pool may be subdivided among several remote WTRUs. This
subdivision may be done by the mobile relay WTRU. This subdivision
may be done by the eNB. A pool may be subdivided based on certain
assignment. The assignment may be to allocate a set of allowed
T-RPTs to a remote WTRU. For example, a remote WTRU may be
restricted to use a certain value of k, or a certain set of T-RPT
indices. The assignment may be based on a set of allowed scheduling
periods. For example, a remote WTRU may be assigned a certain
scheduling period or set of scheduling periods that is distinct
from another remote WTRU. The assignment may be based on a set of
allowed frequency resources. For example, the allowable frequency
resources within a D2D subframe that may be used by a WTRU may be
distinct from the allowable frequency resources that may be used by
another WTRU. The assignment may be based on a hopping pattern. For
example, the chosen hopping pattern to be used by a remote WTRU may
be such that the actual selected resources for different remote
WTRUs may be distinct.
[0215] The mobile relay WTRU and/or the eNB may select the
segregation of the resource pools based on certain criterion. The
criterion may include the relative load of a remote WTRUs
transmission. For example, the mobile relay WTRU and/or the eNB may
ensure a relative equal load for each subdivision by assigning a
number of remote WTRUs having various loads to a subdivision such
that the load on each subdivision is relatively equal to each
other. The criterion may include priority of the remote WTRU or
remote WTRUs traffic. For example, high priority WTRUs may be given
their own subdivision or a subdivision with few other WTRUs to
avoid interference with other WTRUs. The criterion may include
certain fixed/static rules. For example, a subdivision may be
assigned to a fixed number of WTRUs.
[0216] Scheduling resources for D2D communications may be achieved
through mode 1 resource pool configuration for mobile relay
transmission and mode 2 resource pool configuration for remote WTRU
transmission. The eNB may continue to use mode 1 for mobile relay
transmission (e.g., transmission of resources from the mobile relay
WTRU to the remote WTRU). The eNB may allow the remote WTRU to
transmit to the mobile relay WTRU using Mode 2. For example, a
mobile relay WTRU may be mostly used to serve broadcast traffic and
some uplink traffic from the remote WTRU to the eNB. The uplink
traffic from the remote WTRU to the eNB may include a one-to-one
communication link to the network or application server. The eNB
may configure the resource pool(s) to be used for reception by the
remote WTRU and for transmission by the remote WTRU. The resource
pool(s) may be forwarded to the remote WTRU. The eNB may then
schedule transmission by the mobile relay through DCI format 5.
[0217] Service continuity may be maintained by various approaches.
The mobile relay WTRU and/or remote WTRU may implement certain
procedures to maintain service continuity for the remote WTRU.
Service continuity may be maintained in various situations. The
mobile relay may lose connectivity to the eNB. For example, the
remote/mobile relay WTRU may go out of coverage of the eNB. A
mobile relay may be disabled by the eNB. A remote WTRU may transfer
from the use of a mobile relay to another mobile relay. A remote
WTRU may transition between in-coverage connection with an eNB and
connection via a mobile relay. For example, the transition may be
related to a transition between a Uu and PC5. A mobile relay WTRU
may be handed over from one eNB to another eNB. The eNB may assist
or control the procedures.
[0218] Service continuity may be maintained when a mobile relay
loses connectivity with the eNB. The mobile relay WTRU may send a
notification over PC5 when the mobile relay WTRU detects loss of
eNB connection. The mobile relay WTRU may send a notification or
information to the remote WTRU when the mobile relay WTRU has
determined that it may be leaving the coverage of the eNB. The
Uu-loss notification may be sent over PC5 and/or through discovery
transport or communication transport. The Uu-loss notification may
comprise a MAC CE. The Uu-loss notification may be sent using
PHY-layer signaling. For example, the Uu-loss notification may be
sent using PHY-layer signaling as part of the D2DSS, or other
channel. The Uu-loss notification may be sent using RRC layer
control signaling. The mobile relay WTRU may send the message
independently to a remote WTRU. The mobile relay WTRU may use a
mobile relay-specific broadcast mechanism to send the message.
[0219] The Uu-loss notification may sent in response to certain
triggers. The triggers may include the signal quality of the Uu
interface as seen by the mobile relay. For example, the signal
quality of the Uu interface may be seen by the mobile relay through
existing LTE measurements of downlink signal quality. The triggers
may include triggering of a RRC re-establishment procedure. The
triggers may be fixed and/or configured by the network through
signaling. For example, the signaling may include RRC signaling
over Uu. The mobile relay WTRU may trigger a Uu-loss notification
to be sent to a remote WTRU when an explicit message is received
from an eNB indicating that the mobile relay operation of the
mobile relay may be stopped.
[0220] The behavior of the mobile relay WTRU and/or the threshold
of the measured signal quality that triggers the Uu-loss
notification may be set by the network. The network may set a
threshold and potential hysteresis value to avoid that a Uu-loss
notification is triggered for a temporary drop in the signal
quality. The network may configure multiple thresholds. The
multiple thresholds may be used to trigger different behaviors in
the remote WTRU. The behaviors may be communicated along with the
Uu-loss notification to the remote WTRU. For example, if the Uu
signal quality measured by the mobile relay is determined to be
poor, or below a threshold for a time exceeding the hysteresis, the
mobile relay WTRU may send the Uu-loss notification over the PC5
interface to the remote WTRU(s) along with the indication to
perform a behavior. If the threshold is not exceeded, but another
threshold is exceeded, the Uu-loss notification may still be sent,
but with the indication to perform another behavior.
[0221] Upon reception of the Uu-loss notification, the remote WTRU
may perform certain actions. The behavior parameter indicated with
the Uu-loss notification may be used to dictate which behavior or
combination of behaviors the remote WTRU may take. The remote WTRU
may start discovery for another mobile relay. For example, it may
start to transmit model B discovery solicitations and listen to
Model B discovery responses from different mobile relays. The
remote WTRU may initiate a mobile relay re-selection procedure. The
remote WTRU may listen to Model A discovery announcements from
mobile relay WTRUs. The remote WTRU may start to measure link
quality (e.g., on PC5) of the different mobile relays which are
available and send the measurements to the higher layers, based on
discovery messages sent from the mobile relays. The higher layers
of the remote WTRU, along with the measurements provided by lower
layers, may perform mobile relay selection. The remote WTRU may try
to establish one-to-one communication with the mobile relay WTRU
that is selected.
[0222] The following may be an example of using multiple thresholds
to trigger different behaviors in the remote WTRU. If a threshold
is exceeded, for example, the remote WTRU may start discovery for
another mobile relay, listen to Model A discovery announcements,
measure link quality, and await mobile relay selection. If another
threshold is exceeded, the remote WTRU may start discovery for
another mobile relay, listen to Model A discovery announcements,
measure link quality, await mobile relay selection, and try to
establish one-to-one communication with the selected mobile relay
WTRU. If another threshold is exceeded, and a number of activities
had been performed based on the reception of a previous Uu-loss
notification, the remote WTRU may attempt to establish one-to-one
communication with the selected mobile relay, based on the already
selected mobile relay.
[0223] The mobile relay WTRU may send the remote WTRU information
that is provided by the eNB along with the Uu-loss notification.
The eNB may provide information to the remote WTRU during normal
operation of the mobile relay and/or poor connection with the
eNB.
[0224] During normal operation of the mobile relay, the eNB may
send the mobile relay WTRU a list of candidate WTRU IDs which may
replace the mobile relay to which the remote WTRU is connecting if
the mobile relay WTRU goes out of coverage. The list may be
periodically updated by the eNB and sent to the mobile relay WTRU.
The list may be sent via RRC signaling on the Uu interface. The
list may be updated by the Function and sent via the PC3
interface.
[0225] Upon detection of poor radio conditions and/or connection
problems with the eNB, the mobile relay WTRU may be configured to
transmit a D2D control message (e.g., over PC5) to signal the loss
of coverage of the mobile relay. The D2D control message used to
indicate loss of coverage may be referred to a D2D Uu backhaul loss
control message. Poor radio conditions and/or connection problems
may be detected when RLF conditions are triggered, when one or more
of T310, T311, or T301 are running or when T300 has expired, and/or
when the mobile relay WTRU uses exception resources. The D2D Uu
backhaul loss control message may be broadcasted to remote WTRUs.
For example, the broadcasting may use a pre-defined destination
address. The control message may be individually sent to a remote
WTRU using a one-to-one communication path. For example, the
one-to-one communication path may include dedicated WTRU IDs. The
D2D Uu backhaul loss control message may contain certain
information. The D2D Uu backhaul loss control message may contain
loss of coverage indication. The D2D Uu backhaul loss control
message may contain suggested WTRU ID(s) for which the remote WTRU
may try to establish a connection for continuing the service. The
WTRU ID(s) may be provided by the eNB to the mobile relay WTRU
periodically when the mobile relay WTRU is connected to the eNB.
The WTRU ID(s) may be provided when the mobile relay WTRU in
question is losing connection with the eNB. The D2D Uu backhaul
loss control message may contain a list of resources or resource
pools that may be used to communicate with a mobile relay WTRU. For
example, a remote WTRU may be asked to directly establish a
one-to-one communication with a mobile relay WTRU without
performing a full discovery procedure. The eNB may prefer
one-to-one communication. The pools for one-to-one communication
may be different from the pre-configured pools.
[0226] The remote WTRU may receive the D2D Uu backhaul loss control
message signaling the loss of coverage of the eNB by the mobile
relay. The remote WTRU may initiate discovery and/or one-to-one
communication with a suggested WTRU that may act as a replacement
mobile relay. The eNB may inform the replacement mobile relay the
role to support the remote WTRU. The eNB may configure the
replacement mobile relay with appropriate resources. For example,
the replacement mobile relay may be asked to start monitoring the
same temporary mobile group identity (TMGI) before connecting to
the remote WTRUs. The replacement mobile relay may start
transmitting the TMGI and/or E-UTRAN cell global identifier (ECGI)
announcements. For example, the pre-configuration by initiating
discovery and/or one-to-one communication with the replacement WTRU
may allow the replacement mobile relay WTRU to buffer broadcast
data in advance of the connection procedure initiated by the remote
WTRU.
[0227] Service continuity may be maintained when a mobile relay is
disabled by the eNB. The eNB may enable mobile relay context
transfer. The eNB may trigger a Uu-loss notification to force a set
of remote WTRUs to disconnect from a mobile relay. The eNB may
decide to disable or de-activate a mobile relay WTRU based on the
quality of the connection between the mobile relay WTRU and the
eNB. For example, an eNB may evaluate the link quality of the Uu
link between the mobile relay WTRU and the eNB. The evaluation may
be performed periodically evaluate. The evaluation of quality may
be based on periodic measurements of the Uu link quality that are
sent by the mobile relay WTRU to the eNB. The evaluation of link
quality may be based on a detection of loss of communication with
the mobile relay. For example, a loss of communication with the
mobile relay may be detected if the mobile relay no longer
acknowledges transmissions made by the eNB. If the link quality
goes below an acceptable threshold, the eNB may disable the mobile
relay WTRU. The eNB may select a replacement mobile relay WTRU for
the mobile relay WTRU that the eNB is about to disable or
deactivate. The eNB may transfer information to the replacement
mobile relay WTRU and/or configure the replacement mobile relay
WTRU.
[0228] The eNB may send certain information to the replacement
mobile relay WTRU. The eNB may send a mobile relay activation
message. For example, the eNB may send a mobile relay activation
message if the replacement mobile relay was not initially acting as
a mobile relay. The mobile relay activation message may trigger the
WTRU to start behaving as a mobile relay, start transmitting Model
A announcement messages, and/or listening to Model B solicitation
messages. The eNB may send a mobile relay transfer indication. For
example, the eNB may send a mobile relay transfer indication if the
replacement mobile relay WTRU is behaving as a mobile relay and may
start to serve different and/or additional remote WTRUs. The eNB
may send a list of remote WTRUs that are served by the mobile
relay. The list may include identifiers (e.g., L2 ID, PHY layer ID,
and/or the like) of the remote WTRUs. The list may include remote
WTRUs that are being transferred to the replacement mobile relay
WTRU. The eNB may send the resources or resource pools that the
mobile relay WTRU may use to transmit for D2D communications or D2D
discovery. The eNB may send the resources or resource pools on
which the mobile relay WTRU may listen for D2D communications or
D2D discovery. For example, the replacement mobile relay WTRU may
start to use the resource pools that were used by the deactivated
mobile relay. The replacement mobile relay WTRU may use the
resource pools for transmission/reception with the remote WTRUs.
The eNB may send the services to be provided to the remote WTRU(s)
and context information associated with the services. For example,
the deactivated mobile relay may have been monitoring a TMGI for
providing broadcast information. The replacement mobile relay may
or may not monitor the same TMGI. The eNB may indicate one or more
of the following information to the replacement mobile relay WTRU.
The eNB may indicate to replacement mobile relay WTRU TMGIs that
mobile relay WTRU may be configured to monitor. For example, the
TMGIs that the replacement mobile relay WTRU may be configured to
monitor may differ from the TMGIs that the deactivated mobile relay
may have been monitoring. The eNB may indicate to replacement
mobile relay the group ID for PC5 transmissions. The group ID for
PC5 transmissions may have been used by the disabled mobile relay
to communicate to send the eMBMS data to the remote WTRUs. The
remote WTRUs may or may not issue a different TMGI monitoring
request to the replacement mobile relay. The eNB may indicate to
the replacement mobile relay the specific ID (e.g., L2 IDs, PHY ID,
and/or the like) for a remote WTRU that is receiving broadcast for
a TMGI. The eNB may indicate to replacement mobile relay the
address used for the mobile relay broadcast mechanism.
[0229] The replacement mobile relay WTRU may receive the mobile
relay activation message and/or mobile relay transfer message. The
replacement mobile relay WTRU may perform certain actions. The
replacement mobile relay WTRU may start transmitting Model A
announcement or listening and responding to Model B solicitation
messages if a mobile relay activation message is received. The
replacement mobile relay WTRU may start to monitor the TMGI that
the eNB indicated to the replacement mobile relay WTRU. The
replacement mobile relay WTRU may start to transmit the broadcast
information read from the Uu interface for a TMGI over PC5 using an
associated group ID. The replacement mobile relay WTRU may use the
group ID for PC5 communication (e.g., as indicated by the eNB). The
replacement mobile relay WTRU may transmit future broadcast control
messages (e.g., Uu-loss notification message described herein). The
replacement mobile relay WTRU may use the broadcast address that it
previously used, and the replacement mobile relay WTRU may use the
broadcast address that was being used by the disabled mobile relay.
The replacement mobile relay WTRU may send a broadcast message to
the remote WTRUs which were served by the disabled mobile relay.
The broadcast message may indicate that the remote WTRUs may change
their monitored broadcast control address to the broadcast control
address of the replacement mobile relay WTRU.
[0230] Once the replacement mobile relay WTRU has been set up, the
eNB may send a mobile relay deactivation message to the mobile
relay that the eNB is disabling. The mobile relay that the eNB is
disabling may receive the mobile relay deactivation message. The
mobile relay that the eNB is disabling may stop sending Model A
discovery messages. The mobile relay that the eNB is disabling may
stop responding to Model B solicitation messages. Ongoing mobile
relay operations may be stopped. For example, one-to-one
communications with the mobile relay that the eNB is disabling may
be stopped. The mobile relay that the eNB is disabling may stop
monitoring broadcast for TMGIs that are related to its mobile relay
operation. The mobile relay that the eNB is disabling may stop
transmitting broadcast data over the PC5 link.
[0231] If a mobile relay WTRU is being disabled, and the eNB
transfers the information of the remote WTRUs to a different and/or
additional mobile relay, a Uu-loss notification message may be sent
by the mobile relay that the eNB is disabling. Behaviors related to
the transmission (e.g., by the mobile relay WTRU) and reception
(e.g., by the remote WTRU) may be applicable.
[0232] Service continuity may be maintained when a remote WTRU
transfers from a mobile relay to another mobile relay. Mobile
relay-link replacement and termination may be performed. Session
continuity and/or address maintenance may be performed at the
application layer. For example, session continuity and/or address
maintenance may be performed when a remote WTRU may perform
reselection to a different mobile relay (e.g., reselected mobile
relay) based on link quality of the link between the remote WTRU
and a previous mobile relay. The reselected mobile relay may be
notified of the previous or current mobile relay selection and/or
termination of the link with the previous mobile relay.
[0233] A remote WTRU may decide to perform reselection to a
different mobile relay (e.g., reselected mobile relay). The remote
WTRU may send information about mobile relay link that is about to
be tom down. The remote WTRU may send a mobile relay link transfer
indication to the reselected mobile relay. The mobile relay link
transfer indication and the information may be forwarded to
mobility management entity or serving gateway (MME/S-GW) to
preserve the address. Different and/or additional bearers may be
established over the reselected mobile relay. The mobile relay link
transfer indication and the information may be forwarded to
MME/S-GW to maintain the existing PDN connection. The mobile relay
link transfer indication and the information may be sent during the
establishment of the connection for one-to-one communication. The
mobile relay link transfer indication and the information may be
sent during additional message exchanges between the remote WTRU
and the mobile relay WTRU which occur at sometime between discovery
and one-to-one communication establishment.
[0234] A procedure may be used for service continuity. The
procedure may incorporate sending a mobile relay link transfer
indication along with information about mobile relay link that is
about to be tom down, terminating the mobile relay link that is
about to be tom down when the link with the reselected mobile relay
is established. The procedure may include multiple steps. The
following may be an example.
[0235] A remote WTRU may have established a connection with a
mobile relay to which a PDN connection is associated with the EPC.
The remote WTRU, based on triggers described herein, may initiate a
reselection to another mobile relay (e.g., reselected mobile
relay). The remote WTRU may initiate a one-to-one connection with
the reselected mobile relay. The remote WTRU may indicate, during
the one-to-one connection establishment, that the connection is
being established to replace a link with the mobile relay. The
remote WTRU may indicate information about the mobile relay and/or
indicate the mobile relay link transfer. The indication may include
one or more of: the IP address of the remote WTRU, identification
of the remote WTRU (e.g., L2 ID, PHY layer ID, and/or the like),
and identifier of the mobile relay 1 (e.g., L2 ID, PHY layer ID, or
destination group ID). The indication may be transferred via PC5
signaling protocol or over the higher layer message. Information
from lower layers may be obtained by the higher layers of the
remote WTRU once the decision is made to connect to a different
mobile relay. The reselected mobile relay, through NAS signaling,
may trigger a reconfiguration of the routing in the EPC to re-route
packets for the remote WTRU through the reselected mobile relay.
The actual routing reconfiguration may be performed at different
time. The actual routing reconfiguration may be performed
immediately, or it may be delayed until the mobile relay connection
is fully set up with the reselected mobile relay. Following routing
reconfiguration in the EPC, the reselected mobile relay may confirm
the proper configuration of the mobile relay to the remote WTRU.
The remote WTRU may tear-down the connection with the mobile relay,
indicating a mobile relay termination for tearing down the link.
Upon receiving the termination indication, the mobile relay may
send a NAS message to enable the previously configured
route-reconfiguration.
[0236] The remote WTRU may continue to be served by the mobile
relay until the remote/mobile relay WTRU sends the mobile relay
termination indication. For example, the remote WTRU may transmit
uplink data via the mobile relay and/or receive downlink data from
the mobile relay until the remote WTRU sends the mobile relay
termination indication. When the mobile relay termination message
is sent to the mobile relay, the remote WTRU may assume some or all
communication related to certain logical channels and mapped to
mobile relay communication are sent through reselected mobile
relay.
[0237] Mobile relay link transfer and termination may be used to
ensure service continuity between Uu and PC5 connections.
[0238] Service continuity between Uu and PC5 connections may be
maintained. Criteria may be established for initiating mobile relay
selection and connection establishment. When a WTRU is connected to
an eNB, rapid establishment of a mobile relay connection may allow
the WTRU to minimize service interruption. For example, rapid
establishment of a mobile relay connection may allow the WTRU to
minimize service interruption upon deterioration of a Uu link if
the WTRU is connected to an eNB through Uu connection. Mobile relay
connection may involve mobile relay selection and connection
establishment. A WTRU connected to the eNB may perform some steps
in preparation of potential service outage.
[0239] A WTRU connected to the eNB may continuously or periodically
perform mobile relay selection. The mobile relay selection may be
autonomous or through the assistance and/or control of the eNB. The
period for mobile relay selection may be statically configured in
the WTRU. For example, the period for mobile relay selection may be
statically configured and/or provided to the WTRU upon connection
establishment. The period for mobile relay selection may be
statically configured in the function. The period for mobile relay
selection may be configured by the eNB using RRC signaling. The RRC
signaling may be dedicated or broadcast. The period for mobile
relay selection may depend on the value of the link quality or
measurements of the eNB by the WTRU. For example, different
frequencies of mobile relay selection may apply to different ranges
of measured Uu link quality. The WTRU may maintain the information
of the latest selected mobile relay and utilize the information to
initiate a mobile relay connection based on the occurrence of
certain triggers. For example, a trigger may be to move to a mobile
relay. In response to the trigger, the WTRU may attempt a mobile
relay connection with the last selected mobile relay. Once mobile
relay selection succeeds, the WTRU may move concerned Uu traffic to
the selected mobile relay WTRU.
[0240] A WTRU connected to the eNB may start the selection process
at the occurrence of a trigger and then perform connection
establishment and movement to the selected mobile relay upon the
occurrence of another trigger.
[0241] A WTRU connected to the eNB may periodically, or based on
some trigger, perform connection establishment with a mobile relay.
The WTRU may continue to send some or all traffic over the Uu
connection until another trigger occurs. The connection may be
maintained indefinitely or tom down and re-established periodically
based on a potential selection of a mobile relay or a potential
mobile relay reselection. Data may or may not be sent over an
active mobile relay connection until the data transfer trigger
occurs. Periodical keep-alive messages may be transmitted over the
connection to maintain the quality of a mobile relay connection.
Periodical keep-alive messages may be transmitted to prompt
re-connection to a different mobile relay. For instance, keep-alive
messages may comprise discovery or communication messages sent by
the mobile relay WTRU or the remote WTRU in order to have the
receiver measure the quality of the relay connection and decide if
reselection to another mobile relay may be performed. The
keep-alive messages may be application control messages or AS
messages which may or may not contain effective data. Such messages
may be expected by the intended received, and the absence of such
messages may trigger a reselection. Such messages may also comprise
PHY signals or reference signals, allowing the receiver to measure
the signal quality of the mobile relay connection.
[0242] The triggers may include one or more of the following. The
triggers may include direct instructions by the eNB. For example,
the direct instructions by the eNB may be through a message. The
message may include an RRCReconfiguration message. The triggers may
include an indication that the Uu quality as measured by the WTRU
may fall below a threshold. The triggers may include lower layers
declaring out-of-synchronization and/or radio link failure. The
triggers may include RRC connection re-establishment failure and/or
expiry of a timer associated with RRC connection re-establishment.
The triggers may include RLC unrecoverable error. The triggers may
include handover failure.
[0243] Certain procedures that are related to connection
establishment notification and release may be implemented. A remote
WTRU may move between in-network coverage and a mobile relay
connection. The remote WTRU may initiate the transition between
in-network coverage and a mobile relay connection. The remote WTRU
may be prompted to transition between in-network coverage and a
mobile relay connection by the eNB. For example, the remote WTRU
may move from in-network coverage to a mobile relay connection. A
remote WTRU may notify network/application server/upper layers in
the remote WTRU that the remote WTRU has left the coverage. The
upper layers may be notified when data may be sent over a different
connection/bearer/IP address. The AS may initiate the different
connection.
[0244] When moving from in-network-coverage to mobile relay
connection, the remote WTRU, once it has established a connection
to the mobile relay WTRU, may notify the eNB that the mobile relay
connection was successful. The RRC connection on the Uu interface
and/or the EPC connection via the UTRAN may be released. Transfer
of data from the EPC may be started via the mobile relay
connection. The WTRU, when connecting to a mobile relay, may follow
certain procedure/process.
[0245] For example, a remote WTRU may initiate a mobile relay
selection. Mobile relay selection may be assisted by the network.
The remote WTRU may send information about its RRC connection with
the eNB to the mobile relay WTRU (e.g., via PC5 connection) during
one-to-one establishment connection. The information about its RRC
connection with the eNB may be sent as part of the higher layer
signaling to allow the mobile relay WTRU to initiate the transfer
of the traffic/session from the EUTRAN connection. The information
about its RRC connection with the eNB may include identifier of the
remote WTRU that is trying to connect to the mobile relay WTRU
(e.g., L2 ID, PHY ID, 3GPP ID, and/or the like). The information
about its RRC connection with the eNB may include address of the
remote WTRU that was previously assigned by the E-UTRAN connection.
The information about its RRC connection with the eNB may include
identification of the radio bearers over E-UTRAN whose traffic is
being transferred over PC5. The information about its RRC
connection with the eNB may include identification of the eNB to
which the remote WTRU was connected.
[0246] The remote WTRU may receive the connection establishment
success. The remote WTRU may indicate that the mobile relay WTRU
has been properly configured for network access. The remote WTRU
may send a message to the eNB to notify the eNB of the successful
establishment of the mobile relay connection. The mobile relay
WTRU, on behalf of the remote WTRU, may send the message via the Uu
link with the eNB. The message may contain various information. The
message may contain identification of the mobile relay WTRU. The
message may contain identification of the eNB serving the mobile
relay WTRU. The message may contain resource information (e.g.,
resource pools) being used to communicate with the mobile relay
WTRU. The message may contain timing information of the mobile
relay WTRU (e.g., synchronization source information). The message
may contain difference in timing with the eNB that serves the
remote WTRU. The message may contain protocol status or
configuration information (e.g., PDCP status, sequence number,
and/or configuration information).
[0247] The remote WTRU may perform certain actions. The actions may
include autonomously releasing the RRC connection after sending the
message. The actions may include deleting some or all information
associated with the radio bearers that were being used for the
service that is being transferred to the mobile relay WTRU. The
actions may include waiting for an explicit signal from the eNB to
release the RRC connection or tearing down the bearers. For
example, the eNB may send a message that signals the remote WTRU to
release the RRC connection and indicates the release is for
connecting wo the mobile relay WTRU. The actions may include
continuing to use the Uu connection for some or all services until
a criteria is met. The criteria may be for releasing the RRC
connection and/or tearing down the Uu radio bearers and
communicating through the mobile relay WTRU. Some examples of the
criteria are RSRP thresholds, detection of out-of-coverage, RLF,
and/or the like. The actions may include notifying the upper layers
of the presence of a different PC5 link and/or associated bearers.
The actions may be performed by the remote WTRU upon receiving the
connection establishment success. The remote WTRU may use the
different PC5 link and/or associated bearers to send application
data. The remote WTRU may or may not use the Uu link bearers. The
actions may include notifying the AS to transfer un-transmitted
data in the Uu radio bearer buffers (e.g., RLC) to the different
PC5 bearer.
[0248] The remote WTRU may start to assume that some or all
communications performed with the EPC may be accomplished through
the mobile relay WTRU (e.g., over the PC5 interface). The remote
WTRU may start to assume that some or all communications performed
with the EPC may not be over the Uu interface. The remote WTRU may
start to assume that the specific radio bearers have been tom
down.
[0249] When moving from mobile relay connection to network
coverage, the WTRU may provide the identification of the mobile
relay and mobile relay information to the eNB. Providing the
identification of the mobile relay and mobile relay information to
the eNB may be similar to a mobile relay WTRU to mobile relay WTRU
transfer. The WTRU may establish an RRC connection with the eNB.
The WTRU may send the mobile relay information to the network via
the eNB to transfer the EPC connection from the mobile relay to the
eNB. The WTRU may send the mobile relay information to the network
via the eNB to create a different EPC connection. A remote WTRU,
once determining it is within network coverage, may follow certain
procedure/process.
[0250] The remote WTRU, once it has determined it is within network
coverage, may initiate an RRC connection procedure with the
eNB.
[0251] The remote WTRU may send information about the mobile relay
to which it was connected. The information may be sent as part of
the NAS message in the RRC Connection Setup Complete message. The
eNB may forward the information to the MME to initiate a
reconfiguration of the routing of packets associated with the
address. The information may include identifier of the mobile relay
WTRU (e.g., L2 ID, PHY layer ID, or destination group ID). The
information may include a list of services that are provided by the
mobile relay (e.g., the list of TMGIs being monitored). The
information may include the current address that was assigned to
the remote WTRU by the mobile relay WTRU. The information may
include identification of the remote WTRU (e.g., L2 ID, PHY layer
ID, and/or the like). The information may include bearer
information about the D2D link and/or the mobile relay to eNB link.
The information may include protocol status and/or configuration
information (e.g., PDCP status, sequence number, and/or
configuration information).
[0252] The remote WTRU may send a termination indication to the
mobile relay WTRU to issue a disconnection/release from the mobile
relay WTRU. For example, the termination indication may be sent
following completion of the RRC connection and/or successful
initiation of services via the eNB. The termination indication may
be used by the mobile relay WTRU for various purposes. The
termination indication may be used by the mobile relay WTRU to
force a release of D2D resources being maintained in the mobile
relay WTRU for communication with the remote WTRU which is now
in-coverage. The termination indication may be used by the mobile
relay WTRU to notify the eNB. For example, the mobile relay WTRU
may be served by a different eNB from the eNB whose coverage the
remote WTRU is in. The termination indication may be used by the
mobile relay WTRU to confirm to the network that the transfer from
the mobile relay connection to the Uu connection has been
completed.
[0253] Upon receiving the termination indication, the mobile relay
WTRU may perform certain actions. The mobile relay WTRU may release
some or all resources/pools that may have been used to communicate
with the remote WTRU, or the mobile relay WTRU may reconfigure its
pools. For example, the reconfiguration may be based on the fact
that the remote WTRU may no longer use D2D resources. The mobile
relay WTRU may send a message to the eNB that serves the mobile
relay, if the eNB is different from the eNB whose coverage the
remote WTRU is in. Some resources may be released in the eNB that
serves the mobile relay. The resource pools may be reconfigured by
the mobile relay WTRU. The mobile relay WTRU may send a NAS message
to the network to initiate the transfer of data for the remote
WTRU's over the E-UTRAN connection.
[0254] User plane data transfer may be implemented. Data may need
to be transferred between bearers/logical channels in a manner to
avoid loss of data during a transition. A Uu radio bearer serving a
specific application and/or service over Uu may be replaced with
the combination of a PC5 bearer between the remote WTRU and mobile
relay WTRU, and a Uu radio bearer between the mobile relay and
eNB.
[0255] Certain processes and/or procedures may be implemented to
avoid loss of data during the transition. Different processes
and/or procedures may be implemented for the transfer of date from
Uu to PC5 and/or the transfer of date from PC 5 to Uu. Downlink
data may be treated differently from uplink data.
[0256] A fully lossless approach may be used for treating a
downlink data transfer from Uu to PC5. For example, the eNB may
forward RLC PDUs that have yet to be transmitted or RLC PDUs that
were transmitted but not acknowledged over the Uu link via the
mobile relay. The eNB may forward the RLC PDUs while/after it tears
down the radio bearer and/or indicate the destination remote WTRU
for which the RLC PDUs are intended. Forwarding the RLC PDUs may
involve multiple steps. The steps may include the following.
[0257] The remote WTRU may notify the eNB that a radio bearer may
be tom down as the service for that bearer may be supported through
a mobile relay (e.g., as described herein). The radio bearer may be
tom down by the eNB. For example, the radio bearer may be tom down
by the eNB by sending an RRC connection reconfiguration. The eNB
may allow the WTRU move naturally to RLF. The eNB may leave the
radio bearers active and/or stop transmitting data over the radio
bearers. The remote WTRU may delete some or all data associated
with the Uu radio bearers upon reception of the RRC connection
reconfiguration tearing down the bearers. The remote WTRU may
delete some or all data associated with the Uu radio bearers upon
receiving the data packet over the PC5 link destined to the same
application layer entity. The remote WTRU may delete some or all
data associated with the Uu radio bearers immediately after sending
the notification to the eNB that a radio bearer may be tom down.
The eNB may transfer some or all PDUs which have yet to be
transmitted over Uu to the mobile relay WTRU (e.g., following the
notification). A different bearer may be created for transferring
some or all PDUs which have yet to be transmitted over Uu to the
mobile relay WTRU. The bearer that was serving the mobile relay may
be used to transfer some or all PDUs which have yet to be
transmitted over Uu to the mobile relay WTRU. The eNB may continue
to create different and/or additional RLC from packets received
with the old WTRU address (e.g., over Uu), until the application
server stops generating the packets.
[0258] The mobile relay WTRU may be informed that a number of
packets may be sent to the remote WTRU over PC5. The packets may
contain the old address of the WTRU. The packets may be
individually identified with the identifier of the remote WTRU
(e.g., L2 ID, PHY ID, or other). The packets may be identified
through the use of a control message from the eNB to the mobile
relay WTRU. The control message may include RRC, PDCP status
report, /or the like. The message may indicate the packets to be
expected by PDCP SN, count value, /or the like. The mobile relay
WTRU may or may not rely on the correct address to route the
data.
[0259] The mobile relay WTRU may transfer the packets to the
logical channel/PC5 bearer associated with the remote WTRU. The
packets may be transferred for transmission to the remote WTRU. The
packets may be transferred before additional and/or different
packets are created from data that is transmitted to the mobile
relay serving the remote WTRU. The additional and/or different
packets may be created from data using additional and/or different
WTRU IP address that is intended for PC5.
[0260] The remote WTRU may receive the eNB-transferred packets from
the mobile relay WTRU. The remote WTRU may continue
sequencing/numbering and forwarding to upper layers. The
sequencingsequencing/numbering and forwarding to upper layers was
occurring over the Uu radio bearer.
[0261] A time-based lossless approach may be used for treating a
downlink data transfer from Uu to PC5. For example, the eNB may
send some or all PDUs that have yet to be transmitted or PDUs that
were transmitted but not acknowledged over the Uu radio bearer for
a specific time (e.g., signaled to the WTRU) before it tears down
the radio bearer. Sending the PDUs may involve multiple steps. The
steps may include the following. The remote WTRU may notify the eNB
that a radio bearer may be tom down. The service for that bearer
may be supported through a mobile relay (e.g., as described
herein). The eNB may continue to transmit some or all PDUs via the
Uu link until the eNB empties its buffers. The eNB may continue to
attempt transmission/retransmission for a certain time period. The
PDUs may be discarded or transmitted via the mobile relay WTRU upon
expiry of the time period. The eNB may continue to transmit some or
all additional/different packets via the Uu link until the eNB
empties its buffers. The eNB may continue to attempt
transmission/retransmission of additional/different packets for a
certain time period. The additional/different packets may be
discarded or transmitted via the mobile relay WTRU upon expiry of
the time period.
[0262] The remote WTRU may continue to receive data over the bearer
until it is tom down by the eNB or for a specific time period
configured in the WTRU. Upon expiry of the time or reception of the
RRC reconfiguration by the eNB tearing down the bearer, the remote
WTRU may delete some or all data associated with the corresponding
radio bearer. For example, the timer may be pre-configured in the
WTRU or configured by the eNB via RRC signaling.
[0263] A lossless-redundant approach may be used for treating a
downlink data transfer from Uu to PC5. For example, the eNB may
send some or all PDUs it received that are associated with the old
(e.g., over Uu) WTRUs address to the WTRU over the Uu link and to
the mobile relay WTRU over the PC5 link. The applicable procedures
in the mobile relay WTRU may be used. The remote WTRU may discard
duplicate packets received from both links.
[0264] A lossy approach may be used for treating a downlink data
transfer from Uu to PC5. For example, the eNB may discard some or
all packets that it has buffered and additional and/or different
packets destined to the old (e.g., via Uu) address of the WTRU. A
lossy approach may be simple. The lossy approach may result in data
loss as a result of the transition from Uu bearer to PC5 bearer.
The lossy approach may involve one or more of the following
steps.
[0265] The remote WTRU may notify the eNB that a radio bearer may
be tom down. The service for that bearer may be supported through a
mobile relay (e.g., as described herein). The eNB may discard some
or all PDCP PDUs for the radio bearers that are to be tom down. The
eNB may discard additional packets that are received and addressed
to the WTRU and destined to the radio bearers. The remote WTRU may
delete some or all data associated with the Uu radio bearers. The
remote WTRU may delete some or all data associated with the Uu
radio bearers upon reception of the RRC connection reconfiguration
tearing down the bearers. The remote WTRU may delete some or all
data associated with the Uu radio bearers upon receiving the data
packet over the PC5 link destined to the same application layer
entity. The remote WTRU may delete some or all data associated with
the Uu radio bearers after sending the notification to the eNB that
a radio bearer may be tom down.
[0266] A number of approaches may be used to treat uplink data that
the WTRU is transmitting to the eNB during the transition from Uu
to PC5.
[0267] A fully loseless approach may be used for treating an uplink
data transfer from Uu to PC5. For example, the WTRU may transfer
some or all RLC PDUs that have not been transmitted or RLC PDUs
that were transmitted but not acknowledged, from the Uu bearer to a
different PC5 bearer. The transfer of the RLC PDUs may occur (e.g.,
following the establishment of a PC5 connection). In one example,
the remote WTRU may create a different PC5 logical channel for
traffic to be sent to the service that was used and was offered
through a mobile relay. Prior to sending different packets over the
different PC5 logical channel, the remote WTRU may transfer some or
all PDCP PDUs that have not been transmitted or PDCP PDUs that were
transmitted but not acknowledged to the different logical channel.
The remote WTRU may also re-perform some or all PDCP operations
(e.g., compression, ciphering, and/or the like) on the different
packets to take into account security parameters applicable to the
link.
[0268] A time-based lossless approach may be used for treating an
uplink data transfer from Uu to PC5. For example, the WTRU may send
some or all PDUs that have yet to be transmitted or RLC PDUs that
were transmitted but not acknowledged over the Uu radio bearer for
a certain time (e.g., signaled to the WTRU). The remote WTRU, upon
receiving an RRC connection reconfiguration tearing down the bearer
or upon the expiry of a timer, may continue to transmit the PDUs
over the Uu radio bearer. Following a trigger (e.g., timer or radio
bearer tom down), the remote WTRU may discard an unsent or
unacknowledged PDUs or move them to a different PC5 bearer for
transmission.
[0269] A lossy approach may be used for treating an uplink data
transfer from Uu to PC5. For example, the WTRU may discard some or
all PDUs that have not been transmitted or PDUs that were
transmitted but not acknowledged (e.g., following the establishment
of the PC5 connection). The WTRU may discard some or all PDUs that
have not been transmitted or PDUs that were transmitted but not
acknowledged following the transmission of the indication to the
eNB that traffic related to a bearer may be forwarded through a
mobile relay. The WTRU may discard some or all PDUs that have not
been transmitted or PDUs that were transmitted but not acknowledged
following the reception of an RRC connection reconfiguration by the
eNB tearing down the Uu bearers.
[0270] An on-going service may have certain packets. The packets
may be uplink or downlink packets. The packets may be at the mobile
relay and may be delivered to the eNB or WTRU to avoid service
interruption or degradation during the transition (e.g., from
mobile relay connection (PC5) to Uu connection).
[0271] For treating uplink data, the mobile relay WTRU may send
packets residing at the mobile relay WTRU and PDUs (e.g., on the Uu
link) that were transmitted but not acknowledged to the eNB.
[0272] In an example of an Uplink transmission--PC5 to Uu, the
mobile relay WTRU may continue to empty the PDCP transmission
buffer until some or all data at the mobile relay WTRU that was
received from the remote WTRU has been transmitted without change
and acknowledged. The mobile relay WTRU may continue to empty the
PDCP transmission buffer until some or all data at the mobile relay
WTRU that was received from the remote WTRU has been transmitted
without change and acknowledged until the expiry of associated
timers or retry counters. The application in the network may
temporarily receive packets with the mobile relay-assigned source
address for the remote WTRU. For in-sequence delivery, the eNB may
buffer packets received from the WTRU (e.g., previously remote
WTRU) over the Uu connection. The eNB may wait for indication from
the PDCP entity communicating to the mobile relay WTRU before
forwarding PDCP data over the newly established Uu link radio
bearer to upper layers, for in-sequence delivery.
[0273] In an example of an Uplink transmission--PC5 to Uu, the
mobile relay WTRU may flush some/all pending data to be transmitted
to the eNB. The WTRU (e.g., previously remote) may receive from the
eNB, following the establishment of the Uu radio bearer, a status
report (e.g., PDCP or upper layer) reflecting the missing packets
or PDUs at the eNB. The WTRU may start transmission to the eNB over
the Uu radio bearer beginning with the missing packets/PDUs
reflected in the status report. The WTRU may re-transmit a certain
number or PDUs which were already transmitted over the PC5 link.
The number of PDUs to retransmit may be configured by the network
or statically set in the WTRU.
[0274] In an example of an Uplink transmission--PC5 to Uu, the
mobile relay WTRU may flush some or all pending data to be
transmitted to the eNB. The WTRU (e.g., previously remote) may
transmit PDCP PDUs which are due to be transmitted following the
tear-down of the mobile relay connection.
[0275] In an example of a Uplink transmission--PC5 to Uu, which may
be used in conjunction with one or more of other approaches
discussed herein, the remote WTRU may suspend transmission to the
mobile relay WTRU at a point in the initiation of a connection the
eNB (e.g., RACH, RRC Connection establishment, and/or the like) to
avoid transmission of data to the mobile relay which may be flushed
by the mobile relay WTRU.
[0276] For treating downlink data, the mobile relay WTRU may send
data (e.g., IP packets, pending PDCP PDUs) to the WTRU (e.g.,
previously remote). The approaches described herein for uplink may
be used for treating downlink data. The roles of the eNB and the
remote WTRU may be reversed. The approaches discussed herein may be
used for the transfer of the link between a mobile relay and
another mobile relay (e.g., for mobile relay reselection).
[0277] Service continuity may be maintained for mobile relay WTRU
handover from one eNB to another eNB. Mobility for a mobile relay
WTRU may be considered. The mobile relay WTRU may move from the
control of an eNB to another eNB. An eNB may contain information
related to the status of the WTRU as a mobile relay. The eNB may
contain mobile relay context information (e.g., D2D resource pools
used by the mobile relay). The information may be transferred from
an eNB to another eNB. In a handover procedure, the mobile relay
context of an eNB may be transferred to another eNB over the X2
interface. The information which may be transferred over the X2
interface during the handover of a mobile relay WTRU may include
one or more of: indication that the WTRU performing the handover is
acting as a mobile relay, resource pools used by the mobile relay
WTRU for D2D communication (e.g., including those specific to
mobile relay functionality), the number or list of remote WTRUs
being served by the mobile relay, and identification of the
services being used by the collection of remote WTRUs served by the
mobile relay.
[0278] Service continuity may be maintained through mobile
relay-specific broadcast mechanism. A mobile relay may be allowed
to broadcast specific messages to some or all remote WTRUs that are
served by the mobile relay. The broadcast specific messages may be
communicated to a certain mobile relay link. A broadcast specific
message may be sent to some or all the remote WTRUs that are
connected to a mobile relay WTRU via identifiers and/or transmitted
in the SL-BCH.
[0279] A mobile relay may send broadcast control information to
some or all of the remote WTRUs that are connected to the mobile
relay WTRU by addressing them by certain identifiers. The
identifiers may include a L2 ID, application ID, ProSe ID, MAC
Address, or similar identifier. The AS and/or an application layer
may use the identifiers to identify information associated with
mobile relay operation (e.g., control messaging). The identifiers
may allow the mobile relay WTRU to broadcast information specific
to a remote WTRU that is served by the mobileWTRU, or to a subset
or all remote WTRUs which are being served by the relay WTRU. The
mobile relay WTRU may or may not send unicast messages across the
one-to-one communication links to all remote WTRUs. For example,
the identifiers may allow the mobile relay WTRU to send a same
control message to remote WTRUs which may be receiving eMBMS
broadcast from the mobile relay WTRU. The remote WTRUs may or may
not have a one-to-one communication link actively established with
the mobile relay WTRU.
[0280] A broadcast mechanism may be established. The mobile relay
WTRU may send the broadcast address in the discovery message or
during mobile establishment. The mobile relay WTRU may send the
broadcast address as part of the payload of the discovery message.
The broadcast address may be sent in the discovery message such
that the remote WTRUs may listen to the broadcast address for
control information. The discovery message may be a Model A or
Model B discovery message. The broadcast address may be sent during
one-to-one mobile relay establishment. For example, the broadcast
address may be sent during authentication and security
establishment of the L2 secure link following the direct
communication request made by a remote WTRU. The broadcast address
may also be pre-configured or derived from preconfiguration. For
instance, a WTRU may derive the broadcast address it should listen
to based on its location and some specific rules in the WTRUs
pre-configuration. The broadcast address may also be derived from
the mobile relay WTRU L2 ID. The remote WTRU may determine the
broadcast address to listen to based on some specific translation
function applied to the L2 address of the mobile relay WTRU address
it is listening to or being served by.
[0281] The remote WTRU may obtain the broadcast address. The remote
WTRU may listen to control messages from the mobile relay WTRU that
are destined to the broadcast address (e.g., for as long as it uses
the services of the mobile relay WTRU). Such control messages may
come in D2D communication messages or in D2D discovery messages.
For example, even after a one-to-one link has been tom down and the
remote WTRU is listening to eMBMS broadcast through the D2D
communication transport, the mobile relay WTRU may continue to
listen to the broadcast address for messages which may be
pertaining to control sent by the mobile relay.
[0282] The broadcast messages may be transmitted in one or more
dedicated pools reserved for that effect. The specific pools where
broadcast messages may be transmitted by be given by dedicated
signaling or in the SIBs.
[0283] The broadcast message may be transmitted in the SL-BCH. An
IE may be added to the information transmitted on the SL-BCH for
WTRUs which are acting as mobile relays. Reserved bits in the
MasterInformationBlock-SL may be used to transmit the broadcast
message.
[0284] The broadcast message may contain one or more of the
following information: mobile relay WTRU identifier (e.g., L2 ID,
PHY ID, or other), identification of other mobile relays (e.g., for
mobile relay re-direction), TMGI, resource pool configuration for a
remote WTRU, and/or actions that may be performed by the remote
WTRUs. The actions may be identified a code or a few bits in the
message, where a set of bits references a specific type of action
to be performed. Actions may include one or more of the following:
start mobile/stop relay reselection, start/stop discovery or
measurements, switch to/from Uu connection, direct traffic to/from
Uu, suspend/start transmission on PC5, reselect to a
mobiledifferent relay, and/or reconfiguration of Mode 2 TX/RX pools
(e.g., command to change the utilized RXTX resource pools).
[0285] Service continuity may be maintained by using a Uu
connection and a mobile relay connection. The remote WTRU may be
able to maintain a Uu connection and a mobile relay connection. For
example, the WTRU may receive public safety traffic through a
mobile relay WTRU and may receive non-public safety traffic
directly from the eNB on the Uu interface. The mobile relay WTRU
may be connected to the same or a different eNB.
[0286] If a WTRU is being served by an eNB for public safety and
non-public safety services and the WTRU may start to move out of
coverage of the eNB, the WTRU may be moved to a mobile relay to
continue some or all public safety communication. The network may
tear down some or all bearers related to public safety
communication on the Uu link once the mobile relay link has been
established with the mobile relay WTRU. The WTRU may maintain the
connection to the eNB over the Uu interface to continue to be
served by the bearers related to non-public safety. The eNB may
send an indication to the WTRU to trigger the WTRU to select a
mobile relay. The selection may be made by the eNB or the WTRU. The
WTRU may perform connection to the mobile relay, and a connection
to the network may be established through the mobile relay. Once
the mobile relay connection is established, the network may tear
down public-safety related bearers on the Uu link and start to send
the public-safety related traffic using the mobile relay (e.g.,
using a different address or after having reconfigured the WTRU to
use the same address over the mobile relay). The WTRU may continue
to communicate over the Uu interface for non-public safety
services, and over the PC5 interface for some or all public safety
services until the WTRU is out of coverage. Procedures for loss of
coverage of the Uu link may be performed.
[0287] When having a simultaneous Uu and PC5 connection, the WTRU
may be connected to an eNB via Uu connection for non-public safety
traffic, and simultaneously connected to mobile relay WTRU for
public safety traffic which may be connected to a different eNB.
The eNB may or may not be aware of the resources used by the mobile
relay. The eNB may or may not coordinate with the Uu resources used
to communicate with the WTRU. The mobile relay WTRU transmissions
and synchronization sources may or may not be synchronized with the
timing of the eNB.
[0288] The WTRU may send, to the eNB, an identification of the
different eNB to which the mobile relay WTRU is connected. The
identification of the different eNB may be obtained by the WTRU via
eCGI announcement. Identification of the different eNB may be sent
in the mobile relay discovery message by the mobile relay WTRU, or
may be obtained during connection establishment with the mobile
relay WTRU. Using the identification of the different eNB, the eNB
may obtain the timing reference of the mobile relay WTRU (e.g., the
timing difference between the eNBs) and the mobile relay resource
information via X2.
[0289] For example, the WTRU may monitor mobile relay discovery
messages to measure potential mobile relays. Based on mobile relay
selection criteria, the WTRU or the serving eNB may select the
mobile relay WTRU which is served by another eNB. The WTRU may
perform an eCGI procedure to determine the eCGI of the eNB serving
the mobile relay WTRU. Prior to performing a connection
establishment with the mobile relay WTRU, the WTRU may send an
indication of the connection establishment to its serving eNB with
the identification of another eNB (e.g., the eNB serving the mobile
relay WTRU). The eNB serving the WTRU may obtain the timing and
resource information being utilized by the mobile relay via X2
communication with the eNB serving the mobile relay WTRU, and may
schedule ongoing resources on the Uu interface for non-public
safety data communication with the remote WTRU. The eNB may allow
the WTRU to proceed with connection establishment with the mobile
relay WTRU.
[0290] Using the identification of the different eNB, the eNB may
trigger a handover to the different eNB (e.g., if this is
possible). For example, the cell identification of the mobile relay
WTRU to which the WTRU wishes to perform a connection may be sent
to the WTRUs serving eNB. The eNB may initiate/configure
intra/inter frequency measurements in the WTRU and/or may start a
handover of the WTRU to the different eNB, while rejecting the
request to start a mobile relay connection or delaying it until
after the handover.
[0291] The WTRU may send the synchronization information and the
resource pool information of the mobile relay WTRU to its serving
eNB. For example, the remote WTRU may monitor mobile relay
discovery messages to measure potential mobile relays. Based on
mobile relay selection criteria, the remote WTRU or the serving eNB
may select the mobile relay WTRU which is served by another eNB.
The WTRU may send the synchronization reference information (e.g.,
timing difference of the synchronization source of the mobile relay
WTRU with its own serving eNB timing) to the eNB prior to
attempting to establish a connection with the mobile relay WTRU.
The eNB serving the mobile relay WTRU may adjust some or all Uu
resource assignments made to the WTRU (e.g., for non-public safety
traffic) using this information. If the mobile relay WTRU sends a
resource reconfiguration to the WTRU at a point during
communication, the WTRU may send the information to the eNB.
[0292] The WTRU, after sending information about the eNB associated
with the mobile relay, may be rejected from connecting to the
mobile relay. For example, the eNB may send a redirection to the
WTRU or may instruct the WTRU to connect to a different mobile
relay using the Uu link.
[0293] The processes described above may be implemented in a
computer program, software, and/or firmware incorporated in a
computer-readable medium for execution by a computer and/or
processor. Examples of computer-readable media include, but are not
limited to, electronic signals (transmitted over wired and/or
wireless connections) and/or computer-readable storage media.
Examples of computer-readable storage media include, but are not
limited to, a read only memory (ROM), a random access memory (RAM),
a register, cache memory, semiconductor memory devices, magnetic
media such as, but not limited to, internal hard disks and
removable disks, magneto-optical media, and/or optical media such
as CD-ROM disks, and/or digital versatile disks (DVDs). A processor
in association with software may be used to implement a radio
frequency transceiver for use in a WTRU, WTRU, terminal, base
station, RNC, and/or any host computer. WTRU-Network relay,
WTRU-Network mobile relay, and/or mobile relay may be used
interchangeably. ProSe mobile relay and mobile relay may be used
interchangeably in some scenarios.
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