U.S. patent application number 15/414958 was filed with the patent office on 2017-05-11 for signaling of power information for mimo transmission in a wireless communication system.
The applicant listed for this patent is Qualcomm Incorporated. Invention is credited to Josef BLANZ, Ivan Jesus FERNANDEZ-CORBATON.
Application Number | 20170135051 15/414958 |
Document ID | / |
Family ID | 39582855 |
Filed Date | 2017-05-11 |
United States Patent
Application |
20170135051 |
Kind Code |
A1 |
BLANZ; Josef ; et
al. |
May 11, 2017 |
SIGNALING OF POWER INFORMATION FOR MIMO TRANSMISSION IN A WIRELESS
COMMUNICATION SYSTEM
Abstract
An apparatus includes a processor and a memory coupled to the
processor. The memory stores instructions executable by the
processor to perform operations that include determining a
particular number of transport blocks associated with user
equipment (UE) based on a plurality of channel quality indicator
(CQI) indices received from the UE.
Inventors: |
BLANZ; Josef; (Frost,
DE) ; FERNANDEZ-CORBATON; Ivan Jesus; (Almacelles
(Lleida), ES) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Qualcomm Incorporated |
San Diego |
CA |
US |
|
|
Family ID: |
39582855 |
Appl. No.: |
15/414958 |
Filed: |
January 25, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15072038 |
Mar 16, 2016 |
9591594 |
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15414958 |
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13325251 |
Dec 14, 2011 |
9338756 |
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15072038 |
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11971084 |
Jan 8, 2008 |
8837337 |
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13325251 |
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60884820 |
Jan 12, 2007 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W 88/02 20130101;
H04J 13/0044 20130101; H04W 72/085 20130101; H04B 1/707 20130101;
H04B 7/0632 20130101; H04W 52/346 20130101; H04W 88/08 20130101;
H04L 1/0034 20130101; H04W 52/325 20130101; H04W 76/27 20180201;
H04B 7/0426 20130101 |
International
Class: |
H04W 52/34 20060101
H04W052/34; H04J 13/00 20060101 H04J013/00; H04B 7/06 20060101
H04B007/06 |
Claims
1. An apparatus comprising: a receiver configured to wirelessly
receive a plurality of channel quality indicator (CQI) indices at a
Node B from user equipment (UE); and a processor configured to
initiate wireless transmission of a particular number of transport
blocks or fewer than the particular number of transport blocks to
the UE from the Node B, the particular number of transport blocks
associated with the UE and based on the plurality of CQI
indices.
2. The apparatus of claim 1, wherein the processor is further
configured to initiate wireless transmission of power information
related to a designated number of channelization codes to the UE
from the Node B prior to receipt of the plurality of CQI indices,
wherein the power information includes an offset value, and wherein
the power information is indicative of a total power of the
designated number of channelization codes.
3. The apparatus of claim 1, further comprising a transmitter
configured to wirelessly transmit the particular number of
transport blocks or fewer than the particular number of transport
blocks to the UE from the Node B, wherein the processor is further
configured to scale sizes of the transport blocks based on a
designated number of channelization codes and an available number
of channelization codes.
4. A method for wireless communication, the method comprising:
wirelessly receiving a plurality of channel quality indicator (CQI)
indices at a Node B from user equipment (UE); and wirelessly
transmitting a particular number of transport blocks or fewer than
the particular number of transport blocks to the UE from the Node
B, the particular number of transport blocks associated with the UE
and based on a plurality of CQI.
5. The method of claim 4, further comprising wirelessly
transmitting power information related to a designated number of
channelization codes to the UE from the Node B, wherein the power
information includes an offset value, wherein each of the
designated number of channelization codes is an orthogonal variable
spreading factor (OVSF) code, and wherein wirelessly transmitting
the particular number of transport blocks or fewer than the
particular number of transport blocks comprises wirelessly
transmitting the particular number of transport blocks to the UE
from the Node B.
6. The method of claim 4, wherein wirelessly transmitting the
particular number of transport blocks or fewer than the particular
number of transport blocks comprises wirelessly transmitting fewer
than the particular number of transport blocks to the UE from the
Node B.
7. An apparatus comprising: means for wirelessly receiving a
plurality of channel quality indicator (CQI) indices at a Node B
from user equipment (UE); and means for wirelessly transmitting a
particular number of transport blocks or fewer than the particular
number of transport blocks to the UE from the Node B, the
particular number of transport blocks associated with the UE and
based on the plurality of CQI indices.
8. The apparatus of claim 7, wherein the particular number of
transport blocks comprises a preferred number of transport blocks,
and wherein the preferred number of transport blocks is one or
two.
9. A non-transitory computer-readable storage medium storing
instructions executable by a computer to perform operations
comprising: receiving a plurality of channel quality indicator
(CQI) indices at a Node B from user equipment (UE); and initiating
wireless transmission of a particular number of transport blocks or
fewer than the particular number of transport blocks to the UE from
the Node B, the particular number of transport blocks associated
with the UE and based on the plurality of CQI indices.
10. The non-transitory computer-readable storage medium of claim 9,
wherein the operations further comprise initiating wireless
transmission power information related to a designated number of
channelization codes from the Node B to the UE, wherein the power
information includes an offset value, and wherein the power
information is wirelessly sent to the UE via a Radio Resource
Control (RRC) message.
11. An apparatus comprising: a processor configured to initiate
wireless transmission of a plurality of channel quality indicator
(CQI) indices to a Node B from user equipment (UE), wherein the
plurality of CQI indices indicates a particular number of transport
blocks; and a receiver configured to wirelessly receive the
particular number of transport blocks or fewer than the particular
number of transport blocks at the UE from the Node B.
12. The apparatus of claim 11, wherein the receiver is further
configured to wirelessly receive power information related to a
designated number of channelization codes at the UE from the Node
B, wherein the plurality of CQI indices is based on the power
information.
13. The apparatus of claim 11, sizes of the transport blocks are
scaled based on a designated number of channelization codes and an
available number of channelization codes.
14. The apparatus of claim 11, further comprising a transmitter
configured to wirelessly transmit the plurality of CQI indices from
the UE to the Node B.
15. The apparatus of claim 11, wherein wirelessly receiving the
particular number of transport blocks or fewer than the particular
number of transport blocks comprises wirelessly receiving the
particular number of transport blocks at the UE from the Node B via
a multiple-input multiple-output (MIMO) transmission.
16. A method for wireless communication, the method comprising:
wirelessly transmitting a plurality of channel quality indicator
(CQI) indices to a Node B from user equipment (UE), wherein the
plurality of CQI indices indicates a particular number of transport
blocks; and wirelessly receiving the particular number of transport
blocks or fewer than the particular number of transport blocks at
the UE from the Node B.
17. The method of claim 16, wherein wirelessly receiving the
particular number of transport blocks or fewer than the particular
number of transport blocks comprises receiving fewer than the
particular number of transport blocks at the UE from the Node
B.
18. The method of claim 16, further comprising: wirelessly
receiving power information at the UE from the Node B, the power
information indicating a power offset value that is expressed in
decibels; and determining total received power based on the power
offset value and power of a pilot channel.
19. An apparatus comprising: means for wirelessly sending a
plurality of channel quality indicator (CQI) indices to a Node B
from user equipment (UE), wherein the plurality of CQI indices
indicates a particular number of transport blocks; and means for
wirelessly receiving the particular number of transport blocks or
fewer than the particular number of transport blocks or fewer at
the UE from the Node B.
20. A non-transitory computer-readable storage medium storing
instructions executable by a computer to perform operations
comprising: initiating wireless transmission of a plurality of
channel quality indicator (CQI) indices to a Node B from user
equipment (UE), wherein the plurality of CQI indices indicates a
particular number of transport blocks; and receiving the particular
number of transport blocks or fewer than the particular number of
transport blocks at the UE from the Node B.
Description
CLAIM OF PRIORITY
[0001] The present application is a continuation of pending
Continuation application Ser. No. 15/072,038, filed Mar. 16, 2016,
entitled "SINGALING OF POWER INFORMATION FOR MIMO TRANSMISSION IN A
WIRELESS COMMUNICATION SYSTEM," which claims priority to granted
U.S. application Ser. No. 13/325,251, filed Dec. 14, 2011, Grant
No. 9,338,756, grant date May 10, 2016 entitled "SINGALING OF POWER
INFORMATION FOR MIMO TRANSMISSION IN A WIRELESS COMMUNICATION
SYSTEM," which claims priority to granted U.S. application Ser. No.
11/971,084, filed Jan. 8, 2008, Grant No. 8,837,337, grant date
Sep. 16, 2014 entitled "SIGNALING OF POWER INFORMATION FOR MIMO
TRANSMISSION IN A WIRELESS COMMUNICATION SYSTEM," which claims
priority to Provisional U.S. Application No. 60/884,820, filed Jan.
12, 2007, entitled "VIRTUAL POWER OFFSET SIGNALLING IN MIMO." Each
of the above applications is hereby expressly incorporated by
reference herein.
BACKGROUND
[0002] I. Field
[0003] The present disclosure relates generally to communication,
and more specifically to techniques for signaling power information
in a wireless communication system.
[0004] II. Background
[0005] In a wireless communication system, a Node B may utilize
multiple (T) transmit antennas for data transmission to a user
equipment (UE) equipped with multiple (R) receive antennas. The
multiple transmit and receive antennas form a multiple-input
multiple-output (MIMO) channel that may be used to increase
throughput and/or improve reliability. For example, the Node B may
transmit up to T data streams simultaneously from the T transmit
antennas to improve throughput. Alternatively, the Node B may
transmit a single data stream from all T transmit antennas to
improve reception quality by the UE. Each data stream may carry one
transport block of data in a given transmission time interval
(TTI). Hence, the terms "data stream" and "transport block" may be
used interchangeably.
[0006] Good performance (e.g., high throughput) may be achieved by
sending each transport block at the highest possible rate that
still allows the UE to reliably decode the transport block. The UE
may estimate signal-to-interference-and-noise ratios (SINRs) of
each possible precoding combination of transport blocks that might
be transmitted and may then determine channel quality indicator
(CQI) information based on the estimated SINRs of the best
precoding combination of transport blocks. The CQI information may
convey a set of processing parameters for each transport block. The
UE may send the CQI information to the Node B. The Node B may
process one or more transport blocks in accordance with the CQI
information and send the transport block(s) to the UE.
[0007] Data transmission performance may be dependent on accurate
determination and reporting of CQI information by the UE. There is
therefore a need in the art for techniques to facilitate accurate
determination and reporting of CQI information.
SUMMARY
[0008] Techniques for signaling power information to facilitate
accurate determination and reporting of CQI information for a MIMO
transmission are described herein. For a MIMO transmission sent
using code division multiplexing, the SINR of a transport block may
be dependent on power per channelization code, P.sub.OVSF, but may
not be a linear function of P.sub.OVSF.
[0009] In an aspect, a Node B may send power information that may
be used by a UE to determine P.sub.OVSF, which may then be used for
SINR estimation. In one design, the power information comprises a
power offset between the power of a data channel, P.sub.HSPDSCH,
and the power of a pilot channel, P.sub.CPICH. In general, the data
channel may comprise any number of channelization codes.
P.sub.HSPDSCH may be given for a designated number of
channelization codes, M, which may be a known value or provided via
signaling. The Node B may determine P.sub.HSPDSCH based on the
power available for the data channel, {tilde over (P)}.sub.HSPDSCH
the number of channelization codes available for the data channel,
K, and the designated number of channelization codes, M.
P.sub.HSPDSCH may be greater than {tilde over (P)}.sub.HSPDSCH if
the designated number of channelization codes is greater than the
number of available channelization codes.
[0010] The UE may receive the power information from the Node B and
may determine P.sub.OVSF based on the power information and the
designated number of channelization codes. In one design, the UE
may obtain the power offset from the power information and compute
P.sub.HSPDSCH based on the power offset and the known P.sub.CPICH.
The UE may then distribute P.sub.HSPDSCH across at least one
transport block and also across the designated number of
channelization codes to obtain P.sub.OVSF. The UE may estimate the
SINR of each transport block based on P.sub.OVSF and then determine
CQI information for the at least one transport block based on the
SINR of each transport block. The UE may send the CQI information
to the Node B.
[0011] The Node B may receive the CQI information from the UE and
may send at least one transport block in a MIMO transmission to the
UE. In one design, the Node B may send the transport block(s) with
the designated number of channelization codes and at P.sub.OVSF or
higher. In another design, the Node B may send the transport
block(s) with K available channelization codes at P.sub.OVSF or
higher and may scale the size of the transport block(s) based on
the designated number of channelization codes, M, and the number of
available channelization codes, K. In yet another design, the Node
B may scale P.sub.OVSF based on K and M and may then send the
transport block(s) with the K available channelization codes at the
scaled P.sub.OVSF.
[0012] Various aspects and features of the disclosure are described
in further detail below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 shows a wireless communication system.
[0014] FIG. 2 shows a block diagram of a Node B and a UE.
[0015] FIG. 3 shows a timing diagram for a set of physical
channels.
[0016] FIG. 4 shows scaling of the power offset by the Node B.
[0017] FIG. 5 shows a mechanism for sending the power offset by the
Node B.
[0018] FIG. 6 shows a process for determining CQI information by
the UE.
[0019] FIG. 7 shows a process performed by the Node B.
[0020] FIG. 8 shows a process performed by the UE.
DETAILED DESCRIPTION
[0021] The techniques described herein may be used for various
wireless communication systems such as Code Division Multiple
Access (CDMA) systems, Time Division Multiple Access (TDMA)
systems, Frequency Division Multiple Access (FDMA) systems,
Orthogonal FDMA (OFDMA) systems, Single-Carrier FDMA (SC-FDMA)
systems, etc. The terms "system" and "network" are often used
interchangeably. A CDMA system may implement a radio technology
such Universal Terrestrial Radio Access (UTRA), cdma2000, etc. UTRA
includes Wideband-CDMA (W-CDMA) and other CDMA variants. cdma2000
covers IS-2000, IS-95 and IS-856 standards. UTRA is part of
Universal Mobile Telecommunication System (UMTS), and both are
described in documents from an organization named "3rd Generation
Partnership Project" (3GPP). cdma2000 is described in documents
from an organization named "3rd Generation Partnership Project 2"
(3GPP2). These various radio technologies and standards are known
in the art. For clarity, the techniques are described below for
UMTS, and UMTS terminology is used in much of the description
below.
[0022] FIG. 1 shows a wireless communication system 100 with
multiple Node Bs 110 and multiple UEs 120. System 100 may also be
referred to as a Universal Terrestrial Radio Access Network (UTRAN)
in UMTS. A Node B is generally a fixed station that communicates
with the UEs and may also be referred to as an evolved Node B
(eNode B), a base station, an access point, etc. Each Node B 110
provides communication coverage for a particular geographic area
and supports communication for the UEs located within the coverage
area. A system controller 130 couples to Node Bs 110 and provides
coordination and control for these Node Bs. System controller 130
may be a single network entity or a collection of network
entities.
[0023] UEs 120 may be dispersed throughout the system, and each UE
may be stationary or mobile. A UE may also be referred to as a
mobile station, a terminal, an access terminal, a subscriber unit,
a station, etc. A UE may be a cellular phone, a personal digital
assistant (PDA), a wireless device, a handheld device, a wireless
modem, a laptop computer, etc.
[0024] FIG. 2 shows a block diagram of a design of one Node B 110
and one UE 120. In this design, Node B 110 is equipped with
multiple (T) antennas 220a through 220t, and UE 120 is equipped
with multiple (R) antennas 252a through 252r. A MIMO transmission
may be sent from the T transmit antennas at Node B 110 to the R
receive antennas at UE 120.
[0025] At Node B 110, a transmit (TX) data and signaling processor
212 may receive data from a data source (not shown) for all
scheduled UEs. Processor 212 may process (e.g., format, encode,
interleave, and symbol map) the data for each UE and provide data
symbols, which are modulation symbols for data. Processor 212 may
also process signaling (e.g., power information) and provides
signaling symbols, which are modulation symbols for signaling. A
spatial mapper 214 may precode the data symbols for each UE based
on a precoding matrix or vector for that UE and provide output
symbols for all UEs. A CDMA modulator (MOD) 216 may perform CDMA
processing on the output symbols and signaling symbols and may
provide T output chip streams to T transmitters (TMTR) 218a through
218t. Each transmitter 218 may process (e.g., convert to analog,
filter, amplify, and frequency upconvert) its output chip stream
and provide a downlink signal. T downlink signals from T
transmitters 218a through 218t may be sent via T antennas 220a
through 220t, respectively.
[0026] At UE 120, R antennas 252a through 252r may receive the
downlink signals from Node B 110 and provide R received signals to
R receivers (RCVR) 254a through 254r, respectively. Each receiver
254 may process (e.g., filter, amplify, frequency downconvert, and
digitize) its received signal and provide samples to a channel
processor 268 and an equalizer/CDMA demodulator (DEMOD) 260.
Processor 268 may derive coefficients for a front-end
filter/equalizer and coefficients for one or more combiner matrices
for equalizer/CDMA demodulator 260. Unit 260 may perform
equalization with the front-end filter and CDMA demodulation and
may provide filtered symbols. A MIMO detector 262 may combine the
filtered symbols across spatial dimension and provide detected
symbols, which are estimates of the data symbols and signaling
symbols sent to UE 120. A receive (RX) data and signaling processor
264 may process (e.g., symbol demap, deinterleave, and decode) the
detected symbols and provide decoded data and signaling. In
general, the processing by equalizer/CDMA demodulator 260, MIMO
detector 262, and RX data and signaling processor 264 is
complementary to the processing by CDMA modulator 216, spatial
mapper 214, and TX data and signaling processor 212, respectively,
at Node B 110.
[0027] Channel processor 268 may estimate the response of the
wireless channel from Node B 110 to UE 120. Processor 268 and/or
270 may process the channel estimate and/or the derived
coefficients to obtain feedback information, which may include
precoding control indicator (PCI) information and CQI information.
The PCI information may convey the number of transport blocks to
send in parallel and a specific precoding matrix or vector to use
for precoding the transport block(s). A transport block may also be
referred to as a packet, a data block, etc. The CQI information may
convey processing parameters (e.g., the transport block size and
modulation scheme) for each transport block. Processor 268 and/or
270 may evaluate different possible precoding matrices and vectors
that can be used for data transmission and may select a precoding
matrix or vector that can provide the best performance, e.g., the
highest overall throughput. Processor 268 and/or 270 may also
determine the CQI information for the selected precoding matrix or
vector.
[0028] The feedback information and data to send on the uplink may
be processed by a TX data and signaling processor 280, further
processed by a CDMA modulator 282, and conditioned by transmitters
254a through 254r to generate R uplink signals, which may be
transmitted via antennas 252a through 252r, respectively. The
number of transmit antennas at UE 120 may or may not be equal to
the number of receive antennas. For example, UE 120 may receive
data using two antennas but may transmit the feedback information
using only one antenna. At Node B 110, the uplink signals from UE
120 may be received by antennas 220a through 220t, conditioned by
receivers 218a through 218t, processed by an equalizer/CDMA
demodulator 240, detected by a MIMO detector 242, and processed by
an RX data and signaling processor 244 to recover the feedback
information and data sent by UE 120. The number of receive antennas
at Node B 110 may or may not match the number of transmit
antennas.
[0029] Controllers/processors 230 and 270 may direct the operation
at Node B 110 and UE 120, respectively. Memories 232 and 272 may
store program code and data for Node B 110 and UE 120,
respectively. A scheduler 234 may schedule UEs for downlink and/or
uplink transmission, e.g., based on the feedback information
received from the UEs.
[0030] In UMTS, data for a UE may be processed as one or more
transport channels at a higher layer. The transport channels may
carry data for one or more services such as voice, video, packet
data, etc. The transport channels may be mapped to physical
channels at a physical layer. The physical channels may be
channelized with different channelization codes and may thus be
orthogonal to one another in the code domain. UMTS uses orthogonal
variable spreading factor (OVSF) codes as the channelization codes
for the physical channels.
[0031] 3GPP Release 5 and later supports High-Speed Downlink Packet
Access (HSDPA), which is a set of channels and procedures that
enable high-speed packet data transmission on the downlink. For
HSDPA, a Node B may send data on a High Speed Downlink Shared
Channel (HS-DSCH), which is a downlink transport channel that is
shared by all UEs in both time and code. The HS-DSCH may carry data
for one or more UEs in each TTI. For UMTS, a 10 millisecond (ms)
radio frame is partitioned into five 2-ms subframes, each subframe
includes three slots, and each slot has a duration of 0.667 ms. A
TTI is equal to one subframe for HSDPA and is the smallest unit of
time in which a UE may be scheduled and served. The sharing of the
HS-DSCH may change dynamically from TTI to TTI.
[0032] Table 2 lists some downlink and uplink physical channels
used for HSDPA and provides a short description for each physical
channel.
TABLE-US-00001 TABLE 1 Chan- Link nel Channel Name Description
Down- HS- High Speed Physical Carry data sent on the link PDSCH
Downlink Shared HS-DSCH for Channel different UEs. Down- HS- Shared
Control Carry signaling for the link SCCH Channel for HS-DSCH
HS-PDSCH. Uplink HS- Dedicated Physical Carry feedback for DPCCH
Control Channel for downlink transmission HS-DSCH in HSDPA.
[0033] FIG. 3 shows a timing diagram for the physical channels used
for HSDPA. For HSDPA, a Node B may serve one or more UEs in each
TTI. The Node B may send signaling for each scheduled UE on the
HS-SCCH and may send data on the HS-PDSCH two slots later. The Node
B may use a configurable number of 128-chip OVSF codes for the
HS-SCCH and may use up to fifteen 16-chip OVSF codes for the
HS-PDSCH. HSDPA may be considered as having a single HS-PDSCH with
up to fifteen 16-chip OVSF codes and a single HS-SCCH with a
configurable number of 128-chip OVSF codes. Equivalently, HSDPA may
be considered as having up to fifteen HS-PDSCHs and a configurable
number of HS-SCCHs, with each HS-PDSCH having a single 16-chip OVSF
code and each HS-SCCH having a single 128-chip OVSF code. The
following description uses the terminology of a single HS-PDSCH and
a single HS-SCCH.
[0034] Each UE that might receive data on the HS-PDSCH may process
up to four 128-chip OVSF codes for the HS-SCCH in each TTI to
determine whether signaling has been sent for that UE. Each UE that
is scheduled in a given TTI may process the HS-PDSCH to recover
data sent to that UE. Each scheduled UE may send either an
acknowledgement (ACK) on the HS-DPCCH if a transport block is
decoded correctly or a negative acknowledgement (NACK) otherwise.
Each UE may also send PCI and CQI information on the HS-DPCCH to
the Node B.
[0035] FIG. 3 also shows timing offsets between the HS-SCCH, the
HS-PDSCH, and the HS-DPCCH at a UE. The HS-PDSCH starts two slots
after the HS-SCCH. The HS-DPCCH starts approximately 7.5 slots from
the end of the corresponding transmission on the HS-PDSCH.
[0036] A UE may send CQI information to allow a Node B to
appropriately process and transmit data to the UE. In general, CQI
information may be sent for any number of transport blocks or data
streams. For clarity, much of the description below assumes that
one or two transport blocks may be sent in a given TTI and that the
CQI information may be for one or two transport blocks.
[0037] The Node B may transmit two transport blocks to the UE using
one of multiple possible precoding matrices or may transmit a
single transport block using one column/vector of one of the
possible precoding matrices. The UE may evaluate data performance
for different possible precoding matrices and vectors that can be
used by the Node B for data transmission to the UE. For each
precoding matrix or vector, the UE may estimate the quality of each
transport block, which may be given by any suitable metric. For
clarity, the following description assumes that the quality of each
transport block is given by an equivalent SINR for an additive
white Gaussian noise (AWGN) channel, which is referred to as simply
SINR in the description below. The UE may determine data
performance (e.g., the overall throughput) for each precoding
matrix or vector based on the SINR(s) of all transport block(s).
After evaluating all possible precoding matrices and vectors, the
UE may select the precoding matrix or vector that provides the best
data performance.
[0038] For each possible precoding matrix, the UE may estimate the
SINRs of two transport blocks that may be sent in parallel with
that precoding matrix. The transport block with the higher SINR may
be referred to as the primary transport block, and the transport
block with the lower SINR may be referred to as the secondary
transport block. The SINR of each transport block may be dependent
on various factors such as (i) the total power of the HS-PDSCH,
(ii) the number of OVSF codes used for the HS-PDSCH, (iii) channel
conditions, which may be given by channel gains and noise variance,
(iv) the type of receiver processing performed by the UE, (v) the
order in which the transport blocks are recovered if successive
interference cancellation (SIC) is performed by the UE, and (vi)
possibly other factors.
[0039] The SINR of transport block i, SINR.sub.i may be given
as:
SINR.sub.i=F(P.sub.OVSF,X.sub.i), Eq (1)
where
[0040] P.sub.OVSF is the power per OVSF code for the HS-PDSCH,
[0041] X.sub.i includes all other parameters that affect SINR,
and
[0042] F( ) is an SINR function applicable for the UE.
[0043] The SINR function may be dependent on the receiver
processing at the UE and may not be a linear function of
P.sub.OVSF. Thus, if P.sub.OVSF increases by G decibel (dB), then
the amount of improvement in SINR may not be accurately known based
solely on the G dB increase in P.sub.OVSF. This non-linear
relationship between P.sub.OVSF and SINR may be due to code-reuse
interference, which is interference between two transport blocks
using the same OVSF codes. Furthermore, the SINR function may not
be known at the Node B.
[0044] In an aspect, the Node B may send power information that may
be used by the UE to determine the power per OVSF code, P.sub.OVSF,
to use for SINR estimation. The power information may be given in
various forms and may be based on certain assumptions. In one
design, the power information comprises a power offset that is
indicative of the difference between the power of the HS-PDSCH,
P.sub.HSPDSCH, and the power of a reference channel. The reference
channel may be a Common Pilot Channel (CPICH) or some other channel
having known power. In one design, the power of the HS-PDSCH,
P.sub.HSPDSCH, may be determined as follows:
P.sub.HSPDSCH=P.sub.CPICH+.GAMMA., in dB, Eq (2)
where
[0045] P.sub.CPICH is the power of the CPICH, and
[0046] .GAMMA. is the power offset that may be signaled by the Node
B.
[0047] The Node B may signal the power offset .GAMMA. to the UE, as
described below. At the Node B, P.sub.HSPDSCH is the transmit power
of the HS-PDSCH, and P.sub.CPICH is the transmit power of the
CPICH. At the UE, P.sub.HSPDSCH is the received power of the
HS-PDSCH, and P.sub.CPICH is the received power of the CPICH. The
UE may be able to determine P.sub.HSPDSCH based on the signaled
power offset F, as shown in equation (2).
[0048] The Node B and UE may compute P.sub.OVSF in the same manner
based on the available information so that the power per OVSF code
used by the Node B for data transmission can meet or exceed the
P.sub.OVSF used by the UE for SINR estimation. P.sub.OVSF may be
computed in various manners. In one design, P.sub.HSPDSCH may be
distributed evenly to all transport blocks, and P.sub.OVSF may then
be the same for all transport blocks. In another design, a
particular percentage of P.sub.HSPDSCH may be distributed to the
primary transport block, the remaining percentage of P.sub.HSPDSCH
may be distributed to the secondary transport block, and P.sub.OVSF
may be different for the two transport blocks.
[0049] In one design, P.sub.OVSF may be computed based on a
designated number of OVSF codes, M. In one design, the Node B may
provide M via higher layer signaling and/or some other mechanism,
e.g., on a regular basis or whenever there is a change. In another
design, M may be equal to the maximum number of OVSF codes for the
HS-PDSCH (i.e., M=15) or equal to some other predetermined/known
value. In any case, P.sub.OVSF may be obtained by uniformly
distributing P.sub.HSPDSCH across the M OVSF codes, as follows:
P.sub.OVSF=P.sub.HSPDSCH-10log.sub.10(M), in dB. Eq (3)
In equation (3), subtraction in dB is equivalent to division in
linear unit.
[0050] Table 2 lists some parameters used in the description herein
and provides a short description for each parameter.
TABLE-US-00002 TABLE 2 Symbol Description P.sub.HSPDSCH Power
computed by the UE and Node B based on the power offset .GAMMA. and
P.sub.CPICH, which are known to both entities. {tilde over
(P)}.sub.HSPDSCH Power available at the Node for the HS-PDSCH.
P.sub.OVSF Power per OVSF code computed by the UE and Node B based
on the power offset .GAMMA. and P.sub.CPICH. {tilde over
(P)}.sub.OVSF Power per OVSF code available at the Node B for the
HS-PDSCH.
[0051] In general, P.sub.HSPDSCH may be equal to, less than, or
greater than {tilde over (P)}.sub.HSPDSCH. P.sub.HSPDSCH and
P.sub.OVSF may be referred to as signaled or computed values, and
{tilde over (P)}.sub.HSPDSCH and {tilde over (P)}.sub.OVSF may be
referred to as available values.
[0052] The Node B may have K OVSF codes available for the HS-PDSCH,
where K may or may not be equal to the designated number of OVSF
codes. The Node B may scale the power offset .GAMMA. based on the
number of available OVSF codes and the designated number of OVSF
codes.
[0053] FIG. 4 shows scaling of the power offset by the Node B. The
Node B may have K available OVSF codes for the HS-PDSCH, where
1.ltoreq.K.ltoreq.M for the example shown in FIG. 4. The Node B may
also have {tilde over (P)}.sub.HSPDSCH available for the HS-PDSCH.
The Node B may compute {tilde over (P)}.sub.OVSF by distributing
{tilde over (P)}.sub.HSPDSCH uniformly across K available OVSF
codes, as follows:
{tilde over (P)}.sub.OVSF={tilde over
(P)}.sub.HSPDSCH-10log.sub.10(K), in dB. Eq (4)
[0054] The Node B may set P.sub.OVSF equal to {tilde over
(P)}.sub.OVSF. The Node B may then compute P.sub.HSPDSCH such that
P.sub.OVSF is obtained for each of the M designated OVSF codes, as
follows:
P HSPDSCH = P ~ OVSF + 10 log 10 ( M ) = P ~ HSPDSCH + 10 log 10 (
M / K ) , Eq . ( 5 ) in dB . ##EQU00001##
[0055] The Node B may then compute the power offset based on the
computed P.sub.HSPDSCH and the known P.sub.CPICH, as follows:
.GAMMA.=P.sub.HSPDSCH-P.sub.CPICH, in dB. Eq (6)
[0056] If K is less than M, as shown in FIG. 4, then the computed
P.sub.HSPDSCH may be larger than the available {tilde over
(P)}.sub.HSPDSCH at the Node B. If K is greater than M (not shown
in FIG. 4), then the computed P.sub.HSPDSCH may be smaller than the
available {tilde over (P)}.sub.HSPDSCH. In any case, since {tilde
over (P)}.sub.HSPDSCH may or may not be equal to P.sub.HSPDSCH, the
power offset .GAMMA. may be considered as a virtual or hypothetical
power offset used for computation of P.sub.OVSF based on the
designated number of OVSF codes.
[0057] The Node B may send the power information used to determine
P.sub.OVSF in various manners. In one design, the Node B may send
the power information via higher layer signaling and/or some other
mechanism, e.g., on a regular basis or whenever there is a
change.
[0058] FIG. 5 shows a mechanism for sending the power offset
.GAMMA. using a Radio Resource Control (RRC) message in UMTS. The
Node B may send a PHYSICAL CHANNEL RECONFIGURATION message to the
UE in order to assign, replace or release a set of physical
channels used by the UE. This message may include a number of
information elements (IEs), one of which may be a Downlink HS-PDSCH
Information IE that may carry information for the HS-PDSCH. The
Downlink HS-PDSCH Information IE may include a Measurement Feedback
Info IE that may carry information affecting feedback information
sent by the UE on the uplink to the Node B. The Measurement
Feedback Info IE may include a Measurement Power Offset parameter,
which may be set to the power offset .GAMMA. computed as shown in
equation (6). The power offset .GAMMA. may also be sent in other
RRC messages to the UE. The RRC messages and IEs are described in
3GPP TS 25.331, entitled "Radio Resource Control (RRC)," dated
September 2007, which is publicly available.
[0059] The Node B may also send the power offset .GAMMA. in other
manners. The Node B may also send other types of information to
allow the UE to compute P.sub.OVSF. In general, the Node B may send
a relative value (e.g., the power offset) or an absolute value
(e.g., P.sub.HSPDSCH) for the computation of P.sub.OVSF. The Node B
may send the power information when a link for the UE is set up, is
changed, etc.
[0060] The UE may receive the power information (e.g., the power
offset) from the Node B and may compute P.sub.OVSF based on the
power information and other known information. The UE may then use
P.sub.OVSF to determine CQI information.
[0061] FIG. 6 shows a process 600 for determining CQI information
for multiple (e.g., two) transport blocks. The UE may compute the
received power of the HS-PDSCH, P.sub.HSPDSCH, based on the power
offset .GAMMA. received from the Node B and the received power of
the CPICH, P.sub.CPICH, e.g., as shown in equation (2) (block 610).
The UE may next compute P.sub.OVSF based on P.sub.HSPDSCH and the
designated number of OVSF codes, e.g., as shown in equation (3)
(block 612). The UE may estimate the SINR of each transport block
based on P.sub.OVSF and other parameters and in accordance with an
SINR function (block 614).
[0062] The UE may map the SINR of each transport block to a CQI
index based on a CQI mapping table (block 616). The CQI mapping
table may have L entries for L possible CQI levels, where L may be
any suitable value. Each CQI level may be associated with a set of
parameters for a transport block as well as a required SINR. The
set of parameters may include a transport block size, a modulation
scheme, a code rate, etc. The L CQI levels may be associated with
increasing required SINRs. For each transport block, the UE may
select the highest CQI level with a required SINR that is lower
than the estimated SINR of that transport block. The CQI index for
each transport block may indicate one of L possible CQI levels. The
UE may send the CQI indices to the Node B (block 618). The Node B
may transmit transport blocks to the UE based on the CQI indices
received from the UE.
[0063] In one design, symmetric OVSF code allocation is employed,
and the same number and same set of OVSF codes is used for two
transport blocks. In this design, the CQI mapping table may be
defined such that the same number of OVSF codes is used for all CQI
levels. In another design, asymmetric OVSF code allocation is
allowed, and the number of OVSF codes for the secondary transport
block may be different (e.g., fewer) than the number of OVSF codes
for the primary transport block. In this design, the CQI mapping
table may have different numbers of OVSF codes for different CQI
levels, e.g., fewer OVSF codes for one or more of the lowest CQI
levels. The secondary transport block may be sent with a subset of
the OVSF codes used for the primary transport block.
[0064] If a precoding matrix is selected, then the UE may
separately determine two CQI indices for two transport blocks to be
sent in parallel with the selected precoding matrix. If a precoding
vector is selected, then the UE may determine one CQI index for one
transport block to be sent with the selected precoding vector. The
UE may send a single CQI value that can convey either one CQI index
for one transport block or two CQI indices for two transport
blocks. With a granularity of 15 CQI levels for each CQI index in
the case of two transport blocks, a total of 15.times.15=225 CQI
index combinations are possible for two transport blocks. If 8 bits
are used for the single CQI value, then up to 256-225=31 levels may
be used for the CQI index for one transport block.
[0065] In one design, the single CQI value may be determined as
follows:
CQI = { 15 .times. CQI 1 + CQI 2 + 31 when 2 transport blocks are
preferred by the UE CQI S when 1 transport block is preferred by
the UE Eq . ( 7 ) ##EQU00002##
where
[0066] CQIs is a CQI index within {0 . . . 30} for one transport
block,
[0067] CQI.sub.1 is a CQI index within {0 . . . 14} for the primary
transport block,
[0068] CQI.sub.2 is a CQI index within {0 . . . 14} for the
secondary transport block, and
[0069] CQI is an 8-bit CQI value for one or two transport
blocks.
[0070] In the design shown in equation (7), a CQI value within a
range of 0 through 30 is used to convey a CQI index for one
transport block, and a CQI value within a range of 31 through 255
is used to convey two CQI indices for two transport blocks. The UE
may also map the CQI index or indices for one or two transport
blocks to a single CQI value in other manners.
[0071] In one design, the UE may send a PCI/CQI report that may
include two bits for PCI information and 8 bits for CQI
information. The PCI information may convey a precoding matrix or
vector selected by the UE. The CQI information may comprise one
8-bit CQI value computed as shown in equation (7). The ten bits for
the PCI/CQI report may be channel encoded with a (20, 10) block
code to obtain a codeword of 20 code bits. The 20 code bits for the
PCI/CQI report may be spread and sent on the HS-DPCCH in the second
and third slots of the TTI, which are labeled as "CQI" in FIG.
3.
[0072] The Node B may receive the PCI/CQI report from the UE and
determine whether the UE prefers one or two transport blocks and
the CQI index for each preferred transport block based on the
reported CQI value. The Node B may transmit the number of transport
blocks preferred by the UE or fewer transport blocks. For example,
if the UE prefers two transport blocks, then the Node B may
transmit zero, one, or two transport blocks to the UE.
[0073] The UE may determine the CQI index for each transport block
based on P.sub.OVSF, which may be obtained based on the designated
number of OVSF codes, M. The Node B may have K OVSF codes available
for the HS-PDSCH, where K may or may not be equal to M. The Node B
may transmit data to the UE in various manners depending on K, M,
P.sub.OVSF and the available {tilde over (P)}.sub.HSPDSCH at the
Node B.
[0074] If K=M, then the Node B may transmit each transport block
with the K available OVSF codes at P.sub.OVSF or higher to the
UE.
[0075] If K<M, then in one design the Node B may scale down the
transport block size by a factor of K/M and may transmit a
transport block of a smaller size with the K available OVSF codes
at P.sub.OVSF or higher to the UE. For example, if K=10, M=15, and
a transport block size of S is selected by the UE, then the Node B
may transmit a transport block of size 10S/15 with 10 OVSF codes at
P.sub.OVSF to the UE. This design may ensure that the SINR of the
transmitted transport block closely matches the SINR estimated by
the UE since the same P.sub.OVSF is used for both SINR estimation
by the UE and data transmission by the Node B. In another design,
the Node B may scale up P.sub.OVSF by a factor of up to M/K and may
then transmit a transport block of size S or larger at the higher
P.sub.OVSF to the UE. The Node B may predict the improvement in
SINR with the higher P.sub.OVSF and may select the transport block
size accordingly.
[0076] If K>M, then in one design the Node B may scale up the
transport block size by a factor of K/M and may transmit a
transport block of a larger size of KS/M with the K available OVSF
codes at P.sub.OVSF or higher to the UE. In another design, the
Node B may scale down P.sub.OVSF by a factor of up to M/K and may
then transmit a transport block of size S or smaller at the lower
P.sub.OVSF to the UE.
[0077] In general, the Node B may select the number of OVSF codes
to use for the HS-PDSCH based on K, M, {tilde over (P)}.sub.HSPDSCH
and P.sub.HSPDSCH such that P.sub.OVSF or higher can be used for
each OVSF code. The Node B may transmit each transport block with
up to K available OVSF codes at P.sub.OVSF or higher. The Node B
may scale the transport block size based on the number of OVSF
codes used for the HS-PDSCH and the designated number of OVSF codes
used to determine CQI.
[0078] FIG. 7 shows a design of a process 700 performed by the Node
B (or a transmitter). Power information indicative of total power,
P.sub.HSPDSCH, for a designated number of channelization codes, M,
with equal power per channelization code, P.sub.OVSF, may be
determined (block 712). In one design, the power information may
comprise a power offset between the total power for the designated
number of channelization codes for a data channel and the power of
a pilot channel, P.sub.CPICH. The designated number of
channelization codes may be the maximum number of channelization
codes available for data transmission, which is 15 for the
HS-PDSCH. The designated number of channelization codes may also be
a fixed number of channelization codes that is known a priori by
the UE.
[0079] In one design of block 712, the power available for the data
channel, {tilde over (P)}.sub.HSPDSCH and the number of
channelization codes available for the data channel, K, may be
determined. The power per channelization code, {tilde over
(P)}.sub.OVSF for the number of available channelization codes may
be determined based on the available power, P.sub.HSPDSCH. The
total power of the data channel, P.sub.HSPDSCH, may then be
computed based on the designated number of channelization codes and
the power per channelization code, {tilde over (P)}.sub.OVSF e.g.,
as shown in equation (5). The power offset may then be determined
based on the total power of the data channel, P.sub.HSPDSCH, and
the power of the pilot channel, P.sub.CPICH, e.g., as shown in
equation (6). The total power P.sub.HSPDSCH determined based on the
power information may be greater than or less than the available
power {tilde over (P)}.sub.HSPDSCH. The power information may be
sent to the UE, e.g., in an RRC message or via some other means
(block 714).
[0080] At least one CQI index for at least one transport block may
be received from the UE, with the at least one CQI index being
determined by the UE based on the power per channelization code,
P.sub.OVSF (block 716). At least one transport block may be sent to
the UE based on the at least one received CQI index (block 718). In
one design, the transport block(s) may be sent with the designated
number of channelization codes and at the power per channelization
code, P.sub.OVSF, or higher to the UE. In another design, the
transport block(s) may be scaled based on the designated number of
channelization codes and the number of available channelization
codes. The transport block(s) may then be sent with the number of
available channelization codes and at the power per channelization
code, P.sub.OVSF, or higher to the UE. In yet another design, the
power per channelization code may be scaled based on the designated
number of channelization codes and the number of available
channelization codes. The transport block(s) may then be sent with
the number of available channelization codes and at the scaled
power per channelization code to the UE.
[0081] FIG. 8 shows a design of a process 800 performed by the UE
(or a receiver). Power information may be received from the Node B,
e.g., in an RRC message or via some other means (block 812). A
power per channelization code, P.sub.OVSF, for a designated number
of channelization codes may be determined based on the power
information (block 814). In one design of block 814, a power offset
may be obtained from the power information, and the received power
of a data channel, P.sub.HSPDSCH, may be determined based on the
power offset and the received power of a pilot channel,
P.sub.CPICH, e.g., as shown in equation (2). The power per
channelization code, P.sub.OVSF, may then be determined based on
the received power of the data channel, P.sub.HSPDSCH, and the
designated number of channelization codes, e.g., as shown in
equation (3).
[0082] At least one CQI index for at least one transport block may
be determined based on the power per channelization code (block
816). In one design of block 816, at least one SINR of at least one
transport block may be estimated based on the power per
channelization code. At least one CQI index for at least one
transport block may then be determined based on the at least one
SINR and may be sent to the Node B (block 818).
[0083] At least one transport block may be received from the Node
B, with the transport block(s) being transmitted at the power per
channelization code, P.sub.OVSF, or higher by the Node B (block
820). The transport block(s) may be received via a number of
available channelization codes and may have size scaled based on
the designated number of channelization codes and the number of
available channelization codes.
[0084] For clarity, the techniques have been described for data
transmission using OVSF codes. The techniques may also be used for
other types of resources. In general, a Node B may determine power
information indicative of total power for a designated number of
resource elements with equal power per resource element. The
designated number of resource elements may correspond to a
designated number of subcarriers, a designated number of
channelization codes, a designated number of time slots, a
designated number of data streams, a designated number of transport
blocks, a designated number of channels, a designated number of
antennas, etc. The Node B may send the power information to a UE
and may send data with one or more resource elements and at the
power per resource element or higher to the UE.
[0085] Those of skill in the art would understand that information
and signals may be represented using any of a variety of different
technologies and techniques. For example, data, instructions,
commands, information, signals, bits, symbols, and chips that may
be referenced throughout the above description may be represented
by voltages, currents, electromagnetic waves, magnetic fields or
particles, optical fields or particles, or any combination
thereof.
[0086] Those of skill would further appreciate that the various
illustrative logical blocks, modules, circuits, and algorithm steps
described in connection with the disclosure herein may be
implemented as electronic hardware, computer software, or
combinations of both. To clearly illustrate this interchangeability
of hardware and software, various illustrative components, blocks,
modules, circuits, and steps have been described above generally in
terms of their functionality. Whether such functionality is
implemented as hardware or software depends upon the particular
application and design constraints imposed on the overall system.
Skilled artisans may implement the described functionality in
varying ways for each particular application, but such
implementation decisions should not be interpreted as causing a
departure from the scope of the present disclosure.
[0087] The various illustrative logical blocks, modules, and
circuits described in connection with the disclosure herein may be
implemented or performed with a general-purpose processor, a
digital signal processor (DSP), an application specific integrated
circuit (ASIC), a field programmable gate array (FPGA) or other
programmable logic device, discrete gate or transistor logic,
discrete hardware components, or any combination thereof designed
to perform the functions described herein. A general-purpose
processor may be a microprocessor, but in the alternative, the
processor may be any conventional processor, controller,
microcontroller, or state machine. A processor may also be
implemented as a combination of computing devices, e.g., a
combination of a DSP and a microprocessor, a plurality of
microprocessors, one or more microprocessors in conjunction with a
DSP core, or any other such configuration.
[0088] The steps of a method or algorithm described in connection
with the disclosure herein may be embodied directly in hardware, in
a software module executed by a processor, or in a combination of
the two. A software module may reside in RAM memory, flash memory,
ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a
removable disk, a CD-ROM, or any other form of storage medium known
in the art. An exemplary storage medium is coupled to the processor
such that the processor can read information from, and write
information to, the storage medium. In the alternative, the storage
medium may be integral to the processor. The processor and the
storage medium may reside in an ASIC. The ASIC may reside in a user
terminal. In the alternative, the processor and the storage medium
may reside as discrete components in a user terminal.
[0089] In one or more exemplary designs, the functions described
may be implemented in hardware, software, firmware, or any
combination thereof. If implemented in software, the functions may
be stored on or transmitted over as one or more instructions or
code on a computer-readable medium. Computer-readable media
includes both computer storage media and communication media
including any medium that facilitates transfer of a computer
program from one place to another. A storage media may be any
available media that can be accessed by a general purpose or
special purpose computer. By way of example, and not limitation,
such computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM
or other optical disk storage, magnetic disk storage or other
magnetic storage devices, or any other medium that can be used to
carry or store desired program code means in the form of
instructions or data structures and that can be accessed by a
general-purpose or special-purpose computer, or a general-purpose
or special-purpose processor. Also, any connection is properly
termed a computer-readable medium. For example, if the software is
transmitted from a website, server, or other remote source using a
coaxial cable, fiber optic cable, twisted pair, digital subscriber
line (DSL), or wireless technologies such as infrared, radio, and
microwave, then the coaxial cable, fiber optic cable, twisted pair,
DSL, or wireless technologies such as infrared, radio, and
microwave are included in the definition of medium. Disk and disc,
as used herein, includes compact disc (CD), laser disc, optical
disc, digital versatile disc (DVD), floppy disk and blu-ray disc
where disks usually reproduce data magnetically, while discs
reproduce data optically with lasers. Combinations of the above
should also be included within the scope of computer-readable
media.
[0090] The previous description of the disclosure is provided to
enable any person skilled in the art to make or use the disclosure.
Various modifications to the disclosure will be readily apparent to
those skilled in the art, and the generic principles defined herein
may be applied to other variations without departing from the scope
of the disclosure. Thus, the disclosure is not intended to be
limited to the examples and designs described herein but is to be
accorded the widest scope consistent with the principles and novel
features disclosed herein.
* * * * *