U.S. patent application number 17/835609 was filed with the patent office on 2022-09-22 for method and apparatus for preamble transmission.
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 Paul Marinier, Ghyslain Pelletier, Sung-Hyuk Shin, Janet A. Stern-Berkowitz.
Application Number | 20220304071 17/835609 |
Document ID | / |
Family ID | 1000006388305 |
Filed Date | 2022-09-22 |
United States Patent
Application |
20220304071 |
Kind Code |
A1 |
Pelletier; Ghyslain ; et
al. |
September 22, 2022 |
METHOD AND APPARATUS FOR PREAMBLE TRANSMISSION
Abstract
A method performed by a WTRU may comprise measuring a power of a
downlink pathloss reference and comparing the measured power of the
downlink pathloss reference to a threshold. The WTRU may determine
whether to transmit a preamble, on a secondary carrier, based on
whether the measured power of the downlink pathloss reference is
less than the threshold. The method may further comprise not
transmitting the preamble on the secondary carrier in one or more
instance.
Inventors: |
Pelletier; Ghyslain;
(Montreal, CA) ; Marinier; Paul; (Brossard,
CA) ; Shin; Sung-Hyuk; (Northvale, NJ) ;
Stern-Berkowitz; Janet A.; (Little Neck, NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
InterDigital Patent Holdings, Inc. |
Wilmington |
DE |
US |
|
|
Assignee: |
InterDigital Patent Holdings,
Inc.
Wilmington
DE
|
Family ID: |
1000006388305 |
Appl. No.: |
17/835609 |
Filed: |
June 8, 2022 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16793804 |
Feb 18, 2020 |
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17835609 |
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15815317 |
Nov 16, 2017 |
10588154 |
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16793804 |
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14732200 |
Jun 5, 2015 |
9854608 |
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15815317 |
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13468709 |
May 10, 2012 |
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14732200 |
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61484591 |
May 10, 2011 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W 74/0891 20130101;
H04W 56/0045 20130101; H04W 56/0005 20130101; H04W 52/36 20130101;
H04W 52/325 20130101; H04W 74/0833 20130101 |
International
Class: |
H04W 74/08 20060101
H04W074/08; H04W 56/00 20060101 H04W056/00 |
Claims
1. A wireless transmit/receive unit (WTRU) comprising: a
transmitter configured to transmit a first preamble at a first
power level; a receiver configured to receive downlink control
information (DCI), on a first carrier, wherein the DCI indicates a
second carrier; the transmitter configured to, on a condition that
a maximum power level would be exceeded by a second preamble
transmission and another uplink transmission, transmit the second
preamble at a second power level on the second carrier, wherein the
second power level is lower than the first power level; and a
receiver configured to receive a random access response (RAR) to
the second preamble on a primary cell.
2. The WTRU of claim 1, wherein the first carrier and second
carrier are different carriers.
3. The WTRU of claim 1, wherein the first carrier and second
carrier are the same carrier.
4. The WTRU of claim 1, wherein the transmitter is configured to
transmit the first preamble at the first power level based on a
priority of another uplink transmission.
5. The WTRU of claim 1, wherein the transmitter is configured to
transmit the second preamble at the second power level based on a
priority of another uplink transmission.
6. The WTRU of claim 1, further comprising: circuitry configured to
determine whether to transmit a second preamble on the second
carrier based on whether the second preamble would coincide with
another uplink transmission.
7. A wireless transmit/receive unit (WTRU) comprising: a
transmitter configured to transmit a first preamble at a first
power level; a receiver configured to receive downlink control
information (DCI), on a first carrier, wherein the DCI indicates a
second carrier; the transmitter configured to transmit a second
preamble at a second power level on the second carrier, wherein the
second power level is lower than the first power level; and a
receiver configured to receive a random access response (RAR) to
the second preamble on a primary cell.
8. The WTRU of claim 7, wherein the first preamble is transmitted
on a different carrier than the second preamble.
9. The WTRU of claim 7, wherein the first preamble is transmitted
on a same carrier than the second preamble.
10. The WTRU of claim 7, wherein the transmitter is configured to
transmit the first preamble at a first power level based on a
priority of another uplink transmission.
11. The WTRU of claim 7, wherein the transmitter is configured to
transmit the second preamble at the second power level based on a
priority of another uplink transmission.
12. The WTRU of claim 7, further comprising: circuitry configured
to determine whether to transmit a second preamble on the second
carrier based on whether the second preamble would coincide with
another uplink transmission.
13. The WTRU of claim 7, wherein the second power level is
determined based at least in part on a maximum power level and
another uplink transmission.
14. A wireless transmit/receive unit (WTRU) comprising: a
transmitter configured to transmit a first preamble at a first
power level; a receiver configured to receive downlink control
information (DCI), on a first carrier, wherein the DCI indicates a
second carrier; the transmitter configured to transmit a second
preamble at a second power level on the second carrier, wherein the
second power level is lower than the first power level; and a
receiver configured to receive a random access response (RAR) to
the second preamble on a primary cell.
15. The WTRU of claim 14, wherein the first preamble is transmitted
on a different carrier than the second preamble.
16. The WTRU of claim 14, wherein the first preamble is transmitted
on a same carrier than the second preamble.
17. The WTRU of claim 14, wherein the transmitter is configured to
transmit the first preamble at a first power level based on a
priority of another uplink transmission.
18. The WTRU of claim 14, wherein the transmitter is configured to
transmit the second preamble at the second power level based on a
priority of another uplink transmission.
19. The WTRU of claim 14, further comprising: circuitry configured
to determine whether to transmit a second preamble on the second
carrier based on whether the second preamble would coincide with
another uplink transmission.
20. The WTRU of claim 14, wherein the second power level is
determined based at least in part on a maximum power level and
another uplink transmission.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. application Ser.
No. 16/793,804 filed Feb. 18, 2020, which is a continuation of U.S.
application Ser. No. 15/815,317 filed Nov. 16, 2017, which is
issued as U.S. Pat. No. 10,588,154 which is a continuation of U.S.
Non-Provisional application Ser. No. 14/732,200 filed Jun. 5, 2015,
which issued as U.S. Pat. No. 9,854,608, which is a continuation of
U.S. Non-Provisional application Ser. No. 13/468,709 filed May 10,
2012 which claims the benefit of U.S. Provisional Application No.
61/484,591 filed May 10, 2011, the contents of each of which are
hereby incorporated by reference herein.
BACKGROUND
[0002] Third Generation Partnership Project (3GPP) Long Term
Evolution (LTE) Release 8+ operating with a single serving cell
(hereafter LTE R8+) supports up to 100 Mbps in the downlink (DL),
and 50 Mbps in the uplink (UL) for a 2.times.2 configuration. The
LTE downlink transmission scheme is based on an orthogonal
frequency division multiple access (OFDMA) air interface. For the
purpose of flexible deployment, LTE R8+ systems support scalable
transmission bandwidths, one of 1.4, 2.5, 5, 10, 15, or 20 MHz.
[0003] In LTE R8+, each radio frame (10 ms) includes 10 equally
sized sub-frames of 1 ms. Each sub-frame includes 2 equally sized
timeslots of 0.5 ms each. There can be either seven or six
orthogonal frequency division multiplexing (OFDM) symbols per
timeslot. Seven symbols per timeslot are used with normal cyclic
prefix length, and six symbols per timeslot can be used in an
alternative system configuration with the extended cyclic prefix
length. The sub-carrier spacing for the LTE R8/9 system is 15 kHz.
An alternative reduced sub-carrier spacing mode using 7.5 kHz is
also possible.
[0004] A resource element (RE) corresponds to one (1) sub-carrier
during one (1) OFDM symbol interval. Twelve (12) consecutive
sub-carriers during a 0.5 ms timeslot constitute one (1) resource
block (RB). With seven (7) symbols per timeslot, each RB includes
12.times.7=84 REs. A DL carrier may consist of scalable number of
resource blocks (RBs), ranging from a minimum of six (6) RBs up to
a maximum of 110 RBs. This corresponds to an overall scalable
transmission bandwidth of roughly 1 MHz up to 20 MHz. However,
usually a set of common transmission bandwidths is specified, for
example, 1.4, 3, 5, 10 or 20 MHz.
[0005] The basic time-domain unit for dynamic scheduling is one
sub-frame including two consecutive timeslots. This is sometimes
referred to as a resource-block pair. Certain sub-carriers on some
OFDM symbols are allocated to carry pilot signals in the
time-frequency grid. A given number of sub-carriers at the edges of
the transmission bandwidth are not transmitted in order to comply
with spectral mask requirements.
SUMMARY
[0006] A method performed by a wireless transmit/receive unit
(WTRU) may comprise measuring a power of a downlink pathloss
reference and comparing the measured power of the downlink pathloss
reference to a threshold. The WTRU may determine whether to
transmit a preamble, on a secondary carrier, based on whether the
measured power of the downlink pathloss reference is less than the
threshold. The method may further comprise not transmitting the
preamble on the secondary carrier in one or more instance.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] A more detailed understanding may be had from the following
description, given by way of example in conjunction with the
accompanying drawings wherein:
[0008] FIG. 1A is a system diagram of an example communications
system in which one or more disclosed embodiments may be
implemented;
[0009] FIG. 1B is a system diagram of an example wireless
transmit/receive unit (WTRU) that may be used within the
communications system illustrated in FIG. 1A;
[0010] FIG. 1C is a system diagram of an example radio access
network and an example core network that may be used within the
communications system illustrated in FIG. 1A;
[0011] FIG. 2 is an example flow diagram of a network-controlled
preamble transmission;
[0012] FIG. 3 shows example methods for preamble transmissions;
[0013] FIG. 4 is an example of options for handling or avoiding
SCell preamble collisions with other uplink transmissions;
[0014] FIG. 5 shows Examples of the conditions for which the WTRU
may postpone SCell preamble re(transmissions) to a subsequent
occasion;
[0015] FIG. 6 shows scenarios in which a WTRU may avoid selecting a
PRACH that would collide with another transmission;
[0016] FIG. 7 shows an example of the WTRU using a dedicated
preamble and PRACH mask index to perform preamble transmission on
the SCell;
[0017] FIG. 8 is an example of a network-controlled dedicated
preamble retransmission;
[0018] FIG. 9 is an example of method to determine completion of
the network-controlled procedure;
[0019] FIG. 10 is an example E/T/RAPID MAC subheader;
[0020] FIG. 11 is an example E/T/R/R/BI MAC subheader; and
[0021] FIG. 12 is an example MAC RAR.
DETAILED DESCRIPTION
[0022] 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.
[0023] As shown in FIG. 1A, the communications system 100 may
include wireless transmit/receive units (WTRUs) 102a, 102b, 102c,
102d, a radio access network (RAN) 104, a core network 106, a
public switched telephone network (PSTN) 108, the Internet 110, and
other networks 112, though it will be appreciated that the
disclosed embodiments contemplate any number of WTRUs, base
stations, networks, and/or network elements. Each of the WTRUs
102a, 102b, 102c, 102d may be any type of device configured to
operate and/or communicate in a wireless environment. By way of
example, the WTRUs 102a, 102b, 102c, 102d may be configured to
transmit and/or receive wireless signals and may include user
equipment (UE), a mobile station, a fixed or mobile subscriber
unit, a pager, a cellular telephone, a personal digital assistant
(PDA), a smartphone, a laptop, a netbook, a personal computer, a
wireless sensor, consumer electronics, and the like.
[0024] The communications systems 100 may also include a base
station 114a and a base station 114b. Each of the base stations
114a, 114b may be any type of device configured to wirelessly
interface with at least one of the WTRUs 102a, 102b, 102c, 102d to
facilitate access to one or more communication networks, such as
the core network 106, the Internet 110, and/or the networks 112. By
way of example, the base stations 114a, 114b may be a base
transceiver station (BTS), a Node-B, an eNode B, a Home Node B, a
Home eNode B, a site controller, an access point (AP), a wireless
router, and the like. While the base stations 114a, 114b are each
depicted as a single element, it will be appreciated that the base
stations 114a, 114b may include any number of interconnected base
stations and/or network elements.
[0025] The base station 114a may be part of the RAN 104, which may
also include other base stations and/or network elements (not
shown), such as a base station controller (BSC), a radio network
controller (RNC), relay nodes, etc. The base station 114a and/or
the base station 114b may be configured to transmit and/or receive
wireless signals within a particular geographic region, which may
be referred to as a cell (not shown). The cell may further be
divided into cell sectors. For example, the cell associated with
the base station 114a may be divided into three sectors. Thus, in
one embodiment, the base station 114a may include three
transceivers, i.e., one for each sector of the cell. In another
embodiment, the base station 114a may employ multiple-input
multiple output (MIMO) technology and, therefore, may utilize
multiple transceivers for each sector of the cell.
[0026] The base stations 114a, 114b may communicate with one or
more of the WTRUs 102a, 102b, 102c, 102d over an air interface 116,
which may be any suitable wireless communication link (e.g., radio
frequency (RF), microwave, infrared (IR), ultraviolet (UV), visible
light, etc.). The air interface 116 may be established using any
suitable radio access technology (RAT).
[0027] More specifically, as noted above, the communications system
100 may be a multiple access system and may employ one or more
channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA,
and the like. For example, the base station 114a in the RAN 104 and
the WTRUs 102a, 102b, 102c may implement a radio technology such as
Universal Mobile Telecommunications System (UMTS) Terrestrial Radio
Access (UTRA), which may establish the air interface 116 using
wideband CDMA (WCDMA). WCDMA may include communication protocols
such as High-Speed Packet Access (HSPA) and/or Evolved HSPA
(HSPA+). HSPA may include High-Speed Downlink Packet Access (HSDPA)
and/or High-Speed Uplink Packet Access (HSUPA).
[0028] In another embodiment, the base station 114a and the WTRUs
102a, 102b, 102c may implement a radio technology such as Evolved
UMTS Terrestrial Radio Access (E-UTRA), which may establish the air
interface 116 using Long Term Evolution (LTE) and/or LTE-Advanced
(LTE-A).
[0029] In other embodiments, the base station 114a and the WTRUs
102a, 102b, 102c may implement radio technologies such as IEEE
802.16 (i.e., Worldwide Interoperability for Microwave Access
(WiMAX)), CDMA2000, CDMA2000 1.times., CDMA2000 EV-DO, Interim
Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim
Standard 856 (IS-856), Global System for Mobile communications
(GSM), Enhanced Data rates for GSM Evolution (EDGE), GSM EDGE
(GERAN), and the like.
[0030] 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.
[0031] The RAN 104 may be in communication with the core network
106, which may be any type of network configured to provide voice,
data, applications, and/or voice over internet protocol (VoIP)
services to one or more of the WTRUs 102a, 102b, 102c, 102d. For
example, the core network 106 may provide call control, billing
services, mobile location-based services, pre-paid calling,
Internet connectivity, video distribution, etc., and/or perform
high-level security functions, such as user authentication.
Although not shown in FIG. 1A, it will be appreciated that the RAN
104 and/or the core network 106 may be in direct or indirect
communication with other RANs that employ the same RAT as the RAN
104 or a different RAT. For example, in addition to being connected
to the RAN 104, which may be utilizing an E-UTRA radio technology,
the core network 106 may also be in communication with another RAN
(not shown) employing a GSM radio technology.
[0032] The core network 106 may also serve as a gateway for the
WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the Internet
110, and/or other networks 112. The PSTN 108 may include
circuit-switched telephone networks that provide plain old
telephone service (POTS). The Internet 110 may include a global
system of interconnected computer networks and devices that use
common communication protocols, such as the transmission control
protocol (TCP), user datagram protocol (UDP) and the internet
protocol (IP) in the TCP/IP internet protocol suite. The networks
112 may include wired or wireless communications networks owned
and/or operated by other service providers. For example, the
networks 112 may include another core network connected to one or
more RANs, which may employ the same RAT as the RAN 104 or a
different RAT.
[0033] 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.
[0034] 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.
[0035] 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.
[0036] The transmit/receive element 122 may be configured to
transmit signals to, or receive signals from, a base station (e.g.,
the base station 114a) over the air interface 116. For example, in
one embodiment, the transmit/receive element 122 may be an antenna
configured to transmit and/or receive RF signals. In another
embodiment, the transmit/receive element 122 may be an
emitter/detector configured to transmit and/or receive IR, UV, or
visible light signals, for example. In yet another embodiment, the
transmit/receive element 122 may be configured to transmit and
receive both RF and light signals. It will be appreciated that the
transmit/receive element 122 may be configured to transmit and/or
receive any combination of wireless signals.
[0037] In addition, although the transmit/receive element 122 is
depicted in FIG. 1B as a single element, the WTRU 102 may include
any number of transmit/receive elements 122. More specifically, the
WTRU 102 may employ MIMO technology. Thus, in one embodiment, the
WTRU 102 may include two or more transmit/receive elements 122
(e.g., multiple antennas) for transmitting and receiving wireless
signals over the air interface 116.
[0038] 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.
[0039] 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).
[0040] 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.
[0041] The processor 118 may also be coupled to the GPS chipset
136, which may be configured to provide location information (e.g.,
longitude and latitude) regarding the current location of the WTRU
102. In addition to, or in lieu of, the information from the GPS
chipset 136, the WTRU 102 may receive location information over the
air interface 116 from a base station (e.g., base stations 114a,
114b) and/or determine its location based on the timing of the
signals being received from two or more nearby base stations. It
will be appreciated that the WTRU 102 may acquire location
information by way of any suitable location-determination method
while remaining consistent with an embodiment.
[0042] 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-comp ass, a satellite
transceiver, a digital camera (for photographs or video), a
universal serial bus (USB) port, a vibration device, a television
transceiver, a hands free headset, a Bluetooth.RTM. module, a
frequency modulated (FM) radio unit, a digital music player, a
media player, a video game player module, an Internet browser, and
the like.
[0043] FIG. 1C is a system diagram of the RAN 104 and the core
network 106 according to an embodiment. As noted above, the RAN 104
may employ an E-UTRA radio technology to communicate with the WTRUs
102a, 102b, 102c over the air interface 116. The RAN 104 may also
be in communication with the core network 106.
[0044] The RAN 104 may include eNode-Bs 140a, 140b, 140c, though it
will be appreciated that the RAN 104 may include any number of
eNode-Bs while remaining consistent with an embodiment. The
eNode-Bs 140a, 140b, 140c may each include one or more transceivers
for communicating with the WTRUs 102a, 102b, 102c over the air
interface 116. In one embodiment, the eNode-Bs 140a, 140b, 140c may
implement MIMO technology. Thus, the eNode-B 140a, for example, may
use multiple antennas to transmit wireless signals to, and receive
wireless signals from, the WTRU 102a.
[0045] Each of the eNode-Bs 140a, 140b, 140c may be associated with
a particular cell (not shown) and may be configured to handle radio
resource management decisions, handover decisions, scheduling of
users in the uplink and/or downlink, and the like. As shown in FIG.
1C, the eNode-Bs 140a, 140b, 140c may communicate with one another
over an X2 interface.
[0046] The core network 106 shown in FIG. 1C may include a mobility
management gateway entity (MME) 142, a serving gateway 144, and a
packet data network (PDN) gateway 146. While each of the foregoing
elements are depicted as part of the core network 106, it will be
appreciated that any one of these elements may be owned and/or
operated by an entity other than the core network operator.
[0047] The MME 142 may be connected to each of the eNode-Bs 140a,
140b, 140c in the RAN 104 via an S1 interface and may serve as a
control node. For example, the MME 142 may be responsible for
authenticating users of the WTRUs 102a, 102b, 102c, bearer
activation/deactivation, selecting a particular serving gateway
during an initial attach of the WTRUs 102a, 102b, 102c, and the
like. The MME 142 may also provide a control plane function for
switching between the RAN 104 and other RANs (not shown) that
employ other radio technologies, such as GSM or WCDMA.
[0048] The serving gateway 144 may be connected to each of the
eNode Bs 140a, 140b, 140c in the RAN 104 via the S1 interface. The
serving gateway 144 may generally route and forward user data
packets to/from the WTRUs 102a, 102b, 102c. The serving gateway 144
may also perform other functions, such as anchoring user planes
during inter-eNode-B handovers, triggering paging when downlink
data is available for the WTRUs 102a, 102b, 102c, managing and
storing contexts of the WTRUs 102a, 102b, 102c, and the like.
[0049] The serving gateway 144 may also be connected to the PDN
gateway 146, which may provide the WTRUs 102a, 102b, 102c with
access to packet-switched networks, such as the Internet 110, to
facilitate communications between the WTRUs 102a, 102b, 102c and
IP-enabled devices.
[0050] The core network 106 may facilitate communications with
other networks. For example, the core network 106 may provide the
WTRUs 102a, 102b, 102c with access to circuit-switched networks,
such as the PSTN 108, to facilitate communications between the
WTRUs 102a, 102b, 102c and traditional land-line communications
devices. For example, the core network 106 may include, or may
communicate with, an IP gateway (e.g., an IP multimedia subsystem
(IMS) server) that serves as an interface between the core network
106 and the PSTN 108. In addition, the core network 106 may provide
the WTRUs 102a, 102b, 102c with access to the networks 112, which
may include other wired or wireless networks that are owned and/or
operated by other service providers.
[0051] In a LTE R8+ system, the network may control physical radio
resources using the Physical Downlink Control Channel (PDCCH).
Control messages are transmitted using specific formats, for
example, downlink control information (DCI) formats. A wireless
transmit/receive unit (WTRU) determines whether it may act on
control signaling in a given sub-frame by monitoring the PDCCH for
specific data control information messages (DCI formats). The PDCCH
for specific DCI formats may be scrambled using a known radio
network temporary identifier (RNTI) in specific locations, or
search space, using different combinations of physical resources,
for example, control channel elements (CCEs), based on aggregation
levels (AL). Each AL may correspond to either 1, 2, 4, or 8 CCEs. A
CCE includes 36 quadrature phase shift keying (QPSK) symbols, or 72
channel coded bits.
[0052] The PDCCH is conceptually separated in two distinct regions.
The set of CCE locations in which a WTRU may find DCIs it should
act on is referred to as a search space (SS). The SS is split into
the common SS (CSS) and WTRU-specific SS (WTRUSS). The CSS is
common to all WTRUs monitoring a given PDCCH, while the WTRUSS
differs from one WTRU to another. Both SSs may overlap for a given
WTRU in a given sub-frame as this is a function of the
randomization function, and this overlap differs from one sub-frame
to another.
[0053] The set of CCE locations that makes up the CSS and its
starting point is a function of the cell identity and the sub-frame
number. For LTE R8/9, DCIs may only be sent with AL4 (4 CCEs) or
AL8 (8 CCEs) in the CSS. For a sub-frame for which the WTRU
monitors the PDCCH, the WTRU may attempt to decode 2 DCI format
sizes in up to 4 different sets of 4 CCES for AL4 (or 8 blind
decoding) and up to 2 different sets of 8 CCEs for AL8 (or 4 blind
decoding) for a total of at most 12 blind decoding attempts in the
CSS. For example, the 2 DCI format sizes may be formats 1A, 1C, and
3A used for power control.
[0054] The CSS corresponds to CCEs 0-15, implying four decoding
candidates for AL4 (i.e., CCEs 0-3, 4-7, 8-11, 12-15) and two
decoding candidates for AL8, for example, CCEs 0-7, 8-15.
[0055] The set of CCE locations that makes up the WTRUSS and its
starting point is a function of the WTRU identity and the sub-frame
number. For LTE R8+, DCI may be sent with AL1, AL2, AL4 or AL8 in
the WTRUSS. For a sub-frame for which the WTRU monitors the PDCCH,
the WTRU may attempt to decode 2 DCI formats in up to 6 different
CCES for AL1 (i.e., 12 blind decoding), up to 6 different sets of 2
CCEs for AL2 (i.e., 12 blind decoding), up to 2 different sets of 4
CCEs for AL4, for example, 4 blind decoding, and up to 2 different
sets of 8 CCEs for AL8, for example, 4 blind decoding, for a total
of at most 32 blind decoding attempts in the WTRUSS.
[0056] The DCI formats which the WTRU decodes depends on the
configured transmission mode, for example, whether or not spatial
multiplexing is used. There are a number of different DCI formats;
for example, format 0 (UL grant), format 1 (non-MIMO), format 2 (DL
MIMO) and format 3 (power control). The version of each DCI
format(s) the WTRU decodes is governed at least in part by the
configured transmission mode, for example, modes 1-7.
[0057] A summary list with typical usage is presented below: [0058]
DCI format 0 (UL grant) [0059] DCI format 1 (DL assignment) [0060]
DCI format 1A (compact DL assignment/PDCCH order for random access)
[0061] DCI format 1B (DL assignment with precoding info) [0062] DCI
format 1C (very compact DL assignment) [0063] DCI format 1D
(compact DL assignment with precoding info+power offset info)
[0064] DCI format 2 (DL assignment for spatial multiplexing) [0065]
DCI format 2A [0066] DCI format 3 (TPC for PUCCH/PDSCH, two bits)
[0067] DCI format 3A (TPC for PUCCH/PDSCH, single bit)
[0068] A table illustrating the different DCI sizes resulting from
different system bandwidth configurations is provided in Table
1.
TABLE-US-00001 TABLE 1 Bandwidth 6 15 25 50 75 100 Format 0 37 38
41 43 43 44 Format 1A 37 38 41 43 43 44 Format 3/3A 37 38 41 43 43
44 Format 1C 24 26 28 29 30 31 Format 1 35 39 43 47 49 55 Format 1B
(2 tx ant) 38 41 43 44 45 46 Format 1D (2 tx ant) 38 41 43 44 45 46
Format 2 (2 tx ant) 47 50 55 59 61 67 Format 2A (2 tx ant) 44 47 52
57 58 64 Format 1B (4 tx ant) 41 43 44 46 47 49 Format 1D (4 tx
ant) 41 43 44 46 47 49 Format 2 (4 tx ant) 50 53 58 62 64 70 Format
2A (4 tx ant) 46 49 54 58 61 66
[0069] In LTE R8+ systems, whether the control signaling received
on a PDCCH pertains to the uplink component carrier or to the
downlink component carrier is related to the format of the DCI
decoded by the WTRU, and the DCI formats are used to control the
WTRUs communication on the uplink component carrier and on the DL
component carrier of the cell on to which the WTRU is
connected.
[0070] A WTRU may request radio resources for an uplink
transmission by sending a scheduling request (SR) to the eNB. The
SR may be transmitted either on dedicated resources (D-SR) on the
Physical Uplink Control Channel (PUCCH) if configured, or using the
Random Access procedure (RA-SR).
[0071] For an LTE serving cell, a WTRU may determine uplink radio
link failure when it reaches the maximum number of preamble
transmissions for the random access procedure and/or repeated
failure to perform the random access procedure on the concerned
serving cell.
[0072] For an LTE serving cell, a WTRU may determine DL radio link
failure when the radio resource control (RRC) instance receives a
predetermined number (N310) of consecutive "out-of-synch"
indications from the physical layer and a timer T310 subsequently
expires while the WTRU has not recovered from the error condition
that started the timer.
[0073] LTE-Advanced operating with multiple serving cells (LTE
R10+) is an evolution that aims to improve LTE R8+ data rates
using, among other methods, bandwidth extensions, also referred to
as carrier aggregation (CA). With CA, a WTRU may transmit and
receive simultaneously over the physical uplink shared channel
(PUSCH) and the physical downlink shared channel (PDSCH),
respectively, of multiple serving cells. Up to five serving cells
(possibly with or without configured uplink resources) may be used
thus supporting flexible bandwidth assignments up to 100 MHz. In
addition to the baseline functionality of LTE R8+, a number of
additional methods have been introduced to support the simultaneous
operation of a WTRU on multiple serving cells.
[0074] The control information for the scheduling of PDSCH and
PUSCH may be sent on one or more PDCCH(s). In addition to the LTE
R8+ scheduling using one PDCCH for a pair of UL and DL carriers,
cross-carrier scheduling may also be supported on the PDCCH of a
serving cell, for example, the primary cell (PCell), allowing the
network to provide PDSCH assignments and/or PUSCH grants for any
other serving cell, for example, a secondary cell (SCell). When
cross-carrier scheduling is used, a 3-bit carrier indicator field
(CIF) may be used to address the concerned SCell, where each SCells
identifier is derived from RRC configuration.
[0075] When referred to hereafter, the term "component carrier
(CC)" includes, without loss of generality, a frequency on which
the WTRU operates. For example, a WTRU may receive transmissions on
a downlink CC (DL CC). A DL CC may comprise a plurality of DL
physical channels. A WTRU may perform transmissions on an uplink CC
(UL CC). A UL CC may comprise a plurality of UL physical
channels.
[0076] For example, for LTE the downlink physical channels may
include, while not being limited to, a Physical Control Format
Indicator Channel (PCFICH), a Physical Hybrid ARQ Indicator Channel
(PHICH), a Physical Downlink Control Channel (PDCCH), a Physical
Multicast data Channel (PMCH) and a Physical Downlink Shared
Channel (PDSCH). On the PCFICH, the WTRU may receive control data
indicating the size of the control region of the DL CC. On the
PHICH, the WTRU may receive control data indicating hybrid
automatic repeat request (HARQ) positive acknowledgement/negative
acknowledgement feedback (HARQ A/N, HARQ ACK/NACK or HARQ-ACK) for
a previous uplink transmission. On the PDCCH, the WTRU may receive
downlink control information (DCI) messages, mainly used for the
purpose of scheduling of downlink and uplink resources. On the
PDSCH, the WTRU may receive user and/or control data. For example,
a WTRU may transmit on an uplink CC (UL CC).
[0077] For example, for LTE the uplink physical channels may
include, while not being limited to, a Physical Uplink Control
Channel (PUCCH) and a Physical Uplink Shared Channel (PUSCH). On
the PUSCH, the WTRU may transmit user and/or control data. On the
PUCCH, and in some case on the PUSCH, the WTRU may transmit uplink
control information (UCI). UCI may include a channel quality
indicator (CQI), precoding matrix indicator (PMI), rank indicator
(RI), or scheduling request (SR), or HARQ ACK/NACK feedback. On a
UL CC, the WTRU may also be allocated dedicated resources for
transmission of sounding reference signals (SRS).
[0078] A cell may comprise a DL CC which may be linked to a UL CC
based on the system information (SI) received by the WTRU. The SI
may be broadcasted on the DL CC or using dedicated configuration
signaling from the network. For example, when broadcasted on the DL
CC, the WTRU may receive the uplink frequency and bandwidth of the
linked UL CC as part of a system information element. For example,
the WTRU may receive the uplink frequency and bandwidth of the
linked UL CC as part of the system information element when in
RRC_IDLE for LTE, when in IDLE or CELL_FACH for WCDMA, or when the
WTRU does not yet have a radio resource connection to the
network.
[0079] When referred to hereafter, the term "PCell" includes,
without loss of generality, the cell operating of the primary
frequency in which the WTRU may perform the initial access to the
system or the cell indicated as the primary cell in the handover
procedure, or the like. For example, the initial connection access
to the system may be the initial connection establishment procedure
or the connection re-establishment procedure. PCell may correspond
to a frequency indicated as part of the radio resource connection
configuration procedure. Some functions may or may not be supported
on the PCell. For example, the UL CC of the PCell may correspond to
the CC whose physical uplink control channel resources are
configured to carry all HARQ ACK/NACK feedback for a given
WTRU.
[0080] For example, in LTE the WTRU may use the PCell to derive the
parameters for the security functions and for upper layer system
information such as non-access stratum (NAS) mobility information.
Other functions that may be supported on the PCell DL include
system information (SI) acquisition and change monitoring
procedures on the broadcast channel (BCCH), and paging.
[0081] When referred to hereafter, the term "SCell" includes,
without loss of generality, the cell operating on a secondary
frequency which may be configured once a radio resource control
connection is established and which may be used to provide
additional radio resources. System information relevant for
operation in the concerned SCell may be provided using dedicated
signaling when the SCell is added to the WTRU's configuration.
Although the parameters may have different values than those
broadcasted on the downlink of the concerned SCell using the SI
signaling, this information may be referred to as SI of the
concerned SCell independently of the method used by the WTRU to
acquire this information.
[0082] When referred to hereafter, the terms "PCell DL" and "PCell
UL" corresponds to, without loss of generality, the DL CC and the
UL CC of the PCell, respectively. Similarly, the terms "SCell DL"
and "SCell UL" corresponds to the DL CC and the UL CC (if
configured) of an SCell, respectively.
[0083] When referred to hereafter, the term "serving cell"
includes, without loss of generality, a PCell or an SCell. More
specifically, for a WTRU that is not configured with any SCell or
that does not support operation on multiple CCs, for example,
carrier aggregation, there may be one serving cell comprising of
the PCell. For a WTRU that is configured with at least one SCell,
the term "serving cell" includes one or more cells comprising the
PCell and all configured SCell(s).
[0084] When a WTRU is configured with at least one SCell, there may
be one PCell DL and one PCell UL and, for each configured SCell,
there may be one SCell DL and one SCell UL (if configured).
[0085] When referred to hereafter, the term "timing advance (TA)
Group" (TAG) includes, without loss of generality, one or more
serving cells for which a WTRU may apply the same timing advance
offset. For example one or more serving cells may be configured
with uplink resources. For example, the same timing advance offset
may be using a downlink timing reference for each cell, which
reference may or may not be the same cell for all cells of a group.
The cells configured for a WTRU may be associated to either the
primary TAG or to a secondary TAG. For example, a single time
advance command (TAC), either received in a random access response
(RAR) or in a MAC control element (CE), may apply to the TA
corresponding to the uplink transmission of any serving cell in the
same TAG.
[0086] For each cells with configured uplink within a TA group, the
WTRU may apply the same TA offset. Assuming that an WTRU supports
at most two TAs, the configured cells may be associated to either
the primary TA group or to the secondary TA group. The PCell may be
part of the primary TA group.
[0087] A primary TAG may include at least the PCell and zero or
more SCells for which SCells, if configured with resources for
uplink transmissions, may share the same uplink synchronization
characteristics. For example, the SCells may use the PCell DL as
the timing reference for uplink transmissions.
[0088] A secondary TAG may include one or more SCells for which
SCells, if configured with resources for uplink transmissions, may
share the same uplink synchronization characteristics. For example,
a secondary TAG may use either the SCell DL of one of the SCells of
the same TAG or their associate SCell DL and may apply the same TA.
Whether or not an SCell configured with uplink resources belongs to
the primary TAG or to a secondary TAG, the SCell may be configured
semi-statically, for example using RRC control signaling. For
example, when an SCell is added or modified in the WTRU
configuration.
[0089] Examples disclosed herein are related to how a mobile
wireless terminal, for example, a WTRU, when configured for
multicarrier operation, may gain uplink timing alignment on an
SCell of its multicarrier configuration.
[0090] For the random access procedure on the PCell in LTE R8+, the
WTRU may monitor the PDCCH for random access RNTI (RA-RNTI) in the
PDCCH CSS during the RAR window.
[0091] In LTE R11, the WTRU may support a random access procedure,
or a similar method to obtain uplink timing alignment, in
particular for gaining uplink timing advance. If a RACH procedure
may be performed on SCells, a WTRU may monitor the PDCCH for
decoding of RA-RNTI for reception of an RAR. For SCells, in R10
there may be no DCI that needs to be decoded in the CSS for SCells.
Thus, SCells may not define a CSS on the PDCCH of their
corresponding SCell DL for R10 WTRUs. Introducing an RACH on SCells
may require that the WTRU monitors the RA-RNTI for SCells for the
RAR. SCells in LTE R10 define a WTRU search space (WTRUSS) on the
PDCCH, and no CSS. Thus, it may not be possible to receive a DCI
scrambled with an RA-RNTI on the PDCCH of an SCell.
[0092] Examples where a WTRU may monitor the CSS of an SCell, for
the RACH procedure, are disclosed. In particular, if the WTRU uses
a contention-based preamble, such method may be necessary because
an eNB may not know the identity of the WTRU. For example, the WTRU
may use a contention-based preamble in the case of contention-based
random access (CBRA).
[0093] Alternative examples are disclosed in cases where a
dedicated preamble is used on SCells, for example, in the case of
contention free random access (CFRA). In those examples, uplink
timing synchronization may be obtained without the need for the
WTRU to monitor the CSS of an SCell, in particular, if the preamble
transmission is initiated in a manner that is known and/or
controlled by the eNB. For example, by reception of a PDCCH DCI
that orders the WTRU to perform at least a preamble transmission on
the uplink of an SCell.
[0094] Examples of the WTRU obtaining uplink timing alignment for
one or more SCells are disclosed. For example, the SCells may be
configured uplink resources. This may include, more generally, how
a WTRU may perform a RACH procedure, or a variant of the R10 RACH
procedure, or at least a preamble transmission on an SCell and a
proper determination that the procedure is completed for the
preamble transmission.
[0095] For example, the WTRU may perform a procedure that includes
at least one of the following steps to gain uplink timing
synchronization: initiation of the procedure, preamble
transmission, preamble retransmissions, if supported, and
completion of the procedure. Details of each step to gain uplink
timing synchronization are described below.
[0096] A WTRU may initiate a procedure involving the transmission
of a preamble, such as RACH procedure, a variant thereof, or a
procedure to gain uplink timing alignment, either autonomously or
in response to reception of control signaling.
[0097] If initiated autonomously, the WTRU may use a dedicated
preamble and a physical random access channel (PRACH) mask index
from an RRC configuration in case of a CFRA or a variant thereof.
The WTRU may also use a medium access control (MAC) entity to
select a preamble using the conventional LTE R8+ preamble selection
methods in case of a CBRA or a variant thereof is used.
[0098] In a network-controlled preamble transmission, the WTRU may
initiate the procedure upon receipt of control signaling from an
eNB. The WTRU may receive the control signaling from the eNB on the
PDCCH of the concerned SCell or cross-carrier scheduled. For
example, the concerned SCell may be an SCell with configured uplink
resources and configured PRACH resources. For example, the
cross-carrier scheduled may be on the PDCCH of another serving
cell, for example, PCell.
[0099] FIG. 2 is an example flow diagram of a network-controlled
preamble transmission. The WTRU may first receive control signaling
from the network at 210. The control signaling may be a specific
DCI 220, a medium access control (MAC) protocol data unit (PDU)
230, or an RRC PDU 240. The WTRU may then determine the applicable
SCell at 250. Once the applicable SCell is determined, the WTRU may
implicitly activate the SCell at 260 or initiate a preamble
transmission at 270.
[0100] The WTRU may initiate a preamble transmission according to
at least one of the following methods:
[0101] The WTRU may receive a specific DCI, for example, a PDCCH
order to perform a preamble transmission, by decoding a DCI format
1A, by decoding a DCI format scrambled with the WTRU's Cell-RNTI
(C-RNTI), or by decoding a DCI format scrambled with an SCell- (or
TAG-) specific RNTI, which indicates on which SCell (or which TAG)
the procedure may be performed. The DCI may include a dedicated
preamble, a PRACH mask index applicable to the concerned SCell.
[0102] The DCI may indicate that the preamble transmission is for
obtaining uplink timing synchronization.
[0103] The DCI may include a carrier indication field (CIF) which
may be used to determine the identity of the SCell on which uplink
resources the preamble is transmitted.
[0104] The DCI may include an indication of whether the preamble
transmission is an initial transmission, a retransmission, or
alternatively to what retransmission in a sequence of preamble
transmission the retransmission should correspond. For example, an
initial transmission may be codepoint 0, a retransmission may be
codepoint 1, and a sequence of preamble transmission the
retransmission corresponds to may be codepoint 01, 10, 11 in the
case of, at most, three retransmissions. For example, the received
codepoint may correspond to PREAMBLE_TRANSMISSION_COUNTER+1.
[0105] The DCI may include an indication of power settings, for
example, according to a sequence of transmissions as disclosed
above, or an indication to increase by some power step the preamble
transmit power from either a previous preamble transmission attempt
or from a pre-defined value.
[0106] The DCI may include a CIF field, in case of cross-carrier
scheduling, which may indicate a serving cell with configured
uplink resources for which the request for a preamble transmission
applies. Alternatively, the DCI may include a CIF field which may
indicate a serving cell as part of a secondary TAG for which the
request for a preamble transmission applies, for example, for
gaining uplink timing alignment may be applied.
[0107] The DCI may indicate a maximum number of autonomous preamble
retransmissions for the procedure, if autonomous preamble
retransmissions are allowed. For example, an allowed autonomous
retransmission may be an autonomous retransmission following the
end of a window during which the WTRU has not met the conditions
for the completion of the procedure or at expiration of a
retransmission timer.
[0108] The DCI may indicate whether or not the preamble may be
considered as an initial preamble transmission or as a preamble
retransmission.
[0109] The WTRU may receive a MAC PDU including control signaling
that triggers the initiation of the procedure. The MAC PDU may
include a MAC activation/deactivation CE that activates an SCell
for which the corresponding TA timer is stopped or expired. The MAC
PDU may include a MAC control element (CE) that triggers the
transmission of a preamble, for example, for gaining uplink timing
for an SCell with configured uplink resources. The MAC CE may
include a dedicated preamble and a PRACH mask index applicable to
the concerned SCell. The MAC CE may include an indication for the
WTRU to determine the identity of the SCell on which uplink
resources the preamble may be transmitted. For example, the
indication may be either a flag in a bitmap, a cell index field or
based on the activation state of the SCells.
[0110] The MAC PDU may indicate that the preamble transmission may
be for obtaining uplink timing synchronization. The MAC CE may
include an indication of whether the preamble transmission is an
initial transmission, a retransmission, or alternatively to what
retransmission in a sequence of preamble transmissions the
retransmission should corresponds. For example, an initial
transmission may be codepoint 0, a retransmission may be codepoint
1, and a sequence of preamble transmission the retransmission
corresponds to may be codepoint 01, 10, 11 in the case of at most
three retransmissions. For example, the received codepoint may
correspond to PREAMBLE_TRANSMISSION_COUNTER+1. The MAC CE may
include an indication of power settings, for example, according to
a sequence of transmissions as disclosed above, or an indication to
increase by some power step the preamble transmit power from either
a previous preamble transmission attempt or from a pre-defined
value. The MAC CE may indicate a maximum number of autonomous
preamble retransmissions for the procedure, if autonomous preamble
retransmissions are allowed. For example, an allowed autonomous
retransmission may be an autonomous retransmission following the
end of a window during which the WTRU has not met the conditions
for the completion of the procedure, or at expiration of a
retransmission timer. The MAC CE may indicate whether or not the
preamble may be considered as an initial preamble transmission or
as a preamble retransmission.
[0111] The WTRU may receive an RRC PDU including control signaling
that triggers the initiation of the procedure, for example, upon
addition of the SCell to the WTRU configuration. The RRC PDU may
include a dedicated preamble and a PRACH mask index applicable to
the concerned SCell. The RRC PDU may indicate that the preamble
transmission may be for obtaining uplink timing synchronization.
The RRC PDU may include an indication of whether the preamble
transmission is an initial transmission, a retransmission,
alternatively to what retransmission in a sequence of preamble
transmissions the retransmission corresponds. For example, an
initial transmission may be codepoint 0, a retransmission may be
codepoint 1, and a sequence of preamble transmission the
retransmission corresponds to may be codepoint 01, 10, 11 in the
case of at most three retransmissions. For example, the received
codepoint may correspond to PREAMBLE_TRANSMISSION_COUNTER+1. The
RRC PDU may include an indication of power settings, for example,
according to a sequence of transmissions as disclosed above, or an
indication to increase by some power step the preamble transmit
power from either a previous preamble transmission attempt or from
a pre-defined value. The RRC PDU may indicate a maximum number of
autonomous preamble retransmissions for the procedure, if
autonomous preamble retransmissions are allowed. For example, an
allowed autonomous retransmission may be an autonomous
retransmission following the end of a window during which the WTRU
has not met the conditions for the completion of the procedure, or
at expiration of a retransmission timer. Alternatively, the
preamble transmission may be triggered if the SCell is not
considered synchronized. For example, the SCell may not be
synchronized if the TAT corresponding to the SCell is either
stopped or expired.
[0112] The control signaling described above may be received on the
PDCCH of the concerned SCell. For example, the concerned SCell may
be either the SCell on which uplink resource the WTRU may transmit
a preamble or another SCell of the same TA group which may trigger
a preamble on another SCell (with configured PRACH resources) of
the corresponding TAG.
[0113] Alternatively, the WTRU may receive any of the above control
signaling by cross-carrier scheduling on any downlink serving cell
of the WTRU. The reception of any of the above control signaling
may implicitly activate the SCell (with configured PRACH resources)
on which uplink resources the preamble may be transmitted, or all
other SCells of the same TAG for which at least one SCell has a
valid PRACH configuration.
[0114] Any of the above control signaling schemes may trigger the
procedure for a plurality of SCells (with configured uplink and
PRACH resources), or alternatively for at least one such SCell for
each TAG (possibly for one or more secondary TAG).
[0115] In one example, the WTRU may decode a PDCCH scrambled with
the C-RNTI of the WTRU. The WTRU may then determine that it
received a DCI indicating that a procedure to gain uplink timing
alignment may be performed. For example, the DCI indicator may be
performed may be either a RACH procedure or a preamble
transmission. The PDCCH may be either on an activated SCell, if
configured to receive and decode PDCCH on the SCell, or on a PCell
if configured for cross-carrier scheduling and if the concerned
SCell is activated. For example, in the case of CFRA, a DCI format
1A may be used including a dedicated preamble and a PRACH mask
index. The DCI may include an indication that the preamble
transmission is an initial preamble transmission for the procedure
or a retransmission.
[0116] In R8+, the following is used to determine the transmission
power for the preamble on the PCell where at least
preambleInitialReceivedTargetPower and powerRampingStep may be
provided by higher layer signaling.
[0117] A preamble transmission power PPRACH may be determined as:
PPRACH=min{Pcmax,c(i), PREAMBLE_RECEIVED_TARGET_POWER+PLc}_[dBm],
where Pcmax,c(i) is the configured WTRU transmit power for subframe
i of the primary cell and PLc is the downlink pathloss estimate
calculated in the WTRU for the primary cell.
[0118] The random-access procedure may be performed as follows: set
PREAMBLE_RECEIVED_TARGET_POWER
topreambleInitialReceivedTargetPower+DELTA_PREAMBLE+(PREAMBLE_TRANSMISSIO-
N_COUNTER-1)*powerRampingStep. The physical layer may then be
instructed to transmit a preamble using the selected PRACH,
corresponding RA-RNTI, preamble index and
PREAMBLE_RECEIVED_TARGET_POWER.
[0119] FIG. 3 shows example methods for preamble transmissions. The
necessary parameters may be configured by higher layers for SCells
as part of the RACH configuration of the SCell. If after receiving
control signaling from the network at 310, the WTRU determines, for
example, using any example disclosed above, that it needs to
initiate a procedure for the transmission of a preamble at 320, the
WTRU may perform at least one of the following.
[0120] The WTRU may determine the proper power settings according
to an initial preamble transmission at 330 based on at least one of
the following: downlink pathloss reference 332;
PREAMBLE_TRANSMSSION_COUNTER-1 334; no valid pathloss measurement
336; and radio link quality 338. The power setting may be set
according to the downlink pathloss reference at 332. The downlink
pathloss reference may be either the corresponding SCell DL of the
SCell UL used for the transmission of the preamble, any SCell DL of
the TAG of the SCell for which the SCell UL is used for the
transmission of the preamble, or a DL configured using RRC
signaling.
[0121] The power setting may be set according to the
PREAMBLE_TRANSMISSION_COUNTER-1 334. The PREAMBLE_TRANMISSION
COUNTER-1 may be derived from the control signaling that triggered
the preamble transmission. For example, the counter may either be
the received value or the received value+1. An initial transmission
may use the received value [0]+1 in the control signaling. The WTRU
may not apply any power ramping for the SCell, in particular, if
the WTRU is not allowed to perform any autonomous preamble
retransmissions or preamble retransmissions may be eNB
controlled.
[0122] If the WTRU has no valid pathloss measurement 336 for the
pathloss (PL) reference used for the preamble transmission, the
WTRU may determine that the transmission of a preamble may not be
performed. If the WTRU determines that it experiences a low radio
link quality 338, either on the associated SCell DL or on the
downlink of the serving cell used as pathloss reference, the
transmission of a preamble may not be performed. For example, the
radio link problems may be based on a radio link management (RLM)
procedure. For example, the associated SCell DL may be the system
information block 2 (SIB2)-linked SCell DL as per the semi-static
configuration of the WTRU.
[0123] The WTRU may determine 370 the preamble and PRACH resource
for the initial preamble transmissions, according to at least one
of the following. If a dedicated preamble and a PRACH mask index
was received 372 in the control signaling that initiated the
preamble transmission, the WTRU may transmit the preamble in the
indicated PRACH resource. Otherwise, if a dedicated preamble and a
PRACH mask index are configured 374 by RRC for the concerned SCell,
the WTRU may transmit the preamble in the indicated PRACH resource.
Otherwise, the WTRU may either select 376 a preamble and initiate a
contention-based RACH procedure, or stop the procedure 378. For
example, the procedure may be stopped in the case of a false alarm
or an error case. In particular, the WTRU may stop the procedure in
the case that CBRA is not supported for the procedure on
SCells.
[0124] The WTRU may determine 350 the subframe in which the
preamble transmission may be performed. The preamble transmission
may be performed at the first available occasion 352, after a fixed
delay 354 corresponding to a WTRU processing time, or corresponding
to the time necessary to complete activation of the corresponding
SCell, if not activated already. For example, according to R8+
timing of the PCell the WTRU may, if requested by higher layers,
transmit random access preamble in the first subframe n+k2,
k2>=6 where a PRACH resource is available. The timing of the
PCell may also apply to the preamble transmission of an SCell, when
a random access procedure is initiated by a PDCCH order in subframe
n.
[0125] In another example, the WTRU may perform the preamble
transmission in the first subframe corresponding to n+8+k2, where
k2.gtoreq.0 and where a PRACH resource is available. For example,
if the request for the transmission of a preamble is received
before the concerned SCell is activated from reception of control
signaling in subframe n, the WTRU may perform the preamble
transmission in the first subframe.
[0126] If the WTRU determines 340 that a preamble may be
transmitted, the WTRU may perform 342 the preamble transmission in
the corresponding resource using the corresponding power settings.
The WTRU may start 360 a window timer, such as a TAResponseWindow,
which may be the RAR window r.alpha.-ResponseWindowSize, during
which it may expect to complete the procedure.
[0127] If the preamble (re)transmission coincides with another
scheduled uplink transmission, the WTRU may either scale back the
power of the preamble transmission, or alternatively postpone the
preamble (re)transmission to a subsequent occasion.
[0128] FIG. 4 is an example of options for handling or avoiding
SCell preamble collisions with other uplink transmissions. The
preamble (re)transmission coinciding or "colliding" with another
uplink transmission may mean that the subframe in which the
preamble would be transmitted is the same subframe in which another
uplink transmission would be made. The preamble (re)transmission
coinciding with another uplink transmission may mean that the
subframe in which the PRACH carrying the preamble would be
transmitted is the same subframe in which another uplink
transmission would be made. Postponing the preamble
(re)transmission to a subsequent occasion may mean that the WTRU
selects another, may be later, PRACH.
[0129] In FIG. 4, the WTRU may decide to (re)transmit a preamble on
an SCell at 400. The WTRU may then select a PRACH subframe and
PRACH at 405. The WTRU may then determine whether there will be a
collision such as one of the possible collisions shown in FIG. 5 at
410. If there is going to be a possible collision then the WTRU may
postpone the preamble transmission to a later subframe at 415. If
there is no collision expected, then the physical (PHY) layer of
the WTRU may determine whether there will be a collision with
another UL transmission in the PRACH subframe at 435. If the PHY
layer determines there will be no collision, the WTRU may transmit
the preamble using the selected PRACH subframe and PRACH at 450. If
the PHY layer determines that there will be a collision, the PHY
layer may cancel the SCell PRACH transmission at 440. The PHY layer
may then inform the higher layers of the WTRU of the cancellation
at 445. As an alternative, if there is no collision expected at
410, the WTRU may transmit the preamble using the selected PRACH
subframe and PRACH at 450.
[0130] The WTRU may select a PRACH subframe and PRACH to avoid a
collision with a scheduled UL transmission at 420. The WTRU may
then transmit the preamble using the selected PRACH subframe and
PRACH at 450. As an alternative, after selection of the PRACH
subframe and PRACH at 420, the PHY layer of the WTRU may determine
whether there will be a collision with another UL transmission in
the PRACH subframe at 435. If the PHY layer determines there will
be no collision, the WTRU may transmit the preamble using the
selected PRACH subframe and PRACH at 450. If the PHY layer
determines that there will be a collision, the PHY layer may cancel
the SCell PRACH transmission at 440. The PHY layer may then inform
the higher layers of the WTRU of the cancellation at 445.
[0131] The WTRU may select a PRACH subframe and PRACH to avoid a
selection that may collide with one or more of the possibilities
listed in FIG. 6 at 425. The WTRU may then transmit the preamble
using the selected PRACH subframe and PRACH at 450. As an
alternative, after selection of the PRACH subframe and PRACH at
425, the PHY layer of the WTRU may determine whether there will be
a collision with another UL transmission in the PRACH subframe at
435. If the PHY layer determines there will be no collision, the
WTRU may transmit the preamble using the selected PRACH subframe
and PRACH at 450. If the PHY layer determines that there will be a
collision, the PHY layer may cancel the SCell PRACH transmission at
440. The PHY layer may then inform the higher layers of the WTRU of
the cancellation at 445.
[0132] The higher layers of the WTRU, for example, a MAC layer, may
select a PRACH subframe and PRACH at 430. The physical (PHY) layer
of the WTRU may determine whether there will be a collision with
another UL transmission in the PRACH subframe at 435. If the PHY
layer determines there will be no collision, the WTRU may transmit
the preamble using the selected PRACH subframe and PRACH at 450. If
the PHY layer determines that there will be a collision, the PHY
layer may cancel the SCell PRACH transmission at 440. The PHY layer
may then inform the higher layers of the WTRU of the cancellation
at 445.
[0133] FIG. 5 shows examples of the conditions for which the WTRU
may postpone SCell preamble re(transmissions) to a subsequent
occasion. The WTRU may postpone the preamble (re)transmission to a
subsequent occasion if one or more of the following applies: The
WTRU may postpone the preamble (re)transmission if the preamble
(re)transmission coincides 510 with a scheduled UL transmission on
the concerned SCell. The WTRU may postpone the preamble
(re)transmission if the preamble (re)transmission coincides 515
with a scheduled UL transmission on the PCell. The WTRU may
postpone the preamble (re)transmission if the preamble
(re)transmission coincides 520 with a scheduled UL transmission on
any serving cell. The WTRU may postpone the preamble
(re)transmission if the preamble (re)transmission coincides 525
with a scheduled UL transmission on any serving cell in the same
band as the concerned SCell. The WTRU may postpone the preamble
(re)transmission if the preamble (re)transmission coincides 530
with any type of scheduled UL transmission. The WTRU may postpone
the preamble (re)transmission if the preamble (re)transmission
coincides 535 with a specific type of UL transmission such as
ACK/NACK transmission. The WTRU may postpone the preamble
(re)transmission if the preamble (re)transmission coincides 540
with a specific type of UL transmission such as a PUCCH
transmission. The WTRU may postpone the preamble (re)transmission
if the preamble (re)transmission coincides 545 with a specific type
of transmission such as periodic SRS transmission. Alternatively,
when PRACH transmission coincides with periodic SRS transmission in
a subframe, the PRACH may be transmitted and the SRS transmission
may be dropped. The WTRU may postpone the preamble (re)transmission
if the preamble (re)transmission coincides 550 with a specific type
of transmission such as aperiodic SRS transmission. Alternatively,
when PRACH transmission coincides with an aperiodic SRS
transmission in a subframe, the PRACH may be transmitted and the
SRS transmission may be dropped. The WTRU may postpone the preamble
(re)transmission if the preamble (re)transmission coincides 555
with a specific type of UL transmission such as periodic CSI
transmission. Alternatively, when PRACH transmission coincides with
periodic CSI transmission, the PRACH may be transmitted and the
periodic CSI may be dropped. The WTRU may postpone the preamble
(re)transmission if the preamble (re)transmission coincides 560
with a specific UL transmission such as a PRACH scheduled for
transmission on another serving cell.
[0134] When selecting a PRACH, the WTRU may take into account
scheduled uplink transmissions and avoid selecting a PRACH that
collides with a scheduled uplink transmission. For example, the
WTRU may avoid selecting a PRACH in the same subframe as a
scheduled uplink transmission. FIG. 6 shows examples of
transmissions a WTRU may avoid when selecting a PRACH. The WTRU may
avoid selecting a PRACH that may collide with one or more of the
following: The WTRU may avoid selecting a PRACH that may collide
with a scheduled 610 UL transmission on the concerned SCell. The
WTRU may avoid selecting a PRACH that may collide with a scheduled
615 UL transmission on the PCell. The WTRU may avoid selecting a
PRACH that may collide with a scheduled 620 UL transmission on any
serving cell. The WTRU may avoid selecting a PRACH that may collide
with a scheduled 625 UL transmission on any serving cell in the
same band as the concerned SCell. The WTRU may avoid selecting a
PRACH that may collide with any type of scheduled 630 UL
transmission. The WTRU may avoid selecting a PRACH that may collide
with a specific type of UL transmission 635 such as ACK/NACK
transmission. The WTRU may avoid selecting a PRACH that may collide
with a specific type of UL transmission 640 such as a PUCCH
transmission. The WTRU may avoid selecting a PRACH that may collide
with a specific type of transmission 645 such as periodic SRS
transmission. The WTRU may avoid selecting a PRACH that may collide
with a specific type of transmission 650 such as an aperiodic SRS
transmission. The WTRU may avoid selecting a PRACH that may collide
with a specific type of UL transmission 655 such as periodic CSI
transmission. The WTRU may avoid selecting a PRACH that may collide
with a specific UL transmission 660 such as a PRACH scheduled for
transmission on another serving cell.
[0135] The decision to postpone the preamble (re)transmission to a
subsequent occasion may be performed by higher layers in the WTRU.
The decision to postpone the preamble transmission may be made by
the WTRU when it is known in advance that an UL transmission is
scheduled to occur in a certain subframe or subframes. Avoiding
selection of a PRACH that may collide with another uplink
transmission occasion may be performed by higher layers in the
WTRU. The WTRU may avoid selection of a PRACH that may collide with
another uplink transmission when it is known in advance that UL
transmission is scheduled to occur in a certain subframe or
subframes. As an example, higher layers in the WTRU may be or may
include the MAC layer.
[0136] The decision to postpone the preamble (re)transmission may
be performed by the WTRU at the physical layer. For example, the
WTRU PHY layer may postpone or decided to postpone the preamble
(re)transmission, if after the higher layers (e.g., the MAC)
provide a PRACH resource to the physical layer, an UL transmission
is scheduled such as in response to an UL or DL grant (e.g.,
ACK/NACK). The WTRU physical layer may determine that PRACH
transmission is not possible in the designated subframe, for
example, due to a collision with another UL transmission and may
cancel the PRACH transmission.
[0137] The WTRU physical layer may inform the higher layers that
PRACH transmission is not possible in a designated subframe. The
physical layer may inform the higher layers that the PRACH
transmission was cancelled. The WTRU, for example, the higher
layers of the WTRU, may choose another PRACH resource if PRACH
transmission was cancelled. For example, the higher layers may be
or may include the MAC layer. When a PRACH transmission is
cancelled, the WTRU may choose another PRACH resource without
updating one or more of the timers and counters relating to the
random access procedure such as the
PREAMBLE_TRANSMISSION_COUNTER.
[0138] The WTRU may maintain a counter to keep track of the
consecutive number of times the PRACH transmission is cancelled.
The WTRU may maintain a timer to keep track of how long the WTRU is
unable to transmit the PRACH due to collisions with other uplink
transmissions. If the WTRU is unable to transmit the PRACH after a
number of attempts, for example, based on the counter counting the
number of cancellations, or after a period of time, due to
collisions with other uplink transmissions, the WTRU may cease
attempting to transmit the PRACH and may inform the eNB via
signaling, such as via RRC or MAC signaling. This may, for example,
be applicable when the eNB had requested the WTRU to perform a
random access procedure for example for the purpose of timing
alignment.
[0139] The WTRU may postpone the PRACH transmission if WTRU maximum
power would be exceeded in the subframe in which the PRACH is to be
transmitted. The WTRU may determine the required transmit power for
each channel to be transmitted in a given subframe; and if in that
subframe there is a PRACH scheduled to be transmitted, the WTRU may
do one or more of the following. The WTRU may determine if the WTRU
maximum allowed transmit power would be exceeded if all channels
were transmitted simultaneously including the PRACH. If the WTRU
maximum allowed transmit power would be exceeded and a PRACH
transmission is scheduled, the WTRU may cancel the PRACH
transmission. If the PRACH transmission is cancelled, the WTRU may
determine if the maximum WTRU power would be exceeded for the
scheduled channels excluding the PRACH and proceed with scaling as
needed based on the scheduled channels other than the PRACH. The
WTRU maximum allowed transmit power may be the WTRU maximum
configured output power, Pcmax, as defined in LTE. The WTRU maximum
allowed output power may be the WTRU power class power.
[0140] When the WTRU is transmitting in multiple bands, a
determination as to whether maximum allowed transmit power would be
exceeded may be performed on an individual band basis instead of
being performed on a WTRU basis. The determination may also first
be performed on an individual band basis and then performed on a
WTRU basis. When performing the determination on an individual band
basis, the maximum allowed power for the band may be used to
determine whether the maximum allowed transmit power would be
exceeded.
[0141] If the PRACH transmission coincides with another
transmission and the simultaneous transmission is permitted, if
band and/or WTRU maximum output power would be exceeded, the WTRU
may scale the power of the PRACH based on its priority relative to
the other channels being transmitted. In the R10 channel
prioritization, a PUCCH has the highest priority, a PUSCH with a
UCI has the next highest priority, and a PUSCH without a UCI has
the lowest priority.
[0142] A PRACH may be given a priority such that one or more of the
following applies. A PRACH may be transmitted if there is available
power after power is allocated to channels with higher priority. If
after power is allocated to higher priority channels, there is not
enough power to transmit the PRACH without scaling, the PRACH may
be scaled. If after power is allocated to higher priority channels,
there is not enough power to transmit the PRACH without scaling,
the PRACH transmission may be cancelled. If PRACH transmission is
cancelled, the remaining lower priority channels, may be
transmitted with power allocation and scaling as needed. If PRACH
is scaled, the remaining lower priority channels, may be
dropped.
[0143] In one example, a PRACH may have the next highest priority
after a PUSCH with a UCI. In this example, if maximum power may be
exceeded, (band and/or WTRU maximum output power), and if all
channels scheduled to be transmitted in a subframe were to be
transmitted, one or more of the following may apply. Power may
first be allocated to any PUCCH. After allocation of power to any
PUCCH, any remaining power may be allocated to PUSCH with UCI. If
there is not enough power for PUSCH with UCI, the PUSCH with UCI
may be scaled and no other channels would be transmitted. In this
case, the PRACH may be cancelled. If there is remaining power after
allocation to any PUCCH and PUSCH with UCI, power may be allocated
to any PRACH. If there is not enough power for any PUCCH plus any
PUSCH with UCI plus PRACH, the PRACH may be scaled and any PUSCH
without UCI may not be transmitted. If there is not enough power
for any PUCCH plus any PUSCH with UCI plus PRACH, the PRACH
transmission may be cancelled. If PRACH transmission is cancelled,
PUSCH without UCI, may be transmitted with power allocation and
scaling as needed. If there is power remaining after allocating
power to PRACH, PUSCH without UCI may be transmitted with scaling
if needed.
[0144] Power allocation and/or scaling may be performed on a band
basis and/or a WTRU basis.
[0145] FIG. 7 shows an example of the WTRU using a dedicated
preamble and PRACH mask index to perform preamble transmission on
the SCell. In one example, the WTRU may receive 710 control
signaling from the network. The WTRU may also receive 720 a
dedicated preamble and PRACH mask in a PDCCH order in subframe n.
The WTRU may use 730 the dedicated preamble and a PRACH mask index
received in a PDCCH order in subframe n to perform the preamble
transmission on the SCell. The WTRU may determine 740 from the
received control signaling, for example, codepoint 0, that the
request is for an initial preamble transmission and sets 750 the
preamble counter to 1, thereby the WTRU may not apply any power
ramping. The WTRU may use 760 the corresponding SCell DL as the PL
reference, and perform 770 the uplink transmission in the first
subframe n+k2, k2.gtoreq.6 where a PRACH resource is available.
[0146] The WTRU may determine that a preamble may be retransmitted
according to at least one of the following methods. The WTRU
receives control signaling, which indicates that the preamble
transmission is for a retransmission. The WTRU may autonomously
initiate the retransmission of a preamble, for example upon failure
to complete the procedure according to the embodiments described
below. The WTRU may start a window timer, for such as, a
TAResponseWindow, which may be the RAR window
r.alpha.-ResponseWindowSize, during which it may expect to complete
the procedure.
[0147] In one example, a WTRU may not be allowed to autonomously
perform any preamble retransmissions on the uplink resources of an
SCell. A WTRU may perform a preamble retransmission when initiated
by reception of control signaling. In another example, the WTRU may
autonomously perform preamble retransmission for an SCell. The WTRU
may autonomously perform preamble retransmission up to a maximum
number of attempts if, following an initial preamble transmission,
the WTRU has not received after a specific amount of time any time
advance command (TAC) or any uplink grant for an SCell within the
TAG of the SCell on which the preamble was transmitted.
[0148] When the WTRU performs a preamble retransmission, it may
apply power ramping. For autonomous retransmissions, the power
ramping may be applied similarly to that of the PCell, for example,
using a counter to count the number of attempts. For retransmission
requested by the eNB using control signaling, the WTRU may apply a
stepwise increase if the control signaling indicates that the WTRU
needs to ramp-up the power, use a counter of the number of
attempts, or use an indication in the control signaling to
determine the exact power ramping to apply. The counter of the
number of attempts may be reset to its initial value when the WTRU
initiates the first transmission of a preamble for the procedure.
The counter of the number of attempts may also be reset to its
initial value upon deactivation of the corresponding SCell, upon
activation of the corresponding SCell, upon configuration or
reconfiguration of the corresponding SCell, upon configuration or
reconfiguration of the TAG of the SCell, or when the procedure
completes successfully. The power ramping may be limited up to a
maximum value.
[0149] FIG. 8 is an example of a network-controlled dedicated
preamble retransmission. The WTRU may determine 810 that the
initial preamble transmission was not successful, for example,
based on the expiration of the window, for example, a
TAResponse-window, and may have discarded the dedicated preamble
and PRACH mask index used for the initial preamble transmission.
The WTRU may maintain 820 a preamble counter of the number of
preamble transmissions since the initial attempt for the TAG. The
WTRU may receive 830 in subframe n control signaling that includes
a dedicated preamble and a PRACH mask index which indicates that
the WTRU performs a preamble retransmission on the SCell using the
signaled (may be different than for the previous transmission)
dedicated parameters. The WTRU may determine 840 from the control
signaling, for example, codepoint 1, that the request is for a
preamble retransmission and set 850 the preamble counter to the
number of preamble transmissions performed so far for the TAG+1
(i.e., the counter is increased by one unit for every preamble
transmission until the counter is reset). The WTRU may therefore
apply 860 some power ramping. The WTRU may use 870 the
corresponding SCell DL as the PL reference, and perform 880 the
uplink transmission in the first subframe n+k2, k2.gtoreq.6 where a
PRACH resource is available.
[0150] In another example of a network-controlled dedicated
preamble retransmission, the WTRU may receive in subframe n control
signaling that includes a dedicated preamble and a PRACH mask index
which indicates that the WTRU performs a preamble retransmission on
the SCell using the signaled (may be different than for the
previous preamble transmission) dedicated parameters. The WTRU may
determine from the control signaling, for example, codepoint, 2
that the request is for a preamble retransmission corresponding to
a second retransmission in a sequence of preamble transmissions
performed for the TAG, independently of how many preamble
transmissions actually took place since the WTRU has initiated the
procedure. The WTRU may then apply the power ramping that
corresponds to the preamble transmission in the sequence. The WTRU
may use the corresponding SCell DL as the PL reference, and perform
the uplink transmission in the first subframe n+k2, k2.gtoreq.6
where a PRACH resource is available and according to the PRACH mask
index.
[0151] The WTRU may determine whether or not the procedure
involving the transmission of a preamble is complete. The procedure
may be for gaining uplink synchronization, an RACH procedure, or
any of the procedures including one of the examples described
above. The WTRU may determine either the RACH procedure or the
procedure for gaining uplink timing alignment has completed using
the 3GPP R8+ methods. In particular, the WTRU may use the 3GPP r8+
methods in the case of a contention-based procedure on the
SCell.
[0152] Alternatively, the WTRU may determine that the procedure is
completed according to the reception of RAR or other events not
involving RAR. The reception of the RAR may be considered, if the
WTRU decodes a DCI in the CSS of the PDCCH of a serving cell. The
WTRU may then be scheduled with an RAR from the reception of a
PDCCH DCI on the CSS of a PCell, which may include the CIF of the
corresponding SCell (or an SCell in the same TAG). The reception of
the RAR may also be considered if the WTRU may be scheduled with an
RAR from the reception of a PDCCH DCI on the CSS of an SCell.
Alternatively, the reception of the RAR is counted for an SCell for
which the WTRU is configured with a RACH configuration.
Alternatively, the reception of the RAR is counted while a timer is
running, such as an RAR window which includes subframes after the
transmission of a preamble and until successful reception of the
RAR or expiration of the timer.
[0153] Other events for consideration of the procedure completion
may be timer-based completion, maximum number of preamble
retransmissions, reception of control signaling on PDCCH, reception
of MAC control signaling, or contention resolution. For example,
reception of control signaling on PDCCH may be reception of an
uplink grant, reception of a request for an aperiodic SRS
transmission or reception of a DCI scrambled with a specific RNTI.
For example, reception of MAC control signaling may be MAC TAC CE,
MAC RAR, or other MAC CE. For example, contention resolution may be
used if CBRA is used.
[0154] The completion of the procedure may be bound by the
occurrence of at least one of the above or until a specific time
has elapsed, for example, by a reception window, whichever comes
first. For example, if the WTRU does not successfully complete the
procedure during the allocated window, it may determine either that
the procedure is not successful and/or that the procedure has
failed. In the case where the procedure is determined not
successful, the WTRU may perform an autonomous retransmission or
perform no further actions. If the procedure is not successful, the
WTRU may perform an autonomous retransmission after a certain
backoff or may deactivate one or more SCells of the concerned TAG.
In the case where the procedure has failed, the WTRU may discard
the explicitly signaled dedicated preamble (ra-PreambleIndex) and
PRACH mask index (PRACH-Mask-index), deactivate one or more SCells
of the concerned TAG, or perform no further actions. The WTRU may
keep the SCell(s) in their current activation state, and may
monitor the PDCCH for further control signaling that may order a
preamble retransmission for the concerned SCell, or TAG.
[0155] The WTRU may restart the applicable TA timer where the
procedure completes successfully. For example, the WTRU may restart
the TA timer when a TAC is received in the transmission of a
preamble, either in an RAR or in a MAC CE. The WTRU may reset a
counter of preamble transmission to its initial value, for example
reset to 0.
[0156] FIG. 9 is an example method to determine completion of the
network-controlled procedure. The WTRU may determine 910 that the
procedure is completed from the reception of a TAC using C-RNTI in
WTRUSS. The WTRU may monitor 920 the CSS of the SCell during the
RAR window applicable to the transmitted preamble using RA-RNTI in
CSS. Alternatively, the WTRU may monitor the CSS of the PCell
during the RAR window applicable to the transmitted preamble using
RA-RNTI in CSS. The WTRU may then determine 940 that the procedure
is completed based on the reception of a TAC. The WTRU may
determine 930 that the procedure is completed from the reception of
an uplink grant for an uplink shared channel (UL-SCH) transmission
on an SCell UL that is in the same TAG as the SCell UL. After
performing any one of steps 910, 930, or 940, the WTRU may then
discard 950 the preamble and PRACH mask index received in the
control signaling that requested the preamble transmission. The
WTRU may reset 960 the preamble counter. The WTRU may then apply
970 the received TAC to all SCell UL to the concerned TAG. The WTRU
may restart 980 the TA timer applicable to the TAG and consider all
uplink SCells of the TAG time-synchronized with the network.
[0157] In one example, the WTRU may determine that the procedure is
completed from the reception of a TAC. The WTRU may receive the TAC
in a MAC PDU as a MAC TAC CE that includes a TAC for the concerned
TAG and scheduled using a DCI scrambled with the WTRU's C-RNTI on
the WTRUSS of the PDCCH of any activated serving cell. The WTRU may
discard the dedicated preamble and PRACH-mask index received in the
control signaling that requested the preamble transmission, and
reset a preamble counter. The WTRU may apply the received TAC to
all SCell UL of the concerned TAG. The WTRU may restart the TA
timer applicable to the TAG and consider all uplink SCells of the
TAG time-synchronized with the network.
[0158] In another example, the WTRU may monitor the CSS of the
SCell during the RAR window applicable to the transmitted preamble.
The WTRU may determine that the procedure is completed from the
reception of a TAC. The WTRU may receive the TAC in a MAC RAR that
includes a TAC for the concerned TAG and scheduled using a DCI
scrambled with the WTRU's RA-RNTI on the CSS of the PDCCH of any
activated serving cell. The WTRU may discard the dedicated preamble
and PRACH-mask index received in the control signaling that
requested the preamble transmission, and reset the preamble
counter. The WTRU may apply the received TAC to all SCell UL of the
concerned TAG. The WTRU may restart the TA timer applicable to the
TAG and considers all uplink SCells of the TAG time-synchronized
with the network.
[0159] In another example, the WTRU may determine that the
procedure is completed from the reception of an uplink grant for an
UL-SCH transmission on an SCell UL that is in the same TAG as the
SCell UL on which the dedicated preamble was transmitted. The WTRU
may discard the dedicated preamble and PRACH-mask index received in
the control signaling that requested the preamble transmission, and
reset the preamble counter. The WTRU may restart the TA timer
applicable to the TAG and consider all uplink SCells of the TAG
time-synchronized with the network.
[0160] For a preamble transmission on a PCell, the WTRU may perform
RAR reception. Once the Random Access Preamble is transmitted,
regardless of the possible occurrence of a measurement gap, the
WTRU may monitor the PDCCH of the PCell for Random Access Responses
identified by the RA-RNTI. The WTRU may monitor the PDCCH in the RA
Response window which starts at the subframe containing the end of
the preamble transmission plus three subframes and has a length of
r.alpha.-ResponseWindowSize subframes. The RA-RNTI associated with
the PRACH in which the Random Access Preamble is transmitted, is
computed as:
RA-RNTI=1+t_id+10*f_id Equation (1)
where t_id is the index of the first subframe of the specified
PRACH (0.ltoreq.t_id<10), and fid is the index of the specified
PRACH within that subframe, in ascending order of frequency domain
(0.ltoreq.f_id<6). The WTRU may stop monitoring for Random
Access Responses after successful reception of a Random Access
Response containing Random Access Preamble identifiers that matches
the transmitted Random Access Preamble.
[0161] Upon reception of an RAR that corresponds to a preamble
transmitted on an SCell, the WTRU may determine that the procedure
is successfully completed.
[0162] For an SCell, the WTRU may decode the PDCCH for a message 2
(msg2), for example, an RAR or a MAC TAC CE, according to at least
one of the following. The WTRU may monitor for a DCI in the CSS of
the PDCCH of the PCell DL. The WTRU may attempt to decode the DCI
using a RA-RNTI. The DCI may include a CIF for the cross-carrier
scheduling of the RAR on the PDSCH of the cell corresponding to the
CIF, for example, the SCell on which the preamble was transmitted.
For example, the DCI for RAR for the preamble transmission on an
SCell may be received on the PDCCH of the PCell scrambled using
RA-RNTI.
[0163] The WTRU may monitor for a DCI in the WTRUSS of the PDCCH of
the PCell DL. The WTRU may attempt to decode the DCI using the
WTRU's C-RNTI. The DCI may include a CIF for the cross-carrier
scheduling of the msg2 on the PDSCH of the cell corresponding to
the CIF, for example, the SCell on which the preamble was
transmitted. For example, the DCI for RAR for the preamble
transmission on an SCell may be received on the PDCCH of the PCell
scrambled using the WTRU's C-RNTI. As another example, the DCI for
MAC TAC CE for the preamble transmission on an SCell may be
received on the PDCCH of the PCell scrambled using the WTRU's
C-RNTI.
[0164] The WTRU may monitor for a DCI in a CSS of the PDCCH of an
SCell DL. The CSS may be defined in a similar manner as for the
PDCCH of the PCell. The WTRU may attempt decoding for DCI during a
specific number of subframes, for example, during the reception
window of the RAR on the PDCCH of an SCell. The WTRU may attempt
decoding for DCI for an RA-RNTI. The SCell DL may correspond to the
SCell for which the preamble was transmitted, or may correspond to
any SCell of the same TAG as the SCell for which the preamble was
transmitted. The WTRU may attempt to decode the DCI using an
RA-RNTI. The DCI may include a CIF for the cross-carrier scheduling
of the RAR on the PDSCH of the cell corresponding to the CIF, for
example, the SCell on which the preamble was transmitted. For
example, the DCI for RAR for the preamble transmission on an SCell
may be received on the PDCCH of an SCell scrambled using the
RA-RNTI.
[0165] The WTRU may monitor for a DCI in a WTRUSS of the PDCCH of
an SCell DL. The SCell DL may correspond to the SCell for which the
preamble was transmitted, or may correspond to any SCell of the
same TAG as the SCell for which the preamble was transmitted. The
WTRU may attempt to decode the DCI using the WTRU's C-RNTI. The DCI
may include a CIF for the cross-carrier scheduling of the msg2 on
the PDSCH of the cell corresponding to the CIF, for example, the
SCell on which the preamble was transmitted. For example, the DCI
for RAR for the preamble transmission on an SCell may be received
on the PDCCH of an SCell scrambled using the WTRU's C-RNTI. As
another example, the DCI for MAC TAC CE for the preamble
transmission on an SCell may be received on the PDCCH of an SCell
scrambled using the WTRU's C-RNTI.
[0166] The DCI may be scrambled, either with the C-RNTI of the WTRU
or with a RA-RNTI. The DCI may be scramble with the C-RNTI of the
WTRU if the DCI is received in the CSS or WTRUSS of the
corresponding PDCCH. The DCI may be scrambled with a RA-RNTI if the
DCI is received in the CSS of the corresponding PDCCH. In
particular, if CFRA is possible, the WTRU may use C-RNTI to decode
a DCI pertaining to the msg2.
[0167] The WTRU may monitor a PDCCH for the RAR using specific
aggregation levels, for example, AL4 and AL8.
[0168] The RA-RNTI, if used, may be derived using at least one of
the following. The WTRU may derive the RA-RNTI at least in part
using an index of the first subframe of the specified PRACH, or the
index of the specific PRACH (similar to a case where the preamble
transmission would have been performed on the PCell UL).
Alternatively, the RA-RNTI may be derived at least in part using an
index of the serving cell on which the preamble was transmitted.
For example, this may be done by adding the value of the
corresponding servCellIndex. Alternatively, the RA-RNTI may be
derived at least in part using an index of the TAG of the serving
cell on which the preamble was transmitted. For example, this may
be done by adding the value of the corresponding
t.alpha.-groupIndex. Alternatively, the RA-RNTI may be derived
using an additional value configured by RRC for the WTRU.
[0169] If a DCI is successfully decoded for a msg2 corresponding to
an SCell, either on the PDCCH of the PCell or of the SCell, the DCI
may include a CIF. The received DCI may cross-carrier the msg2, in
particular, if C-RNTI is used to schedule the msg2.
[0170] In the case of cross-carrier scheduling for RACH on the
SCell, as the number of HARQ process bits are 3 bits, same size as
for CIF, which are reserved in case of format 1A using RA-RNTI,
instead of including the 3 bit CIF field in the PDCCH, the reserved
HARQ process number field may be replaced with the 3 bit CIF. The
WTRU may use the HARQ process bits in the DCI format to determine
to what SCell the received control signaling is applicable.
[0171] In LTE R8+, the MAC RAR is defined as follows: A MAC PDU
includes a MAC header and zero or more MAC Random Access Responses
(MAC RAR) and optionally padding. The MAC header is of variable
size.
[0172] A MAC PDU header includes one or more MAC PDU subheaders;
each subheader corresponding to a MAC RAR except for the Backoff
Indicator subheader. If included, the Backoff Indicator subheader
is only included once and is the first subheader included within
the MAC PDU header.
[0173] The MAC header may be of variable size and includes the
following fields: E, T, R, BI, and RAPID. E may be the Extension
field wherein a flag indicates if more fields are present in the
MAC header or not. The E field may be set to "1" to indicate at
least another set of E/T/RAPID fields follows. The E field may be
set to "0" to indicate that a MAC RAR or padding starts at the next
byte.
[0174] T may be the Type field wherein a flag indicates whether the
MAC subheader contains a Random Access ID or a Backoff Indicator.
The T field may be set to "0" to indicate the presence of a Backoff
Indicator field in the subheader (BI). The T field may be set to
"1" to indicate the presence of a Random Access Preamble ID field
in the subheader (RAPID).
[0175] R may be the Reserved bit, set to "0". BI may be the Backoff
Indicator field that identifies the overload condition in the cell.
The size of the BI field may be 4 bits. RAPID may be the Random
Access Preamble IDentitfier field that identifies the transmitted
Random Access Preamble. The size of the RAPID field may be 6 bits.
The MAC header and subheaders are octet aligned.
[0176] FIG. 10 is an example E/T/RAPID MAC subheader. A MAC PDU
subheader may consist of the three header fields E/T/RAPID as
illustrated in FIG. 10. Octet 1 in FIG. 10 includes three header
fields E 1001, T 1002, and RAPID 1003. FIG. 11 is an example
E/T/R/R/BI MAC subheader. A MAC PDU subheader may consist of three
header fields, but for the Backoff Indicator (BI) subheader which
includes the five header field E/T/R/R/BI as illustrated in FIG.
11. Octet 1 in FIG. 11 includes five header fields, E 1101, T 1102,
R 1103, R 1103, and BI 1104.
[0177] FIG. 12 is an example MAC RAR. A MAC RAR may include the
four fields R/Timing Advance Command/UL Grant/Temporary C-RNTI as
illustrated in FIG. 12. The timing Advance Command field may
indicate the index value, TA (0, 1, 2, . . . 1282), used to control
the amount of timing adjustment that the WTRU may have to apply.
The size of the Timing Advance Command field may be 11 bits. The UL
Grant field may indicate the resources to be used on the UL. The
size of the UL Grant field may be 20 bits. The Temporary C-RNTI
field may indicate the temporary identity that is used by the WTRU
during Random Access. The size of the Temporary C-RNTI field may be
16 bits.
[0178] Octet 1 in FIG. 12 includes R 1201 and Timing Advance
Command 1202. Octet 2 in FIG. 12 includes Timing Advance Command
1203 and UL Grant 1204. Octet 3 in FIG. 12 includes UL Grant 1205.
Octet 4 in FIG. 12 includes UL Grant 1206. Octet 5 in FIG. 12
includes Temporary C-RNTI 1207. Octet 6 in FIG. 12 includes
Temporary C-RNTI 1208. Padding may occur after the last MAC RAR.
Presence and length of padding is implicit based on TB size, size
of MAC header and number of RARs.
[0179] A MAC PDU for RAR may additionally include at least one of
the following: an identity of the SCell for which the RAR is
applicable or a TAG identifier of the SCell for which the RAR is
applicable. The identity of the SCell may be WTRU-specific, for
example, it may correspond to the servCellIndex or it may
correspond to the CIF. The identity of the SCell may be
cell-specific such as a cell identity. The identity of a TAG
identifier may be WTRU-specific, for example, it may correspond to
a configured TAG identity.
[0180] For example, a WTRU may receive a MAC PDU containing an RAR
with an identity of the SCell for which the RAR is applicable. The
MAC PDU may be cross-scheduled on the PDCCH of the PCell using a
DCI scrambled with the WTRU's C-RNTI. Alternatively, the MAC PDU
may be scheduled using a DCI scrambled with a RA-RNTI.
[0181] The WTRU may use a window or a timer during which it expects
reception of control signaling that completes the procedure. Upon
expiration of the timer, if the WTRU has not received any such
control signaling, the WTRU may determine that a preamble
retransmission may be performed, if WTRU-autonomous retransmission
are allowed. Alternatively, the WTRU may determine that the
procedure has completed. For example, the WTRU may determine that
the procedure was either unsuccessful or has failed.
[0182] If the WTRU performs preamble retransmission for an SCell,
either autonomously or under the control of the eNB, and the WTRU
determines that it has reached the maximum number of preamble
transmissions without successfully completing the procedure, the
WTRU may determine that the procedure is either unsuccessful or has
failed. The maximum number of preamble transmissions may be
configured by higher layers.
[0183] The WTRU may determine that the procedure is successful upon
reception of control signaling on PDCCH. Upon reception of control
signaling on PDCCH that corresponds to a preamble transmitted on an
SCell, the WTRU may determine that the procedure is successfully
completed.
[0184] The WTRU may determine that the procedure is successful if
the WTRU receives a grant for an uplink transmission on an SCell of
the TAG that corresponds to the SCell UL on which the preamble was
transmitted. For example, reception of a DCI format indicating an
uplink transmission, which may be received either on the PDCCH of
the SCell or on another serving cell using cross-carrier
scheduling. The DCI format may be format 0. The WTRU may determine
that the procedure is successful if the WTRU receives a request for
an aperiodic SRS on an SCell of the TAG that corresponds to the
SCell UL on which the preamble was transmitted. For example, a
reception of the request may be received either on the PDCCH of the
SCell or on another serving cell using cross-carrier
scheduling.
[0185] The WTRU may determine that the procedure is completed upon
receipt of a request for initiating the transmission of a preamble
on another SCell of the TAG that corresponds to the SCell UL on
which the preamble was transmitted. In particular, the WTRU may
determine the procedure is successful upon receipt of any of the
above case where a dedicated preamble is used for the transmission
of a preamble on an SCell. The WTRU may determine that the
procedure is successful, if the control signaling indicating an
uplink transmission is received in the time specified for the
completion of the procedure, for example, a window.
[0186] The WTRU may determine that the procedure is successful if
the WTRU receives a DCI format scrambled with the WTRU's C-RNTI for
the SCell. The WTRU may determine that the procedure is successful
if the WTRU receives a DCI format scrambled with the RA-RNTI that
corresponds to the preamble transmitted for the SCell. The WTRU may
determine that the procedure is successful if the WTRU receives a
DCI format scrambled with a specific RNTI, which RNTI indicates
termination of the procedure, for example a TA-RNTI. In particular
the WTRU may determine that the procedure is successful where a
dedicated preamble is used for the transmission of a preamble on an
SCell, or if the control signaling indicates an uplink transmission
is received in the time specified for the completion of the
procedure. For example, the time specified for the completion of
the procedure may be a window. The control signaling may indicate
to the WTRU that the eNB has successfully received the transmitted
preamble.
[0187] The WTRU may determine that the procedure is successful upon
reception of MAC control signaling. The WTRU may determine that the
procedure is successful upon reception of a MAC PDU that contains
at least a TAC applicable to the SCell and/or TAG of the SCell for
which a preamble was transmitted. For example, a TAC applicable to
the SCell may be inside a MAC TAC CE control element or inside a
MAC RAR. The MAC PDU may be received on the PDSCH of an SCell DL
that is part of the concerned TAG, for example, the PDSCH of the
SCell DL that corresponds to the SCell UL on which the preamble was
transmitted, or on the PDSCH of any serving cell. The WTRU may
determine that the procedure is successful upon reception of MAC
control signaling in case a dedicated preamble is used for the
transmission of a preamble on an SCell. For example, if the
corresponding MAC control signaling is received in the time
specified for the completion of the procedure, for example, a
window. Upon reception of MAC control signaling that corresponds to
a preamble transmitted on an SCell, the WTRU may determine that the
procedure is successfully completed.
[0188] If the WTRU is allowed to transmit a preamble that is
selected by the MAC, such as a contention-based procedure, the WTRU
may determine that the procedure is successful according to similar
criterion as for the contention-based procedure of 3GPP R8+. For
example, in the contention-based procedure of 3GPP R8+ when the
WTRU either the contention-based procedure is successful, or
otherwise the contention-based procedure fails.
[0189] Although features and elements are described above in
particular combinations, one of ordinary skill in the art will
appreciate that each feature or element can be used alone or in any
combination with the other features and elements. In addition, the
methods described herein may be implemented in a computer program,
software, or firmware incorporated in a computer-readable medium
for execution by a computer or processor. Examples of
computer-readable media include electronic signals (transmitted
over wired or wireless connections) and computer-readable storage
media. Examples of computer-readable storage media include, but are
not limited to, a read only memory (ROM), a random access memory
(RAM), a register, cache memory, semiconductor memory devices,
magnetic media such as internal hard disks and removable disks,
magneto-optical media, and optical media such as CD-ROM disks, and
digital versatile disks (DVDs). A processor in association with
software may be used to implement a radio frequency transceiver for
use in a WTRU, UE, terminal, base station, RNC, or any host
computer.
* * * * *