U.S. patent application number 14/958979 was filed with the patent office on 2016-03-24 for method and apparatus for high speed downlink packet access link adaptation.
The applicant listed for this patent is InterDigital Technology Corporation. Invention is credited to Christopher R. Cave, Rocco Di Girolamo, Paul Marinier.
Application Number | 20160088503 14/958979 |
Document ID | / |
Family ID | 39619114 |
Filed Date | 2016-03-24 |
United States Patent
Application |
20160088503 |
Kind Code |
A1 |
Cave; Christopher R. ; et
al. |
March 24, 2016 |
METHOD AND APPARATUS FOR HIGH SPEED DOWNLINK PACKET ACCESS LINK
ADAPTATION
Abstract
A method of high speed downlink packet access (HSDPA) link
adaptation, comprises receiving a channel quality measurement
metric over a Measured Results on random access channel (RACH)
information element (IE). The link is adapted based upon the
received channel quality metric.
Inventors: |
Cave; Christopher R.;
(Dollard-des-Ormeaux, CA) ; Di Girolamo; Rocco;
(Laval, CA) ; Marinier; Paul; (Brossard,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
InterDigital Technology Corporation |
Wilmington |
DE |
US |
|
|
Family ID: |
39619114 |
Appl. No.: |
14/958979 |
Filed: |
December 4, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14527333 |
Oct 29, 2014 |
9237469 |
|
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14958979 |
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12048797 |
Mar 14, 2008 |
8902763 |
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14527333 |
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60895385 |
Mar 16, 2007 |
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Current U.S.
Class: |
370/252 |
Current CPC
Class: |
H04W 28/18 20130101;
H04W 74/08 20130101; H04W 76/28 20180201; H04L 5/0057 20130101;
H04W 24/08 20130101; H04W 74/0833 20130101; H04W 48/16
20130101 |
International
Class: |
H04W 24/08 20060101
H04W024/08; H04W 76/04 20060101 H04W076/04; H04L 5/00 20060101
H04L005/00; H04W 74/08 20060101 H04W074/08 |
Claims
1. A method of high speed downlink packet access (HSPDA)
implemented in a wireless transmit/receive unit (WTRU), comprising:
performing a channel quality metric measurement during a
discontinuous reception (DRX) cycle of a network while the WTRU is
in a state in which the WTRU does not have a dedicated link; and
transmitting to a network node channel quality data based on the
channel quality metric measurement.
2. The method of claim 1 wherein the transmitting comprises
transmitting the channel quality data in a radio resource control
(RRC) message.
3. The method of claim 1 wherein transmitting comprises
transmitting the channel quality data in a Measured Results on
random access channel (RACH) information element (IE).
4. The method of claim 1 wherein performing of the channel quality
metric measurement occurs during a period when the network is not
sending data to the WTRU.
5. The method of claim 1 wherein the channel quality metric
measurement includes at least one of an inter-RAT measurement and
an inter-frequency measurement.
6. The method of claim 1 wherein a channel quality metric
measurement period is matched to a multiple of the DRX cycle.
7. The method of claim 1 wherein the transmitting is performed
while the WTRU is in a Cell_FACH state, a Cell.sub.-- PCH state, a
URA_PCH state, or an Idle state.
8. A processor associated with a wireless transmit/receive unit
(WTRU) configured to perform a channel quality metric measurement
of a network during a discontinuous reception (DRX) cycle of the
network while the WTRU is in a state in which the WTRU does not
have a dedicated link on the network.
9. The processor of claim 8 wherein the processor is configured to
cause the transmission of channel quality data based on the channel
quality metric measurement in a radio resource control (RRC)
message.
10. The processor of claim 9 wherein the processor is configured to
cause the transmission of the channel quality data in a Measured
Results on random access channel (RACH) information element
(IE).
11. The processor of claim 8 wherein the processor is configured to
perform the channel quality metric measurement during a period when
the network is not sending data to the WTRU.
12. The processor of claim 8 wherein the channel quality metric
measurements include at least one of an inter-RAT measurement and
an inter-frequency measurement.
13. The processor of claim 8 wherein the processor is configured to
cause the transmission of the channel quality data while the WTRU
is in a Cell_FACH state, a Cell.sub.-- PCH state, a URA_PCH state,
or an Idle state.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation application of U.S.
Non-provisional patent application Ser. No. 14/527,333 filed Oct.
29, 2014, which is a continuation application of U.S.
Non-provisional patent application Ser. No. 12/048,797 filed Mar.
14, 2008, now U.S. Pat. No. 8,902,763, which claims the benefit of
U.S. Provisional Application No. 60/895,385, filed Mar. 16, 2007
and which are incorporated by reference as if fully set forth.
FIELD OF INVENTION
[0002] This application is related to wireless communications.
BACKGROUND
[0003] High Speed Downlink Packet Access (HSDPA) is a feature that
was introduced in Release 5 of the third generation partnership
project (3GPP) specifications to operate in a cell dedicated
channel (Cell_DCH) state. A key operating principle of HSDPA is to
share a very fast downlink (DL) pipe, the high-speed downlink
physical shared channel (HS-DPSCH). A universal terrestrial radio
access network (UTRAN) can configure up to 15 HS-DPSCHs, and each
of these can by shared by all wireless transmit/receive units
(WTRUs) on a per transmission time interval (TTI) basis, (i.e.,
every 2 msec). As a result, the information on the downlink
channels can be destined to different WTRUs at an interval of every
2 msec. In order to allow WTRUs to determine ownership of the
information on these shared channels, a Node-B also sends a set of
parallel high speed shared control channels (HS-SCCHs). Among other
things, these channels provide details allowing the WTRUs to
determine if the information on the HS-DPSCH is for them, and if
so, to recover the transmitted information.
[0004] In HSDPA, the Node-B tries to make a better use of the
downlink capacity by using several concepts, such as adaptive
modulation and coding (AMC), retransmissions using a hybrid
automatic repeat request (H-ARQ) scheme, and Node-B scheduling. All
of these operate at a very fast rate, directed toward taking
advantage of the changing channel conditions perceived by the
WTRUs. In order to accomplish this, the Node-B schedules
transmissions in order to maximize downlink throughput, (e.g.,
using 16-quadrature amplitude modulation (QAM) for a WTRU very
close to the Node-B and using quadrature phase shift keying (QPSK)
for a WTRU at cell edge). This fast scheduling is complemented with
H-ARQ at a physical layer, allowing retransmission of transport
blocks that are received in error. Furthermore, multiple
simultaneous H-ARQ processes are permitted in order to maximize
utilization.
[0005] Every 2 msec, the Node-B schedules transmissions on the
HS-DPSCH based on WTRU channel conditions, the status of its own
downlink buffers, and status of the parallel H-ARQ processes. In
addition, the Node-B tailors the transmission bit rates to the
specific WTRUs by adapting the modulation, coding, and transport
block size. To achieve this, the Node-B requires the following
information from the WTRUs:
[0006] Channel Quality Indication (CQI): an index into a table
which provides the maximum MCS and transport block the WTRU can
support, based on the received DL signal power, the interference
from other cells, and the WTRU receiver capability; and
[0007] Positive acknowledgement (ACK)/negative acknowledgement
(NACK) feedback for the H-ARQ processes.
[0008] This feedback information is provided on a high speed
dedicated physical control channel (HS-DPCCH). The CQI information
is provided periodically, with periodicity determined by the UTRAN.
The ACK/NACK information is only provided in response to a packet
being received on the downlink. Some of the main attributes of the
HS-DPCCH include:
[0009] Every WTRU having an access to the HSPDA has its own
dedicated control channel and as a result the WTRU can easily
provide the feedback information;
[0010] The channel is power controlled; this is accomplished
through a closed loop mechanism using the downlink dedicated
physical control channel (DPCCH), which always accompanies HSDPA
transmission;
[0011] The information on the HS-DPCCH is heavily coded to aid in
detection; and
[0012] The information on the HS-DPCCH is time aligned (but
delayed) with respect to the UL DPCCH.
[0013] As part of Release 7 of 3GPP, using the high speed shared
channel for WTRUs in a Cell_FACH state has been considered. The
properties of a WTRU in a Cell_FACH state are quite different from
those for a WTRU in a Cell_DCH state including the following:
[0014] The only uplink mechanism for Release 7 WTRUs in a Cell_FACH
state is through a random access mechanism, over the random access
channel (RACH);
[0015] The WTRUs autonomously update the UTRAN as to their cell
location through CELL UPDATE and URA UPDATE procedures;
[0016] The WTRU can be configured for forward access channel (FACH)
measurement occasions--these are periods during which the WTRU
takes measurements on inter-radio access technology (RAT) and/or
inter-frequency cells;
[0017] The WTRUs make the following physical layer measurements:
[0018] common pilot channel (CPICH) received signal code power
(RSCP): The received signal code power measured on the primary
CPICH; and [0019] CPICH Ec/No: The received energy per chip divided
by the power density in the band. The CPICH Ec/No is defined as
CPICH RSCP/UTRA Carrier received signal strength indicator (RSSI).
The UTRA Carrier RSSI is not measured in Cell_FACH, but only in
Cell_DCH. It is the received wide band power, including thermal
noise and noise generated in the receiver, within the bandwidth
defined by the receiver pulse shaping filter; and
[0020] Physical layer measurements are reported to the UTRAN via
layer 3 signalling through the Measured Results on RACH
mechanism.
[0021] The measured results on RACH mechanism are designed to
provide some feedback information to the UTRAN regarding the
current state of the downlink. The mechanism may be controlled by
the network, which broadcasts, as part of its system information in
system information block 11 (SIB11) and SIB12, the information
element (IE) "Intra-frequency reporting quantity for RACH
Reporting". This IE tells all WTRUs in the cell the quantity to
measure. The choices are highlighted in Table 1 below, along with
the granularity of the reported quantity and the length of the
coded information sent to the UTRAN.
TABLE-US-00001 TABLE 1 Size of Coded Quantity Determined by/from
Granularity Information CPICH as measured by PHY layer -120 to -25
dBm 7 RSCP (in steps 1 dBm) CPICH as measured by PHY layer -24 dB
to 0 dB 6 Ec/No (in steps of 0.5 dB) Pathloss Pathloss in dB =
Primary CPICH 46 to 158 dB 7 Tx power - CPICH RSCP. (in steps of 1
dB) Where Primary CPICH Tx power is found in the IE "Primary CPICH
Tx power", and CPICH RSCP is as measured in PHY layer No 0
report
[0022] Referring to Table 1 above, a WTRU takes the appropriate
measurements and reports these to the higher layers, (e.g., radio
resource control (RRC)). In a Cell_FACH state, the base measurement
period is 200 msec, but this can be higher if a FACH Measurement
Occasion is configured for monitoring inter-frequency and inter-RAT
cells. The accuracy of the measurement is defined to be .+-.6 dB
for the current cell.
[0023] The information is sent to higher layers to be included in
the IE "Measured results on RACH", in a number of RRC messages
including: CELL UPDATE, RRC CONNECTION REQUEST, INITIAL DIRECT
TRANSFER, UPLINK DIRECT TRANSFER, and MEASUREMENT REPORT messages.
Unlike the majority of other measurements and quantities available
at the RRC, those carried in the IE "Measured results on RACH" can
not be filtered by the RRC prior to transmission.
[0024] The IE contains the configured measured quantity for the
current cell and all other intra-frequency cells in the monitored
set (the monitored set includes a list of cells that the UTRAN has
told the WTRU to monitor). The IE may also contain the configured
measured quantity for inter-frequency cells.
[0025] For RRC messages transmitted on a common control channel
(CCCH), the maximum allowed message size should not be exceeded
when forming the IE "Measured results on RACH". To achieve this,
the WTRU may limit the number of included neighbor cells included
in the report, or omit the IE "Measured results on RACH"
altogether.
[0026] If HSDPA is to be used in a Cell_FACH state, the main
problem is the lack of a dedicated uplink channel and the resulting
absence of feedback. Without this information, the advantages of
HSDPA are significantly reduced.
[0027] Several proposals addressed to solve the feedback issue have
already been made. In one proposal, it has been proposed to
transmit CQI information over:
[0028] The RACH transport channel either in preamble or
message;
[0029] A new shared common uplink channels; and
[0030] Shared uplink code space.
[0031] However, the techniques described above require changes to
the WTRU physical layer. As there is a strong push to limit these
changes, it has been proposed to use the "Measured Results on RACH"
mechanism to transmit channel quality information to the UTRAN. As
the information is embedded in an RRC message IE, the UTRAN radio
network controller (RNC) would need to forward the channel quality
information to the Node-B so that it may perform its adaptive
modulation and coding.
[0032] Using the "Measured Results on RACH" mechanism to provide
channel quality feedback has a number of problems, however. For
example:
[0033] 1. The measured quantity (metric) that is fedback and
subsequently used by the Node-B is either CPICH RSCP or CPICH
Ec/No. Problems that may be associated with both these measures
include: [0034] 1) RSCP only measures received power on a single
code and does not provide any indication about the neighbour cell
interference experienced by the WTRU. [0035] 2) Ec/No provides a
ratio of the power received on the CPICH to the total received
downlink power (CPICH Ec/No=CPICH RSCP/UTRA Carrier RSSI). As the
denominator is the total received DL power, the range of the metric
is somewhat reduced compared to a pure carrier/interference ratio.
Additionally, the downlink received power (i.e., RSSI) is not
necessarily measured in the Cell_FACH state. If it is not, then
when making a CPICH Ec/No calculation, the physical layer uses the
last calculated RSSI value while in Cell_DCH state. If a UE stays
in Cell_FACH for an extended period of time, this value will be
outdated, and the measure will be no better than the CPICH RSCP.
[0036] 3) These measures fail to take into account the WTRU
receiver capability. It is possible that for the same CPICH RSCP,
WTRUs with different receiver architectures could support very
different modulation, coding, and transport block sizes. [0037] 4)
There is poor correlation between the RSCP and Ec/No and the actual
CQI.
[0038] 2. As WTRUs in Cell_PCH move across cell boundaries, the
UTRAN refreshes their channel quality information based on
information received in the CELL UPDATE message. If these WTRUs
transition to Cell_FACH, the UTRAN will have up-to-date channel
quality information which it can relay to the Node-B. On the other
hand, as WTRUs in URA_PCH cross UTRAN routing area (URA)
boundaries, they inform the network with a URA UPDATE message. As
this message does not carry the IE "Measured Results on RACH", the
network will typically have out-of-date channel quality
information.
[0039] 3. The quantities reported in the IE: "Measured Results on
RACH" cannot be filtered at the WTRU RRC. As there is a latency
between the instant the measurement is made and the time the Node-B
is privy to this information, using non-averaged results may result
in sub-optimum performance.
[0040] 4. The Measured Results on RACH mechanism is currently
controlled on a per-cell basis through information broadcast in the
system information. As a result, all WTRUs in a cell are required
to report the same information. This limits the flexibility of the
reporting mechanism as the UTRAN may favor one measure over the
other depending on the eventual use. For instance, the pathloss may
be a better measure for cell reselection, but the CPICH Ec/No may
be better for channel quality reporting.
SUMMARY
[0041] A method and apparatus for high speed downlink packet access
link adaptation is disclosed. The method includes receiving a
channel quality measurement metric over a Measured Results on
random access channel (RACH) information element (IE). A link is
adapted based upon the received channel quality metric
BRIEF DESCRIPTION OF THE DRAWINGS
[0042] A more detailed understanding may be had from the following
description, given by way of example in conjunction with the
accompanying drawings wherein:
[0043] FIG. 1 shows an example wireless communication system
including a plurality of WTRUs, a radio network controller (RNC),
and a Node B;
[0044] FIG. 2 is an example functional block diagram of a WTRU and
the Node B of FIG. 1; and
[0045] FIG. 3 is a flow diagram of a method of HSDPA link
adaptation.
DETAILED DESCRIPTION
[0046] When referred to hereafter, the terminology "wireless
transmit/receive unit (WTRU)" includes but is not limited to a user
equipment (UE), a mobile station, a fixed or mobile subscriber
unit, a pager, a cellular telephone, a personal digital assistant
(PDA), a computer, or any other type of user device capable of
operating in a wireless environment. When referred to hereafter,
the terminology "base station" includes but is not limited to a
Node-B, a site controller, an access point (AP), or any other type
of interfacing device capable of operating in a wireless
environment.
[0047] FIG. 1 shows a wireless communication system 100 including a
plurality of WTRUs 110 and a Node B 120. As shown in FIG. 1, the
WTRUs 110 are in communication with the Node B 120. It should be
noted that, although an example configuration of WTRUs 110 and Node
B 120 is depicted in FIG. 1, any combination of wireless and wired
devices may be included in the wireless communication system 100.
In addition, an RNC 130 is in communication with the Node B
120.
[0048] FIG. 2 is a functional block diagram 200 of a WTRU 110 and
the Node B 120 of the wireless communication system 100 of FIG. 1.
As shown in FIG. 2, the WTRU 110 is in communication with the Node
B 120. The Node B 120 is configured to tailor HSDPA link
adaptation, and the WTRU 110 provides channel quality feedback,
(e.g., in the IE "Measured Results on RACH"), to aid the Node B 120
in performing link adaptation.
[0049] In addition to the components that may be found in a typical
WTRU, the WTRU 110 includes a processor 115, a receiver 116, a
transmitter 117, and an antenna 118. The receiver 116 and the
transmitter 117 are in communication with the processor 115. The
antenna 118 is in communication with both the receiver 116 and the
transmitter 117 to facilitate the transmission and reception of
wireless data.
[0050] In addition to the components that may be found in a typical
Node B, the Node B 120 includes a processor 125, a receiver 126, a
transmitter 127, and an antenna 128. The processor 125 is
configured to perform a method of HSDPA link adaptation. The
receiver 126 and the transmitter 127 are in communication with the
processor 125. The antenna 128 is in communication with both the
receiver 126 and the transmitter 127 to facilitate the transmission
and reception of wireless data.
[0051] FIG. 3 is a flow diagram of a method 300 of HSDPA link
adaptation. In step 310, the WTRU 110 includes a channel quality
measurement metric in a Measured Results on RACH IE and transmits
the channel quality measurement metric to the Node B 120. In one
example, the channel quality measurement metric is included in
radio resource controller (RRC) signalling.
[0052] The channel quality measurement metric that the WTRU 110
transmits may include a CPICH C/I based on parameters calculated in
Cell_FACH, Cell_PCH, URA_PCH, and Idle states. For instance, the
following may be defined:
CPICH C/I=CPICH RSCP/(UTRA Carrier RSSI-CPICH RSCP), Equation
(1)
where all units are in W. Additionally, a new measure may be
defined taking into account the received signal code power, the
total interference, and the WTRUs 110 capability.
[0053] Alternatively, existing measurements to the WTRU 110 channel
quality measurement metrics may be modified and reported over the
Measured Results on RACH IE. For example, the WTRU 110 calculated
CQI may be forwarded to the higher layers as a measurement quantity
and reported over the Measured Results on RACH IE or UTRA Carrier
RSSI may be measured in the Cell_FACH state in order to improve the
relevance of the CPICH Ec/No measure.
[0054] The Measured Results on RACH IE may be configured per WTRU
110 instead of per cell. Additionally, The WTRU 110 may send one or
more channel quality metrics in the IE. The WTRU 110 may give
priority to certain metrics. For example, for CCCH traffic, such as
a CELL UPDATE message after a cell reselection, priority may be
given the channel quality measurements that can aid link
adaptation. Layer 3 filtering may also occur for any of the
physical layer measurements described above.
[0055] Once the Node B 120 receives the channel quality measurement
metric, it forwards it to the RNC 130 (step 320) where the RNC
interprets the channel quality measurement metric and forwards
channel quality information back to the Node B 120 (step 330). The
Node B may then tailor link adaptation based upon the channel
quality information (step 340). Additionally, the Node B 340 may
tailor the link adaptation based upon the type of filtering allowed
for the WTRU 110 reported channel measure.
[0056] Additionally, in order to address WTRUs 110 that are in
URA_PCH and subsequently transitioning to Cell_FACH, the Measured
Results on RACH IE may be included in the URA UPDATE message. As
neighboring cell measurements have less relevance in URA_PCH, the
WTRU 110 may be hardcoded to only report measurement quantities
based on the current cell, whether it be an existing measurement or
a new measurement.
[0057] Any of the measurements that are reported by the WTRU 100,
existing or new, may be synchronized with the WTRUs 110 FACH
Measurement Occasions and/or any discontinuous reception (DRX)
cycle currently defined in Cell_FACH state, Cell_PCH state, URA_PCH
state or idle mode, This can be achieved by matching the
measurement period to a multiple of the DRX cycle.
[0058] Alternatively, synchronization may be achieved by WTRU 110
measuring the reported quantity at the next opportunity provided by
the DRX cycle following the expiration of the measurement period.
For instance, if the measurement period is set to 300 ms, while the
DRX cycle repeats itself every 200 ms, and if the last measurement
took place during the last opportunity provided by the DRX cycle
(t=0 ms), the WTRU 110 would measure at t=400 ms instead of t=300
ms.
[0059] In addition, the list of RRC messages that include the IE
"Measured Results on RACH" may be expanded. For example, the IE may
be included in any of the following messages: UE CAPABILITY
INFORMATION, COUNTER CHECK, RADIO BEARER SETUP COMPLETE, TRANSPORT
CHANNEL RECONFIGURATION COMPLETE, PHYSICAL CHANNEL RECONFIGURATION
COMPLETE, UTRAN MOBILITY INFORMATION CONFIRM, or any other
messages.
[0060] Although features and elements are described above in
particular combinations, each feature or element can be used alone
without the other features and elements or in various combinations
with or without other features and elements. The methods or flow
charts provided herein may be implemented in a computer program,
software, or firmware incorporated in a computer-readable storage
medium for execution by a general purpose computer or a processor.
Examples of computer-readable storage mediums include 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).
[0061] Suitable processors include, by way of example, 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 Arrays (FPGAs)
circuits, any other type of integrated circuit (IC), and/or a state
machine.
[0062] A processor in association with software may be used to
implement a radio frequency transceiver for use in a wireless
transmit receive unit (WTRU), user equipment (UE), terminal, base
station, radio network controller (RNC), or any host computer. The
WTRU may be used in conjunction with modules, implemented in
hardware and/or software, such as a camera, a video camera module,
a videophone, a speakerphone, a vibration device, a speaker, a
microphone, a television transceiver, a hands free headset, a
keyboard, a Bluetooth.RTM. module, a frequency modulated (FM) radio
unit, a liquid crystal display (LCD) display unit, an organic
light-emitting diode (OLED) display unit, a digital music player, a
media player, a video game player module, an Internet browser,
and/or any wireless local area network (WLAN) or Ultra Wide Band
(UWB) module.
* * * * *