U.S. patent application number 15/273879 was filed with the patent office on 2017-05-11 for system and method for allocating transmission resources.
The applicant listed for this patent is TELEFONAKTIEBOLAGET LM ERICSSON (PUBL). Invention is credited to David Hammarwall, George Jongren.
Application Number | 20170135086 15/273879 |
Document ID | / |
Family ID | 44303392 |
Filed Date | 2017-05-11 |
United States Patent
Application |
20170135086 |
Kind Code |
A1 |
Hammarwall; David ; et
al. |
May 11, 2017 |
SYSTEM AND METHOD FOR ALLOCATING TRANSMISSION RESOURCES
Abstract
Methods for wirelessly transmitting user data and control
information using a plurality of transmission layers include
encoding bits of control information to form control codewords and
encoding bits of user data to form user data codewords. The method
also includes generating a plurality of vector symbols based on the
control codewords and the user data codewords. Each vector symbol
includes a plurality of modulation symbols that are each associated
with a transmission layer over which the associated modulation
symbol will be transmitted. Generating the plurality of vector
symbols includes interleaving bits of the control codewords and
bits of the user data codewords so that the control information is
carried in modulation symbols associated with the same transmission
layers in the vector symbols transmitted during the subframe that
carry the control information. The method also includes
transmitting the plurality of vector symbols to a receiver over a
plurality of transmission layers.
Inventors: |
Hammarwall; David;
(VALLENTUNA, SE) ; Jongren; George; (SUNDBYBERG,
SE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
TELEFONAKTIEBOLAGET LM ERICSSON (PUBL) |
Stockholm |
|
SE |
|
|
Family ID: |
44303392 |
Appl. No.: |
15/273879 |
Filed: |
September 23, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14957759 |
Dec 3, 2015 |
9480056 |
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15273879 |
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14250528 |
Apr 11, 2014 |
9237565 |
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14957759 |
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13104373 |
May 10, 2011 |
8705574 |
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14250528 |
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61332867 |
May 10, 2010 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04L 25/03929 20130101;
H04B 7/0456 20130101; H04B 7/0669 20130101; H04L 1/1671 20130101;
H04L 5/0091 20130101; H04L 1/0079 20130101; H04L 5/00 20130101;
H04W 72/04 20130101; H04B 7/0413 20130101; H04L 1/0071 20130101;
H04B 7/04 20130101; H04L 1/1664 20130101; H04W 72/0413 20130101;
H04L 5/0053 20130101; H04W 72/0406 20130101; H04B 7/0486 20130101;
H04L 5/0057 20130101; H04L 1/003 20130101 |
International
Class: |
H04W 72/04 20060101
H04W072/04; H04L 5/00 20060101 H04L005/00; H04L 25/03 20060101
H04L025/03; H04B 7/0456 20060101 H04B007/0456 |
Claims
1. A method for wirelessly transmitting user data and control
information using a plurality of transmission layers, comprising:
encoding bits of a first type of control information to form one or
more control codewords of the first type of control information;
encoding bits of a second type of control information to form one
or more control codewords of the second type of control
information; encoding bits of user data to form one or more user
data codewords; generating a plurality of vector symbols based on
the control codewords of the first type of control information, the
control codewords of the second type of control information, and
the user data codewords, each vector symbol comprising a plurality
of modulation symbols that are each associated with a transmission
layer over which the associated modulation symbol will be
transmitted, wherein generating the plurality of vector symbols
comprises interleaving bits of the one or more control codewords of
the first type of control information, bits of the one or more
control codewords of the second type of control information, and
bits of the one or more user data codewords such that: the first
type of control information is carried in modulation symbols
associated with all transmission layers in vector symbols
transmitted during the subframe that carry the first type of
control information, and at least one of the generated vector
symbols that carries control information of the second type also
carries user data; and transmitting the plurality of vector symbols
to a receiver over a plurality of transmission layers.
2. The method of claim 1, wherein the second type of control
information comprises a channel quality indication (CQI) and a
precoder matrix indication (PMI).
3. The method of claim 1, wherein the second type of control
information comprises a channel quality indication (CQI)
information.
4. The method of claim 1, wherein the second type of control
information comprises a precoder matrix indication (PMI).
5. The method of claim 1, wherein generating the plurality of
vector symbols comprises mapping bits of at least one control
codeword to a vector symbol in a manner such that for each pair of
neighboring bits in the control codeword a first bit of the pair is
mapped to at least a first layer of a corresponding vector symbol
and a second bit of the pair is mapped to at least a second layer
of the corresponding vector symbol different from the first
layer.
6. The method of claim 1, wherein generating the plurality of
vector symbols comprises: segmenting at least one codeword into at
least two segments; and mapping bits of a first segment of the
control word to at least a first layer of a corresponding vector
symbol; and mapping bits of a second segment of the control word to
at least a second layer of the corresponding vector symbol
different from the first layer.
7. The method of claim 1, wherein generating the plurality of
vector symbols comprises generating at least one vector symbol by:
replicating one or more bits of control information for
transmission to a plurality of encoders; encoding the replicated
control information in parallel at the plurality of encoders; and
mapping the encoded control information onto every layer of the
vector symbol.
8. The method of claim 1, wherein the first type of control
codewords comprises codewords carrying Hybrid Automatic Repeat
ReQuest (HARQ) bits and rank indication (RI) bits.
9. The method of claim 1, wherein the first type of control
codewords comprises codewords carrying Hybrid Automatic Repeat
ReQuest (HARQ) bits.
10. The method of claim 1, wherein the first type of control
codewords comprises codewords carrying rank indication (RI)
bits.
11. The method of claim 1, wherein interleaving bits of the one or
more control codewords and bits of the one or more user data
codewords comprises: multiplexing a first control codeword and a
first user data codeword before interleaving the bits of the one or
more control codewords and the bits of the one or more user data
codewords; and interleaving bits of the multiplexed first control
codeword and first user data codeword with bits of a second control
codeword.
12. An apparatus for wirelessly transmitting user data and control
information using a plurality of transmission layers, comprising: a
plurality of antennas; a transceiver operable to transmit vector
symbols over a plurality of transmission layers using the plurality
of antennas; and a processor operable to: encode bits of a first
type of control information to form one or more control codewords
of the first type of control information; encode bits of a second
type of control information to form one or more codewords of the
second type of control information encode bits of user data to form
one or more user data codewords; generate a plurality of vector
symbols based on the control codewords of the first type of control
information, the control codewords of the second type of control
information, and the user data codewords, each vector symbol
comprising a plurality of modulation symbols that are each
associated with a transmission layer over which the associated
modulation symbol will be transmitted, wherein generating the
plurality of vector symbols comprises interleaving bits of the one
or more control codewords of the first type of control information,
bits of the one or more control codewords of the second type of
control information, and bits of the one or more user data
codewords such that: the first type of control information is
carried in modulation symbols associated with all transmission
layers in vector symbols transmitted during the subframe that carry
the first type of control information, and at least one of the
generated vector symbols that carries control information of the
second type also carries user data; and transmit the plurality of
vector symbols to a receiver over a plurality of transmission
layers using the transceiver.
13. The apparatus of claim 12, wherein the second type of control
information comprises a channel quality indication (CQI) and a
precoder matrix indication (PMI).
14. The apparatus of claim 12, wherein the first type of control
codewords comprises codewords carrying Hybrid Automatic Repeat
ReQuest (HARQ) bits and codewords carrying Rank Indication (RI)
bits.
15. The apparatus of claim 12, wherein the first type of control
codewords comprises codewords carrying Hybrid Automatic Repeat
ReQuest (HARQ) bits.
16. The apparatus of claim 12, wherein the first type of control
codewords comprises codewords carrying rank indication (RI)
bits.
17. The apparatus of claim 12, wherein the second type of control
information comprises a channel quality indication (CQI).
18. The apparatus of claim 12, wherein the second type of control
information comprises a precoder matrix indication (PMI).
19. The apparatus of claim 12, wherein the plurality of vector
symbols is transmitted to the receiver over a physical uplink
shared channel (PUSCH).
Description
PRIORITY CLAIM UNDER 35 U.S.C. .sctn.119(e)
[0001] This Application is a continuation of U.S. patent
application Ser. No. 14/957,759, filed Dec. 3, 2015, which is a
continuation of U.S. patent application Ser. No. 14/250,528 filed
Apr. 11, 2014, now U.S. Pat. No. 9,237,565, which is a continuation
of U.S. patent application Ser. No. 13/104,373, filed May 10, 2011,
now U.S. Pat. No. 8,705,574, which claims the benefit of U.S.
Provisional Patent Application No. 61/332,867, filed May 10, 2010.
The respective disclosures of these applications are hereby
incorporated by reference.
TECHNICAL FIELD OF THE INVENTION
[0002] This disclosure relates in general to wireless communication
and, more particularly, to resource allocation for multi-antenna
transmissions.
BACKGROUND OF THE INVENTION
[0003] Multi-antenna transmission techniques can significantly
increase the data rates and reliability of wireless communication
systems, especially in systems where the transmitter and the
receiver are both equipped with multiple antennas to permit the use
of multiple-input multiple-output (MIMO) transmission techniques.
Advanced communication standards such as Long Term Evolution (LTE)
Advanced utilize MIMO transmission techniques that may permit data
to be transmitted over multiple different spatially-multiplexed
channels simultaneously, thereby significantly increasing data
throughput.
[0004] While MIMO transmission techniques can significantly
increase throughput, such techniques can greatly increase the
complexity of managing radio channels. Additionally, many advanced
communication technologies, such as LTE, rely on a substantial
amount of control signaling to optimize the configuration of
transmitting devices and their use of the shared radio channel.
Because of the increased amount of control signaling in advanced
communication technologies, it is often necessary for user data and
control signaling to share transmission resources. For example, in
LTE systems, control signaling and user data are, in certain
situations, multiplexed by user equipment ("UE") for transmission
over a physical uplink shared channel ("PUSCH").
[0005] However, conventional solutions for allocating transmission
resources are designed for use with single layer transmission
schemes in which only a single codeword of user data is transmitted
at a time. As a result, such resource allocation solutions fail to
provide optimal allocation of transmission resources between
control information and user data when MIMO techniques are being
utilized to transmit data on multiple layers simultaneously.
SUMMARY OF THE INVENTION
[0006] In accordance with the present disclosure, certain
disadvantages and problems associated with wireless communication
have been substantially reduced or eliminated. In particular,
certain devices and techniques for allocating transmission
resources between control information and user data are
described.
[0007] In accordance with one embodiment of the present disclosure,
a method for wirelessly transmitting user data and at least a first
type of control information using a plurality of transmission
layers including encoding bits of a first type of control
information to form one or more control codewords and encoding bits
of user data to form one or more user data codewords. The method
also includes generating a plurality of vector symbols based on the
control codewords and the user data codewords. Each vector symbol
includes a plurality of modulation symbols that are each associated
with a transmission layer over which the associated modulation
symbol will be transmitted. Generating the plurality of vector
symbols includes interleaving bits of the one or more control
codewords and bits of the one or more user data codewords so that
the first type of control information is carried in modulation
symbols associated with the same transmission layers in all the
vector symbols transmitted during the subframe that carry the first
type of control information. The method also includes transmitting
the plurality of vector symbols to a receiver over a plurality of
transmission layers.
[0008] Additional embodiments include apparatuses capable of
implementing the above method and/or variations thereof.
[0009] Important technical advantages of certain embodiments of the
present invention include increasing the benefits gained from
transmission diversity and simplifying processing of multi-antenna
transmissions. Particular embodiments enable control information
and user data to be divided into separate vector symbols so that
control and data are time multiplexed, as opposed to being
transmitted in parallel. In particular embodiments, this separation
may be attained without incurring significant additional control
overhead and may enable reuse of conventional uplink processing
modules. Other advantages of the present invention will be readily
apparent to one skilled in the art from the following figures,
descriptions, and claims. Moreover, while specific advantages have
been enumerated above, various embodiments may include all, some,
or none of the enumerated advantages.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] For a more complete understanding of the present invention
and its advantages, reference is now made to the following
description, taken in conjunction with the accompanying drawings,
in which:
[0011] FIG. 1 is a functional block diagram illustrating a
particular embodiment of a multi-antenna transmitter;
[0012] FIG. 2 is a functional block diagram illustrating a
particular embodiment of a carrier modulator that may be used in
the transmitter of FIG. 1;
[0013] FIG. 3 is a transmission resource grid for an example
subframe in a wireless communication system;
[0014] FIGS. 4A-4C provide further details on specific portions a
particular embodiment of the transmitter;
[0015] FIGS. 5A-5C also provide further details on specific
portions a particular embodiment of the transmitter;
[0016] FIG. 6 is a functional block diagram illustrating an
alternative embodiment of the transmitter;
[0017] FIG. 7 is a functional block diagram providing further
details on a channel encoder utilized by the embodiment shown in
FIG. 6;
[0018] FIGS. 8A and 8B illustrate operation of various embodiments
of the transmitter in transmitting example control information and
user data;
[0019] FIG. 8A-1 illustrates a matrix showing a mapping of control
information and user data on a first layer of the resulting vector
symbols.
[0020] FIG. 8A-2 illustrates a matrix showing the mapping of
control information and user data on a second layer of the
resulting vector symbols.
[0021] FIG. 8A-3 illustrates the channel interleaver output for the
first channel.
[0022] FIG. 8B-1 illustrates a matrix showing the mapping of
control information and user data on a first layer of the resulting
vector symbols.
[0023] FIG. 8B-2 illustrates a matrix showing the mapping of
control information and user data on a second layer of the
resulting vector symbols.
[0024] FIG. 8B-3 illustrates the extended channel interleaver
output.
[0025] FIG. 9 is a structural block diagram showing the contents of
an example embodiment of the transmitter; and
[0026] FIG. 10 is a flowchart illustrating example operation of a
particular embodiment of the transmitter.
DETAILED DESCRIPTION OF THE INVENTION
[0027] FIG. 1 is a functional block diagram illustrating a
particular embodiment of a multi-antenna transmitter 100. In
particular, FIG. 1 shows a transmitter 100 configured to multiplex
certain control signaling with user data for transmission over a
single radio channel. By intelligently implementing the coding,
interleaving, layer mapping, and other aspects of the transmission,
transmitter 100 may be able to improve upon the resulting
allocation of user data and control signaling to transmission
resources, as described further below.
[0028] Control signaling can have a critical impact on the
performance of wireless communication systems. As used herein,
"control signaling" and "control information" refers to any
information communicated between components for purposes of
establishing communication, any parameters to be used by one or
both of the components in communicating with one another (e.g.,
parameters relating to modulation, encoding schemes, antenna
configurations), any information indicating receipt or non-receipt
of transmissions, and/or any other form of control information. In
LTE systems, control signaling in the uplink direction includes,
for example, Hybrid Automatic Repeat reQuest (HARQ)
Acknowledgments/Negative Acknowledgements (ACK/NAKs), precoder
matrix indicators (PMIs), rank indicators (RIs), and channel
quality indicators (CQIs), which are all used by the eNodeB to get
confirmation of successful reception of transport blocks or to
improve the performance of downlink transmissions.
[0029] Although control signaling is often transmitted on separate
control channels, such as the physical uplink control channel
(PUCCH) in LTE, under certain circumstances it may be beneficial or
necessary to transmit control signaling on the same channel as
other data. For example, in LTE systems, when a periodic PUCCH
allocation coincides with a scheduling grant for a user equipment
(UE) to transmit user data, the user data and control signaling
share transmission resources to preserve the single-carrier
property of the discrete Fourier transform, spread orthogonal
frequency-division multiplexing (DFTS-OFDM) transmission techniques
used by LTE UEs. Furthermore, when a UE receives a scheduling grant
to transmit data on the physical uplink shared channel (PUSCH), it
typically receives information from the eNodeB related to the
characteristics of the uplink radio propagation channel and other
parameters that can be used to improve the efficiency of PUSCH
transmissions. Such information may include modulation and coding
scheme (MCS) indicators as well as, for UEs capable of using
multiple transmission antennas, PMIs or RIs. As a result, UEs may
be able to use this information to optimize PUSCH transmissions for
the radio channel, thereby increasing the amount of data that can
be transmitted for a given set of transmission resources. Thus, by
multiplexing control signaling with the user data transmitted on
PUSCH, a UE can support significantly larger control payloads than
when transmitting control signaling by itself on PUCCH.
[0030] In such circumstances, it may be possible for transmitter
100 to multiplex control signaling and user data in the same manner
as is proposed by Release 8 of the LTE standard. Under such a
scheme, some or all control signals are distributed onto multiple
codewords (e.g., by repetition or by a serial-to-parallel
conversion) and each codeword is then processed individually. After
symbol modulation, the two sequences of modulated symbols are
mapped onto their assigned layers to form a sequence of vector
symbols. As used herein, a "vector symbol" may represent any
collection of information that includes an information element
associated with each transmission layer over which the information
is to be transmitted. The vector symbols are then modulated onto
appropriate carriers and transmitted.
[0031] However, using this technique to allocate transmission
resources (e.g., vector symbols) to particular elements of user
data or control information, can make it difficult to separate
control information from user data so that the two types of
information are mapped onto separate vector symbols. Separation of
this sort may be desirable for certain types of control
information. The difficulty in doing this is primarily due to the
interleavers used by most conventional devices to map modulation
symbols into a subframe resource grid, such as the example grid
shown in FIG. 3. In Release 8 LTE user equipment (UE), the
interleaver maps modulation symbols of concatenated CQI/PMI and
data codewords into the subframe resource grid in a row first, and
column next order. However, the carrier modulator for such UEs
reads DFTS-OFDM symbols out of the interleaver in a column first
fashion, making it difficult to determine what the resulting
allocation of control and user data will be.
[0032] Furthermore, if a particular user data codeword is mapped
to, e.g., two layers, then the part of the control codeword to be
multiplexed with the data codeword must cover a multiple of two
entire rows in the resource grid. Otherwise, there will be columns
in the grids that have an odd number of modulation symbols carrying
control information, in which case user data and control will be
mixed in a single vector symbol. This can cause significantly more
overhead to be used for transmissions of control information since
LTE Release 8 permits a control codeword to use any fraction of a
row in the transmission resource grid to reduce overhead.
Reconfiguring the Release 8 scheme to remove the above constraint
on control resource allocation would involve significant redesign
of either the channel interleaver or the multiplexing unit
specified by Release 8. Additionally, it would create significant
inter-dependencies between the layer mapping and the components
responsible for processing the user data and control information.
Such interdependencies can result in complex implementations and
may significantly complicate backwards compatibility.
[0033] As a result, certain embodiments of transmitter 100 may be
configured to allocate a given type of control information to the
same, specific elements of the vector symbols that carry that type
of control information. For example, a particular type of control
information may be allocated to the elements associated with the
first layer and second layer in all the vector symbols that carry
that type of control information. Thus, in such embodiments, a
given type of control information may be mapped to the same layers
in all vector symbols that are used to transmit the relevant
control information. Furthermore, particular embodiments of
transmitter 100 isolate all or some (e.g., certain types) of the
control signaling transmitted during a particular subframe on
separate vector symbols, with the relevant control information
being transmitted on vector symbols that do not carry any user
data. As a result, the relevant control signaling will be time
multiplexed with the user data transmitted during the same
subframe, instead of being transmitted in parallel with that user
data.
[0034] Maintaining a consistent mapping of control information to
the various layers across all the vector symbols carrying the
control information may provide numerous advantages depending on
the configuration of transmitter 100. In particular embodiments,
maintaining a consistent mapping may increase the diversity
benefits provided by the multiple transmission layers, as a given
portion of the transmitted control information is more likely to be
transmitted on multiple layers simultaneously than with
conventional techniques for allocating transmission resources.
Moreover, for particular embodiments of transmitter 100, the
modulation and encoding schemes for the various layers are designed
to ensure that the mapping pattern for the relevant types of
control information is the same on all layers used to transmit that
control information. This guarantees that a given portion of the
control information will be transmitted simultaneously on all
layers over which it is to be transmitted. Additionally, by
isolating at least a portion of the control information on separate
vector symbols, transmitter 100 may simplify processing on the
receiving end, as the receiver may be able to perform identical
processing on the control information received on every layer. As a
result, certain embodiments of transmitter 100 may provide numerous
operational benefits. Specific embodiments, however, may provide
some, none, or all of these benefits.
[0035] As described further below, the various embodiments of
transmitter 100 may implement the described allocation techniques
using any of numerous different structural and/or functional
configurations. FIG. 1 illustrates a particular embodiment of
transmitter 100 configured to perform the described allocation
techniques on a "per-layer" basis. In particular embodiments, as
shown in FIG. 1, particular embodiments of transmitter 100 may
include one or more layer mappers 104 and one or more bit
distributors 106 capable of splitting (by replication and/or by
segmentation) the user data and control information to be
transmitted onto separate datapaths 102, with each datapath 102
being associated with a particular one of the transmission layers
to be used for the transmission. By performing the
codeword-to-layer mapping in the bit-level domain prior to control
and data multiplexing, certain embodiments of transmitter 100
configured for per-layer processing may offer the additional
benefit of permitting reuse of single stream components responsible
for the modulation, scrambling, interleaving, encoding, or other
processing in single-antenna transmitters.
[0036] Additionally, in particular embodiments, such as the one
illustrated in FIG. 1, transmitter 100 may isolate certain types of
control information onto separate vector symbols but permit other
types of control information to be transmitted on vector symbols
that are also carrying user data on other layers. Different types
of control information may have different robustness requirements,
may utilize different encoding schemes, or may be treated
differently during transmission for various other reasons.
Consequently, it may be more beneficial to isolate certain types of
control information on separate vector symbols than it is to
isolate other types of control information. For example, in LTE,
Hybrid Automatic Repeat reQuest (HARQ) Acknowledgments/Negative
Acknowledgements (ACK/NAKs) and rank indications (RIs) are
typically only a few bits in length, and their successful
transmission may be critical to system operation. As a result, HARQ
ACK/NAKs and RIs may have different encoding requirements and may
require special timing within a subframe (e.g., being transmitted
near a reference signal in resource grid 400). By contrast, control
information such as precoder matrix indications (PMIs) and channel
quality indications (CQIs) may be of lesser importance and
transmitter 100 may spread these types of control information
throughout the subframe.
[0037] Thus, in the example embodiment illustrated by FIG. 1,
transmitter 100 implements different processing for different types
of control information. For example, in the illustrated example, a
first type or types of control information (represented here by
ACK/NAK bits 134 and RI bits 136) are input into separate bit
distributors to be distributed to the various layers and encoded
before being combined with any user data codewords 130 by
interleaver 112. Particular embodiments transmitter 100 are
configured to ensure that this first type of control information is
ultimately allocated to vector symbols 140 that are not also
carrying user data. By contrast, a second type or type(s) of
control information (represented here by a CQI codeword 132
containing encoded CQI and/or PMI information) is concatenated, in
the embodiment of FIG. 1, with one or more user data codewords 130
by a multiplexer 108 before being interleaved with the other types
of control information (here, ACK/NAK bits 134 and RI bits 136).
The second type(s) of control information may end up being
transmitted in vector symbols 140 that also carry user data.
[0038] The embodiment of transmitter 100 illustrated by FIG. 1
includes one or more layer mappers 104 and one or more bit
distributors 106 that associate their inputs with one or more of
the various layers for processing. More specifically, layer mappers
104 receive user data codewords 130 (in this example, a user data
codeword 130a and a user data codeword 130b) and CQI codewords 132
and map bits of these codewords to one of the transmission layers
to be used by transmitter 100 for the relevant transmission. Bit
distributor 106a receives unencoded ACK/NAK bits 134 and replicates
the ACK/NAK bits 134 on each of the layers on which control
information will be transmitted. In the illustrated example this
involves replicating ACK/NAK on all of the layers that will be used
for the transmission. Bit distributor 106b receives unencoded RI
bits 136 and replicates the RI bits 136 on each of the layers on
which control information will be transmitted. As with the ACK/NAK
bits 134, this may involve replicating RI bits 136 on all of the
layers that will be used to transmit control information.
[0039] Because the illustrated embodiment of transmitter 100 in
FIG. 1 implements a per-layer processing scheme, each transmission
layer available to transmitter 100 is associated with a separate
datapath 102 comprising various elements responsible for processing
the user data and control information that will be transmitted over
the associated transmission layer. As a result, bit distributors
106a and 106b replicate their input bits for every datapath 102
over which the first type(s) of control information will be
transmitted. A channel encoder 110a and a channel encoder 110b in
each datapath 102 then encode the control information output by bit
distributors 106a and b, respectively. The encoding performed by
the various channel encoders 110 in transmitter 100 may be the same
for all of the channel encoders 110 or may differ based on, for
example, the transmission layer involved or the type of control
information being encoded. Channel encoders 110a and 110b in each
datapath 102 then output a control codeword to an interleaver 112
associated with the same layer as the relevant channel encoders
110.
[0040] Meanwhile, layer mapper 104a outputs one or more bits of
user data codeword 130a or user data codeword 130b to each of the
datapaths 102 associated with a layer over which the relevant user
data codeword 130 will be transmitted. Similarly, layer mapper 104b
outputs one or more bits of a control codeword of a second type of
control information (here, CQIs and/or PMIs) to each of the
datapaths 102 associated with a layer over which this second type
of control information will be transmitted. In particular
embodiments, transmitter 100 may map the second type of control
information to the various layers in a manner designed to
facilitate the efficient allocation of user data and control
information to transmission resources. As one example, in
particular embodiments, transmitter 100 encodes the second type of
control information prior to its layers. This encoding may be
performed with a rate matching such that the length of the
resulting control codeword is an even multiple of
Q ' of l = 1 r Q m , l , ##EQU00001##
where Q.sub.m,l is the number of bits of each modulation symbol on
layer l, and r is the total number of layers that will be used to
transmit the user data codeword 130 with which this control
codeword will be multiplexed. Thus, the number of bits in the
resulting control codeword will be equal to
Q ' l = 1 r Q m , l ##EQU00002##
[0041] As another example, transmitter 100 may map a number of bits
equal to Q'Q.sub.m,l to each of the l layers over which this
control codeword (and its multiplexed user data codeword 130) will
be transmitted. Additionally, transmitter 100 may, as part of this
mapping layers, segment the control codeword into r parts, where r
is the number of layers used to transmit this control codeword and
where the part assigned to layer l has the length Q'Q.sub.m,l
bits.
[0042] As another example of the mapping that transmitter 100 may
use for the second type of control information, transmitter 100 may
perform a serial-to-parallel operation of the coded symbols in the
control codeword such that,
CW l ( k ) = CW ( k Q m , l l ~ = 1 r l ~ .noteq. l Q m . l ~ + l ~
= 1 l - 1 Q m , l ~ + k ) , ##EQU00003##
where CW.sub.l(k) denotes the k-th bit (counting from 0) of this
control codeword mapped to layer l (counting from 1) and CW(m)
denotes the m-th bit (counting from 0) of the control codeword
prior to bit-level layer mapping. A benefit of this option is that
it guarantees that the same number of modulated symbols is required
for the second type of control information on all layers, which may
permit a design where control information and user data are fully
mapped to separate vectors symbols.
[0043] Similarly, transmitter 100 may also perform the
codeword-to-layer mapping of the user data codewords 130a-b in a
manner designed to improve the subsequent allocation of user data
and control information to transmission resources. As one example,
transmitter 100 may perform the codeword-to-layer mapping of user
data codewords 130a-b using a serial-to-parallel (S/P) operation
such that in each pair of neighboring bits, the first bit is
assigned to one layer and the rest is assigned to the other layer.
This option has the benefit that it is simple to implement and that
it does not introduce any additional delays. As another example,
the bit-level codeword-to-layer mapping of the data may include a
codeblock segmentation operation such that the first half of the
codeword is assigned to one layer and the second half to the other
layer. This option has the benefit that it enables advanced per
layer successive per-layer interference cancellation at the
receiver, since it is likely that there will be entire block
segments (including a cyclic redundancy check (CRC)) assigned fully
to a single layer.
[0044] Once user data codewords 130 and CQI codewords 132 have been
mapped to various layers to be used by transmitter 100 for the
transmission, a multiplexer 108 in each datapath 102 then
multiplexes the bits of user data codewords 130a-b and the bits of
the CQI codeword 132 output to the relevant datapath 102, resulting
in the CQI codeword 132 being concatenated with the user data
codewords 130 on one or more layers. The output of each multiplexer
108 is then received by an interleaver 112 in the same datapath
102.
[0045] Each interleaver 112 then allocates encoded bits of user
data and control information to transmission resources on the layer
associated with that interleaver 112. Each interleaver 112 may map
user data and control information to a resource grid such as the
example resource grid illustrated by FIG. 3. Interleavers 112
associated with the various datapaths 102 in transmitter 100 may
perform this interleaving in any suitable manner. In the embodiment
shown by FIG. 1, transmitter 100 uses a per-layer processing scheme
to transmit user data and control information. As a result, the
illustrated embodiment may use conventional interleaving techniques
on each layer, including interleaving techniques that might also be
used in single antenna transmissions.
[0046] For example, particular embodiments of transmitter 100 may
implement the channel interleaving specified by LTE Release 8 for
each layer. LTE Release 8 interleaving utilizes a matrix of coded
symbols (groups of Q.sub.m bits, where Q.sub.m is the number of
bits forming a modulation symbol). Each column in this matrix
corresponds to a DFTS-OFDM symbol. Under LTE Release 8
interleaving, the coded symbols (groups of Q.sub.m bits) of the RI
codeword are inserted in the assigned positions (as indicated in
the example resource grid of FIG. 3). Next, the concatenated
CQI/user data codewords (resulting from the multiplexing of CQI
codewords 132 and user data codewords 130) are inserted around the
RI codeword in a row-first order. Then, coded symbols of HARQ
codeword (groups of Q.sub.m bits) on a particular layer are
inserted in the assigned positions shown in FIG. 3, puncturing the
user data and potentially the CQI information.
[0047] Additionally, as explained above, the interleavers 112 for
the various layers used by transmitter 100 may allocate user data
and control information in such a manner that some or all of the
control information may be allocated to separate vector symbols 140
that do not carry any user data. Because the illustrated embodiment
in FIG. 1 uses a per-layer technique for processing user data and
control information to be transmitted, the various interleavers 112
in the transmitter of FIG. 1 may achieve this separation in part by
performing similar or identical interleaving on each of the layers
used for a transmission. Furthermore, particular embodiments of
transmitter 100 may also utilize the same modulation scheme on all
layers for a given type of data, resulting in an identical mapping
of control information and user data to transmission resources on
every layer.
[0048] Once interleaving has been performed, the output of the
channel interleaver on each layer is read out of the interleaving
matrix a column at a time. These interleaved outputs are then
scrambled by scramblers 114 in each datapath 102 and subsequently
modulated by symbol modulators 116. In particular embodiments, the
scrambling sequences performed by the respective scramblers 114 on
each of the layers is initialized using a different seed. For
example, scramblers 114 may scramble the output of the interleaver
on their respective layer by perform the scrambling operation
defined in .sctn.5.3.1 of 3GPP TS 36.211 V9.1.0, "E-UTRA, Physical
Channels and Modulation" (which is herein incorporated by reference
in its entirety) but with a layer-specific scrambling sequence,
such as a layer-specific generator seed c.sub.init=c.sub.init (q)
for a layer q. Furthermore, in particular embodiments, scramblers
114 use a layer-specific scrambling sequence seed c.sub.init
defined by the following equation:
c.sub.init=n.sub.RNTI2.sup.15+q2.sup.13+.left
brkt-bot.n.sub.s/2.right brkt-bot.2.sup.9+N.sub.IC.sup.cell.
where q is the layer associated with the sequence seed, n.sub.RNTI
is a radio network temporary identifier for transmitter 100,
n.sub.s is a slot number within a radio frame, and
N.sub.ID.sup.cell is a cell identifier associated with a cell in
which vector symbols 140 are to be transmitted.
[0049] After symbol modulators 116 for each of the layers generate
modulation symbols from the output of their corresponding
scramblers 114, a set of modulation symbols from each of the
datapaths 102 are collectively input into carrier modulator 118 as
one or more vector symbols 140. Carrier modulator 118 modulates
information from vector symbols 140 onto a plurality of
radiofrequency (RF) subcarrier signals. Depending on the
communication technologies supported by transmitter 100, carrier
modulator 118 may also process the vector symbols 140 to prepare
them for transmission, such as by precoding vector symbols 140. The
operation of an example embodiment of carrier modulator 118 for LTE
implementations is described in greater detail below with respect
to FIG. 2. After any appropriate processing, carrier modulator 118
then transmits the modulated subcarriers over a plurality of
transmission antennas 120.
[0050] As explained above, if each of the channel interleavers 112
in the various datapaths 102 are configured to interleave input
bits in the same manner (e.g., reading in bits in a row-by-column
manner and reading out bits in a column-by-row manner), control
information of the first type(s) will be output an vector symbols
140 that contain only that type of control information and do not
include any user data. For the illustrated example, this means that
bits from ACK/NAK codewords and RI codewords are carried by vector
symbols 140 that do not contain any user data. By contrast, control
information of the second type(s) will be mixed with user data in
the vector symbols 140 output to carrier modulator 118. For the
illustrated example, this means that bits from CQI codewords 132
are carried by vector symbols 140 that may also carry bits of user
data on other layers.
[0051] Thus, by interleaving control information and user data such
that vector symbols 140 carrying certain types of control
information do not include any other type of data, transmitter 100
may improve transmit diversity gains achieved by the multi-antenna
transmissions made by transmitter 100. Transmitter 100 may also
reduce computational complexity in the processing performed both by
transmitter 100 itself or by devices that receive the information
transmitted by transmitter 100. Additionally, although the
description herein focuses on implementation of the described
resource allocation techniques in wireless communication networks
supporting LTE, the described resource allocation techniques may be
utilized in conjunction with any appropriate communication
technologies including, but not limited to LTE, High-Speed Packet
Access plus (HSPA+), and Worldwide Interoperability for Microwave
Access (WiMAX).
[0052] FIG. 2 is a functional block diagram showing in greater
detail the operation of a particular embodiment of carrier
modulator 118. In particular, FIG. 2 illustrates an embodiment of
carrier modulator 118 that might be used by an embodiment of
transmitter 100 that utilizes DFTS-OFDM as required for uplink
transmissions in LTE. Alternative embodiments may be configured to
support any other appropriate type of carrier modulation. The
illustrated embodiment of carrier modulator 118 includes a DFT 202,
a precoder 204, an inverse DFT (IDFT) 206, and a plurality of power
amplifiers (PAs) 208.
[0053] Carrier modulator 118 receives vector symbols 140 output by
layer mapper 110. As received by carrier modulator 118, vector
symbols 140 represent time domain quantities. DFT 202 maps vector
symbols 140 to the frequency domain. The frequency-domain version
of vector symbols 140 are then linearly precoded by precoder 204
using a precoding matrix, W, that is (N.sub.T.times.r) in size,
where N.sub.T represents the number of transmission antennas 120 to
be used by transmitter 100 and r represents the number of
transmission layers that will be used by transmitter 100. This
precoder matrix combines and maps the r information streams onto
N.sub.T precoded streams. Precoder 204 then generates a set of
frequency-domain transmission vectors by mapping these precoded
frequency-domain symbols onto a set of sub-carriers that have been
allocated to the transmission.
[0054] The frequency-domain transmission vectors are then converted
back to the time domain by IDFT 206. In particular embodiments,
IDFT 206 also applies a cyclic prefix (CP) to the resulting
time-domain transmission vectors. The time-domain transmission
vectors are then amplified by power amplifiers 208 and output from
carrier modulator 118 to antennas 120, which are used by
transmitter 100 to transmit the time-domain transmission vectors
over a radio channel to a receiver.
[0055] As explained above, the described allocation techniques can
be implemented in a variety of different ways by different
embodiments of transmitter 100. FIGS. 4A-8B illustrate in greater
detail the functionality of various embodiments of transmitter 100
that are capable of implementing the described allocation
techniques.
[0056] FIGS. 4A-4C and 5A-5C illustrate one variation on a
particular portion of transmitter 100. Specifically, FIG. 4A shows
an embodiment of transmitter 100 that includes an expanded view of
layer mapper 104b responsible for mapping codewords of the second
type of control information (again, CQI codewords 132 for purposes
of the example in FIG. 1) to the various transmission layers. In
this expanded view, layer mapper 104b includes a control-to-data
distributor 402 and a codeword-to-layer mapper 404. In the
illustrated embodiment, the codeword-to-layer mapper 404 is
identical to the layer mapper 104a for user data codewords 130. In
this embodiment of transmitter 100, control-to-data distributor 402
distributes bits of CQI codewords 132 onto a number of sets of
bits, each set associated with a user data codeword 130 (although
some of these sets may be empty). Codeword-to-layer mapper 404 then
maps the various portions of the CQI codeword 132 to different
transmission layers based on the user data codeword 130 that the
relevant portion of the CQI codeword 132 has been assigned to.
[0057] FIG. 4B shows example operation for a particular portion of
transmitter 100 that is configured as shown by FIG. 4A. In the
illustrated example, codeword-to-layer mapper 104 receives two user
data codewords 130a-b and control-to-data distributor 402
distributes a single CQI codeword 132 between the two user data
codewords 130a-b. Layer mapper 104a and codeword-to-layer mapper
404 then map user data codewords 130a-b and the distributed CQI
codeword 132, respectively, to associated transmission layers, as
shown by FIG. 4B.
[0058] FIG. 4C illustrates a related embodiment of transmitter 100
in which control-to-data distributor 402 utilizes a specific
distribution function. In particular, FIG. 4C illustrates an
embodiment in which control-codeword-to-data-codeword distributor
402 maps the relevant CQI codeword 132 to only one of the two user
data codewords 130 to be transmitted.
[0059] Alternative embodiments of transmitter 100 may produce
identical output using other configurations of the
codeword-to-layer mapper 104 and the multiplexer 108. For example,
FIG. 5A shows another embodiment of the same portion of transmitter
100 in which the codeword-to-layer mapper 104 is moved behind the
multiplexer 108 in the relevant datapath 102. Despite this
modification, the combination of components can be configured to
produce the same output as the embodiment illustrated by FIG. 4A,
as shown by the operating example of FIG. 5B. Similarly, FIG. 5C
illustrates another configuration of the same portion of
transmitter 100. As with FIG. 4C, FIG. 5C illustrates a specific
example of FIG. 5A in which control-to-data distributor 402 maps
CQI codeword 132 onto only one of the two user data codewords 130
to be transmitted. Thus, as FIGS. 4A-4C and FIGS. 5A-5C show,
transmitter 100 can be configured to operate in the same manner
regardless of whether layer mapping occurs before or after the user
data and control multiplexing performed by multiplexer 108.
[0060] Additionally, as a variation on the per-layer embodiment of
transmitter 100 that is illustrated by FIG. 1, particular
embodiments of transmitter 100 may be capable of performing
"per-codeword" processing of input user data codewords 130 under
which a separate datapath 602 is associated with each user data
codeword 130 to be transmitted as opposed to each transmission
layer to be used.
[0061] FIG. 6 illustrates an alternative embodiment of transmitter
100 in which the allocation techniques described above are
implemented by modifying conventional interleaving and channel
encoding methods. FIG. 6 shows such an embodiment of transmitter
100. Specifically, the embodiment illustrated by FIG. 6 includes an
extended channel interleaver 612 and an extended channel encoder
610 that perform modified versions of the interleaving and channel
coding performed by, for example, LTE Release 8 user equipment when
transmitting multiplexed user data and control information on the
PUSCH.
[0062] In particular embodiments, extended channel encoder 610
performs conventional channel coding to unencoded bits of a first
type(s) of control information. For the example of FIG. 6, these
types of control information again include RI information and HARQ
feedback information. In addition to this channel encoding,
extended channel encoder 610 may also perform additional operations
to facilitate the use of the allocation techniques described above.
In particular embodiments, this may involve replicating encoded
bits of the control information to match the number of copies of
each encoded bit to the number of layers that will be to transmit
the relevant codeword.
[0063] For example, FIG. 7 illustrates in greater detail a
particular embodiment of extended channel encoder 610. As shown by
FIG. 7, the illustrated embodiment of extended channel encoder 610
includes a channel encoder 620 which may operate similarly or
identically to channel encoder 110 of FIG. 1.
[0064] Additionally, the illustrated embodiment of extended channel
encoder 610 includes a layer replicator 622. Layer replicator 622
receives an input sequence of encoded control information bits and
repeats each bit of the sequence once for every layer on which the
codeword associated with the relevant datapath will be transmitted.
Thus, as shown in FIG. 7, for an example input bit sequence of
o.sub.0o.sub.1, channel encoder 620 encodes the input bits to
generate an encoded bit sequence, Depending on the number of layers
that will be used to transmit the user data codeword 130 associated
with the relevant layer replicator 622, layer replicator 622 may
replicate individual bits of the encoded sequence so that the
resulting replicated bit sequence includes multiple copies of each
bit in the encoded sequence. Specifically, the replicated bit
sequence includes a number of copies of each encoded bit equal to
the number of layers that will be used to transmit the user data
control word 130 associated with this datapath 102. The example
extended channel encoder 610 shown in FIG. 7 is assumed to be
associated with a user data codeword 130 that will be transmitted
on two transmission layers. Thus, layer replicator 622 replicates
each bit of the encoded bit sequence (q.sub.0q.sub.1) once so that
the replicated bit sequence includes two copies of each encoded bit
(q.sub.0q.sub.0q.sub.1q.sub.1).
[0065] Returning to FIG. 6, the illustrated embodiment of
transmitter 100 combines the modified channel coding provided by
extended channel encoder 610 with a modified interleaving technique
provided by extended channel interleaver 612. As with extended
channel encoder 610, extended channel interleaver 612 performs a
version of a conventional interleaving technique (e.g., the
interleaving specified by LTE Release 8) that has been modified to
implement the allocation techniques described above with respect to
FIG. 1. More specifically, a conventional interleaver implementing
the interleaving specified by LTE Release 8 utilizes a matrix of
coded symbols (groups of Q.sub.m bits, where Q.sub.m is the number
of bits forming a modulation symbol). Each column in this matrix
corresponds to a DFTS-OFDM symbol. Under LTE Release 8
interleaving, the coded symbols (groups of Q.sub.m bits) of the RI
codeword are inserted in the assigned positions (as indicated in
the example resource grid of FIG. 4). Next, the concatenated
CQI/user data codewords (resulting from the multiplexing of CQI
codewords 132 and user data codewords 130) are inserted around the
RI codeword in a row-first order. Then, coded symbols of ACK/NAK
codeword (groups of Q.sub.m bits) are inserted in the assigned
positions shown in FIG. 4, puncturing the user data and potentially
the CQI information.
[0066] In particular embodiments, the Release 8 interleaving scheme
is modified for use by extended channel interleaver 612 such that
each column in the interleaver matrix represents the DFTS-OFDM
symbols that are to be transmitted in parallel on the layers
associated with the corresponding user data codeword 130. Moreover,
the particular interleaving pattern implemented by extended channel
interleaver 612 under this extended interleaving scheme depends on
the number of layers a particular control or user data codeword is
mapped onto. If a codeword is mapped to L layers, then every Lth
coded symbol (group of Q.sub.m bits) in a column is associated with
the same layer. That is, the coded symbols of the different layers
are interlaced. Additionally, the interleaver matrix is filled in
groups of LQ.sub.m coded bits (contrary to the conventional
interleaver that is filled in groups of Q.sub.m bits). The grouping
of LQ.sub.m coded bits ensures time-alignment between the layers
associated with a particular codeword, in a similar or identical
fashion to that described above with respect to the embodiment of
FIG. 1.
[0067] When the interleaving of extended channel interleaver 612 is
combined with the replication of coded symbols of a first type or
types of control information (HARQ and RI information in this
example) that is performed by extended channel encoder 610, the
coded symbols of the first type(s) of control information will be
repeated on all layers of the resulting vector symbols 140 carrying
the first type of control information. Thus, the first type(e) of
control information will be isolated on separate vector symbols 140
from the user data, with the relevant control information being
transmitted on vector symbols 140 that do not carry any user
data.
[0068] Consequently, with the extensions to the conventional
interleaving and channel encoding operations described above, the
per-codeword processing embodiment of transmitter 100 shown in FIG.
7 is capable of implementing the same allocation techniques
described above with respect to the pre-layer embodiment shown in
FIG. 1. Moreover, if the scrambling operations of the per-layer and
the per-codeword embodiment are selected appropriately the output
of the two embodiments may be identical on a bit-by-bit level. For
example, if two sequences are used for the per-codeword processing
(one for each codeword), then the per-layer processing formulation
can be implemented with the scrambling sequences split onto the two
associated layers such that every other group of Q.sub.m bits
mapped to every other associated layer. Conversely, if four
separate sequences are used for the per-layer processing, the two
associated with a single codeword can be interlaced in groups of
Q.sub.m bits to form a per-codeword scrambling sequence. For each
of these cases, the output of the per-layer embodiment and the
per-codeword embodiment (with extended interleaver and channel
coders) will be identical.
[0069] FIGS. 8A and 8B provide an example demonstrating this point.
FIG. 8A illustrates PUSCH signaling and UCI multiplexing for a
per-layer processing embodiment of transmitter 100 similar to that
shown in FIG. 1. In particular, FIG. 8A depicts an embodiment of
transmitter 100 that incorporates the CQI/PMI and user data
layer-mapping and multiplexing configuration shown in FIG. 5C, but
the exact same results can be achieved with the configuration shown
in FIG. 4C. For each part of the processing the output on the
branches are illustrated via matrix 800a-c where each column
corresponds to a DFTS-OFDM symbol. In particular, matrix 800a
illustrates the mapping of control information and user data on a
first layer of the resulting vector symbols 140, and matrix 800b
illustrates the same for a second layer. Matrix 800c illustrates
the output of channel interleaver 112 for the first layer. FIG.
8A-1 illustrates a matrix 800a showing a mapping of control
information and user data on a first layer of the resulting vector
symbols. FIG. 8A-2 illustrates a matrix 800b showing the mapping of
control information and user data on a second layer of the
resulting vector symbols. FIG. 8A-3 illustrates the channel
interleaver 112 output 800c for the first layer.
[0070] FIG. 8B illustrates PUSCH signaling and UCI multiplexing for
a per-codeword processing embodiment similar to that of FIG. 7. As
with FIG. 8A, matrices 810a-c are used to illustrate the output of
particular branches where each column corresponds to a DFTS-OFDM
symbol (or to interlaced DFTS-OFDM symbols as output by extended
channel interleaver 612). In particular, matrix 810a illustrates
the mapping of control information and user data on a first layer
of the resulting vector symbols 140, and matrix 810b illustrates
the same for a second layer. Matrix 810c illustrates the output of
extended channel interleaver 612. FIG. 8B-1 illustrates a matrix
810a showing the mapping of control information and user data on a
first layer of the resulting vector symbols. FIG. 8B-2 illustrates
a matrix 810b showing the mapping of control information and user
data on a second layer of the resulting vector symbols. FIG. 8B-3
illustrates the extended channel interleaver 612 output 810c.
[0071] In general, FIGS. 8A and 8B illustrate the processing of
encoded user data, CQI, RI, and HARQ-ACK symbols are illustrated
for a per-layer and a per-codeword processing embodiment,
respectively. In the figures a four-layer transmission is shown,
and the CQI codeword is multiplexed with the first user data
codeword. As can be seen from the final output of each layer, the
resulting resource mapping is the same in both figures. The same
conclusion follows analogously for other transmission ranks and
CQI-to-data codeword mappings.
[0072] FIG. 9 is a structural block diagram showing in greater
detail the contents of a particular embodiment of transmitter 100.
Transmitter 100 may represent any suitable device capable of
implementing the described resource allocation techniques in
wireless communication. For example, in particular embodiments,
transmitter 100 represents a wireless terminal, such as an LTE user
equipment (UE). As shown in FIG. 9, the illustrated embodiment of
transmitter 100 includes a processor 910, a memory 920, a
transceiver 930, and a plurality of antennas 120.
[0073] Processor 910 may represent or include any form of
processing component, including dedicated microprocessors,
general-purpose computers, or other devices capable of processing
electronic information. Examples of processor 910 include
field-programmable gate arrays (FPGAs), programmable
microprocessors, digital signal processors (DSPs),
application-specific integrated circuits (ASICs), and any other
suitable specific- or general-purpose processors. Although FIG. 9
illustrates, for the sake of simplicity, an embodiment of
transmitter 100 that includes a single processor 910, transmitter
100 may include any number of processors 910 configured to
interoperate in any appropriate manner. In particular embodiments,
some or all of the functionality described above with respect to
FIGS. 1-2 and 4-8B may be implemented by processor 910 executing
instructions and/or operating in accordance with its hardwired
logic. Similarly, in particular embodiments, some or all of the
functional blocks described above with respect to FIGS. 1-2 and
4-8B may represent processor 910 executing software.
[0074] Memory 920 stores processor instructions, equation
parameters, resource allocations, and/or any other data utilized by
transmitter 920 during operation. Memory 920 may comprise any
collection and arrangement of volatile or non-volatile, local or
remote devices suitable for storing data, such as random access
memory (RAM), read only memory (ROM), magnetic storage, optical
storage, or any other suitable type of data storage components.
Although shown as a single element in FIG. 9, memory 920 may
include one or more physical components local to or remote from
transmitter 100.
[0075] Transceiver 930 transmits and receives RF signals over
antennas 340a-d. Transceiver 100 may represent any suitable form of
RF transceiver. Although the example embodiment in FIG. 9 includes
a certain number of antennas 340, alternative embodiments of
transmitter 100 may include any appropriate number of antennas 340.
Additionally, in particular embodiments, transceiver 930 may
represent, in whole or in part, a portion of processor 910.
[0076] FIG. 10 is a flowchart illustrating example operation of a
particular embodiment of transmitter 100 in allocating user data
and control information to transmission resources. In particular,
FIG. 10 illustrates example operation for a particular embodiment
of transmitter 100 that transmits certain types of control
information (in this case, ACK/NAK and RI information) in vector
symbols 140 that contain only control information, while
transmitting other types (in this case, CQI/PMI information) in
vector symbols 140 that include both control information and user
data. The steps illustrated in FIG. 10 may be combined, modified,
or deleted where appropriate. Additional steps may also be added to
the example operation. Furthermore, the described steps may be
performed in any suitable order.
[0077] Operation begins in the illustrated example with transmitter
100 encoding the various types of information to be transmitted
during a particular subframe. Thus, at step 1002, transmitter 100
encodes bits of a first type of control information to form one or
more control codewords. At step 1004, transmitter 100 encodes bits
of a second type of control information to form one or more control
codewords. Transmitter 100 also encodes bits of user data, at step
1006, to form one or more user data codewords. Depending on the
types of information to be transmitted and the performance
requirements of the communication system, transmitter 100 may use a
common encoding scheme or multiple different encoding schemes to
encode the information. In particular embodiments, transmitter 100
may replicate bits of the first type of control information (before
or after encoding) to ensure that, in any vector symbol 140
carrying the first type of control information, the first type of
control information is mapped to all transmission layers used for
the transmission. Additionally, in particular embodiments,
transmitter 100 may encode bits of the second type of control
information at a rate to form a first codeword such that a number
of bits in the first codeword is equal to
CW l CQI / PMI ( k ) = CW CQI / PMI ( k Q m , l l ~ = 1 r Q m . l ~
+ l ~ = 1 l - 1 Q m , l ~ + k ) ##EQU00004##
where Q' is an integer and Q.sub.m,l is a number of bits of each
modulation symbol on layer l and r is a total number of layers over
which a user data codeword to be multiplexed with the second type
of control information will be transmitted. This may ensure that
the second type of control information is mapped to the same
transmission layers in all vector symbols 140 that carry the second
type of control information, even if other transmission layers are
used to transmit user data.
[0078] After all of the information to be transmitted during the
relevant subframe has been encoded, transmitter 100 combines the
control information to be transmitted with the user data. In
particular embodiments, transmitter 100 may combine various types
of control information with user data in different ways. For
example, in the illustrated embodiment, at step 1008, transmitter
100 multiplexes certain types of control information (i.e., encoded
CQI information) with user data codewords prior to allocating
control information and user data to transmission resources.
Transmitter 100 may distribute this control information to one or
more user data codewords so that encoded bits of the control
information are concatenated with the relevant user data
codeword(s). For example, in particular embodiments, transmitter
100 segments each control codeword of the second type into a number
of parts that is equal to the total number of layers (r) over which
the relevant user data codeword(s) to be multiplexed will be
transmitted. Transmitter 100 may perform this segmenting in such a
manner that, when transmitter 100 subsequently allocates the
various types of control information and user data to transmission
resources, the part of segmented control codeword that is assigned
to a particular layer (l) will have a length equal to (Q'.times.
Q.sub.m,l) bits. Alternatively, transmitter 100 may distribute the
second type of control codeword such that:
Q ' .times. l = 1 r Q m , l , ##EQU00005##
where CW.sub.l.sup.CQI/PMI(k) denotes the k-th bit (starting
counting from 0) of the control codeword mapped to layer l
(starting counting from 1) and CW.sup.CQI/PMI(m) denotes the m th
bit (starting counting from 0) of the codeword prior to layer
mapping.
[0079] Transmitter 100 then generates a plurality of vector symbols
140 based on the control codewords and the user data codewords.
Each vector symbol 140 comprises a plurality of modulation symbols
that are each associated with a transmission layer over which the
associated modulation symbol will be transmitted. As part of
generating these vector symbols 140, transmitter 100 interleaves
bits of the first type of control information with bits of one or
more user data control codewords, including any bits of the second
type of control information that have been concatenated with user
data codewords at step 1010. In particular embodiments, transmitter
100 interleaves the control information and user data such that
control information of a particular type is mapped to the same
layers in all vector symbols 140 transmitted during the relevant
subframe that carry the relevant type of control information.
Additionally, in particular embodiments, transmitter 100
interleaves the control information and user data in a manner such
that control information of certain types (e.g., ACK/NACK
information and RI information) is mapped to separate vector
symbols 140 from user data. Furthermore, in particular embodiments,
transmitter 100 interleaves the control information and user data
in a manner such that other types of control information are mapped
to vector symbols 140 to which user data is also mapped. However,
in particular embodiments, these other types of control information
are still mapped to the same set of transmission layers in all
vector symbols 140 transmitted during the subframe that carry the
relevant type(s) of control information.
[0080] After interleaving the bits of control information and user
data, transmitter 100 may scramble the interleaved bits. Thus, in
the illustrated example, transmitter 100 generates a scrambling
sequence or sequences, at step 1012, and applies the scrambling
sequence to groups of the interleaved bits, at step 1014. In
particular embodiments, transmitter generates a scrambling sequence
for each layer particular based on a sequence seed (c.sub.init)
associated with that layer. For example, transmitter 100 may
generate a scrambling sequence based on a sequence seed
c.sub.init=n.sub.RNTI2.sup.15+q2.sup.13+.left
brkt-bot.n.sub.s/2.right brkt-bot.2.sup.9+N.sub.ID.sup.cell, where
q is the layer associated with the sequence seed, n.sub.RNTI is a
terminal radio network temporary id, n.sub.s is a slot number
within a radio frame, and N.sub.ID.sup.cell is a cell identifier
associated with a cell in which the vector symbols 140 are to be
transmitted. After generating the scrambling sequence(s), in such
embodiments, transmitter 100 scrambles each group of interleaved
bits by its corresponding scrambling sequence, as shown at step
1014.
[0081] Once transmitter 100 has generated vector symbols 140 and
performed any suitable processing, transmitter 100 transmits the
generated vector symbols 140 at step 1016. As explained above, in
particular embodiments, each type of control information is mapped
to the same layers in all of the vector symbols 140 that carry that
type of control information. Additionally, certain types of control
information (e.g., ACK/NAK information and RI information here) are
mapped to separate vector symbols 140 so that no vector symbols
carrying these types of control information also carry user data.
However, other types of control information (e.g., CQI information
here) may be mapped to vector symbols 140 that also carry user
data. Operation of transmitter 100 with respect to transmitting the
relevant control information and user data may then end as shown in
FIG. 10.
[0082] Although the present invention has been described with
several embodiments, a myriad of changes, variations, alterations,
transformations, and modifications may be suggested to one skilled
in the art, and it is intended that the present invention encompass
such changes, variations, alterations, transformations, and
modifications as fall within the scope of the appended claims.
* * * * *