U.S. patent application number 15/065120 was filed with the patent office on 2016-09-15 for reconfiguration and handover procedures for fuzzy cells.
This patent application is currently assigned to INTERDIGITAL PATENT HOLDINGS, INC.. The applicant listed for this patent is INTERDIGITAL PATENT HOLDINGS, INC.. Invention is credited to Samian Kaur, Phillip J. Pietraski, Ana Lucia A. Pinheiro, Stephen E. Terry, Carl Wang.
Application Number | 20160270140 15/065120 |
Document ID | / |
Family ID | 44351696 |
Filed Date | 2016-09-15 |
United States Patent
Application |
20160270140 |
Kind Code |
A1 |
Kaur; Samian ; et
al. |
September 15, 2016 |
RECONFIGURATION AND HANDOVER PROCEDURES FOR FUZZY CELLS
Abstract
A wireless transmit/receive unit (WTRU) for providing dual
connectivity. The WTRU may receive a reconfiguration message from a
source eNode-B that may identify a resource. The WTRU may send a
reconfiguration complete message to the source eNode-B that may
indicate that the WTRU may be configured to use the resource. The
WTRU may maintain a first connection the source eNode-B using a
component carrier while establishing a second connection to the
target eNode-B using the resource.
Inventors: |
Kaur; Samian; (Plymouth
Meeting, PA) ; Pietraski; Phillip J.; (Jericho,
NY) ; Pinheiro; Ana Lucia A.; (Portland, OR) ;
Terry; Stephen E.; (Northport, NY) ; Wang; Carl;
(Melville, NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
INTERDIGITAL PATENT HOLDINGS, INC. |
Wilmington |
DE |
US |
|
|
Assignee: |
INTERDIGITAL PATENT HOLDINGS,
INC.
Wilmington
DE
|
Family ID: |
44351696 |
Appl. No.: |
15/065120 |
Filed: |
March 9, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13703343 |
Apr 15, 2013 |
9326211 |
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PCT/US2011/040066 |
Jun 10, 2011 |
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15065120 |
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61353639 |
Jun 10, 2010 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W 76/27 20180201;
H04W 74/0833 20130101; H04W 36/18 20130101; H04L 5/0035 20130101;
H04W 36/28 20130101; H04W 76/15 20180201; H04W 24/10 20130101; H04W
36/0072 20130101; H04W 36/30 20130101 |
International
Class: |
H04W 76/02 20060101
H04W076/02; H04W 74/08 20060101 H04W074/08; H04W 76/04 20060101
H04W076/04; H04W 24/10 20060101 H04W024/10 |
Claims
1. An apparatus for providing dual connectivity for a wireless
transmit/receive unit (WTRU), the apparatus comprising: a
processor, the processor being configured to: send an allocation
request to a target eNode-B to request a resource for the WTRU;
receive an acknowledgement message from the target eNode-B
indicating that the resource has been allocated for the WTRU; and
send a reconfiguration message to the WTRU to instruct the WTRU to
maintain a first connection to the source eNode-B using a component
carrier while establishing a second connection to the target
eNode-B using the resource.
2. The apparatus of claim 1, wherein the component carrier is a
first component carrier and the resource is a second component
carrier.
3. The apparatus of claim 1, wherein the processor is further
configured to receive a reconfiguration complete message from the
WTRU indicating that the WTRU is configured to use the
resource.
4. The apparatus of claim 1, wherein the processor is further
configured to notify the target eNode-B that the WTRU is configured
to use the resource.
5. The apparatus of claim 1, wherein the processor is further
configured to identify the resource.
6. The apparatus of claim 1, wherein the processor is further
configured to receive a measurement report from the WTRU.
7. The apparatus of claim 1, wherein the processor is further
configured to receive a recommendation message from the target
eNode-B that identifies the resource.
8. An apparatus for providing dual connectivity for a wireless
transmit/receive unit (WTRU), the apparatus comprising: a
processor, the processor being configured to: receive an allocation
request from a source eNode-B that requests a resource for the
WTRU; send an acknowledgement message to the source eNode-B
indicating that the resource has been allocated for the WTRU; and
establishing a connection to the WTRU using the resource such that
the WTRU can also maintain a connection to the source eNode-B using
a component carrier.
9. The apparatus of claim 8, wherein the acknowledgement message
further indicates that the resource can be used to split data
between the source eNode-B and the target eNode-B.
10. The apparatus of claim 8, wherein the component carrier is a
first component carrier and the resource is a second component
carrier.
11. The apparatus of claim 8, wherein the processor is further
configured to receive a reconfiguration complete message from the
source eNode-B indicating that the WTRU is configured to use the
resource.
12. The apparatus of claim 1, wherein the allocation request
identifies the resource.
13. The apparatus of claim 1, wherein the processor is further
configured to send a recommendation message to the source eNode-B
that identifies the resource.
14. A wireless transmit/receive unit (WTRU) for providing dual
connectivity, the WTRU comprising: a processor, the processor being
configured to: receive a reconfiguration message from a source
eNode-B that identifies a resource; sending a reconfiguration
complete message to the source eNode-B that indicates that the WTRU
is configured to use the resource; and maintaining a first
connection to the source eNode-B using a component carrier while
establishing a second connection to the target eNode-B using the
resource.
15. The WTRU of claim 14, wherein the component carrier is a first
component carrier and the resource is a second component
carrier.
17. The WTRU of claim 14, wherein the processor is further
configured to receive data via the first component carrier and the
second component carrier.
18. The WTRU of claim 14, wherein the processor is further
configured to establish the second connection to the target eNode-B
using the resource by establishing the second connection via a
random access procedure.
19. The WTRU of claim 14, wherein the processor is further
configured to send a measurement report to the source eNode-B.
20. The WTRU of claim 14, wherein the processor is further
configured to receive the reconfiguration message via medium access
control (MAC) or a radio resource control (RRC) signaling.
Description
[0001] This application is the continuation of U.S. patent
application Ser. No. 13/703,343 filed on Dec. 10, 2012, which is
the 35 U.S.C. .sctn.371 National Stage of Patent Cooperation Treaty
Application No. PCT/US2011/040066 filed on Jun. 10, 2011, which
claims the benefit of U.S. provisional application No. 61/353,639
filed on Jun. 10, 2010, the contents of which are hereby
incorporated by reference herein, for all purposes.
BACKGROUND
[0002] In wireless networking, component carrier cooperation among
multiple component carriers may be utilized to increase data
throughput. For example, a fuzzy cell deployment may enable a user
equipment (UE) to stay near cell center by handing over the UE to
multiple component carriers (CCs) at different locations.
Conventional support of component carrier cooperation takes place
at a single serving eNode-B.
SUMMARY
[0003] With the introduction of fuzzy cells, simultaneously
maintaining data connections from multiple CCs on multiple eNode-Bs
may be needed. Moreover, it may be desirable to fully realize the
benefits of the data throughput increased by fuzzy cell
deployment.
[0004] As disclosed herein, component carrier cooperation (CCC) may
be implemented among different component carriers across multiple
sites to increase the cell-edge user data throughput. The component
carrier cooperation may include carrier specific reconfiguration
and handover procedures for fuzzy cells.
[0005] For example, a UE may transmit data via multiple component
carriers associated with multiple eNode-Bs. The UE may receive a
component carrier cooperation handover command from a source
eNode-B. While maintaining a connection with a component carrier on
the source eNode-B, the UE may establish a connection with another
component carrier on a target eNode-B based on the component
carrier cooperation handover command.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] FIG. 1A is a system diagram of an example communications
system in which one or more disclosed embodiments may be
implemented.
[0007] 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.
[0008] 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.
[0009] FIG. 2 depicts example primary and secondary cells.
[0010] FIG. 3 illustrates example measurement events that may be
used to support secondary cell handovers.
[0011] FIG. 4 illustrates fuzzy cell concept with non-uniform Tx
power and cooperative Tx from multiple site.
[0012] FIG. 5 illustrates an example access stratus for data
splitting for fuzzy cells.
[0013] FIG. 6 depicts another example access stratum for data
splitting for fuzzy cells.
[0014] FIG. 7 illustrates example data flow split procedures at an
eNode-B.
[0015] FIG. 8 illustrates example hard handover procedures.
[0016] FIG. 9 illustrates an example fuzzy cell deployment.
[0017] FIG. 10 illustrates an example two base-station fuzzy cell
deployment.
[0018] FIG. 11 depicts example reconfiguration procedures for fuzzy
cells.
[0019] FIG. 12 illustrates another example two base-station fuzzy
cell deployment.
[0020] FIG. 13 illustrates another example two base-station fuzzy
cell deployment.
[0021] FIG. 14 illustrates example fuzzy cell deployments.
[0022] FIG. 15 illustrates an example method for handover
triggering with fuzzy cell development.
[0023] FIGS. 16A-B illustrate downlink fuzzy cell coverage.
[0024] FIG. 17 illustrates example asymmetric uplink channel
allocation.
[0025] FIG. 18 illustrates fuzzy cell concept in heterogeneous
networks.
[0026] FIG. 19 illustrates an example embodiment for fast
activation/deactivation for fuzzy cells.
DETAILED DESCRIPTION
[0027] As disclosed herein, component carrier cooperation (CCC) may
be implemented among different component carriers across multiple
sites to increase the cell-edge user data throughput. The component
carrier cooperation may include carrier specific reconfiguration
and handover procedures for fuzzy cells.
[0028] For example, a UE may transmit data via multiple component
carriers associated with multiple eNode-Bs. The UE may receive a
component carrier cooperation handover command from a source
eNode-B. While maintaining a connection with a component carrier on
the source eNode-B, the UE may establish a connection with another
component carrier on a target eNode-B based on the component
carrier cooperation handover command.
[0029] In one example embodiment, a source eNode-B may enable
and/or perform a handover of a wireless transmit/receive unit
(WTRU) that may be transmitting via a plurality of component
carriers, the method comprising. The eNode-B may receive a
measurement report from the WTRU. The measurement report may
comprise a first signal quality of a first component carrier and a
second signal quality of a second component carrier. The
measurement report may comprise a channel quality indication (CQI)
for each secondary serving cell (Scell) associated with a cell
identification and associated with either the eNode-B or the target
eNode-B. The measurement report may identify a differential seen in
a channel estimation between one or more Scells associated with a
cell identification. The measurement report may comprise carrier
specific time to trigger (TTT) values.
[0030] The source eNode-B may transmit a component carrier
cooperation (CCC) handover command to a target eNode-B. A second
component carrier associated with the target eNode-B may be
identified. The second component carrier may be identified by
analyzing a measurement report received from the WTRU. The CCC
handover command may instruct the target eNode-B to establish the
second connection to the WTRU using the second component
carrier.
[0031] The source eNode-B may receive a recommendation message from
the target eNode-B that may identify the second component
carrier.
[0032] The source eNode-B may transmit a reconfiguration message to
the WTRU. The reconfiguration message may instruct the WTRU to use
the second component carrier associated with the target eNode-B.
The reconfiguration message may be sent via medium access control
(MAC) or radio resource control (RRC) signaling.
[0033] The source eNode-B may instruct the WTRU to establish a
second connection to the target eNode-B using the second component
carrier associated with the target eNode-B while a first connection
to the WTRU using a first component carrier associated with the
source eNode-B may be maintained. This may be done, for example,
via the CCC handover command.
[0034] In another example embodiment, a WTRU may enable and/or
perform handover of the WTRU. A measurement report may be
generated. The measurement report may indicate that a handover
event occurred. Additionally, the measurement report may comprise a
first signal quality of a first component carrier and a second
signal quality of a second component carrier. The measurement
report may comprise a channel quality indication (CQI) for each
secondary serving cell (Scell) associated with a cell
identification and associated with either the eNode-B or the target
eNode-B. The measurement report may identify a differential seen in
a channel estimation between one or more Scells associated with a
cell identification. The measurement report may comprise carrier
specific time to trigger (TTT) values. The measurement report may
enable a CCC handover command to be transmitted to a target
eNode-B, the CCC handover command may instruct the target eNode-B
to establish a second connection to the WTRU using the second
component carrier.
[0035] The WTRU may transmit the measurement report to the source
eNode-B.
[0036] The WTRU may receive a handover request message from the
source eNode-B. The handover request message may instruct the WTRU
to use the second component carrier and may be received via medium
access control (MAC) or radio resource control (RRC) signaling.
[0037] In another example embodiment, a target eNode-B may enable
and/or perform handover of a wireless transmit/receive unit (WTRU)
that may send data via a plurality of component carriers. The
target eNode-B may receive a component carrier cooperation (CCC)
handover command from a source eNode-B, the CCC handover command
may identify a second component carrier. The CCC handover command
may instruct the target eNode-B to establish a second connection to
the WTRU using the second component carrier.
[0038] The target eNode-B may transmit an acknowledgement message
to the source eNode-B, the acknowledgement message may indicate
that the second component carrier may be available. The
acknowledgement may enable the source eNode-B to instruct the WTRU
to use the second component carrier.
[0039] The target eNode-B may establish, while a WTRU maintains a
first connection with a first component carrier associated with the
source eNode-B, a second connection with a second component carrier
associated with a target eNode-B. This may be done, for example,
via a component carrier cooperation handover command. Establishing
the second connection with the second component carrier may
comprise enabling the WTRU to use the second component carrier via
medium access control (MAC) or radio resource control (RRC)
signaling.
[0040] The target eNode-B may transmit a recommendation message
identifying a third component carrier associated with the target
eNode-B.
[0041] In another example embodiment, a WTRU may enable and/or
perform handover of the WTRU. The WTRU may receive an initial
configuration message. The initial configuration message may enable
the WTRU to use a first component carrier and a second component
carrier.
[0042] The WTRU may generate measurement report. The measurement
report may indicate that a handover event occurred. Additionally,
the measurement report may comprise a first signal quality of a
first component carrier and a second signal quality of a second
component carrier. The measurement report may comprise a channel
quality indication (CQI) for each secondary serving cell (Scell)
associated with a cell identification and associated with either
the eNode-B or the target eNode-B. The measurement report may
identify a differential seen in a channel estimation between one or
more Scells associated with a cell identification. The measurement
report may comprise carrier specific time to trigger (TTT) values.
The measurement report may enable a CCC handover command to be
transmitted to a target eNode-B, the CCC handover command may
instruct the target eNode-B to establish the second connection to
the WTRU using the second component carrier.
[0043] The WTRU may transmit the measurement report to a source
eNode-B. The WTRU may receive a handover request message from the
source eNode-B. The handover request message may instruct the WTRU
to perform MAC fast activation and MAC fast deactivation. The WTRU
may perform MAC fast deactivation to disconnect a first connection
to the source eNode-B with a first component carrier associated
with the source eNode-B. The WTRU may perform MAC fast activation
to establish a second connection to the target eNode-B with a
second component carrier associated with the target eNode-B. The
WTRU may receive an initial configuration message, the initial
configuration message enabling the WTRU to use the first component
carrier and the second component carrier.
[0044] 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 the like.
[0045] As shown in FIG. 1A, the communications system 100 may
include wireless transmit/receive units (WTRUs) 102a, 102b, 102c,
102d, a radio access network (RAN) 104, a core network 106, 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 the like.
[0046] 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 at least one of the WTRUs 102a, 102b, 102c, 102d to
facilitate access to one or more communication networks, such as
the core network 106, 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 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.
[0047] The base station 114a may be part of the RAN 104, 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.
[0048] The base stations 114a, 114b may communicate with one or
more of the WTRUs 102a, 102b, 102c, 102d over an air interface 116,
which may be any suitable wireless communication link (e.g., radio
frequency (RF), microwave, infrared (IR), ultraviolet (UV), visible
light, etc.). The air interface 116 may be established using any
suitable radio access technology (RAT).
[0049] 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 the like. For example, the base station 114a in the RAN 104 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 116 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).
[0050] 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 116 using Long Term Evolution (LTE) and/or LTE-Advanced
(LTE-A).
[0051] 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 the like.
[0052] 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 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.
[0053] The RAN 104 may be in communication with the core network
106, 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 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
104 and/or the core network 106 may be in direct or indirect
communication with other RANs that employ the same RAT as the RAN
104 or a different RAT. For example, in addition to being connected
to the RAN 104, which may be utilizing an E-UTRA radio technology,
the core network 106 may also be in communication with another RAN
(not shown) employing a GSM radio technology.
[0054] The core network 106 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 104 or a
different RAT.
[0055] 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.
[0056] 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 106,
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.
[0057] 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 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.
[0058] 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 116. 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.
[0059] 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 116.
[0060] 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.
[0061] 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 106 and/or the removable memory 132. The
non-removable memory 106 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 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).
[0062] 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
the like.
[0063] 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 116 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 method
while remaining consistent with an embodiment.
[0064] 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.RTM. module, a
frequency modulated (FM) radio unit, a digital music player, a
media player, a video game player module, an Internet browser, and
the like.
[0065] FIG. 1C is a system diagram of the RAN 104 and the core
network 106 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 106.
[0066] The RAN 104 may include eNode-Bs 140a, 140b, 140c, 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 140a, 140b, 140c 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 140a, 140b, 140c may
implement MIMO technology. Thus, the eNode-B 140a, for example, may
use multiple antennas to transmit wireless signals to, and receive
wireless signals from, the WTRU 102a.
[0067] Each of the eNode-Bs 140a, 140b, 140c 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 the like. As shown in FIG.
1C, the eNode-Bs 140a, 140b, 140c may communicate with one another
over an X2 interface.
[0068] The core network 106 shown in FIG. 1C may include a mobility
management gateway (MME) 142, a serving gateway 144, and a packet
data network (PDN) gateway 146. 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.
[0069] The MME 142 may be connected to each of the eNode-Bs 142a,
142b, 142c in the RAN 104 via an S1 interface and may serve as a
control node. For example, the MME 142 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 the
like. The MME 142 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.
[0070] The serving gateway 144 may be connected to each of the
eNode Bs 140a, 140b, 140c in the RAN 104 via the S1 interface. The
serving gateway 144 may generally route and forward user data
packets to/from the WTRUs 102a, 102b, 102c. The serving gateway 144
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 the like.
[0071] The serving gateway 144 may also be connected to the PDN
gateway 146, 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.
[0072] The core network 106 may facilitate communications with
other networks. For example, the core network 106 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 106 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
106 and the PSTN 108. In addition, the core network 106 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.
[0073] FIG. 2 depicts example primary cells, such as primary
serving cells, and secondary cells, such as secondary serving
cells.
[0074] As disclosed herein, component carrier cooperation (CCC) may
be implemented among different component carriers across multiple
sites to increase the cell-edge user data throughput. The component
carrier cooperation may include carrier specific reconfiguration
and handover procedures for fuzzy cells. For example, a UE may
transmit data via multiple component carriers associated with
multiple eNode-Bs. The UE may receive a component carrier
cooperation handover command from a source eNode-B. While
maintaining a connection with a component carrier on the source
eNode-B, the UE may establish a connection with another component
carrier on a target eNode-B based on the component carrier
cooperation handover command.
[0075] As illustrated in FIG. 2, handover in LTE advanced carrier
aggregation may include changing a Primary Serving Cell (PCell),
such as PCell 210. If the target cell belongs to the same carrier
frequency as the source, then the handover may be an
intra-frequency handover as the target cell and the source may be
intra-frequency neighbors, such as intra-frequency neighbors 230.
If the target cell belongs to another carrier frequency than the
source, then the handover may be an inter-frequency as the target
cell and the source may be inter-frequency neighbors, such as
inter-frequency neighbors 240. Activation and deactivation may
refer to Secondary Serving Cells (SCells), such as SCell 220, as a
carrier can still be active from a mobility measurement viewpoint
while being deactivated from a Dedicated Physical Control Channel
(PDCCH) viewpoint.
[0076] At Radio Resource Control (RRC) connection establishment
and/or re-establishment, one serving cell may provide security
input, such as ECGI, PCI and/or ARFCN, and the NAS mobility
information (e.g. TAI). The serving cell may be referred to as the
PCell, such as PCell 210. For example, in the downlink, the carrier
corresponding to the PCell 210 may be the Downlink Primary
Component Carrier (DL PCC). In the uplink, the carrier
corresponding to the PCell 210 may be the Uplink Primary Component
Carrier (UL PCC).
[0077] Depending on the capabilities of a UE, SCells, such as Scell
220, may be configured to form, together with the PCell, such as
PCell 210, a set of serving cells. For example, in the downlink,
the carrier corresponding to SCell 220 may be a Downlink Secondary
Component Carrier (DL SCC). In the uplink, the carrier
corresponding to SCell 220 may be an Uplink Secondary Component
Carrier (UL SCC). The configured set of serving cells for the UE
may include one PCell and zero, one or more SCells. The PCell, such
as PCell 210, may be changed with handover procedure, for example,
with security key change and/or RACH procedure.
[0078] FIG. 3 illustrates example measurement events that may be
used to support secondary cell handovers. For example, to support
secondary cell handovers, measurement event A6 may be introduced.
Measurement event A6 may be an event in which an intra-frequency
neighbor may become offset better than a SCell for which neighbor
cells on an SCC are compared to the SCell of that SCC.
[0079] FIG. 4 illustrates fuzzy cell concept with non-uniform Tx
power and cooperative Tx from multiple site.
[0080] In current and evolving cellular systems, it is generally
difficult to offer uniform user experience, e.g., throughput and
QoS, as user experience at cell-edge may be limited by interference
from other cells. Component carriers may be used to mitigate the
cell edge problem where the UE is in the good coverage of a certain
component carrier at a given time. Overlaying Component Carriers
(CCs) with different cell edges by coordinating adjacent eNode-Bs
(cell sites) may vary the transmit power of each CC in a way that
changes the distance to the cell edge. Overlaying CCs may enable
the UE to stay near a cell center by handing the UE over to
different CCs at different locations while the network may maintain
a desirable frequency reuse factor, for example, a frequency reuse
factor of 1.
[0081] As shown in FIG. 4, in a fuzzy cell, the UE may receive data
from multiple CCs originating from multiple sites. For example, at
410, the UE 102 may receive high data throughput by using carrier
aggregation using two CCs, e.g. CC A and CC B from a first site
such as eNode-B 430. When UE 102 moves to 420, data rate may be
maintained with CC A from eNode-B 430, while CC B may be with a
second site such as eNode-B 440. eNode-B 430 and/or eNode-B 430 may
be eNode-B 140 shown with respect to FIG. 1C. Referring again to
FIG. 4, in one embodiment, the first and/or the second site may be
an eNode-B, a RRH, or the like.
[0082] In one embodiment, data flow splitting may be determined. To
support the data for a UE across multiple sites, how to split and
route the corresponding data amongst multiple sites may be
determined. The determination may be based on the quality of
service (QoS) requirements of the UE and/or the average load being
experienced at each CC. Each data flow may be assigned with
resources such as transmission capacity and latency and/or
retransmission buffering that may support the requested QoS. The
average expected load at each CC may be derived by network planner,
but the instantaneous resources available for a UE on a CC may
depend on the channel conditions and may be dynamically allocated
by the eNode-B scheduler. Determining how much data may be sent to
each CC may depend on resource availability at each cooperating
site.
[0083] FIG. 5 illustrates an example access stratus for data
splitting for fuzzy cells. In an example embodiment, data flow
splitting may be implemented at the access stratum in the serving
or master eNode-B, such as eNode-B 430. As shown in FIG. 5, the
data may be split at the MAC layer in the transmission entity
(eNode-B) access stratum stack, based on a scheduling decision. The
base station may make scheduling decisions based on dynamic input
from the UE as well as one or more candidate eNode-Bs. The Hybrid
ARQ functionality may be left unchanged. For example, the HARQ
acknowledgements may be routed to the corresponding eNode-B on the
PUCCH channels. In this embodiment, data may be sent to the master
eNode-B, such as eNode-B 430, and then a portion of that data may
be re-routed to the other eNode-B(s), such as eNodeB 440.
[0084] FIG. 6 depicts another example access stratum for data
splitting for fuzzy cells. In another embodiment, data flow
splitting may be implemented at the Core Network, for example, at
the serving gateway (S-GW) to send separate flows of data to the
participating eNode-Bs, such as eNode-B 430 and/or 440. The
configuration and UE-Context control entity in core network (EMM
and S-GW) and RAN (RRC) may be extended to exchange configuration
over a modified S1 interface, such as IP Packet 510, to configure
and support S-GW data-split subflows to different eNode-Bs, such as
eNode-B 430 and/or 440. This embodiment may reduce the load in the
backhaul, and may reduce duplication of traffic flows due to data
flow splitting at the source eNode-B.
[0085] FIG. 7 illustrates example data flow split procedures at an
eNode-B. At 710, multiplexing may take into account the available
bandwidth from the other side then FORWARD RLC PDU as part of data
multiplexing. At 720, the MAC scheduler may assume semi-persistent
scheduling when handling payload selection for CA cell in other
sites. The perceived bandwidth may be updated periodically by
participating sites. At 730, an X2 interface tunneling path may
need to be established during CA cell configuration to support
forwarding of RLC PDU. At 740, X2 signaling for control info
exchange between CA cells. At 750, a new buffering entity may need
to be introduced to support inter-working MAC relay to minimize the
impact of X2 interface latency. Note that the RLC PDU resizing
support may not be desirable to minimize introduced complexity. At
760, the MAC scheduler at participating site may perform NORMAL
scheduling with one adjustment. The RLC PDU size may be fixed as
delivered by serving eNode-B. The scheduler may have one new
responsibility that may be to estimate guarantee BW (bit rate)
periodically and provides it to serving eNode-B via X2
signaling.
[0086] FIG. 8 illustrates example hard handover procedures. As
shown in FIG. 8, when a UE in CONNECTED mode moves between two
cells, backward handover or predictive handover may be carried out.
In this type of handover, the source cell, based on measurement
reports from the UE, may determine the target cell and may query
the target cell if the target cell has enough resources to
accommodate the UE. The target cell may also prepare radio
resources before the source cell may command the UE to handover to
the target cell.
[0087] In one example embodiment, each eNode-B in a synchronized
deployment of eNode-Bs may be capable of supporting UEs on multiple
CCs. The UE may be capable of receiving a set of CCs where each CC
may correspond to a site. For example, each CC may be transmitted
from a different site. In current frameworks, support for carrier
aggregation is typically limited to one serving eNode-B. A UE would
have one RRC connection with the network, with one special cell
that provides security and NAS information.
[0088] As shown in FIG. 4, at 410, the UE may be associated with an
RRC connection with eNode-B 430, and established component carrier
set of CC A and CC B. Hence, the UE may be associated with a
serving cell or special cell at eNode-B 430, and may get the
security and NAS mobility information from eNode-B 430 until a
serving cell handover takes place. However, a UE may have
difficulty maintaining a data connection simultaneously from a CC
on different eNode-B, such as eNode-B 440, than eNode-B 430. As
shown in FIG. 4, when the UE moves into a location where there is a
coverage overlap from CCs on two different eNode-Bs, such as at
420, the network radio resource management (RRM) entity may need to
determine whether to handover to another site.
[0089] FIG. 9 illustrates an example fuzzy cell deployment. To
implement carrier specific handover in a fuzzy cell deployment, a
UE context with the target eNode-B may be established before actual
handover procedure. This may allow the UE to begin to receive
user-plane traffic from the target eNode-B, while continuing to
receive traffic from the source eNode-B. As shown in FIG. 9,
eNode-B 930 and eNode-B 940 may be deployed with CCs on two
frequencies, which are represented by the slashed area and the
dotted area. For example, eNode-B 930 may deploy with CC A and
eNode-B 940 may deploy with CC B. eNode-B 930 and/or 940 may be
eNode-B 140 shown with respect to FIG. 1C.
[0090] Referring again to FIG. 9, eNode-B 930 may be the master
eNode-B, and eNode-B 940 may be the cooperating eNode-B. In FIG. 9,
PCell 938 may be the primary serving cell associated with the
master eNode-B, and Scell 935 may be the secondary serving cell
associated with the master eNode-B. UE 102 may be connected to a
source eNode-B, such as eNode-B 930, and may be handed over to a
target eNode-B, such as eNode-B 940. At 910, UE 102 may be
connected to eNode-B 930 via a PCell such as cell Pcell 938 and a
SCell such as 935.
[0091] In one example embodiment, RRC based handover procedure may
be extended to enable carrier level fuzzy handovers. In another
example embodiment, Scell fast activation/deactivation procedures
may be extended to enable fuzzy handovers.
[0092] FIG. 10 illustrates an example two base-station fuzzy cell
deployment. As shown in FIG. 10, eNode-B 1030 and eNode-B 1040 may
be deployed with CCs on different frequencies; the slashed area and
the dotted area represent the different frequencies. UE 102 may be
connected to a source eNode-B, such as eNode-B 1030, and may be
handed over to a target eNode-B, such as eNode-B 1040. This
embodiment may be used to trigger data-splitting operations when a
UE moves in a straight line from eNode-B 1030 to eNode-B 1040.
eNode-B 1040 and/or eNode-B 1040 may be eNode-B 140 shown with
respect to FIG. 1C.
[0093] As shown in FIG. 10, at 1010 UE 102 may be connected to
eNode-B 1030 via a PCell such as cell A2 and a SCell such as cell
A1. In one example, the UE may have two QoS services configured
including a QoS for VoIP calls and a QoS for data calls. As shown,
eNode-B 1030 may route the data traffic on A1 and A2.
[0094] When UE 102 moves from 1010 to 1015, eNode-B 1030 may
continue to route traffic through A2. Based on the channel
conditions, as UE 102 moves towards the cell-edge of A1, the
scheduling decision at eNode-B 1030 may redirect most UE traffic
through A2, and may prioritize VoIP traffic to prevent voice
quality from degrading at cell edge. The measurement report may
include signal quality of each component carrier of neighbor
eNode-Bs. UE 102 may measure the pilot signal strength of each
component carrier of neighboring eNode-Bs using the different FFT
modules. For example, UE 102 may measure the piolot signal strength
of each component carrier of eNode-B 1040. FIG. 11, which will be
further described, below depicts example reconfiguration procedures
for fuzzy cells.
[0095] As shown in FIG. 10, as UE 102 continues to move from 1015
to 1020, the source eNode-B may identify and select an appropriate
target carrier on the target eNode-B. For example, eNode-B 1030 may
select B1 on eNode-B 1040 based on measurement report, the carrier
load and/or the like. The target eNode-B such as eNode-B 1040 may
override the selection decision based on load and/or scheduling
metrics of the target eNode-B.
[0096] Upon selecting a target carrier, eNode-B 1030 may send a
handover request message, such as a CCC Reconfiguration Request
message, to eNode-B 1040 to request the preparation of a handover.
For example, the handover command may be referred to as CCC-HO
command requests the use of B1 as a borrowed resource or CCC. The
eNode-B 1040 may check whether the selected target component
carrier may be used as a CCC. If eNode-B 1040 may accommodate the
UE using the selected CCC, it sends an ACK to the source eNode-B
(eNode-B 1030). The target eNode-B (eNode-B 1040) may recommend a
new component carrier to the source eNode-B (eNode-B 1030).
[0097] UE 102 may be configured to use the new cell B1 by either
MAC or RCC signaling.
[0098] When the random access procedure with the target eNode-B is
successfully completed, the UE may be able to start using B1 as a
secondary component carrier. The UE may need to send an RRC
establishing completion message to the network on completion of
synchronization. In one embodiment, if data-splitting is being
performed at the S-GW, a message may also be relayed to eNode-B
1040. This may be done to allow creation of the RRC connection in
eNode-B 1040.
[0099] In one embodiment, data-splitting may be performed in the
access stratum at source eNode-B (eNode-B 1030). eNode-B 1030 may
initiate data-splitting through the inter-working function (IWF).
In another embodiment, data-splitting is performed in the S-GW. In
this embodiment, after receiving the RRC establishing completion
message, eNode-B 1030 or eNode-B 1040 may send a data-splitting
request to the S-GW. The S-GW may decide (based on service QCI and
delay requirements) to either bi-cast or data-split each incoming
GTP tunnel. For example, the S-GW might decide to send the VoIP
packets to both source eNode-B (eNode-B 1030) and target eNode-B
(eNode-B 1040) and non-VoIP packets to the eNode-B with better
signal quality. In addition, eNode-B 1030 may forward the non-VoIP
traffic to the target eNode-B 1040.
[0100] When UE 102 moves to 1020 and/or when the signal quality of
A2 may degrade below the predefined threshold, eNode-B 1030 may
send a full handover request message to the eNode-B 1040. The
target eNode-B 1040 may send ACK to eNode-B 1030 and a PATH_SWITCH
message to S-GW. After receiving the full handover ACK message,
eNode-B 1030 may send a full handover indicator to UE 102. UE 102
may be fully served by eNode-B 1040.
[0101] In one embodiment, the above fuzzy cell handover procedure
may reduce user-plane interruption time. In the fuzzy cell
deployment, due to the overlaying CCs, the UE may have a non-cell
edge CC to get its traffic. The cell edges may be staggered such
that the eNode-Bs may have a way to route the higher-priority data
to the UE. As such, the number dropped packets due to cell edge
degradation may be reduced. In addition, RRC Connection
establishment may be moved out of the critical path, thus removing
the interruption due to RRC signaling shown in FIG. 8.
[0102] In one embodiment, a UE context may be established at the
cooperating eNode-B such as eNode-B 1040 in FIG. 10. The UE context
may enable the other cooperating eNode-Bs in a fuzzy set to operate
for data-splitting operation. The UE context may include
information required for the eNode-B 1040 to operate the
inter-working function, and/or multiplexing/combining of data-flows
as required by the specific technique in use. For example, when the
data-split decision is performed at the S-GW, or when the
data-split decision is performed in the PDCP layer in the source
eNode-B, the UE context may include multiple keys, one from each
site (eNode-B).
[0103] In another embodiment, a RRC connection may be created in
the cooperating eNode-B or the target eNode-B, with a standby
state. When the eNode-B has the RRC in the standby state, while the
regular over the air RRC procedures may be halted, the RRC may
still be responsible for configuration of the lower layers. When
the trigger for a full handover is triggered, or when a Radio Link
Failure condition is detected by the Master eNode-B, then RRC
connection in the cooperating eNode-B may transition to another
state such as idle or connected. As the Radio Link Failure
condition may be monitored at the Active RRC in the Master eNode-B,
the Master eNode-B may send a message to the cooperating eNode-Bs
to request one of them to become the Master eNode-B.
[0104] As illustrated in FIG. 10, there may be critical handover
locations and/or measurement events that may be used for triggering
mobility procedures at 1010, 1015, 1020, and 1025. The following
table provides examples of measurement events (Event), which are
illustrated with respect to FIG. 3, and further described
below:
TABLE-US-00001 1010 1015 1020 1025 Position 1 Position 2 Position 3
Position 4 Pcell A2 A2 A2->B1 B1 Scell A1 A1->B1 B1->A2
A2->B2 Event A6 A3 A6
[0105] Referring now to FIG. 10, at 1010, UE 102 may have an
established RRC connection with eNode-B 1030. The CA may be started
with 2 CC aggregations. The network configuration may assign UE to
associate Pcell on CC A2 and Scell on CC A1. A measuring event may
not be triggered as long as UE 102 is moving within the cell
boundary of CC A1.
[0106] At 1015, intra-frequency Scell handover may occur. Event A5
may be triggered for CC A1 (Pcell) and CC B1 when a measurement of
a Pcell, such as CC A1, falls below a threshold and a measurement
of a neighbor cell (Ncell) is greater than a threshold.
Additionally, event A6 may be triggered for CC B1 and CC A1
(serving) when a measurement of a neighbor cell, which may include
an offset, is greater than an Scell, such as CC A1.
[0107] Detection of a candidate for Pcell may be performed when
event A5 occurs as event A5 may indicate that both CC A2 and CC B1
are in extended fuzzy handover zone. In detecting a candidate for
Pcell, the network may take note of potential Pcell handover and
may make necessary preparations and/or configurations, but may not
perform Pcell handover at that time.
[0108] For example, the network may start handing over the data
flow on A1 to A2 at 1015 (position 2) on detection of a good
candidate, such as CC B1. The handing over may complete a position
shortly after position 2 on successful indication of the handoff
procedure. eNode-B 1030 may use modified RRC reconfiguration
procedures to handover CC A1 to CC B2 as described above.
[0109] At 1020, inter-frequency Pcell handover may occur. Event A3
may be triggered for CC B1 and CC A1 (Pcell) when a measurement of
a neighbor cell, which may include an offset, is greater than a
Pcell, such as CC A1.
[0110] Event A3 may be used to detect a better candidate for a
primary service cell, when, for example, a UE leaves CC A2 and
enters CC B1. In one embodiment, which is further described below,
for event A3, an offset may be set to zero such that the event
would be triggered at midpoint between the two cells to indicate
that CC A2 is the same or worse than CC B2. It may be desirable to
have the triggering point of event A3 set at the midpoint between
eNode-B 1030 and eNode-B 1040 to enable the maximum fuzzy handover
region to guard against ping-pong effect by ensuring that CC A2 and
CC B1 are swapped at that midpoint.
[0111] At 1025, intra-frequency Scell handover may occur. Event A6
may be triggered for CC B2 and CC A2 (serving) when a measurement
of a neighbor cell, which may include an offset, is greater than a
Scell, such as CC A2. In one embodiment, the network may start
handing over the data flow on CC A2 to CC B2 at 1025 when a good CC
candidate, such as CC B2, is detected.
[0112] FIG. 11 depicts example reconfiguration procedures for fuzzy
cells. For example, UE 102 that may be connected to a source
eNode-B, such as eNode-B 1030, may be handed over to a target
eNode-B, such as eNode-B 1040.
[0113] At 1160, source eNode-B 1130 sends a RRC control message to
UE 102. UE 102 detects that a trigger event occurs, performs a
measurement, and sends a measurement report to source eNode-B
1130.
[0114] At 1170, source eNode-B 1130 receives the measurement report
from UE 102 and proceeds to determine a carrier for CG HO decision.
Source eNode-B 1130 then requests a carrier such as CC OH from
target eNode-B 1140. Target eNode-B 1140 transmits an
acknowledgment (ACK) message to source eNode-B 1130 that may enable
source eNode-B 1130 to handover UE 102 to target eNode-B 1140.
Source eNode-B 1130 may then send a CCC reconfiguration message to
UE 102. In one embodiment, UE 102 may perform DL synchronization
and/or timing advance. UE 102 may transmit a CCC reconfiguration
complete message to source eNode-b 1130, which may relay a CCC
complete message to target eNode-B 1140. After receiving the CCC
complete message, target eNode-B 1140 may transmit a CCC ACK
message to source eNode-B 1130 and data splitting may be initiated.
For example, data may be split between source eNode-B 1130 and
target eNode-B 1140.
[0115] UE 102 may transmit a measurement report to source eNode-B
1130. When a HO condition is satisfied, source eNode-B 1130 may
send a HO request to target eNode-B 1140.
[0116] At 1180, target eNode-B 1140 may send a path switch request
to SGW 1150 and may transmit a HO response to source eNode-B 1130.
Source eNode-B 1140 may send a HO command to UE 102. SGW 1150 may
send a path switch response to target eNode-B 1140. MME 1145 may
send a modify bearer request to SGW 1150 and may receive a modify
bearer response. RRC handover may complete using CCC between UE 102
and target eNode-B 1140. Target eNode-B 1140 may then send a UE
context release message to source eNode-B 1130.
[0117] FIG. 12 illustrates another example two base-station fuzzy
cell deployment. As shown in FIG. 12, eNode-B 1030 and eNode-B 1040
may be deployed with CCs on different frequencies; the slashed area
and the dotted area represent the different. FIG. 12 depicts a
handover procedure to maintain carrier data flow when a UE
traverses a network with Pcell and Scell deployment from eNode-B
1030 to eNode-B 1040 in a triangular path frequencies. As
illustrated in FIG. 12, there may be critical handover location
and/or measurement events that may be used for triggering mobility
procedures at 1185, 1190, 1195, 1200, 1205, and 1210. The following
table provides examples of measurement events (Event), which are
illustrated with respect to FIG. 3, and further described
below:
TABLE-US-00002 1185 1190 1195 1280 1205 1210 Posi- Posi- Posi-
Posi- Posi- Posi- tion 1 tion 2 tion 3 tion 4 tion 5 tion 6 Pcell
A2 A2 A2 A2->B1 B1 B1 Scell A1 (Deac- B1 A2 (Deac- B2 tivated/
tivated/ Decon- Decon- figured) figured) Event A4 or A6 A3/A4
A6
[0118] At 1185, the UE may be moving within the cell boundary of CC
A1. When the UE moves within the cell boundary of CC A1, a
measurement event may not be triggered.
[0119] At 1190, a SCC may be stopped. Event A2 may be triggered
when a measurement of a serving cell, such as CC A1, is below a
threshold. For example, as a UE, such as UE 102, moves away from
the effective CC A1 coverage, the network may stop the data flow on
CC A1, which may cause a loss of an active aggregated CC (Scell
A1->stops). Several embodiment, which are described below, may
provide procedures for stopping the data flow on CC A1. For
example, if data-split at S-GW is used, a modified path switch
request may be sent to S-GW to stop the data-flow splitting.
[0120] At 1195, a SCC may be started. Event A4 may be triggered for
CC B1 when a measurement of a neighbor cell is greater than a
threshold. Event A5 may be triggered for CC A2 (Pcell) and/or CC B1
when a Pcell, such as CC A2, is lower than a threshold and Ncell is
greater than a threshold. Event A4 and/or A5 may be used to provide
for the detection of a candidate for Pcell. For example, if A5 is
triggered, this may indicate that both CC A2 and CC B1 are in an
extended fuzzy handover zone. The network may take note of
potential Pcell handover and may make necessary configurations or
preparations, but may not perform Pcell handover at that time. In
one example embodiment, network may start data-splitting the data
flow on to CC B1 at 1195 on detection of a good candidate for
Scell, such as CC B1.
[0121] At 1200, inter-frequency Pcell handover may occur. Event A3
may be triggered for CC B1 and CC A1 (Pcell) when a measurement of
a neighbor cell, which may include an offset, is greater than a
Pcell, such as CC A1. Event A3 may be used to provide for the
detection of a better candidate for Pcell (Pcell A2->B1).
[0122] In one embodiment, which is further described below, for
event A3, an offset may be set to zero such that the event would
trigger at this position (1200) to indicate that CC A2 is the same
or worse than CC B1. It may then be desirable to hand off PCC to CC
B1. Additionally, it may be desirable to have the triggering point
of event A2 to be set soon after the midpoint between eNode-B 1030
and eNode-B 1040 to enable maximum fuzzy handover region in order
to guard against pint-pong effect by ensuring that CC A2 and CC B1
are swapped at that midpoint.
[0123] At 1205, Scell A2 may be stopped. Event A2 may be triggered
for CC A2 when a serving CC, such as CC A2, is less than a
threshold. Event A2 may be used to detect quality degradation on CC
A2 in order to stop the data flow on CC A2 at 1205. For example, if
data-split at S-GW is used, a modified path switch request may be
sent to S-GW to stop data-flow splitting.
[0124] In one example embodiment, CC A2 deactivation may occur. For
example, a fast deactivation message may be sent to the UE. Data
flow may then stop on CC A1 when deactivation completes. CC A2 may
remain as an inactive CA candidate. In another example embodiment,
CC A2 may be released. A RCC reconfiguration message may be sent to
the UE. CC A2 may be released and may be removed from the CA set
when a RRC reconfiguration message is received from the UE.
[0125] At 1210, Scell B2 may be started. Event A4 may be triggered
for CC B2 when a measurement for a neighbor cell may be greater
than a threshold. Event A4 may be used to detect a good Scell
candidate, such as a CC B2, and start data-splitting the data flow
on to CC B2. In one example embodiment, fast activation for CC B2
may be used. For example, if CC B2 is an inactive member of CA
candidate set, CC B2 may be activated using fast activation
procedure. The fast activation procedure may assume RRC
reconfiguration has configured CC B2 prior to the UE reaching
position 2 (1190). In another example embodiment, CC B2 aggregation
may occur. For example, eNode-B 1040 may send a RCC reconfiguration
request to the UE to add CC B2 to the aggregated bandwidth.
[0126] In one embodiment, the above fuzzy cell handover procedure
may reduce user-plane interruption time. In the fuzzy cell
deployment, due to the overlaying CCs, the UE may have a non-cell
edge CC to get its traffic. The cell edges may be staggered such
that the eNode-Bs may have a way to route the higher-priority data
to the UE. As such, the number dropped packets due to cell edge
degradation may be reduced. In addition, RRC Connection
establishment may be moved out of the critical path, thus removing
the interruption due to RRC signaling shown in FIG. 8.
[0127] In one embodiment, a UE context may be established at the
cooperating eNode-B such as eNode-B 1040 in FIG. 12. The UE context
may enable the other cooperating eNode-Bs in a fuzzy set to operate
for data-splitting operation. The UE context may include
information required for the eNode-B 1040 to operate the
inter-working function, and/or multiplexing/combining of data-flows
as required by the specific technique in use. For example, when the
data-split decision is performed at the S-GW, or when the
data-split decision is performed in the PDCP layer in the source
eNode-B, the UE context may include multiple keys, one from each
site (eNode-B).
[0128] In another embodiment, a RRC connection may be created in
the cooperating eNode-B or the target eNode-B, with a standby
state. When the eNode-B has the RRC in the standby state, while the
regular over the air RRC procedures may be halted, the RRC may
still be responsible for configuration of the lower layers. When
the trigger for a full handover is triggered, or when a Radio Link
Failure condition is detected by the master eNode-B, then RRC
connection in the cooperating eNode-B may transition to another
state such as idle or connected. As the Radio Link Failure
condition may be monitored at the active RRC in the master eNode-B,
the master eNode-B may send a message to the cooperating eNode-Bs
to request one of them to become the master eNode-B.
[0129] FIG. 13 illustrates another example two base-station fuzzy
cell deployment.
[0130] As shown in FIG. 13, eNode-B 1030 and eNode-B 1040 may be
deployed with CCs on different frequencies; the slashed area and
the dotted area represent the different frequencies. UE 102 may be
connected to a source eNode-B, such as eNode-B 1030, may be handed
over to a target eNode-B, such as eNode-B 1040. This embodiment may
be used to trigger data-splitting operations when a UE moves in a
straight line from eNode-B 1030 to eNode-B 1040. eNode-B 1040
and/or eNode-B 1040 may be eNode-B 140 shown with respect to FIG.
1C.
[0131] In one example embodiment, it may be preferable to use a
Fast activation/deactivation procedure to, for example, deactivate
Scell A1, which may be configured on a first frequency, and
activate Scell B1, which may also be configured on the first
frequency.
[0132] As illustrated in FIG. 13, there may be critical handover
locations and/or measurement events that may be used for triggering
mobility procedures at 1220, 1225, 1230, and 1235. The following
table provides examples of measurement events (Event), which are
illustrated with respect to FIG. 3, and further described
below:
TABLE-US-00003 1220 1225 1230 1235 Position 1 Position 2 Position 3
Position 4 Pcell A2 A2 A2->B1 B1 Scell A1 A1->B1 B1->A2
A2->B2 Procedure Act/Deactivation A3 Act/Deactivation
[0133] As shown in FIG. 13, at 1220 UE 102 may have an established
RRC connection with eNode-B 1030. The CA may be started with 2 CC
aggregations. The network configuration may assign UE to associate
Pcell on CC A2 and Scell on CC A1. A measuring event may not be
triggered as long as UE 102 is moving within the cell boundary of
CC A1.
[0134] At 1225, intra-frequency Scell handover may occur. Event A5
may be triggered for CC A1 (Pcell) and CC B1 when a measurement of
a Pcell, such as CC A1, falls below a threshold and a measurement
of Ncell is greater than a threshold. Additionally, event A6 may be
triggered for CC B1 and CC A1 (serving) when a measurement of a
neighbor cell, which may include an offset, is greater than an
Scell, such as CC A1. For example, the network may start handing
over the data flow on A1 to A2 at 1015 (position 2) on detection of
a good candidate, such as CC B1.
[0135] Detection of a candidate for Pcell may be performed when
event A5 occurs as event A5 may indicate that both CC A2 and CC B1
are in extended fuzzy handover zone. In detecting a candidate for
Pcell, the network may take note of potential Pcell handover and
may make necessary preparations and/or configurations,
[0136] At 1225, MAC fast activation and deactivation may be used to
deactivate Scell A1 and activate Scell B1. This may be done, for
example, to reduce RRC signaling due to frequent Scell handovers,
which may offset some of the gains achieved by fuzzy cell
deployment.
[0137] In one example embodiment, the UE may be preconfigured with
multiple Scells on a secondary frequency, and a new physical
layer/MAC-level trigger. This may be done to enable deactivation of
Scell A1 and activation of Scell B1, shown with respect to FIG. 3.
The serving eNode-B may simultaneously perform signaling with the
cooperating eNode-B to initiate data-splitting,
[0138] Referring again to FIG. 13, in an example embodiment, the
trigger to perform activation/deactivation and initiate
data-splitting may require a new measurement. This may be
accomplished by configuring the UE to report multiple CQIs, one for
each configured Scell with associated cell-id. The network may
correlate the CQI received from the UE to perform
activation/deactivation based on the channel conditions. The UE may
also measure more than one CQI in each frequency such that the
activation/deactivation procedure may handle a change in physical
cell-id.
[0139] In another example embodiment, Scellx and Scelly, shown with
respect to FIG. 3, may share the same cell-id
(Scellx=Scelly=Scell). For example, referring again to FIG. 13,
Scell A1 and Scell B1 may share the same cell-id. As shown in FIG.
13, the trigger may be based on a differential seen in the channel
estimation (using DM-RS) as the UE move to 1225. The L1 reporting
may be extended to additionally report this new metric and the
network may heuristically use this to detect a transition from
Scellx to Scelly. For example, the L1 reporting may be used by the
network to detect a transition from Scell A1 to Scell B1.
[0140] At 1230, inter-frequency Pcell handover may occur. Event A3
may be triggered for CC B1 and CC A1 (Pcell) when a measurement of
a neighbor cell, which may include an offset, is greater than a
Pcell, such as CC A1.
[0141] Event A3 may be used to detect a better candidate for a
primary service cell, when, for example, a UE leaves CC A2 and
enters CC B1. In one embodiment, which is further described below,
for event A3, an offset may be set to zero such that the event
would be triggered at midpoint between the two cells to indicate
that CC A2 is the same or worse than CC B2. It may be desirable to
have the triggering point of event A3 set at the midpoint between
eNode-B 1030 and eNode-B 1040 to enable the maximum fuzzy handover
region to guard against ping-pong effect by ensuring that CC A2 and
CC B1 are swapped at that midpoint.
[0142] At 1235, intra-frequency Scell handover may occur. Event A6
may be triggered for CC B2 and CC A2 (serving) when a measurement
of a neighbor cell, which may include an offset, is greater than a
Scell, such as CC A2. In one embodiment, the network may start
handing over the data flow on CC A2 to CC B2 at 1235 when a good CC
candidate, such as CC B2, is detected.
[0143] At 1235, MAC fast activation and deactivation may be used to
deactivate Scell A2 and activate Scell B2. This may be done, for
example, to reduce RRC signaling due to frequent Scell handovers,
which may offset some of the gains achieved by fuzzy cell
deployment.
[0144] In one example embodiment, the UE may be preconfigured with
multiple Scells on a secondary frequency, and a new physical
layer/MAC-level trigger. This may be done to enable deactivation of
Scell A2 and activation of Scell B2. The serving eNode-B may
simultaneously perform signaling with the cooperating eNode-B to
initiate data-splitting,
[0145] In an example embodiment, the trigger to perform
activation/deactivation and initiate data-splitting may required a
new measurement. This may be accomplished by configuring the UE to
report multiple CQIs, one for each configured Scell with associated
cell-id. The network may correlate the CQI received from the UE to
perform activation/deactivation based on the channel conditions.
The UE may also measure more than one CQI in each frequency such
that the activation/deactivation procedure may handle a change in
physical cell-id.
[0146] In another example embodiment, Scellx and Scelly, shown with
respect to FIG. 3, may share the same cell-id
(Scellx=Scelly=Scell). For example, referring again to FIG. 13,
Scell A2 and Scell B2 may share the same cell-id. As shown in FIG.
13, in this embodiment, the trigger may be based on a differential
seen in the channel estimation (using DM-RS) as the UE move to
1235. The L1 reporting may be extended to additionally report this
new metric and the network may heuristically use this to detect a
transition from Scellx to Scelly. For example, the L1 reporting may
be used by the network to detect a transition from Scell A2 to
Scell B2.
[0147] In one embodiment, the above fuzzy cell handover procedure
may reduce user-plane interruption time. In the fuzzy cell
deployment, due to the overlaying CCs, the UE may have a non-cell
edge CC to get its traffic. The cell edges may be staggered such
that the eNode-Bs may have a way to route the higher-priority data
to the UE. As such, the number dropped packets due to cell edge
degradation may be reduced. In addition, RRC Connection
establishment may be moved out of the critical path, thus removing
the interruption due to RRC signaling shown in FIG. 8.
[0148] In one embodiment, a UE context may be established at the
cooperating eNode-B such as eNode-B 1040 in FIG. 13. The UE context
may enable the other cooperating eNode-Bs in a fuzzy set to operate
for data-splitting operation. The UE context may include
information required for the eNode-B 1040 to operate the
inter-working function, and/or multiplexing/combining of data-flows
as required by the specific technique in use. For example, when the
data-split decision is performed at the S-GW, or when the
data-split decision is performed in the PDCP layer in the source
eNode-B, the UE context may include multiple keys, one from each
site (eNode-B).
[0149] In another embodiment, a RRC connection may be created in
the cooperating eNode-B or the target eNode-B, with a standby
state. When the eNode-B has the RRC in the standby state, while the
regular over the air RRC procedures may be halted, the RRC may
still be responsible for configuration of the lower layers. When
the trigger for a full handover is triggered, or when a radio link
failure condition is detected by the master eNode-B, then RRC
connection in the cooperating eNode-B may transition to another
state such as idle or connected. As the radio link failure
condition may be monitored at the Active RRC in the master eNode-B,
the master eNode-B may send a message to the cooperating eNode-Bs
to request one of them to become the master eNode-B.
[0150] FIG. 14 illustrates example fuzzy cell deployments. As shown
in FIG. 14, there are numerous deployment options that may be used
to achieve the gains of fuzzy cell deployment. The methods
described herein may be used individually or in combination with
each other to enable mobility handling in each of the deployments
depicted in FIG. 14.
[0151] FIG. 15 illustrates an example method for handover
triggering with fuzzy cell development. In order to support
handover in LTE-A with carrier aggregation, per carrier UE
measurement and reporting over aggregated downlink carriers may
need to be defined, including carrier-specific RSRP and/or RSRQ.
Current mechanisms do not support intra-frequency measurements
because measurements are based on serving cells. For example, an
eNodeB owns 3 carriers F1/F2/F3. UE is using F1 and F2 and F1 is
the serving cell. When the signal quality of F3 is better than F2,
there is no measurement scheme to cover it and the UE cannot report
this situation. The current mechanisms need to be enhanced to
support carrier-specific measurements including from non-serving
cells.
[0152] Currently mechanisms specify the new measurement cycle for
measurements on deactivated secondary Scells, which may have a
different range of values as compared to Pcells. However, the
measurements of the Scell are occurring less frequently, the Scell
measurements as observed by the UE can significantly lag the true
radio conditions, especially when compared to the Pcell. UE
includes in measurement reports L3 filtered measurements of the
Scell. This can lead to the Scell being reported as better than the
Pcell, which can result in a Pcell change procedure.
[0153] FIG. 15 illustrates L3 HO triggering misdetection that may
occur due to different reporting cycles. In one example embodiment,
L3 HO triggering misdetection may be prevented by aligning the
measurement cycles for the activated and deactivated cells so that
the minimum delta is the view of the radio conditions between the
configured carriers. In another example embodiment, L3 HO
triggering misdetection may be prevented by employing carrier
specific TTT values to create larger hysteresis for deactivated
Scells measurement reports.
[0154] The measurement event A3 may be configured by the network to
set the desired handover condition. In one example embodiment, the
measurement event A3 may be configured to improve signaling receive
quality. For example, event A3 offset value may be set closer to or
at zero may cause UE to signal event A3 as soon as a stronger
neighbor cell than Pcell is detected. This setting may enhance the
fuzzy cell deployment benefit of better connectivity by ensuring
the UE may be associated with a none-cell edge CC for control
signaling on Pcell. This may reduce the likelihood of call
failures.
[0155] In another example embodiment, the measurement event A3 may
be configured to minimize HO occurrence. For example, event A3
offset value may be set to a higher value will delay the handover
trigger till UE gets closer to the cell-edge of current Pcell. This
setting may enhance the fuzzy cell deployment benefit of extending
handover tolerance zone as shown in FIG. 16.
[0156] FIGS. 16A-B illustrate downlink fuzzy cell coverage. As
shown in FIGS. 16A-B, T is the handover tolerance zone that may
include the hysteresis region for HO triggering. As illustrated by
FIG. 16B, fuzzy cell deployment may create a wider T and the value
of increased range H is proportional to the offset value.
[0157] Referring again to FIG. 15, the network can may the UE
service class (QCI) to adjust the HO event trigger offset to
balance between improving signaling receive quality and minimizing
HO occurrence in order to optimize user satisfaction. For example,
if the UE requested service is voice call, the acceptable RLC error
rate at 10.sup.-2 is much lower than streaming video at 10.sup.-5.
Therefore, the network may set the configure event A3/A6 with a
smaller offset (optimize signal reception quality) such that UE
with voice call service may perform HO at a higher than SINR than
UE with streaming voice call. This may allow both users to get
benefit of HO signaling improvement with fuzzy cell and also lowers
service disruption with minimal HO occurrence without affecting
user satisfaction.
[0158] FIG. 17 illustrates an example asymmetric uplink channel
allocation. As shown in FIG. 17, one of the possible deployment
possibilities is that there is a single uplink shared channel for
multiple downlink carriers. In case of MAC-AS data-splitting
option, the UE may send and may receive HARQ acknowledgements
to/from the corresponding base-stations. In case of data-splitting
at the S-GW, the UE needs to provide feedback for MAC (HARQ
acknowledgements) and RLC (RLC Acknowledged modes) to each eNode-Bs
from which is receives downlink traffic. The UE may maintain
separate buffers and processing at MAC, RLC and PDCP for each
eNode-B. Feedback messages may be sent back to the master eNode-B
that may create and may forward RLC acknowledgement reports to all
the other eNode-Bs in the cooperating eNode-Bs.
[0159] In one embodiment, per carrier UE measurement and reporting
over aggregated downlink carriers may be modified to support
handover in LTE-A with carrier aggregation. For example,
carrier-specific RSRP and/or RSRQ may be included. Intra-frequency
measurements may be provided, and carrier-specific measurements
including from non-serving cells may be supported. For example, an
eNode-B may own three carriers F1, F2, and F3. UE may use F1 and
F2, and F1 may be the serving cell. When the signal quality of F3
is better than F2, a measurement scheme may be provided to report
that F3 is more desirable than F2.
[0160] A handover procedure may trigger the target eNode-B and the
UE to generate fresh keys for ciphering and encryption algorithm,
derived from {K.sub.eNode-B*, NCC} pair sent from the source
eNode-B. The target eNode-B 1040 may use this tuple to generate a
fresh K.sub.eNode-B. The K.sub.UPenc key may be used (derived from
K.sub.eNode-B) for protection of User-Plane traffic with a
particular encryption algorithm. In the case that UE maintains RRC
Connection with eNode-B 1030 as it moves from Position 1 (1240) to
Position 2 (1245), the PDCP entity running in target eNode-B such
as eNode-B 1040 may continue using the same keys as source eNode-B
(eNode-B 1030). This may allow the UE to receive PDCP entities from
different eNode-Bs simultaneously. The keys may be exchanged with
the Handover Command in the handover preparation phase from the
source to target eNode-B. The information may also be conveyed
during the Initial Context Setup from the S-GW.
[0161] FIG. 18 illustrates fuzzy cell concept in heterogeneous
networks. In an example embodiment, a fuzzy cell may be established
between one or more pico cells and a macro cell. For example, in a
heterogeneous deployment, it may be possible to create fuzzy cell
configuration for a UE, such as UE 102, by receiving one carrier
from the macro enode-B, such as macro eNode-B 1246, and another
carrier from a pico enode-B, such as pico enode-B 1250. In one
example embodiment, pico eNode-B 1250 and macro eNode-B 1246 may be
deployed with CCs on two frequencies, which are represented by the
slashed area and the dotted area. For example. Macro eNode-B 1246
and/or pico eNode-B 1250 may be eNode-B 140 shown with respect to
FIG. 1C.
[0162] FIG. 19 illustrates an example embodiment for fast
activation/deactivation for fuzzy cells. For example, UE 102 that
may be connected to a source eNode-B, such as source eNode-B 1960,
may be handed over to a target eNode-B, such as eNode-B 1970.
[0163] At 1990, source e-node-B 1960 may transmit an initial
configuration for CC2 to UE 102. The initial configuration for CC2
may include information regarding one or more Scells, such as
Scellx and Scelly. Ue 102 may detect that a trigger event occurred,
may perform a measurement, and may send a measurement report to
source eNode-B 1960. Source eNode-B 1960 receives the measurement
report from UE 102 and proceeds to determine a carrier for CG HO
decision. Source eNode-B 1960 then requests a carrier as CC OH from
target eNode-B 1970. Target eNode-B 1970 may transmit an
acknowledgment (ACK) message to source eNode-B 1960 that may enable
source eNode-B 1960 to handover UE 102 to target eNode-B 1970.
Source eNode-B 1960 may then send a handover request message, such
as a MAC CE activation/deactivation message, to UE 102. The
handover request message may be a MAC CE activation/deactivation
message. The handover request message may instruct and/or enable UE
102 to perform fast MAC activation on a first Scell, such as
Scelly, and to perform a fast MAC deactivation on a second Scell,
such as Scellx.
[0164] At 1995, UE 102 may perform fast MAC activation on a first
Scell, such as Scelly, and perform a fast MAC deactivation on a
second Scell, such as Scellx. UE 102 may perform DL synchronization
and/or timing advance. UE 102 may transmit an acknowledgment
message to source eNode-B 1960. Source eNode-B 1960 may transmit a
CCC complete message to target eNode-B 1970. Target eNode-B 1970
may transmit a CCC acknowledgement message to source eNode-B 1960.
Upon receiving the CCC acknowledgement message, data splitting may
occur as described above. For example, data splitting may occur as
illustrated in FIG. 5, FIG. 6, or FIG. 7. Data may then be
forwarded from source eNode-B 1960 to target eNode-B 1970.
[0165] Although features and elements are described above in
particular combinations, one of ordinary skill in the art will
appreciate that each feature or element can be used alone or in any
combination with the other features and elements. In addition, the
methods described herein may be implemented in a computer program,
software, or firmware incorporated in a computer-readable medium
for execution by a computer or processor. Examples of
computer-readable media include electronic signals (transmitted
over wired or wireless connections) and 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 internal hard disks and removable disks,
magneto-optical media, and optical media such as CD-ROM disks, and
digital versatile disks (DVDs). A processor in association with
software may be used to implement a radio frequency transceiver for
use in a WTRU, UE, terminal, base station, RNC, or any host
computer.
* * * * *