U.S. patent application number 15/239015 was filed with the patent office on 2016-12-08 for channel selection for uplink access.
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 Christopher R. Cave, Paul Marinier, Diana Pani.
Application Number | 20160360520 15/239015 |
Document ID | / |
Family ID | 46750458 |
Filed Date | 2016-12-08 |
United States Patent
Application |
20160360520 |
Kind Code |
A1 |
Pani; Diana ; et
al. |
December 8, 2016 |
CHANNEL SELECTION FOR UPLINK ACCESS
Abstract
Systems, methods, and instrumentalities are disclosed for a
wireless transmit/receive unit (WTRU) to transmit uplink
information. The WTRU may have information such as data or control
information to transmit to a network. The (WTRU) may request a
common enhanced dedicated channel (E-DCH) resource from the
network. The WTRU may receive an indication from the network to
fallback using a random access channel, e.g. a Release 99 Random
Access Channel (R99 RACH), a Release 99 Physical Random Access
Channel (R99 PRACH), etc. The indication may be received via an
acquisition indicator (E-AI). The indication may be a value of the
E-AI. The WTRU may determine whether a condition is met. The WTRU
may transmit the uplink information over the R99 PRACH if the
condition is met.
Inventors: |
Pani; Diana; (Montreal,
CA) ; Marinier; Paul; (Brossard, CA) ; Cave;
Christopher R.; (Dollard-des-Ormeaux, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
InterDigital Patent Holdings, Inc. |
Wilmington |
DE |
US |
|
|
Assignee: |
InterDigital Patent Holdings,
Inc.
Wilmington
DE
|
Family ID: |
46750458 |
Appl. No.: |
15/239015 |
Filed: |
August 17, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14816778 |
Aug 3, 2015 |
9462580 |
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15239015 |
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14301759 |
Jun 11, 2014 |
9131488 |
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14816778 |
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|
13570647 |
Aug 9, 2012 |
8792447 |
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14301759 |
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61522504 |
Aug 11, 2011 |
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61555201 |
Nov 3, 2011 |
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61589760 |
Jan 23, 2012 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W 72/0453 20130101;
H04W 72/0413 20130101; H04W 74/0833 20130101; H04W 72/0406
20130101 |
International
Class: |
H04W 72/04 20060101
H04W072/04; H04W 74/08 20060101 H04W074/08 |
Claims
1-20. (canceled)
21. A method to transmit uplink information, the method comprising:
requesting, by a wireless transmit/receive unit (WTRU), a common
enhanced dedicated channel (E-DCH) resource from a network; and
receiving an indication from the network to fallback to a Release
99 Physical Random Access Channel (R99 PRACH).
22. The method of claim 21, wherein the indication is received via
an acquisition indicator (E-AI).
23. The method of claim 22, wherein the indication is a value of
the E-AI.
24. The method of claim 21, wherein the indication is an E-DCH
resource index.
25. The method of claim 21, wherein the uplink information is at
least one of control information or data.
26. The method of claim 21, further comprising: receiving, from the
network, an information element (IE) that configures the channel
for fallback to R99 PRACH.
27. The method of claim 21, wherein the WTRU utilizes a preamble
indicating that the WTRU supports fallback to the R99 PRACH when
requesting the common E-DCH resource from the network.
28. The method of claim 21, further comprising: determining whether
a condition is met, the condition being met if the WTRU has data to
transmit on a common control channel (CCCH) or a dedicated control
channel (DCCH).
29. The method of claim 28, further comprising: transmitting the
uplink information over the R99 PRACH when the condition is met and
backing off from accessing the network when the condition is not
met.
30. The method of claim 29, wherein backing off comprises: ignoring
the indication from the network to fallback to the R99 PRACH;
waiting for a time; and attempting to access the network.
31. A wireless transmit/receive unit (WTRU) configured to transmit
uplink information, the WTRU comprising: a processor configured to:
request a common enhanced dedicated channel (E-DCH) resource from a
network; and receive an indication from the network to fallback to
a Release 99 Physical Random Access Channel (R99 PRACH).
32. The WTRU of claim 31, wherein the indication is received via an
acquisition indicator (E-AI).
33. The WTRU of claim 32, wherein the indication is a value of the
E-AI.
34. The WTRU of claim 31, wherein the indication is an E-DCH
resource index.
35. The WTRU of claim 31, wherein the uplink information is at
least one of control information or data.
36. The WTRU of claim 31, wherein the processor is further
configured to receive, from the network, an information element
(IE) that configures the channel for fallback to R99 PRACH.
37. The WTRU of claim 31, wherein the processor is configured to
request the common E-DCH resource from the network utilizing a
preamble indicating that the WTRU supports fallback to the R99
PRACH.
38. The WTRU of claim 31, wherein the processor is further
configured to determine whether a condition is met, the condition
being met if the WTRU has data to transmit on a common control
channel (CCCH) or a dedicated control channel (DCCH).
39. The WTRU of claim 38, wherein the processor is further
configured to transmit the uplink information over the R99 PRACH
when the condition is met and back off from accessing the network
when the condition is not met.
40. The WTRU of claim 39, wherein backing off comprises: the
processor further configured to: ignore the indication from the
network to fallback to the R99 PRACH; wait for a time; and attempt
to access the network.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 14/301,759, filed on Jun. 11, 2014, which is a
continuation of U.S. patent application Ser. No. 13/570,647, filed
Aug. 9, 2012, which issued as U.S. Pat. No. 8,792,447 on Jul. 29,
2014; which claims the benefit of U.S. Provisional Patent
Application No. 61/522,504, filed Aug. 11, 2011, U.S. Provisional
Patent Application No. 61/555,201, filed Nov. 3, 2011, and U.S.
Provisional Patent Application No. 61/589,760, filed Jan. 23, 2012,
the contents of which are hereby incorporated by reference
herein.
BACKGROUND
[0002] Mobile networks have experienced continuous increases in
data traffic due in part to the introduction of new mobile services
and applications. Such traffic may be characterized by its high
level of burstiness and/or small packet sizes. In Universal Mobile
Telecommunications Systems (UMTS), mobile devices experiencing
varying traffic demands may be maintained in non-fully connected
states during periods of low activity, such as, but not limited to
CELL_FACH or CELL_PCH. The non-fully connected states may help to
provide a user experience that is closer to "always-on
connectivity," while maintaining low battery consumption.
SUMMARY
[0003] Systems, methods, and instrumentalities are disclosed for a
wireless transmit/receive unit (WTRU) to transmit uplink
information. The WTRU may have information such as data or control
information to transmit to a network. The (WTRU) may request a
common enhanced dedicated channel (E-DCH) resource from the
network. The WTRU may receive an indication from the network to
fallback using a random access channel, e.g. a Release 99 Random
Access Channel (R99 RACH), a Release 99 Physical Random Access
Channel (R99 PRACH), etc. The indication may be received via an
acquisition indicator (E-AI). The indication may be a value of the
E-AI. The WTRU may determine whether a condition is met. The WTRU
may transmit the uplink information over the R99 PRACH if the
condition is met.
[0004] The condition may be met if one or more of the following is
established: the channel for transmission is capable of being
mapped to the R99 RACH; the channel for transmission may be
configured with a fixed Radio Link Control (RLC) Protocol Data Unit
(PDU) size; or the channel for transmission belongs to a list of
channels that is predefined in the WTRU, whereby the list may
include one or more of a common control channel (CCCH) or a
dedicated control channel (DCCH). If the condition is not met, the
WTRU may back off from accessing the network, ignore the indication
from the network to fallback to the R99 PRACH, wait for a time, and
attempt to access the network.
DESCRIPTION OF THE DRAWINGS
[0005] FIG. 1A is a system diagram of an example communications
system in which one or more disclosed embodiments may be
implemented.
[0006] 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.
[0007] 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.
[0008] 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.
[0009] 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.
[0010] FIG. 2 illustrates an exemplary fallback.
DETAILED DESCRIPTION
[0011] 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.
[0012] 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.
[0013] 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 the like.
[0014] 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 106/107/109, 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 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.
[0015] 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.
[0016] 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).
[0017] 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
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).
[0018] 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).
[0019] 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 IX, 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.
[0020] 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 106/107/109.
[0021] 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.
[0022] 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.
[0023] 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.
[0024] 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), 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.
[0025] 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.
[0026] The transmit/receive element 122 may be configured to
transmit signals to, or receive signals from, abase 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.
[0027] 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.
[0028] 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.
[0029] 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 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).
[0030] 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.
[0031] 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 method
while remaining consistent with an embodiment.
[0032] 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 the like.
[0033] 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.
[0034] 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 the like.
[0035] 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.
[0036] 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.
[0037] 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.
[0038] 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.
[0039] 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.
[0040] 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.
[0041] 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 the like. As shown in FIG.
1D, the eNode-Bs 160a, 160b, 160c may communicate with one another
over an X2 interface.
[0042] 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.
[0043] 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 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.
[0044] 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 the like.
[0045] 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.
[0046] 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.
[0047] 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.
[0048] 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 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 the like.
[0049] 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.
[0050] 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.
[0051] 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.
[0052] 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.
[0053] 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.
[0054] Systems, methods, and instrumentalities are disclosed for a
wireless transmit/receive unit (WTRU) to transmit uplink
information. The WTRU may have information such as data or control
information to transmit to a network. The (WTRU) may request a
common enhanced dedicated channel (E-DCH) resource from the
network. The WTRU may receive an indication from the network to
fallback using a random access channel, e.g. a Release 99 Random
Access Channel (R99 RACH), a Release 99 Physical Random Access
Channel (R99 PRACH), etc. The indication may be received via an
acquisition indicator (E-AI). The indication may be a value of the
E-AI. The WTRU may determine whether a condition is met. The WTRU
may transmit the uplink information over the R99 PRACH if the
condition is met.
[0055] The condition may be met if one or more of the following is
established: the channel for transmission is capable of being
mapped to the R99 RACH; the channel for transmission may be
configured with a fixed Radio Link Control (RLC) Protocol Data Unit
(PDU) size; or the channel for transmission belongs to a list of
channels that is predefined in the WTRU, whereby the list may
include one or more of a common control channel (CCCH) or a
dedicated control channel (DCCH). If the condition is not met, the
WTRU may back off from accessing the network, ignore the indication
from the network to fallback to the R99 PRACH, wait for a time, and
attempt to access the network.
[0056] A wireless transmit/receive unit (WTRU) may be in an idle
state or a connected state. Based on the WTRU mobility and activity
while in the connected state, a universal terrestrial radio access
network (UTRAN) may direct the WTRU to transition between a number
of sub-states, which may include one or more of the following:
CELL_PCH, URA_PCH, CELL_FACH, or CELL_DCH states. User plane
communication between the WTRU and the UTRAN may be possible while
in CELL_FACH and CELL_DCH states. The CELL_DCH state may be
characterized by dedicated channels in uplink and downlink. On the
WTRU side, the CELL_DCH state may correspond to continuous
transmission and/or reception and may be demanding on user power
requirements. The CELL_FACH state may not use dedicated channels
and, thus may allow better power consumption at the expense of a
lower uplink and downlink throughput.
[0057] Uplink communication may be achieved through a random access
channel (RACH) mapped to a physical random access channel (PRACH).
The RACH may be a contention-based channel. A power ramp-up
procedure may be used to acquire a channel and/or to adjust
transmit power. An RACH may be a shared channel used for an initial
access to obtain dedicated resources and/or to transmit small
amount of data. There may be collisions between two or more WTRUs
trying to access the channel simultaneously.
[0058] The RACH procedure may have a channel acquisition stage,
which may use a slotted-ALOHA mechanism, followed by an RACH
message transmission stage. For example, a WTRU that wants to
access a channel may randomly select a signature and transmit an
RACH preamble to a Node B during a randomly selected access slot at
a certain transmit power level. If the Node B detects the signature
and if an associated resource is free, the Node B may transmit a
positive acknowledgement (ACK) on an acquisition indicator channel
(AICH). After receiving an acquisition indicator (AI) (e.g., ACK),
on the AICH, the WTRU may transmit an RACH message. If the
associated resource is unavailable, the Node B may respond with a
negative acknowledgement (NACK) on the AICH. This may trigger a
back-off mechanism at the WTRU. The WTRU may start a back-off timer
(e.g., Tbol). After expiry of the timer, a preamble ramping cycle
count may be incremented and the procedure may start again. This
may restart the RACH procedure at a later random time. If the RACH
preamble from the WTRU is not detected at the Node B, an AI may not
be transmitted on the AICH. If the WTRU fails to receive an AI
after transmission of the RACH preamble, the WTRU may try again in
a subsequent access slot with a randomly chosen signature and/or a
higher transmit power. This may continue up to a maximum number of
times.
[0059] The signature may be chosen randomly from a list of
available signatures and/or the RACH access procedure may be
anonymous. The Node B may not know which WTRU is accessing the
channel until the Node B decodes the RACH message. When two or more
WTRUs happen to choose the same signature in the same access slot
and one of them is detected by the Node B, the Node B may transmit
an ACK. The WTRUs may interpret this as a having acquired the
channel and may access the channel simultaneously to transmit RACH
messages. This may cause a collision on the RACH messages. When a
collision occurs, the RACH messages may not be decoded correctly.
Collisions may be difficult to detect and/or incur additional
delays.
[0060] The RACH procedure may be divided between the medium access
control (MAC) layer and the physical layer. The physical layer may
control, for example, the preamble transmission, signature
selection, access slot selection, and/or preamble transmit power.
The MAC layer may control, for example, the interpretation of the
AICH response (for example, ACK, NACK, and/or no response), and/or
the start of the physical layer procedure. Transmission failure and
successful completion of the MAC procedure may be indicated
individually for each logical channel, for example, using
primitives (such as but not limited to, CMAC-STATUS-Ind for the
radio resource control (RRC) and/or MAC-STATUS-Ind for the radio
link control (RLC)).
[0061] The uplink transmission mechanism in CELL_FACH state may be
modified by combining the RACH channel acquisition stage with an
enhanced dedicated channel (E-DCH). The procedure may be referred
to as enhanced uplink for CELL_FACH and IDLE mode. The Node B may
select an E-DCH resource from a set of common E-DCH resources that
may be shared amongst the WTRUs. The Node B may respond to a WTRU
channel access request by assigning one of these resources. The
WTRU may then start transmission over the assigned E-DCH transport
channel.
[0062] One channel selection scheme may be that common E-DCH
capable WTRUs may use common E-DCH when operating in a cell that
supports common E-DCH. Otherwise, the WTRU may use the Release 99
RACH. In another channel selection scheme, the use of both R99 RACH
and common E-DCH may be used by WTRUs in cells that support both
channels. Common E-DCH capable WTRUs may "fallback" to R99 RACH for
UL transmission if, for example, common E-DCH resources are
congested and/or simply because the nature of the UL transmission
is better suited to the R99 RACH channel.
[0063] Criteria that may be used for selection of the UL channel
may be disclosed. This may include, but is not limited to, whether
the WTRU or the RAN should make the channel selection. The
selection criteria may be coordinated between WTRU and RAN, e.g.,
to ensure that, for example, there is no confusion between nodes
while ensuring backwards compatibility for WTRUs that are not
capable of fallback to R99 RACH.
[0064] A fallback to R99 RACH may result in transmission of data
over a R99 PRACH from a logical channel configured with flexible a
RLC PDU configuration. For example, the R99 RACH may not support
MAC segmentation and/or may transmit a limited set of Transport
Block Sizes (TBSs). As a result, RLC PDUs created for transmission
over common E-DCH may not be compatible for transmission over R99
RACH.
[0065] Implementations described herein may relate to selection
between common E-DCH and R99 RACH channels for UL transmission in
Idle mode, URA_PCH, CELL_PCH and/or CELL_FACH states. As referred
to herein, "fallback to R99 RACH" may refer to the use of the R99
RACH channel for transmission of UL control information and/or data
by a WTRU that may be capable of transmitting over common E-DCH
while operating in a cell that may be capable of reception over
both R99 RACH and common E-DCH. As referred to herein, the term
"non-DCH states" may be used to describe a state where the WTRU may
not be fully connected to the RAN (for example, does not have a set
of dedicated resources for DL reception and UL transmission). For
example, with specific reference to UMTS networks, the term
"non-DCH states" may refer to one or more of the following states:
IDLE Mode, URA_PCH State, CELL_PCH State, or CELL_FACH State. Other
types of access networks may utilize similar non-DCH states to
which the implementations described herein may be applicable.
[0066] A WTRU may determine when to perform R99 RACH access.
Example triggers are described herein which may be used
individually or in any combination. For example, the triggers may
be used in conjunction with the triggering conditions and/or
selection criteria described in PCT/US08/80971, entitled SELECTING
TRANSMISSION PARAMETERS FOR CONTENTION-BASED ACCESS IN WIRELESS
SYSTEMS, filed Oct. 23, 2008, which is incorporated herein by
reference.
[0067] A common E-DCH access failure may refer to one or more of
the following: A NACK on the extended acquisition indicators
(E-AI), a number of consecutive NACKs, a number of NACKs over a
period of time; a NACK on the acquisition indicator channel (AICH)
if no E-AI is configured; a collision resolution failure; no
response on the AI (e.g., within a certain time duration); or a
maximum number of preamble attempts is reached.
[0068] A WTRU may use one or more of buffer content, network
signaling or congestion level to determine whether to fallback to
R99 RACH. For example, if a common E-DCH access fails, if the
network redirects to the WRTU to use R99 RACH, and/or if the WRTU
is capable of R99 RACH fallback, then the WTRU may determine
whether it can use R99 RACH, e.g., if one or more of conditions are
met. A condition may be that a buffer size is below a threshold
(which may be configurable or predefined). For example, WTRUs with
larger buffer size may re-try a common E-DCH access procedures
rather than fallback to R99 RACH. After a predefined number of
re-tries, the WTRU may determine that it may be appropriate to
fallback to R99 RACH. A condition may be that the total UL data
that needs to be transmitted may fit into a R99 RACH TTI according
to the allowed TBS and power in the WTRU. A condition may be that
the UL logical channel or logical channel type belongs to a list of
logical channels that may be mapped and/or that may be allowed to
fallback to PRACH. For example, the WTRU may be allowed to fallback
and % or transmit UL information from the list of logical channels
over the R99 RACH. The WTRU may be allowed to fallback and/or
transmit UL information for certain logical channels from the list
of logical channels over the R99 RACH. The list of which logical
channels may be allowed to be transmitted over R99 RACH may be
configured, for example, by the network via RRC signaling and/or
predefined in the WTRU. For example, a predefined set of logical
channels may be configured in the WTRU and/or the network may
configure the WTRU with which logical channel type(s) the WTRU may
fallback to R99 RACH. Such logical channels may be of the signaling
type that may comprise higher priority data and/or lower payloads
than data traffic channels. An example of such a channel type may
be CCCH logical channel type. When configured and/or predefined
with CCCH, the WTRU may determine it may fallback to R99 PRACH if
the UL data to transmit is of CCCH type. An example of such a
channel type may be DCCH. For example, if the network redirects the
WTRU to fallback to R99 RACH (e.g., the E-AI value and/or the E-DCH
resource index correspond to the fallback stored in the WTRU), the
WTRU may check if the UL data transmission comprises data from the
predefined and/or configured list (e.g., if the data is from CCCH
logical channel types or DCCH), and then the WTRU may fallback for
transmission to R99 RACH. If the logical channel for UL
transmission is not one that is allowed by the configured logical
channel types (e.g., DTCH), then the WTRU may not perform RACH
fallback. A condition may be that a dedicated E-RNTI may or may not
be configured for that WTRU. Other conditions may also trigger the
fallback use of R99 RACH.
[0069] A dedicated RRC signal and/or message may be used to
configure the WTRU to use R99 RACH for UL transmission. For
example, the message may correspond to a RRC message configuring
the WTRU to use R99 RACH. The configuration may be performed using,
for example, a Cell Update Confirm message, a RRC reconfiguration
message, and/or a System information message. For example, an
Information Element (IE) may be broadcasted indicating to WTRUs
capable of fallback to R99 RACH to use R99 RACH for UL
transmission. The indication to fallback to R99 RACH may include
additional criteria that may be used by a WTRU to determine if it
should fallback to R99 RACH. For example, the fallback to R99 RACH
may apply to a group of WTRUs for which a particular identifier
and/or WRTU identity (e.g., E-RNTI) lies within a predefined and/or
signaled range of values. Fallback to R99 RACH may apply for
certain types of traffic (e.g., CCCH) and/or to WTRUs operating in
certain states (e.g., IDLE mode and URA_PCH).
[0070] The RRC signaling may indicate the time duration for which a
fallback to R99 RACH may be performed after the reception of that
message. For example, a timer may be reset upon receipt of the
message. Once the timer expires, the WTRU may start using common
E-DCH again. An explicit message may be used to explicitly indicate
to the WTRU to stop performing fallback to R99 RACH. The time
duration for which a fallback to R99 RACH may be performed may be
signaled using system information.
[0071] A Radio Link Protocol (RLC) configuration may be used when
determining to fallback to R99 RACH. For example, a R99 RACH may
not be used with flexible RLC PDU configuration, as the transport
block supported by RACH may be fixed and/or the MAC used for R99
access may not have segmentation capabilities. The RLC PDU
configuration may be taken into account when determining the
fallback decision/triggers. The WTRU may use R99 RACH if one or
more criteria related to the RLC may be satisfied, e.g., as
described herein. The criteria may be that the logical channel
which has UL data to transmit may be configured with fixed RLC PDU.
The criteria may be whether the logical channel may be configured
with TM or UM RLC. The criteria may be whether the RLC PDUs already
created in the RLC entity may fit in the allowed TB sizes of the
R99 RACH. The criteria may be that there may be no RLC PDUs in the
retransmission buffer. The criteria may be that there may be no RLC
PDUs already created in the RLC entity (e.g., there are not RLC
PDUs already pre-generated but not yet transmitted, and/or there
are not RLC PDUs to be retransmitted). For example, if RLC PDUs are
already created, the size of the RLC PDUs on the logical channel
may correspond to an allowed RLC PDU size, as broadcasted in the
system information and/or provided to the WTRU via an RRC message.
If there are RLC PDUs already created, the RLC PDUs may be smaller
than or equal to the allowed RLC PDU size that may be broadcasted
as part of the RACH system information. For example, the RLC PDUs
that are smaller may be any size or a size that is a function of
the allowed size (e.g. a fraction).
[0072] The criteria described herein may be used by the WTRU to
determine one or more of the following. The criteria described
herein may be used by the WTRU to determine whether to autonomously
fallback. The criteria may be used by the WTRU to determine whether
to fallback after a network indication (e.g., if the network
indicates fallback and the criteria is not met, the WTRU may ignore
the network indication). The criteria described herein may be used
by the WTRU to determine whether it is permitted to fallback and
perform a R99 RACH selection. The criteria described herein may be
used by the WTRU to determine whether to use R99 RACH. The criteria
described herein may be used by the WTRU to determine the above and
indicate to the network that the criteria may be met (e.g., the
WTRU may fallback to R99 RACH).
[0073] For example, the network may determine channel control. As
referred to hereafter, a channel or resource selection in a non-DCH
state may include one or more of the following channel selections:
R99 RACH, Common E-DCH. Common E-DCH with 2 ms TTI, or Common E-DCH
with 10 ms TTI.
[0074] A channel or resource selection may also be used
interchangeably with TTI selection and/or transport channel
selection. For example, TTI selection may correspond to a selection
of a common E-DCH with 2 ms or 10 ms TTI. Transport channel
selection may correspond to a selection between RACH and common
E-DCH. Implementations may be described herein where the network
may dynamically control the TTI and/or transport channel
selection.
[0075] The WTRU may perform an initial TTI and/or transport channel
selection and may indicate a TTI and/or transport channel selection
preference to the network. The network may dynamically control the
TTI and/or transport channel selection.
[0076] The WTRU may perform a preamble transmission based on, for
example, a common E-DCH and/or WTRU capability. The network may
dynamically control the UL resources that the WTRU may use for UL
transmission.
[0077] The WTRU may perform an initial TTI and/or transport channel
selection based on a number of criteria and preferred resource
access. For example, upon selecting a TTI and/or transport channel,
the WTRU may initiate an UL RACH procedure by selecting a preamble
from a group of preambles that correspond to the selection of the
WTRU.
[0078] For example, the WTRU may determine to use, that it is
allowed to use, and/or that it may prefer to use a R99 RACH
resource if one or more of the following conditions are
satisfied/established. The conditions may include, but are not
limited to, one or more of the following: the WTRU is be capable of
fallback to R99 RACH; the network is capable of R99 RACH fallback;
the buffer size of the WTRU is below a threshold; the WTRU is
transmitting data corresponding to a logical channel that is in a
list of allowed/configured logical channels for which R99 RACH may
be allowed (e.g., CCCH); a common E-DCH access has failed; or any
of the conditions related to a fallback to R99 RACH are satisfied.
For example, the WTRU may determine that there are no already
created RLC PDUs in the RLC entity. For example, the WTRU may
determine that there are no RLC PDUs already created in the RLC
entity (e.g., in the retransmission buffer or in the RLC created
but not yet transmitted) that may correspond to a size different
than the allowed broadcasted RLC PDU size.
[0079] The WTRU may perform TTI selection (e.g., select a preamble
from a set of 2 ms TTI resources or 10 ms TTI resources) if one or
more of the following conditions are met. The conditions may
include, but are not limited to, one or more of the following: the
WTRU is capable of concurrent 2 ms and 10 ms TTI operation (e.g.,
the WTRU may choose between 2 ms and 10 ms TTI for UL common E-DCH
access); the network is capable of concurrent 2 ms and 10 ms TTI
operation; the WTRU is transmitting data corresponding to a logical
channel that is in a list of allowed/configured logical channels
for which concurrent 2 ms and 10 ms TTI operation may be allowed
the WTRU may determine to use 2 ms or 10 ms TTI resources based on
select conditions (such as, but not limited to WTRU power
headroom); the buffer size in the WTRU may also be used to select
the TTI; or the buffer size may be used in addition to, for
example, the power margin and/or WTRU headroom criteria (e.g., if
the power margin may be above a threshold and/or the buffer
occupancy may be above a threshold, the WTRU may select the 2 ms
TTI; and if the buffer may be below a threshold, the WTRU may
select the 10 ms TTI).
[0080] Based on TTI selection and/or the transport channel
selection, the WTRU may determine the preamble to use for UL
preamble transmission.
[0081] If the WTRU determines to fallback (e.g., select R99 RACH),
the WTRU may autonomously fallback to R99 RACH resources (e.g.,
PRACH system information) and may perform the R99 procedure to
determine the preamble from the set of allowed preambles for R99
RACH (e.g., the legacy R99 RACH).
[0082] For example, if the WTRU determines to select and/or
determine that it is allowed to use RACH to transmit data, it may
chose a preamble from a set of preamble reserved to distinguish
WTRUs that may use and/or that may prefer to use R99 RACH over
common E-DCH.
[0083] Preamble groups may be reserved and may be used by WTRUs
that may select a different TTI for common E-DCH. For example, a
group of preambles may be reserved for WTRUs that prefer to use a
TTI different than the TTI used for the common E-DCH resources
(e.g., legacy common E-DCH resources). For example, two groups of
preambles may be reserved for 2 ms and 10 ms TTIs respectively for
WTRUs that may select the TTI.
[0084] At least a set of preamble resources may be reserved and/or
may be broadcasted/signaled for WTRUs that can make use of
transmission on either R99 RACH or common E-DCH and/or for WTRUs
that can perform TTI selection on common E-DCH. A set of preamble
resources may correspond to one or more of the following
parameters: a set of preamble signatures; a separate scrambling
code; or a set of reserved access slots.
[0085] For transport channel selection, preamble resources may be
reserved to be used by WTRUs that may be allowed to and/or prefer
to perform R99 RACH transmission, e.g., according to any of the
selection criteria discussed herein, which may be referred to as
"R99 fallback PRACH resources." If the selection criteria as
described herein is met and/or the WTRU determines that it is
allowed to and/or prefers to use R99 RACH, then the WTRU may select
a preamble signature and/or a scrambling code from the R99 fallback
PRACH resources and/or may initiate preamble transmission. For
example, the scrambling code may be specific to R99 fallback
resources and/or it may be common to the common E-DCH resources.
The selection, for example as described herein, may be carried out
at the beginning of the PRACH procedure and/or at a preamble
retransmission.
[0086] For TTI selection, a preamble resource may be reserved
according to one or more of the following. Preamble resources
(e.g., one or more new preamble resources may be configured) may be
reserved for one or more WTRUs that may support 2 ms and 10 ms TTI
selection. Preamble resources for 2 ms and/or 10 ms TTI selection
may be signaled. For example, preamble resources (e.g., new
preamble resources) may be reserved/signaled for WTRUs that support
a TTI other than the TTI signaled for the common E-DCH WTRUs (e.g.,
legacy common E-DCH WTRUs). For example, if the common E-DCH
resources (e.g., legacy common E-DCH resources) have a TTI
configuration of 10 ms, preamble resources (e.g., new preamble
resources) may be reserved for WTRUs that select 2 ms TTI according
to the criteria above.
[0087] A set of preamble resources may correspond to one or more
of: a set of preamble signatures; a separate scrambling code; or a
set of reserved access slots. Preamble resources may be reserved
according to one or more of the following. One scrambling code may
be used for R99 fallback capable WRTUs and one scrambling code for
common E-DCH WRTUs. The preamble signatures within the scrambling
code used for common E-DCH may be divided between common E-DCH
WRTUs (e.g., legacy common E-DCH WRTUs) and concurrent 2 ms/10 ms
TTI WRTUs, where preamble signatures may be reserved for 2 ms TTI
access and 10 ms TTI access. For example, one scrambling code may
be used for concurrent 2 ms/10 ms TTI capable WRTUs and a another
scrambling code may be used for the fallback R99 capable WRTUs. For
example, one scrambling code may be used for concurrent 2 ms/10 ms
TTI capable WRTUs and fallback R99 WRTUs. The preamble signatures
within this scrambling code may be divided according to one or more
of the following. Preamble signatures may be divided between 2 ms
and 10 ms common E-DCH access. The set of preamble resources may be
signaled for 2 ms and a another set may be signaled for the 10 ms
common E-DCH, for example, in addition to the legacy common E-DCH
preamble resource set. For example, if the WRTU uses any of these
signatures and/or scrambling code, it may mean that the WRTU is R99
fallback capable. Preamble signatures may not be divided further
for R99 RACH fallback capable WRTUs. For example, preamble
signatures may be divided between 2 ms and 10 ms common E-DCH
access and R99 RACH fallback capable WRTUs. For example, a WRTU may
choose to use a preamble signature from the R99 RACH fallback set
of resources if the conditions described below are met.
[0088] A WTRU may determine which set of reserved preambles to use
for initial preamble access according to different criteria and/or
preferred channel access. For example, the WRTU may determine to
select a preamble from a R99 RACH fallback set of resources if one
or more of conditions are met. The conditions may include one or
more of the following: that the WTRU is fallback to R99 RACH
capable; that a common E-DCH access has failed; that the buffer
size of the WTRU is below a threshold; that the WTRU is
transmitting data corresponding to a logical channel that is in a
list of allowed/configured logical channels for which R99 RACH may
be allowed (e.g., CCCH and/or DCCH); or any of the conditions
described herein for a fallback to R99 RACH are met.
[0089] Based on the UL resource selection (e.g., R99 RACH or 2 ms
and/or 10 ms common E-DCH), the WTRU may determine which PRACH
resources to use for preamble transmission.
[0090] A WRTU may determine whether to select a preamble from a set
of concurrent 2 ms and 10 ms TTI resources if one or more of the
following conditions are met: the WRTU is capable of concurrent 2
ms and 10 ms TTI operation (e.g., it may chose between 2 ms and 10
ms TTI for UL common E-DCH access); the WRTU is transmitting data
corresponding to a logical channel that is in a list of
allowed/configured logical channels for which R99 RACH is possible
(e.g., CCCH); or the WRTU determines within the 2 ms and 10 ms TTI
set, the group from which resources are chosen.
[0091] A WTRU may determine to transmit and/or that it prefers to
transmit on R99 RACH. The WTRU may select a preamble from the R99
RACH fallback PRACH resources. If the WTRU determines that it
prefers to use common E-DCH, the WTRU may determine the TTI to use
based on the TTI selection criteria described above. The WTRU may
select a preamble from the PRACH resources corresponding to a
chosen TTI value from the reserved group of preambles.
[0092] If PRACH resources are broadcasted for a TTI configuration
different than the common E-DCH (e.g., legacy common E-DCH), then
the WTRU may chose a preamble from that set of PRACH resources, for
example, if the WTRU selects a different TTI than the common E-DCH
(e.g., legacy common E-DCH). Otherwise, the WTRU may select a
preamble from the PRACH resources signaled for the common E-DCH
resources (e.g., legacy common E-DCH resources).
[0093] This may allow the network to determine that WTRUs making
such access may be UL channel selection capable, such as but not
limited to fallback to R99 RACH capable and/or concurrent 2 ms/10
ms TTI capable and/or have potentially met the criteria above
and/or expressed a choice of UL channel. The network may use this
information to determine what resources to allocate to the WTRU
(e.g., RACH or Common E-DCH, and, within common E-DCH it may
determine whether to use 2 ms TTI or 10 ms TTI).
[0094] The WTRU may use one or more of the UL channel resources in
a flexible way controlled by the network. For example, a set of
preamble resources may be reserved for a group of WTRUs that may
make use of transmission on R99 RACH and/or common E-DCH.
[0095] Using the pool of selected preamble resources, for example,
the WTRU may start performing the preamble ramp-up phase according
to procedures (e.g., legacy procedures) and may wait for an
explicit indication to determine which set of resources to use.
Even though the preamble resources may be split and/or grouped for
different UL accesses, the physical resources used for UL access
(e.g., the PRACH and/or the Common E-DCH resources) may be split
from resources (e.g., legacy resources), or, the same resources may
be used. For example, a default association between the preamble
group and UL resources may be defined.
[0096] The determination of which resources to use for UL access
may be based on a set of rules and/or on explicit signaling by the
network. The decision making process in the WTRU may be according
to one or more of the following. A reserved preamble group may have
a default associated set of UL resources. If the WRTU chooses the
preamble from the dedicated R99 fallback RACH preamble set, the
default set of resources associated with this preamble set may be a
set of R99 RACH resources. The R99 RACH resources may be associated
to a set of PRACH resources (e.g., legacy PRACH resources) (e.g.,
the first PRACH configuration if more than one is available), or a
set of specific R99 fallback PRACH info may be defined and used.
For example, the preamble group associated with a 2 ms TTI or a 10
ms TTI common E-DCH may have as a default set a set of the common
E-DCH resource set configured with 2 ms or 10 ms respectively. The
2 ms preamble set and 10 ms preamble set may have as a default set
the same common pool of E-DCH resources. The common E-DCH resources
may be used with any TTI value. This common E-DCH resource set may
correspond to the legacy set of Common E-DCH resources and/or to a
set of common E-DCH resources (e.g., new set of common E-DCH
resources). If the legacy common E-DCH resource is chosen, the
default set may be the common E-DCH configuration (e.g., legacy
common E-DCH configuration). If the WTRU selects the common E-DCH
set, then the network may not redirect the WTRU to another UL
resource, for example, because it may not be aware that the WTRU
supports such UL resource selection.
[0097] An AICH may be used to acknowledge the use of a default set
of resources and the E-AI may be used to explicitly redirect the
WRTU to a different set of resources. After choosing a preamble
from a preamble group, the WRTU may transmit the preamble and may
monitor the AICH. If an ACK on the AICH is received, this may be
interpreted as an acknowledgment that the defined default set of
resources associated to the selected preamble may be used. If a
preamble from R99 fallback PRACH resources is chosen and/or an ACK
was received on the AICH and/or the default resources are the R99
RACH resources, then the WTRU may initiate the R99 RACH message
part transmission using the default physical set of resources
signaled/broadcasted on the SIB. The scrambling code and/or
signature sequences of the selected preamble may be used to
determine the channelization code and/or perform UL transmission.
For example, if a 2 ms TTI preamble is transmitted and an ACK is
received, the WTRU may initiate common E-DCH transmission using the
2 ms TTI configuration and use the common E-DCH resource
corresponding to the resource.
[0098] A NACK on the AICH may indicate a failure to access the
default associated resources (e.g., if the default chosen may be a
resource other than the legacy common E-DCH). The WTRU, after a
failure to access the default resource, may retry again after a
back off timer. The WTRU may use a preamble chosen from a different
group of resources, or, from the same set of resources. For
example, if initial access was with R99 fallback RACH and a NACK
was received, the WTRU may retry again after a back-off time
expires using the common E-DCH. The WTRU may attempt on the other
non-default resources if failure to the default resources was
detected for N attempts, where N may be network configurable and/or
may correspond to the maximum number of preamble transmissions.
This may be applicable if no Extended Acquisition Indicator (EAI)
is configured. This mechanism may be applicable for some WTRUs and
for some specific default resources (e.g., for R99 RACH). This
mechanism may be applied to the scenario where a NACK is received
on the EAI. This may be applied by the WTRU if a NACK may be
received on the EAI, and/or if a NACK may be received for N
attempts. For example, an EAI may be a value that corresponds to a
combination of a signaled signature and modulation signal.
[0099] The reception of a NACK may signal to the WTRU that it may
start monitoring the EAI for, for example, an explicit resource
indication on the other non-default resource set and/or an index to
a set of resources signaled on the default set. An index signaled
over the EAI may correspond to an index to a non-default set. A
non-default set may correspond to another UL channel and/or another
TTI value. If the R99 RACH is the default set, then the non-default
set may correspond to a common E-DCH set (e.g., the legacy common
E-DCH set with one TTI configuration or a common E-DCH set which
may have any TTI configuration). An assumption may be made that a
R99 fallback compatible WTRU also supports TTI selection. The E-AI
may signal an index which may be used in conjunction with the
selected R99 fallback preamble to determine which common E-DCH
index to use.
[0100] If the default set is a 2 ms TTI set, then the EAI may
correspond to an index for the 10 ms TTI set. If the default set is
a common E-DCH set, then an EAI may be used to signal a fallback to
R99 RACH. This may indicate a preamble index to use for UL access
and/or a PRACH index. The EAI may be used to signal what UL channel
to use according to any of the methods described herein.
[0101] The reception of a NACK may trigger the WTRU to start
monitoring the EAI. The EAI may indicate what resource the WRTU may
use. For example, one or more EAI values may be used to indicate
one UL resource. The remaining EAI values may be used to indicate
another UL resource. For example, for transport channel selection,
at least one or a subset of UL resources may be used to indicate
the use of R99 PRACH (e.g., an index to a signature sequence, s)
and the remaining subset may be used to indicate a common E-DCH
index. For example, at least one value of the EAI may be used
and/or reserved to indicate that the WRTU should perform a R99 RACH
fallback and/or perform a R99 RACH access using signaled PRACH
information. A reserved EAI value may be used by WRTUs that perform
access using a preamble from one of the group of preambles that
indicate support of R99 RACH access (e.g., either the R99 fallback
preambles and/or the concurrent 2 ms/10 ms TTI preambles, for
example, under the assumption that such WTRUs support R99
fallback). The EAI value corresponding to a fallback may be a
predefined value (e.g., the same value as used for NACK over the
EAI or any new value). The reserved value may be configured and or
signaled to the WTRU. A value in the list of common E-DCH resources
(e.g., a common E-DCH resource index) may be reserved for R99 RACH
fallback indication. The reserved value may be configured via RRC
signaling and/or predefined. The WTRU may receive which index
and/or value that may correspond to a R99 fallback as part of the
R99 fallback configuration information and/or the values may be
predefined. For example, if the received EAI value (e.g., signature
and/or modulation symbol) is equal to the configured and/or stored
R99 fallback value, then the WTRU may determine that it may
fallback to R99 RACH transmission, for example, if the criteria
described herein are met. For example, if the received and/or
calculated E-DCH resource index is equal to the configured and/or
stored R99 fallback index, then the WTRU may perform R99 RACH
transmission, for example, if the other criteria described herein
are met.
[0102] A subset of the EAI values (e.g., k) may be used to indicate
an index to a set of 2 ms common E-DCH resources. Another subset of
EAI values (e.g., 1) may be used to indicate an index to a set of
10 ms TTI resources. For example, if 16 common E-DCH resources are
used for 10 ms TTI and 16 for 2 ms TTI, the WRTU may determine to
use a 10 ms common E-DCH resource if the indicated value received
over the E-AI would correspond to a resource from 0-15 (e.g., 0 to
k-1) and a 2 ms resource if the index corresponds to a value of
16-31 (e.g., k to l+k-1). This may be achieved if the 2 ms and 10
ms TTI resources are maintained as one list, if the first x
resources correspond to the 2 ms TTI configuration, and the
remaining resources correspond to a 10 ms TTI configuration. The
EAI may be used to signal a value that may be then used to
determine an index to the common E-DCH list. Based on the common
E-DCH index, the WRTU may determine if the associated resource has
a 2 ms or a 10 ms TTI configuration. If the index, for example,
corresponds to a value between 0 and x-1, then the resource may be
a 2 ms TTI resource, otherwise it may be a 10 ms TTI resource.
[0103] The EAI may be used to signal any of the UL channels and/or
resources. The index determined after reception of the EAI may
correspond to a R99 PRACH, 2 ms TTI, or 10 ms TTI. A list of values
may be reserved on the EAI to signal a R99 PRACH, a 2 ms TTI,
and/or a 10 ms TTI. For example, one or more indexes may refer to 2
ms TTI (0 . . . x-1), one or more indexes may refer to 10 ms TTI (x
. . . x+y-1), and one or more indexes may be used to indicate a
fallback to a R99 PRACH for UL access, where x may be the list of
configured 2 ms TTI resources, y may be the list of configured 10
ms common E-DCH resources, and the sum of the resources do not
exceed a certain maximum number (e.g., 32).
[0104] For example, if the common E-DCH resources between the 2 ms
TTI and the 10 ms TTI configuration are split, then the default
common E-DCH index, X, for a TTI configuration may correspond to
X=Siglnd mod (N), where N may be the maximum number of common E-DCH
resources configured with the corresponding selected TTI. The
default common E-DCH index X may be determined based on a WTRU's
initial TTI selection (e.g., N may correspond to the maximum number
of common E-DCH resources with the selected TTI).
[0105] The default X value may be dependent on whether an ACK on
the AICH is received or whether an EAI is received. If an ACK is
received, the value X and the common E-DCH index to use may be
determined as described herein. If an EAI is received and the full
EAI range of values is used to signal any index to a common E-DCH
list that includes both 2 ms TTI and 10 ms TTI, then the value X
may be determined by X=Siglnd mod (N), where N may be the maximum
common E-DCH resources for TTI configurations. If the E-AI values
are split to signal different TTI configurations, then N may
correspond to the maximum common E-DCH resources with a TTI
configuration corresponding to the TTI associated to the EAI
value.
[0106] Siglnd may be the Nth PRACH preamble signature corresponding
to the AI that is configured available in the cell and
corresponding to E-DCH transmission for Enhanced Uplink in
CELL_FACH state and IDLE mode for selected TTI configurations.
[0107] If an E-AI is used to signal an index to a common E-DCH
resource, the WTRU may use the formula (X+EAI value) mod Y, where Y
may be the total number of common E-DCH resources (e.g., regardless
of the TTI configuration). The WTRU may use the formula (X+EAI
value) mod N, where N may be the maximum number of common E-DCH
resources with a corresponding TTI configuration. The corresponding
TTI configuration may be determined based on a default mapping
and/or based on the value of the EAI (e.g., that may be reserved as
described herein).
[0108] Two or more E-AIs may be configured to indicate an UL
channel to use. The WRTU may monitor for two or more E-AIs (e.g.,
simultaneously). Depending on which EAI the resource index is
received, the WRTU may determine which UL channel to use.
[0109] A list of R99 RACH resources and/or common E-DCH resources
may be signaled and/or associated to the preamble set. The AI may
be used to acknowledge the use of a resource associated to the
index of the preamble randomly selected (e.g., it may be either R99
RACH or common E-DCH). The EAI may be used to signal an index.
Based on this index and/or the preamble selected, the WTRU may
determine the index to the resource it may use.
[0110] A common E-DCH resource may be used with 2 ms TTI or 10 ms
TTI configuration. The AI and/or the EAI may indicate to the WRTU
which TTI it may use for the corresponding common E-DCH resource.
The preamble group may be separated between the 2 ms TTI and 10 ms
TTI, but the common E-DCH resource list may be one list and each
resource may be used with any TTI configuration. The WRTU may
determine what UL channel it wants to use (e.g., PRACH or common
E-DCH). If the WTRU chooses a common E-DCH, the WTRU may determine
what TTI configuration it wants to use. If the WTRU chooses a 2 ms
TTI, then a preamble from the 2 ms TTI preamble group may be
chosen. In order to determine whether it is allowed to use a 2 ms
TTI or 10 ms TTI, one or more of the following techniques may be
used. An ACK on the AICH may be used as an indication that the
E-DCH resource associated with the chosen preamble and the TTI
configuration corresponding to the preamble group that should be
used. A NACK on the AICH may be used as an indication that the WRTU
should not use the chosen TTI (e.g., the TTI associated with the
preamble group). The WRTU may monitor the EAI to determine what
resource it may use with the TTI (e.g., the new TTI). The NACK may
be used as an indication that the WRTU may monitor the EAI. The
WRTU may not have determined what TTI it may use.
[0111] The EAI may be used to indicate to the WRTU what TTI it
should use. For example, the reserved field of the AICH may be used
to indicate which TTI the WRTU should use. The response on the AICH
(e.g., ACK/NACK) may be used in combination with the reserved field
to determine what TTI to use. The reserved field may be used to
indicate two values or just one value (e.g., two values may be used
to indicate what TTI value to use, and one value may used to
indicate whether the WRTU should change the chosen TTI value). If
an ACK is received on the AICH, the WRTU may determine to the use
the associated common E-DCH index with a TTI configuration as
indicated in the reserved field of the EAI. If an NACK is received
on the AICH, the WRTU may determine to monitor an EAI (if
configured) for a resource indication. The TTI that the WRTU may
use for the signaled resource over the EAI may be the TTI as
indicated on the reserved field with the NACK.
[0112] The network may control channel selection (e.g., TTI or
transport channel selection) for individual and/or groups of WTRUs.
The network may control the fallback or use of R99 RACH for UL
transmission. The WTRU may wait for an indication to fallback to
R99 RACH. The network may control the common E-DCH channel type the
WRTU should use, such as, but not limited to, a 10 ms or a 2 ms
common E-DCH channel. After triggering a preamble transmission, the
WTRU may wait for signaling to determine which UL channel to use,
such as, but not limited to, to fallback or use R99 RACH, to use 2
ms TTI, and/or to use 10 ms TTI. For example, at least one value in
the E-AI may be reserved and/or used to signal fallback to R99
RACH, fall back to another TTI value for Common E-DCH, and/or to
signal what TTI the WRTU should use for common E-DCH. Upon
reception of this value over the E-AI, the WTRU may autonomously
fallback to R99 RACH, may autonomously fallback to using another
TTI value (e.g., other than the requested one), or may start using
the TTI value indicated by the reserved value of the AICH and/or
the E-AI in the case of TTI selection. The reception of a NACK
(e.g., on the E-AI if the E-AI is configured, or on the AI if no
E-AI is configured) may also serve as signaling used to control the
WRTU and indicate a fallback. At least one resource index and/or a
set of resources in the list of common E-DCH may be reserved for a
specific UL channel (e.g., used for fallback to R99 RACH or to use
2 ms TTI or 10 ms TTI). When a fallback to R99 RACH capable WRTU
and/or a WRTU that may be capable of changing TTI values for common
E-DCH receives this resource allocation over the E-AI, the WTRU may
select the indicated channel for transmission (e.g., R99 RACH or a
common E-DCH with the indicated TTI value). WTRUs (e.g., legacy
WTRUs) may use the resource indicated by the index as a common
E-DCH resource. For example, the reserved field of the AICH and/or
the E-AICH may be used to indicate to the WTRU to fallback to R99
RACH and/or to select another TTI.
[0113] A secondary E-AICH code may be monitored by fallback to R99
RACH capable WRTUs and/or WRTUs capable of changing TTI values for
common E-DCH. The secondary E-AICH may be configured by a network
(e.g., by broadcast signaling and/or via dedicated signaling). The
network may be fallback to R99 RACH capable and/or capable of
changing the Common E-DCH TTI UL access. The secondary E-AI may be
used to indicate a fallback to R99 RACH and/or a common E-DCH TTI.
The secondary E-AI may be used to indicate a preamble resource from
the R99 PRACH resources that the WTRU may use for its RACH access.
The secondary E-AI may be further used to indicate a preamble
and/or common E-DCH resource configured with a TTI and/or a common
E-DCH resource index with a specific TTI.
[0114] In order for the WTRU to determine whether and when to
monitor the secondary E-AI, one or more criteria may be used. The
criteria may include, but are not limited to, that a UL channel
selection capable WTRU (e.g., fallback to R99 RACH and/or common
E-DCH with different TTIs) may monitor the primary and secondary
E-AICH. The reserved field in the AICH may be used to indicate to
the WTRU to monitor the secondary EAI. The reserved field of the
AICH may be used to signal a value that may correspond to an
indication that the WTRU should fallback to R99 RACH and/or that it
should change TTIs. The reserved field of the AICH may be used to
signal to the WTRU that it should monitor a EAI (e.g., a secondary
E-AI) to potentially receive a resource assignment and/or any other
signal. Detection of NACK signaled on the primary E-AI may be used
as a criterion. Upon reception of a NACK on the E-AI and/or in the
AI (e.g., if a primary EAI is not configured for legacy WTRUs), a
UL channel selection capable WTRU may start to monitor a secondary
EAI. The WTRU may start monitoring the EAI a certain time period
after one of the conditions described herein are met.
[0115] The network may determine the capabilities of WTRUs by the
use of one or more (e.g., a set of) reserved preamble groups for
R99 RACH capable WTRUs (e.g., as determined by the criteria
described herein). The network may use any of the implementations
described herein to indicate to a WTRU whether to fallback to R99
RACH or to common E-DCH.
[0116] A WTRU may perform transport channel selection. The WTRU may
indicate a preference for resources. The WTRU may determine if the
WTRU and the network support transport channel selection and/or
fallback to R99 RACH. The WTRU may determine if the criteria
described herein are met. For example, the WTRU may determine if
the buffer status is below or equal to a threshold. The WTRU may
determine whether RLC PDUs are created and present in a
retransmission buffer. If there are no RLC PDUs in the buffer, the
WTRU may determine if RLC PDUs with a size different and/or greater
than the allowed RLC PDU size for the RACH are present.
[0117] If the criteria are met, the WTRU may select a preamble from
the R99 RACH fallback and may initiate a preamble ramp-up
procedure. Based on the selected preamble, the network may
determine the preference and/or type of WTRU performing uplink
access and may determine the transport channel to use. If the WTRU
fails to meet the criteria, the WTRU may select a preamble from the
common E-DCH preambles (e.g., legacy common E-DCH preambles). In
such instances, when the network receives the preamble, the network
may not know that the WTRU is R99 RACH capable and, therefore, may
not have the option to send the WTRU to R99 RACH.
[0118] The WTRU's default resources may be the common E-DCH
resources. The WTRU may start using the common E-DCH resource
associated with a default common E-DCH index, X, in response to
receiving an ACK on the AICH. For example, X=Singlnd mod Y, where
Singlnd may be the Nth preamble of the R99 fallback preamble list.
The TTI configuration to use for the common E-DCH may be the TTI
configuration of the common E-DCH resources (e.g., legacy common
E-DCH resources) or, the common E-DCH may be provided to the WTRU
using any of the examples described herein. The EAI may be used to
signal the WTRU to fallback or use the R99 RACH by any of the
implementations described herein, such as but not limited to: a
NACK on the EAI; a reserved common E-DCH index; or a reserved value
of EAI. The other EAI values may be used to redirect the WTRU to
use a different common E-DCH resource index other than the default
X. When no EAI is configured, a NACK on the AICH may signal such
WTRUs to start using the R99 RACH.
[0119] The WTRU's default resources may be the R99 RACH resources.
The WTRU may choose a preamble from the R99 fallback RACH
preambles. An ACK on the AICH may imply that the WTRU has been
acknowledged to fallback or to start using the R99 RACH. The NACK
and/or EAI may be used to signal an index to a common E-DCH
according to any of the implementations described herein.
[0120] A WTRU may perform transport channel selection and may use a
set of reserved preambles to signal that it supports R99 RACH. For
example, the preambles may be reserved for R99 and/or they may be
the preambles used for TTI selection (e.g., the preambles for 2 ms
and/or 10 ms TTI configuration) that imply that the WTRU also
supports R99 fallback. The network may not be aware of the WTRU
buffer and/or RLC status. The network may still redirect the WTRU
to use the R99 RACH according to any of the implementations
described herein. This may be applicable where the network is aware
of the WTRU buffer and/or RLC status (e.g., that the criteria is
not met), but the network still may have the option to redirect the
WTRU to use R99 RACH. For example, if the criteria to fallback is
dependent on the logical channel type, the WTRU may fallback (e.g.,
only fallback) if the uplink transmission belongs to the predefined
list and/or configured allowed channels (e.g., CCCH and/or DCCH may
be part of the channel list). If the WTRU is R99 fallback capable,
after performing a random access procedure trying to acquire a
common E-DCH resource, the WTRU may monitor the AICH and/or E-AI to
determine if a NACK on the AICH may be received. If the EAI value
and/or corresponding E-DCH resource index received is equivalent to
the index corresponding to the fallback, and if there may be CCCH
uplink data to transmit and CCCH fallback is allowed or if there
may be DCCH uplink data to transmit and DCCH fallback is allowed,
then the WTRU may perform R99 RACH fallback. If the conditions
above are not met (e.g., if there is DTCH data to transmit), then
the WTRU may not fallback to R99 RACH. Where the logical channel
type allowed to fallback to R99 RACH is CCCH (e.g., only CCCH),
then if the WTRU has DCCH or DTCH data for transmission, the WTRU
may determine not to fallback to R99 RACH. Upon reception of an
indication to start using R99 RACH, the WTRU may start using R99
RACH regardless of the buffer status and/or RLC status (e.g., the
WTRU may re-create the RLC PDUs or may create other RLC PDUs, for
example, in an attempt to transmit as much data as possible). The
WTRU may start using R99 RACH and, if the RLC status and/or buffer
status are not met, may use the RACH to transmit a TVM report. The
WTRU may ignore the network indication to fallback to R99 RACH,
back off, and may try to access the UL again. For example, the WTRU
may ignore the indication from the network to fallback using a
random access channel (e.g., R99 RACH, R99 PRACH, etc.), may wait
for a time (e.g., back off for a predetermined amount of time), and
then may re-attempt to access the network. When attempting the UL
access, the WTRU may decide to choose a preamble from the common
E-DCH resources (e.g., legacy common E-DCH resources), which may
not allow the network to know that the WTRU may be R99 fallback
capable. This may increase the chances of accessing the UL over the
common E-DCH.
[0121] The WTRU may perform TTI selection based on one or more of
the criteria described herein (e.g., capability and
power/headroom). Preambles (e.g., new preambles) may be reserved to
signal a TTI indication other than the TTI configuration signaled
on the common E-DCH list (e.g., legacy common E-DCH list). If the
WTRU selects a TTI configuration other than the TTI used for the
common E-DCH (e.g., legacy common E-DCH), then the WTRU may chose a
preamble from the signaled PRACH resourced (e.g., new signaled
PRACH resourced) for the TTI configuration (e.g., the new TTI
configuration). The network may determine a preference of the WTRU.
The network may become aware that the WTRU is TTI selection
capable. The network may use any of the implementations described
herein to acknowledge the selection or redirect the WTRU to a
different TTI. If the WTRU selects the same TTI as the TTI signaled
on the common E-DCH resource (e.g., legacy common E-DCH resource),
then the WTRU may pick a preamble from the common E-DCH PRACH
resources (e.g., legacy common E-DCH PRACH resources). The network
may not know that this WTRU is capable of TTI selection and may not
redirect the WTRU to use any other TTI. The AICH may be used
according to the rules (e.g., the legacy rules) to indicate the
common E-DCH index of the resources (e.g., legacy resources).
[0122] Preambles (e.g., new preambles) may be signaled for 2 ms TTI
and 10 ms TTI configurations (e.g., for WTRUs capable of TTI
configuration). Based on the chosen TTI, the WTRU may select the
preamble from either the 2 ms or the 10 ms group. The network may
be aware of the preference and that the WTRU may be TTI selection
capable. The network may use any of the implementations described
herein to redirect the WTRU.
[0123] Allowing a fallback to R99 RACH may result in transmissions
of data over a R99 PRACH from a logical channel configured with
flexible RLC PDU configuration. For example, considering that R99
RACH may not have segmentation capabilities and may transmit a
limited set of TBS, a flexible PDU RLC may coordinate the RLC PDU
creation with the R99 RACH transport format selection.
[0124] The RLC configuration in non-DCH states may correspond to
flexible RLC PDU sizes. In order to enable transmission over R99
RACH, the RLC may create "radio aware RLC PDUs," such that the RLC
PDUs may be created to fit within a selected RACH TBS without MAC
layer segmentation. For example, the WTRU may determine the RLC PDU
size based on one or more of the following criteria. A criterion
may be the selected TBS size. A criterion may be the minimum
selected TBS size and/or available number of bits quantized to the
lowest allowed TBS size that is equal to or smaller than selected
TBS. A criterion may be the minimum selected TBS size, available
number of bits, and/or available power quantized to the lowest
allowed TBS size that is equal to or smaller than selected TBS.
[0125] If the WTRU performs delayed radio aware RLC PDU creation
when configured with fallback to R99 RACH and attempting a common
E-DCH access, then the WTRU may start creating RLC PDUs after the
E-DCH resource has been allocated to the WTRU. This procedure may
prevent the WTRU from prematurely generating RLC PDUs that it may
not be able to transmit over the R99 RACH. For example, the size of
the delayed RLC PDUs might be decided according to any combination
of the following criteria. A criterion may be the number of bits
that may be transmitted according to, for example, the default
grant broadcasted. A criterion may be the minimum between number of
bits that may be transmitted according to, for example, the default
grant and/or an allowed TBS from the set of the R99 RACH transport
formats. An allowed TBS may correspond to, for example, the
smallest TBS and/or the largest TBS. A criterion may be the minimum
allowed TBS, available data, and/or default grant quantized to an
allowed TBS size that may be smaller than the default grant. The
size of the delayed RLC PDUs may be decided based on a broadcasted
RLC PDU size.
[0126] MAC segmentation may be allowed for transmission over R99
RACH. For example, the MAC-i/is sub-layer may segment RLC PDUs (or
MAC-d PDUs) prior to delivery to the MAC-e sublayer for
transmission over RACH. A MAC-i/is header may be included in the
R99 RACH transmission in order to allow the Node B to reassemble
the segments received across multiple R99 RACH transmissions.
[0127] Upon a redirection/acknowledgement to R99 RACH, the WTRU may
perform one or more of the following. The WTRU may initiate a RACH
preamble transmission procedure (e.g., a new RACH preamble
transmission procedure) using the PRACH information of the R99 RACH
resources (e.g., legacy R99 RACH resources). This procedure may be
accelerated using any of the implementations described herein. The
WTRU may initiate a PRACH message transmission upon reception of a
redirection/acknowledgment to use R99 RACH (e.g., legacy R99 RACH).
The timing to initiate the PRACH message transmission with respect
to the AICH may be maintained. For example, the WTRU may use any
combination of the following physical channel parameters to perform
the PRACH message transmission: a scrambling code of the preamble
selected from the R99 fallback PRACH resources; the signature
sequence, s, of the preamble selected from the R99 fallback RACH
resources and/or used to determine a channelization code; or the
other physical channel parameters, transport channel formats, etc.,
that may be extracted from the PRACH information (e.g., legacy
PRACH information) (for example, if more than one PRACH info is
selected, then the resources of the first one or a predefined one
may be used). PRACH information (e.g., new PRACH information) may
be broadcasted to be used from such WTRUs.
[0128] After selection and/or redirection of the R99 RACH channel
for transmission, the WTRU may attempt to access the R99 RACH
and/or may perform UL transmission of data and/or control
information. Upon completion of this procedure, wherein completion
may refer to transmission of the data over the air interface or
RACH failure, the WTRU may have data in its buffer. If the WTRU
immediately performs access to common E-DCH again, the same
congestion may still occur. After attempting E-DCH access, the WTRU
may fail again and may perform another fallback to R99 RACH. This
may result in access delays and/or ping-ponging between different
RACH accesses.
[0129] The behavior of the WTRU after a fallback to R99 RACH may be
controlled. For example, a timer (e.g., a prohibit timer, a
back-off timer, etc.) may be utilized to prevent the WTRU from
attempting access on the common E-DCH for a certain period of time.
The timer may be started in one or more of triggers. A trigger may
be that the WTRU determines that a fallback to R99 RACH has to be
performed. A trigger may be that a R99 RACH procedure has been
completed as a result of a fallback to R99 RACH. A trigger may be
that UL data was transmitted over the air using the R99 RACH. If
another UL access attempt has to be performed by the WTRU and the
timer is still running, then the WTRU may perform a R99 access. If
the timer is not running, the WTRU may access the common E-DCH
and/or re-evaluate the criteria to choose which RACH resources to
use. If the timer is running and the WTRU has data to transmit,
then the WTRU may trigger a TVM report to the network, which may
indicate the reason of the trigger.
[0130] The WTRU may fallback to R99 after a common E-DCH failure or
direct network indication even if the criteria above are not met. A
traffic volume measurement (TVM) report may be triggered upon
fallback to R99 RACH. For example, a TVM may be triggered if the
WTRU falls back to R99 and various conditions are satisfied. A
condition may be, for example, that the buffer size is above a
threshold. This threshold may be a fallback to R99 RACH specific
threshold and/or may be smaller than the threshold to trigger a TVM
report for a WTRU using common E-DCH. A condition may be, for
example, that the logical channel with UL data belongs to a list of
logical channels the WTRU may not be allowed to use R99 RACH, or to
a list that may trigger a TVM report. For example, at least two
events may be configured for TVM reporting in the WTRU. One may be
used when the WTRU is using common E-DCH and one may be used when
the WTRU has performed a fallback to R99 RACH.
[0131] Faster RACH access may be provided where the WTRU may switch
from a Common E-DCH access attempt to a R99 RACH access attempt,
and vice versa. These situations may include, without limitation, a
WTRU falling back to R99 RACH after having attempted common E-DCH
access; a WTRU falling back to R99 RACH after an explicit command
from the network after having attempted to connect to a common
E-DCH resource; and/or a WTRU performing access and potentially
transmission on the R99 RACH and determining that more data remains
in the buffer and then attempting access to a common E-DCH
resource.
[0132] In order to speed up such accesses, the WTRU may speed up
the preamble phase, for example, by using a preamble power that is
a function of the last preamble power used on the previous resource
(e.g., common E-DCH resource or R99 RACH resource). The preamble
power may correspond to one or more of the following. The preamble
power may be the same power as the last preamble transmitted on the
other resources. The preamble power may be the power of the last
preamble transmitted on the other resources plus a configured
offset.
[0133] The WTRU may speed up the access to the other resource by,
for example, receiving a dedicated resource indication by the
network. The resource indication may include an index to a preamble
signature of the set of resources the WTRU is being signaled to
access. In the case where a specific signal may be used by the
network to signal a fallback to R99 RACH, this signal may include
an index to a preamble resource (e.g., a scrambling code and/or a
signature sequence, s, or index to PRACH info, if multiple PRACH
info are signaled, that should be used by the WTRU). The index may
be transmitted to the WTRU by means of an EAI. The signal may
indicate the resource index and/or the common E-DCH value to use.
Implementations by which the WTRU may determine that the EAI may be
used to signal a UL channel selection (e.g., R99 RACH or TTI value)
may be described herein. For example, a secondary EAI may be used
to signal an index to a R99 PRACH preamble index and/or a common
E-DCH resource index from a group of resources corresponding to a
TTI value and/or a preamble index corresponding to a TTI value
other than the requested value. Upon reception of this index, the
WTRU may start the UL transmission on the indicated channel (e.g.,
RACH or common E-DCH with the indicated TTI). This may be performed
with or without an acknowledgment required. The WTRU may determine
the power to use based on the last preamble transmission on the
common E-DCH resource. The WTRU may start preamble transmission
using the last used power on the other channel.
[0134] FIG. 2 illustrates an exemplary fallback. The method 200 of
FIG. 2 may be utilized by a WTRU to determine if it may fallback
using a random access channel (e.g., R99 RACH, R99 PRACH, etc.) to
transmit uplink information to a network. The WTRU may have uplink
information such as, but not limited to, data or control
information to transmit to a network. At step 201, a WTRU may
request a common E-DCH resource from the network. For example, the
WTRU's default resources may be the common E-DCH resources.
[0135] After requesting a common E-DCH resource from the network,
the WTRU may receive an indicator from the network to fallback to a
random access channel (e.g., R99 RACH, R99 PRACH, etc.), thereby
completing step 202. The indication may be received via an
acquisition indicator (e.g., E-AI). The indication may be a value
of the E-AI. One or more E-AI values may be used to indicate the
use of a random access channel (e.g., R99 RACH, R99 PRACH, etc.)
and one or more E-AI values may be used to indicate a common E-DCH
index. For example, at least one value of the E-AI may be used to
indicate that the WTRU may perform a fallback to a random access
channel (e.g., R99 RACH, R99 PRACH, etc.). The WTRU may receive the
indication from the network to fallback regardless of whether or
not the network is aware of the WTRU buffer and/or RLC status.
[0136] At step 203, the WTRU may determine if a condition is met.
The condition may be met if one or more of the following is
established: the channel for transmission is capable of being
mapped to the R99 RACH; the channel for transmission may be
configured with a fixed RLC PDU size; and/or the channel for
transmission belongs to a list of channels that is predefined in
the WTRU, whereby the list may include CCCH and/or DCCH. The
condition may also be met if one or more of the conditions
described herein are established.
[0137] If the WTRU determines that the condition is met, then the
WTRU may fallback to the random access channel (e.g., R99 RACH, R99
PRACH, etc.) and may transmit the uplink information over the
random access channel (e.g., R99 RACH, R99 PRACH, etc.), thereby
completing step 204. For example, the WTRU may access the network
with a PRACH R99 signature to transmit uplink information over the
R99 RACH. The WTRU may initiate a RACH preamble transmission
procedure using the PRACH information of the R99 RACH resource
(e.g., legacy R99 RACH resources).
[0138] If the WTRU determines that the condition is not met, then
the WTRU may back off from accessing the network, thereby
completing step 205. The WTRU may determine that the condition is
not met if one or more of the conditions described herein are not
established. For example, the WTRU may determine that the condition
is not met if the channel for transmission does not belong to the
list of channels that is predefined in the WTRU. The WTRU may
ignore the indication from the network to fallback to the random
access channel (e.g., R99 RACH, R99 PRACH, etc.). The WTRU may wait
for a time (e.g., a predetermine amount of time) and/or may
re-attempt to access the network.
[0139] 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, UE, terminal, base
station, RNC, and/or any host computer.
* * * * *