U.S. patent application number 14/193509 was filed with the patent office on 2014-09-04 for codebook and codebook search.
The applicant listed for this patent is Xiaogang Chen, Jong-Kae Fwu, Qinghua Li, Yuan Zhu. Invention is credited to Xiaogang Chen, Jong-Kae Fwu, Qinghua Li, Yuan Zhu.
Application Number | 20140247860 14/193509 |
Document ID | / |
Family ID | 51420937 |
Filed Date | 2014-09-04 |
United States Patent
Application |
20140247860 |
Kind Code |
A1 |
Zhu; Yuan ; et al. |
September 4, 2014 |
CODEBOOK AND CODEBOOK SEARCH
Abstract
Briefly, in accordance with one or more embodiments, a codebook
used to provide a precoding matrix indicator and/or channel state
information comprises one or more rank-1 codewords and at least one
or more rank-2 codewords exhibiting a nesting property with the
rank-1 codewords, and one or more rank-2 codewords not exhibiting a
nesting property with the rank-1 codewords. Further, the rank-1
codewords may include at least some Discrete Fourier Transform
(DFT) vectors, and at least some vectors that are optimized for a
cross polarize array of antennas if the array of antennas is cross
polarized. The codebook may be utilized for single-user
multiple-input, multiple-output (SU-MIMO) or multi-user
multiple-input, multiple-output (MU-MIMO).
Inventors: |
Zhu; Yuan; (Beijing, CN)
; Li; Qinghua; (San Ramon, CA) ; Chen;
Xiaogang; (Beijing, CN) ; Fwu; Jong-Kae;
(Sunnyvale, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Zhu; Yuan
Li; Qinghua
Chen; Xiaogang
Fwu; Jong-Kae |
Beijing
San Ramon
Beijing
Sunnyvale |
CA
CA |
CN
US
CN
US |
|
|
Family ID: |
51420937 |
Appl. No.: |
14/193509 |
Filed: |
February 28, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61771698 |
Mar 1, 2013 |
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Current U.S.
Class: |
375/219 ;
375/267 |
Current CPC
Class: |
H04W 76/23 20180201;
H04M 15/8044 20130101; H04L 12/184 20130101; H04W 88/02 20130101;
H04B 7/0452 20130101; H04W 36/14 20130101; H04W 36/165 20130101;
H04W 76/20 20180201; H04W 84/18 20130101; H04W 4/06 20130101; H04W
24/02 20130101; H04W 76/14 20180201; H04W 72/0406 20130101; H04W
72/085 20130101; H04W 76/30 20180201; Y02D 30/70 20200801; H04L
45/74 20130101; H04W 36/22 20130101; H04W 16/14 20130101; H04L
25/03 20130101; H04L 65/608 20130101; H04W 12/04 20130101; H04B
7/0626 20130101; H04W 48/20 20130101; H04W 88/08 20130101; H04W
72/044 20130101; H04W 24/08 20130101; H04L 65/4038 20130101; H04W
4/80 20180201; H04W 76/27 20180201; Y02B 70/30 20130101; H04J 3/12
20130101; H04W 72/10 20130101; H04W 88/06 20130101; H04L 67/02
20130101; H04W 12/02 20130101; H04L 5/0037 20130101; H04W 48/10
20130101; H04W 4/10 20130101; H04W 72/087 20130101; H04W 76/10
20180201; H04W 52/244 20130101; H04L 65/80 20130101; H04W 72/005
20130101; H04B 7/0486 20130101; H04W 24/10 20130101 |
Class at
Publication: |
375/219 ;
375/267 |
International
Class: |
H04B 7/04 20060101
H04B007/04; H04B 1/38 20060101 H04B001/38 |
Claims
1. A user equipment (UE), comprising: a wireless transceiver having
an array of one or more antennas; and a processor coupled to the
wireless transceiver and a memory coupled to the processor, the
memory having a codebook stored therein, wherein the codebook
comprises: one or more rank-1 codewords; at least one or more
rank-2 codewords exhibiting a nesting property with the rank-1
codewords; and one or more rank-2 codewords not exhibiting a
nesting property with the rank-1 codewords.
2. A user equipment as claimed in claim 1, wherein the rank-1
codewords include at least some Discrete Fourier Transform (DFT)
vectors, and at least some vectors that are optimized for the array
of antennas if the array of antennas is cross polarized.
3. A user equipment as claimed in claim 1, wherein the processor is
configured to perform a search of the codebook for single-user
multiple-input, multiple-output (SU-MIMO) by: performing a channel
state information (CSI) search to find a best precoding matrix
indicator (PMI) for the rank-1 codewords and the rank-2 codewords
to maximize channel capacity; selecting a better rank; and
reporting the better rank and the best PMI and CQI for the better
rank.
4. A user equipment as claimed in claim 1, wherein the processor is
configured to perform a search of the codebook for multi-user
multiple-input, multiple-output (MU-MIMO) by: performing a channel
state information (CSI) search to find a best precoding matrix
indicator (PMI) for the rank-1 codewords and the rank-2 codewords
using each column of each codeword as a rank-1 precoder; selecting
a better rank; and reporting the better rank and the best PMI and
CQI for the better rank to an enhanced Node B.
5. A user equipment as claimed in claim 1, further comprising a
touch screen to receive a touch input to control the processor.
6. A user equipment (UE), comprising: a wireless transceiver having
an array of one or more antennas; and a processor coupled to the
wireless transceiver and a memory coupled to the processor, the
memory having a codebook stored therein, wherein the codebook
comprises: one or more rank-1 codewords; and one or more rank-2
codewords; wherein the rank-1 codewords include at least some
Discrete Fourier Transform (DFT) vectors, and at least some vectors
that are optimized for the array of antennas if the array of
antennas is cross polarized.
7. A user equipment as claimed in claim 6, wherein at least one or
more rank-2 codewords exhibit a nesting property with the rank-1
codewords; and one or more rank-2 codewords do not exhibit a
nesting property with the rank-1 codewords.
8. A user equipment as claimed in claim 6, wherein the processor is
configured to perform a search of the codebook for single-user
multiple-input, multiple-output (SU-MIMO) by: performing a channel
state information (CSI) search to find a best precoding matrix
indicator (PMI) for the rank-1 codewords and the rank-2 codewords
to maximize channel capacity; selecting a better rank; and
reporting the better rank and the best PMI and CQI for the better
rank.
9. A user equipment as claimed in claim 6, wherein the processor is
configured to perform a search of the codebook for multi-user
multiple-input, multiple-output (MU-MIMO) by: performing a channel
state information (CSI) search to find a best precoding matrix
indicator (PMI) for the rank-1 codewords and the rank-2 codewords
using each column of each codeword as a rank-1 precoder; selecting
a better rank; and reporting the better rank and the best PMI and
CQI for the better rank to an enhanced Node B.
10. A user equipment as claimed in claim 6, further comprising a
touch screen to receive a touch input to control the processor.
11. A method to perform a codebook search, comprising: performing a
channel state information (CSI) search to find a best precoding
matrix indicator (PMI) for rank-1 codewords and rank-2 codewords of
the codebook; selecting a better rank; and reporting the better
rank and the best PMI and CQI for the better rank.
12. A method as claimed in claim 11, wherein said performing is
implemented for single-user multiple-input, multiple-output
(SU-MIMO).
13. A method as claimed in claim 11, wherein said performing is
implemented for multi-user multiple-input, multiple-output
(MU-MIMO) by using each column of each codeword as a rank-1
precoder.
14. A method as claimed in claim 11, wherein the codebook
comprises: one or more rank-1 codewords; at least one or more
rank-2 codewords exhibiting a nesting property with the rank-1
codewords; and one or more rank-2 codewords not exhibiting a
nesting property with the rank-1 codewords.
15. A method as claimed in claim 11, wherein the rank-1 codewords
include at least some Discrete Fourier Transform (DFT) vectors, and
at least some vectors that are optimized for the array of antennas
if the array of antennas is cross polarized.
16. An article of manufacture comprising a non-transitory medium
having instructions thereon that, if executed, result in:
performing a channel state information (CSI) search to find a best
precoding matrix indicator (PMI) for rank-1 codewords and rank-2
codewords of the codebook; selecting a better rank; and reporting
the better rank and the best PMI and CQI for the better rank.
17. An article as claimed in claim 16, wherein said performing is
implemented for single-user multiple-input, multiple-output
(SU-MIMO).
18. An article as claimed in claim 16, wherein said performing is
implemented for multi-user multiple-input, multiple-output
(MU-MIMO) by using each column of each codeword as a rank-1
precoder.
19. An article as claimed in claim 16, wherein the codebook
comprises: one or more rank-1 codewords; at least one or more
rank-2 codewords exhibiting a nesting property with the rank-1
codewords; and one or more rank-2 codewords not exhibiting a
nesting property with the rank-1 codewords.
20. An article as claimed in claim 16, wherein the rank-1 codewords
include at least some Discrete Fourier Transform (DFT) vectors, and
at least some vectors that are optimized for the array of antennas
if the array of antennas is cross polarized.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims the benefit of U.S.
Provisional Application No. 61/771,698 (Attorney Docket No.
P54838Z) filed Mar. 1, 2013. Said Application No. 61/771,698 is
hereby incorporated herein in its entirety.
BACKGROUND
[0002] Channel state information (CSI) is used to provide
information about a transmission channel between a transmitting
device and a receiving device. The CSI is fed back from the
receiving device to the transmitting device so that the
transmitting device may adjust its transmissions to account for the
conditions of the channel. As part of this feedback, a precoding
matrix indicator (PMI) from a codebook may be feedback so that the
transmitter may apply a selected precoding matrix to its
transmission to adjust to the channel. In general, as codebooks are
enhanced for more advanced transmission techniques, the codebooks
also may be reused to ensure compatibility with previous standards
while modifying the codebooks for advanced transmission techniques.
Furthermore, codeword searches may be optimized for the modified
codebooks.
DESCRIPTION OF THE DRAWING FIGURES
[0003] Claimed subject matter is particularly pointed out and
distinctly claimed in the concluding portion of the specification.
However, such subject matter may be understood by reference to the
following detailed description when read with the accompanying
drawings in which:
[0004] FIG. 1 is a diagram of a wireless communication system
capable of utilizing a codebook to feed back a precoding matrix
indicator/channel state information in accordance with one or more
embodiments;
[0005] FIG. 2 is a conceptual diagram of a codebook having nested
codewords and non-nested codewords in accordance with one or more
embodiments;
[0006] FIG. 3 is a conceptual diagram of a codebook having at least
some vectors optimized for cross-polarized antennas in accordance
with one or more embodiments;
[0007] FIG. 4 is a diagram of cross polarized antennas for which
the codebook of FIG. 3 may be designed to optimize performance in
accordance with one or more embodiments;
[0008] FIG. 5 is a flow diagram of a method to perform a codeword
search for a single user multiple-input, multiple output (SU-MIMO)
system in accordance with one or more embodiments;
[0009] FIG. 6 is a flow diagram of a method to perform a codeword
search for a multi-user multiple-input, multiple output (MU-MIMO)
system in accordance with one or more embodiments;
[0010] FIG. 7 is a block diagram of an information handling system
capable of utilizing a codebook and/or performing a codebook search
in accordance with one or more embodiments; and
[0011] FIG. 8 is an isometric view of an information handling
system of FIG. 6 that optionally may include a touch screen in
accordance with one or more embodiments.
[0012] It will be appreciated that for simplicity and/or clarity of
illustration, elements illustrated in the figures have not
necessarily been drawn to scale. For example, the dimensions of
some of the elements may be exaggerated relative to other elements
for clarity. Further, if considered appropriate, reference numerals
have been repeated among the figures to indicate corresponding
and/or analogous elements.
DETAILED DESCRIPTION
[0013] In the following detailed description, numerous specific
details are set forth to provide a thorough understanding of
claimed subject matter. However, it will be understood by those
skilled in the art that claimed subject matter may be practiced
without these specific details. In other instances, well-known
methods, procedures, components and/or circuits have not been
described in detail.
[0014] In the following description and/or claims, the terms
coupled and/or connected, along with their derivatives, may be
used. In particular embodiments, connected may be used to indicate
that two or more elements are in direct physical and/or electrical
contact with each other. Coupled may mean that two or more elements
are in direct physical and/or electrical contact. However, coupled
may also mean that two or more elements may not be in direct
contact with each other, but yet may still cooperate and/or
interact with each other. For example, "coupled" may mean that two
or more elements do not contact each other but are indirectly
joined together via another element or intermediate elements.
Finally, the terms "on," "overlying," and "over" may be used in the
following description and claims. "On," "overlying," and "over" may
be used to indicate that two or more elements are in direct
physical contact with each other. However, "over" may also mean
that two or more elements are not in direct contact with each
other. For example, "over" may mean that one element is above
another element but not contact each other and may have another
element or elements in between the two elements. Furthermore, the
term "and/or" may mean "and", it may mean "or", it may mean
"exclusive-or", it may mean "one", it may mean "some, but not all",
it may mean "neither", and/or it may mean "both", although the
scope of claimed subject matter is not limited in this respect. In
the following description and/or claims, the terms "comprise" and
"include," along with their derivatives, may be used and are
intended as synonyms for each other.
[0015] Referring now to FIG. 1, a diagram of a wireless
communication system capable of utilizing a codebook to feed back a
precoding matrix indicator/channel state information in accordance
with one or more embodiments will be discussed. As shown in FIG. 1,
wireless communication system 100 may comprise enhanced node B
(eNB) 110 to communicate with user equipment (UE) 112 via channel
114. In some embodiments, eNB 110 may include one or more antennas
116 and UE 112 likewise may have one or more antennas 118 for
example to implement multiple-input, multiple-output (MIMO)
communications. Where there is a single UE 112, eNB 110 may
communicate with UE 112 via single-user MIMO (SU-MIMO), and where
there are more than one UEs 112, eNB 110 may communicate with the
UEs 112 via multi-user MIMO (MU-MIMO). For purposes of example, a
single UE 112 will be discussed herein, although the concepts also
may apply to multiple UEs 112, and the scope of the claimed subject
matter is not limited in this respect. In order to optimize
throughput between the eNB 110 and UE 112, eNB 110 may transmit
training, reference, or pilot signals to UE 112 via channel 114 so
that UE 112 may calculate a precoding matrix indicator (PMI),
channel state information (CSI) and/or a rank index (RI) as
feedback 120 to eNB 110. As part of such feedback 120, rank-1
codeword (RANK-1) 122 and/or rank-2 codeword (RANK-2) 124, as
selected from a codebook and as calculated by UE 112 as optimizing
downlink transmission performance via channel 114, may be fed back
to eNB 110 wherein the rank-1 codeword 122 and the rank-2 codeword
124 may be modified as discussed herein. Based at least in part on
feedback 120 received from UE 112, eNB 110 may utilize a precoding
matrix for downlink transmissions via channel 114 to one or more
UEs 112. An example codebook with modified Rank-2 codewords is
shown in and described with respect to FIG. 2, below.
[0016] Referring now to FIG. 2, a conceptual diagram of a codebook
having nested codewords and non-nested codewords in accordance with
one or more embodiments will be discussed. In one or more
embodiments, codebook 200 may be utilized by UE 112 of FIG. 1 to
provide feedback 120 to eNB 110 to optimize downlink channel
transmissions. Codebook 200 of FIG. 2 has been modified to relax
the nesting structure utilized by prior codebooks. For example,
under the Third Generation Partnership Project (3GPP) Standard, the
4Tx codebook of Release 8 of the 3GPP standard utilizes a nesting
structure wherein if the codebook has a rank-1 codeword vector, v,
which is a 4.times.1 vector, the codebook must have at least one
rank-2 codeword which is a 4.times.2 matrix and which contains the
same rank-1 codeword as one of its columns. The same rule also
applies to rank-3 and rank 4-codebooks, and so on. One of the main
reason for using a nesting structure is reduced codeword search
complexity. When UE 112 is searching for a higher rank codebook in
order to perform rank adaptation, the search results of a lower
rank codebook can be reused. From a performance point of view,
however, the nesting property of the codebook may degrade the
performance for reducing search complexity.
[0017] In accordance with one or more embodiments, codebook 200 may
be designed to optimize performance in terms of throughput. In the
4Tx codebook of Release 8 of the 3GPP standard, the nesting
structure is implemented by selecting the columns after Householder
reflection. The higher rank codeword, which has more columns than
the lower rank one, always uses the lower rank codeword as the
first columns and then selects the remaining columns from the
square matrix generated by Householder reflection with the first
column of the lower rank codeword. In contrast, the design of
codebook 200 of FIG. 2 optimizes throughput optimized codebook by
relaxing this nesting property. As shown in FIG. 2, codebook 200
may include rank-1 codewords and rank-2 codewords 212. In the
rank-2 codewords 212, a rank-2 codeword may have columns that are
different from any rank-1 codeword. For example, the rank-2
codeword may include any two columns from the Householder matrix
instead of always picking the first column of the Householder
matrix as one of rank-2 codeword column. As a result, the rank-2
codewords 212 of codebook 200 may include some nested codewords 214
that exhibit the nesting property, and some non-nested codewords
216 that do not exhibit the nesting property. Table 1, below,
illustrates an example of the 6-bit codebook for rank 1 and rank 2.
The rank-1 vector may be the same as the rank-1 vector as described
in Release 8 of the 3GPP standard. As a modified rank-2 codebook
200, column selection of rank 2 may be optimized for throughput
performance, for example as determined via computer simulation.
From an examination of the example codebook of Table 1, it can be
seen that some codewords still maintain the nesting property
whereas others do not.
TABLE-US-00001 TABLE 1 6-bit codebook of 4Tx antennas rank-1 and
rank-2 Codebook Number of layers .upsilon. index u.sub.n 1 2 0
u.sub.0 = [1 -1 -1 -1].sup.T W.sub.0.sup.(1) .sup.
W.sub.0.sup.(14)/{square root over (2)} 1 u.sub.1 = [1 -j 1
j].sup.T W.sub.1.sup.(1) .sup. W.sub.1.sup.(12)/{square root over
(2)} 2 u.sub.2 = [1 1 -1 1].sup.T W.sub.2.sup.(1) .sup.
W.sub.2.sup.(12)/{square root over (2)} 3 u.sub.3 = [1 j 1
-j].sup.T W.sub.3.sup.(1) .sup. W.sub.3.sup.(12)/{square root over
(2)} 4 u.sub.4 = [1 (-1 - j)/{square root over (2)} -j (1 -
j)/{square root over (2)}].sup.T W.sub.4.sup.(1) .sup.
W.sub.4.sup.(14)/{square root over (2)} 5 u.sub.5 = [1 (1 -
j)/{square root over (2)} j (-1 - j)/{square root over (2)}].sup.T
W.sub.5.sup.(1) .sup. W.sub.5.sup.(14)/{square root over (2)} 6
u.sub.6 = [1 (1 + j)/{square root over (2)} -j (-1 + j)/{square
root over (2)}].sup.T W.sub.6.sup.(1) .sup.
W.sub.6.sup.(13)/{square root over (2)} 7 u.sub.7 = [1 (-1 +
j)/{square root over (2)} j (1 + j)/{square root over (2)}].sup.T
W.sub.7.sup.(1) .sup. W.sub.7.sup.(13)/{square root over (2)} 8
u.sub.8 = [1 -1 1 1].sup.T W.sub.8.sup.(1) .sup.
W.sub.8.sup.(12)/{square root over (2)} 9 u.sub.9 = [1 -j -1
-j].sup.T W.sub.9.sup.(1) .sup. W.sub.9.sup.(14)/{square root over
(2)} 10 u.sub.10 = [1 1 1 -1].sup.T W.sub.10.sup.(1)
W.sub.10.sup.(13)/{square root over (2)} 11 u.sub.11 = [1 j -1
j].sup.T W.sub.11.sup.(1) W.sub.11.sup.(13)/{square root over (2)}
12 u.sub.12 = [1 -1 -1 1].sup.T W.sub.12.sup.(1)
W.sub.12.sup.(12)/{square root over (2)} 13 u.sub.13 = [1 -1 1
-1].sup.T W.sub.13.sup.(1) W.sub.13.sup.(13)/{square root over (2)}
14 u.sub.14 = [1 1 -1 -1].sup.T W.sub.14.sup.(1)
W.sub.14.sup.(13)/{square root over (2)} 15 u.sub.15 = [1 1 1
1].sup.T W.sub.15.sup.(1) W.sub.15.sup.(12)/{square root over (2)}
16 u.sub.16 = [1 -e.sup.j2.pi.2/32 -e.sup.j4.pi.2/32
-e.sup.j6.pi.2/32].sup.T W.sub.16.sup.(1) W.sub.16.sup.(23)/{square
root over (2)} 17 u.sub.17 = [1 -e.sup.j2.pi.10/32
-e.sup.j4.pi.10/32 -e.sup.j6.pi.10/32].sup.T W.sub.17.sup.(1)
W.sub.17.sup.(34)/{square root over (2)} 18 u.sub.18 = [1
-e.sup.j2.pi.18/32 -e.sup.j4.pi.18/32 -e.sup.j6.pi.18/32].sup.T
W.sub.18.sup.(1) W.sub.18.sup.(13)/{square root over (2)} 19
u.sub.19 = [1 -e.sup.j2.pi.26/32 -e.sup.j4.pi.26/32
-e.sup.j6.pi.26/32].sup.T W.sub.19.sup.(1)
W.sub.19.sup.(34)/{square root over (2)} 20 u.sub.20 = [1
-e.sup.j2.pi.6/32 -e.sup.j4.pi.6/32 -e.sup.j6.pi.6/32].sup.T
W.sub.20.sup.(1) W.sub.20.sup.(13)/{square root over (2)} 21
u.sub.21 = [1 -e.sup.j2.pi.14/32 -e.sup.j4.pi.14/32
-e.sup.j6.pi.14/32].sup.T W.sub.21.sup.(1)
W.sub.21.sup.(24)/{square root over (2)} 22 u.sub.22 = [1
-e.sup.j2.pi.22/32 -e.sup.j4.pi.22/32 -e.sup.j6.pi.22/32].sup.T
W.sub.22.sup.(1) W.sub.22.sup.(12)/{square root over (2)} 23
u.sub.23 = [1 -e.sup.j2.pi.30/32 -e.sup.j4.pi.30/32
-e.sup.j6.pi.30/32].sup.T W.sub.23.sup.(1)
W.sub.23.sup.(14)/{square root over (2)} 24 u.sub.24 = [1 -1 -j
-j].sup.T W.sub.24.sup.(1) W.sub.24.sup.(23)/{square root over (2)}
25 u.sub.25 = [1 -j j -1].sup.T W.sub.25.sup.(1)
W.sub.25.sup.(12)/{square root over (2)} 26 u.sub.26 = [1 1 -j
j].sup.T W.sub.26.sup.(1) W.sub.26.sup.(34)/{square root over (2)}
27 u.sub.27 = [1 j j 1].sup.T W.sub.27.sup.(1)
W.sub.27.sup.(13)/{square root over (2)} 28 u.sub.28 = [1 -1 j
j].sup.T W.sub.28.sup.(1) W.sub.28.sup.(12)/{square root over (2)}
29 u.sub.29 = [1 -j -j 1].sup.T W.sub.29.sup.(1)
W.sub.29.sup.(13)/{square root over (2)} 30 u.sub.30 = [1 1 j
-j].sup.T W.sub.30.sup.(1) W.sub.30.sup.(12)/{square root over (2)}
31 u.sub.31 = [1 j -j -1].sup.T W.sub.31.sup.(1)
W.sub.31.sup.(14)/{square root over (2)} 32 u.sub.32 = [1
-e.sup.j2.pi./32 -e.sup.j4.pi./32 -e.sup.j6.pi./32].sup.T
W.sub.32.sup.(1) W.sub.32.sup.(12)/{square root over (2)} 33
u.sub.33 = [1 -e.sup.j2.pi.9/32 -e.sup.j4.pi.9/32
-e.sup.j6.pi.9/32].sup.T W.sub.33.sup.(1) W.sub.33.sup.(34)/{square
root over (2)} 34 u.sub.34 = [1 -e.sup.j2.pi.17/32
-e.sup.j4.pi.17/32 -e.sup.j6.pi.17/32].sup.T W.sub.34.sup.(1)
W.sub.34.sup.(14)/{square root over (2)} 35 u.sub.35 = [1
-e.sup.j2.pi.25/32 -e.sup.j4.pi.25/32 -e.sup.j6.pi.25/32].sup.T
W.sub.35.sup.(1) W.sub.35.sup.(13)/{square root over (2)} 36
u.sub.36 = [1 -e.sup.j2.pi.5/32 -e.sup.j4.pi.5/32
-e.sup.j6.pi.5/32].sup.T W.sub.36.sup.(1) W.sub.36.sup.(12)/{square
root over (2)} 37 u.sub.37 = [1 -e.sup.j2.pi.13/32
-e.sup.j4.pi.13/32 -e.sup.j6.pi.13/32].sup.T W.sub.37.sup.(1)
W.sub.37.sup.(34)/{square root over (2)} 38 u.sub.38 = [1
-e.sup.j2.pi.21/32 -e.sup.j4.pi.21/32 -e.sup.j6.pi.21/32].sup.T
W.sub.38.sup.(1) W.sub.38.sup.(34)/{square root over (2)} 39
u.sub.39 = [1 -e.sup.j2.pi.29/32 -e.sup.j4.pi.28/32
-e.sup.j6.pi.29/32].sup.T W.sub.39.sup.(1)
W.sub.39.sup.(14)/{square root over (2)} 40 u.sub.40 = [1
-e.sup.j2.pi.3/32 -e.sup.j4.pi.3/32 -e.sup.j6.pi.3/32].sup.T
W.sub.40.sup.(1) W.sub.40.sup.(13)/{square root over (2)} 41
u.sub.41 = [1 -e.sup.j2.pi.11/32 -e.sup.j4.pi.11/32
-e.sup.j6.pi.11/32].sup.T W.sub.41.sup.(1)
W.sub.41.sup.(23)/{square root over (2)} 42 u.sub.42 = [1
-e.sup.j2.pi.19/32 -e.sup.j4.pi.19/32 -e.sup.j6.pi.19/32].sup.T
W.sub.42.sup.(1) W.sub.42.sup.(24)/{square root over (2)} 43
u.sub.43 = [1 -e.sup.j2.pi.27/32 -e.sup.j4.pi.27/32
-e.sup.j6.pi.27/32].sup.T W.sub.43.sup.(1)
W.sub.43.sup.(24)/{square root over (2)} 44 u.sub.44 = [1
-e.sup.j2.pi.7/32 -e.sup.j4.pi.7/32 -e.sup.j6.pi.7/32].sup.T
W.sub.44.sup.(1) W.sub.44.sup.(12)/{square root over (2)} 45
u.sub.45 = [1 -e.sup.j2.pi.15/32 -e.sup.j4.pi.15/32
-e.sup.j6.pi.15/32].sup.T W.sub.45.sup.(1)
W.sub.45.sup.(13)/{square root over (2)} 46 u.sub.46 = [1
-e.sup.j2.pi.23/32 -e.sup.j4.pi.23/32 -e.sup.j6.pi.23/32].sup.T
W.sub.46.sup.(1) W.sub.46.sup.(12)/{square root over (2)} 47
u.sub.47 = [1 -e.sup.j2.pi.31/32 -e.sup.j4.pi.31/32
-e.sup.j6.pi.31/32].sup.T W.sub.47.sup.(1)
W.sub.47.sup.(12)/{square root over (2)} 48 u.sub.48 = [1 (-1 -
j)/{square root over (2)} j (-1 + j)/{square root over (2)}].sup.T
W.sub.48.sup.(1) W.sub.48.sup.(34)/{square root over (2)} 49
u.sub.49 = [1 (1 - j)/{square root over (2)} -j (1 + j)/{square
root over (2)}].sup.T W.sub.49.sup.(1) W.sub.49.sup.(13)/{square
root over (2)} 50 u.sub.50 = [1 (1 + j)/{square root over (2)} j (1
- j)/{square root over (2)}].sup.T W.sub.50.sup.(1)
W.sub.50.sup.(23)/{square root over (2)} 51 u.sub.51 = [1 (-1 +
j)/{square root over (2)} -j (-1 - j)/{square root over (2)}].sup.T
W.sub.51.sup.(1) W.sub.51.sup.(12)/{square root over (2)} 52
u.sub.52 = [1 (-1 - j)/{square root over (2)} -1 (-1 - j)/{square
root over (2)}].sup.T W.sub.52.sup.(1) W.sub.52.sup.(12)/{square
root over (2)} 53 u.sub.53 = [1 (-1 - j)/{square root over (2)} 1
(-1 + j)/{square root over (2)}].sup.T W.sub.53.sup.(1)
W.sub.53.sup.(13)/{square root over (2)} 54 u.sub.54 = [1 (1 +
j)/{square root over (2)} -1 (1 + j)/{square root over (2)}].sup.T
W.sub.54.sup.(1) W.sub.54.sup.(12)/{square root over (2)} 55
u.sub.55 = [1 (-1 + j)/{square root over (2)} 1 (1 - j)/{square
root over (2)}].sup.T W.sub.55.sup.(1) W.sub.55.sup.(14)/{square
root over (2)} 56 u.sub.56 = [1 (-1 - j)/{square root over (2)} 1
(1 + j)/{square root over (2)}].sup.T W.sub.56.sup.(1)
W.sub.56.sup.(23)/{square root over (2)} 57 u.sub.57 = [1 (-1 -
j)/{square root over (2)} -1 (1 - j)/{square root over (2)}].sup.T
W.sub.57.sup.(1) W.sub.57.sup.(23)/{square root over (2)} 58
u.sub.58 = [1 (1 + j)/{square root over (2)} 1 (-1 - j)/{square
root over (2)}].sup.T W.sub.58.sup.(1) W.sub.58.sup.(23)/{square
root over (2)} 59 u.sub.59 = [1 (-1 + j)/{square root over (2)} -1
(-1 + j)/{square root over (2)}].sup.T W.sub.59.sup.(1)
W.sub.59.sup.(14)/{square root over (2)} 60 u.sub.60 = [2 0 0
0].sup.T W.sub.60.sup.(1) W.sub.60.sup.(12)/{square root over (2)}
61 u.sub.61 = [0 2 0 0].sup.T W.sub.61.sup.(2)
W.sub.61.sup.(12)/{square root over (2)} 62 u.sub.62 = [0 0 2
0].sup.T W.sub.62.sup.(3) W.sub.62.sup.(13)/{square root over (2)}
63 u.sub.63 = [0 0 0 2].sup.T W.sub.63.sup.(4)
W.sub.63.sup.(23)/{square root over (2)}
[0018] It should be noted that in the above example codebook of
Table 1, the rank-1 vectors reuse all of the 32 4Tx Discrete
Fourier Transform (DFT) vectors as defined in Release 10 of the
3GPP standard for an 8Tx codebook. It should be noted that DFT
vectors may be used for both a uniform linear array (ULA) of
antennas and cross polarized antennas, but when DFT vectors are
used for cross polarized antennas, there is a limitation that the
phase difference between the two antennas having the same position
but different polarization directions has to be twice as much as
the phase difference between two antennas of the same polarization
direction. A modified rank-1 codebook for addressing such cross
polarization is shown in and described with respect to FIG. 3,
below.
[0019] Referring now to FIG. 3, a conceptual diagram of a codebook
having at least some vectors optimized for cross-polarized antennas
in accordance with one or more embodiments will be discussed.
Codebook 200 of FIG. 3 may be substantially similar to the codebook
200 of FIG. 2 optionally having at least some rank-2 codewords that
are non-nested, with the modification that at least some of the
rank-1 codewords may include one or more Discrete Fourier Transform
(DFT) vectors 218 and at last some of the rank-1 codewords may
include one or more vector optimized for cross polarization (X-POL)
220 if the antennas are cross polarized. An example of cross
polarization of antennas is shown in and described with respect to
FIG. 4, below. In one example embodiment, one modification of the
rank-1 codewords 210 may be where half of the DFT vectors 218 may
be utilized, and the remaining half of the DFT vectors may be
replaced with non-DFT vectors 220 specifically optimized for cross
polarized antennas. An example of such a codebook using DFT vectors
218 and non-DFT vectors 220 is shown in Table 2, below.
TABLE-US-00002 TABLE 2 6-bit codebook of 4Tx antennas Rank-1 and
Rank-2 Codebook Number of layers .upsilon. index u.sub.s 1 2 0
u.sub.0 = [1 -1 -1 -1].sup.T W.sub.0.sup.(1) .sup.
W.sub.0.sup.(14)/{square root over (2)} 1 u.sub.1 = [1 -j 1
j].sup.T W.sub.1.sup.(1) .sup. W.sub.1.sup.(12)/{square root over
(2)} 2 u.sub.2 = [1 1 -1 1].sup.T W.sub.2.sup.(1) .sup.
W.sub.2.sup.(12)/{square root over (2)} 3 u.sub.3 = [1 j 1
-j].sup.T W.sub.3.sup.(1) .sup. W.sub.3.sup.(12)/{square root over
(2)} 4 u.sub.4 = [1 (-1 - j)/{square root over (2)} -j (1 -
j)/{square root over (2)}].sup.T W.sub.4.sup.(1) .sup.
W.sub.4.sup.(14)/{square root over (2)} 5 u.sub.5 = [1 (1 -
j)/{square root over (2)} j (-1 - j)/{square root over (2)}].sup.T
W.sub.5.sup.(1) .sup. W.sub.5.sup.(14)/{square root over (2)} 6
u.sub.6 = [1 (1 + j)/{square root over (2)} -j (-1 + j)/{square
root over (2)}].sup.T W.sub.6.sup.(1) .sup.
W.sub.6.sup.(13)/{square root over (2)} 7 u.sub.7 = [1 (-1 +
j)/{square root over (2)} j (1 + j)/{square root over (2)}].sup.T
W.sub.7.sup.(1) .sup. W.sub.7.sup.(13)/{square root over (2)} 8
u.sub.8 = [1 -1 1 1].sup.T W.sub.8.sup.(1) .sup.
W.sub.8.sup.(12)/{square root over (2)} 9 u.sub.9 = [1 -j -1
-j].sup.T W.sub.9.sup.(1) .sup. W.sub.9.sup.(14)/{square root over
(2)} 10 u.sub.10 = [1 1 1 -1].sup.T W.sub.10.sup.(1)
W.sub.10.sup.(13)/{square root over (2)} 11 u.sub.11 = [1 j -1
j].sup.T W.sub.11.sup.(1) W.sub.11.sup.(13)/{square root over (2)}
12 u.sub.12 = [1 -1 -1 1].sup.T W.sub.12.sup.(1)
W.sub.12.sup.(12)/{square root over (2)} 13 u.sub.13 = [1 -1 1
-1].sup.T W.sub.13.sup.(1) W.sub.13.sup.(13)/{square root over (2)}
14 u.sub.14 = [1 1 -1 -1].sup.T W.sub.14.sup.(1)
W.sub.14.sup.(13)/{square root over (2)} 15 u.sub.15 = [1 1 1
1].sup.T W.sub.15.sup.(1) W.sub.15.sup.(12)/{square root over (2)}
16 u.sub.16 = [1 -e.sup.j2.pi.2/32 -e.sup.j4.pi.2/32
-e.sup.j6.pi.2/32].sup.T W.sub.16.sup.(1) W.sub.16.sup.(23)/{square
root over (2)} 17 u.sub.17 = [1 -e.sup.j2.pi.10/32
-e.sup.j4.pi.10/32 -e.sup.j6.pi.10/32].sup.T W.sub.17.sup.(1)
W.sub.17.sup.(34)/{square root over (2)} 18 u.sub.18 = [1
-e.sup.j2.pi.18/32 -e.sup.j4.pi.18/32 -e.sup.j6.pi.18/32].sup.T
W.sub.18.sup.(1) W.sub.18.sup.(13)/{square root over (2)} 19
u.sub.19 = [1 -e.sup.j2.pi.26/32 -e.sup.j4.pi.26/32
-e.sup.j6.pi.26/32].sup.T W.sub.19.sup.(1)
W.sub.19.sup.(34)/{square root over (2)} 20 u.sub.20 = [1
-e.sup.j2.pi.6/32 -e.sup.j4.pi.6/32 -e.sup.j6.pi.6/32].sup.T
W.sub.20.sup.(1) W.sub.20.sup.(13)/{square root over (2)} 21
u.sub.21 = [1 -e.sup.j2.pi.14/32 -e.sup.j4.pi.14/32
-e.sup.j6.pi.14/32].sup.T W.sub.21.sup.(1)
W.sub.21.sup.(24)/{square root over (2)} 22 u.sub.22 = [1
-e.sup.j2.pi.22/32 -e.sup.j4.pi.22/32 -e.sup.j6.pi.22/32].sup.T
W.sub.22.sup.(1) W.sub.22.sup.(12)/{square root over (2)} 23
u.sub.23 = [1 -e.sup.j2.pi.30/32 -e.sup.j4.pi.30/32
-e.sup.j6.pi.30/32].sup.T W.sub.23.sup.(1)
W.sub.23.sup.(14)/{square root over (2)} 24 u.sub.24 = [1 -1 -j
-j].sup.T W.sub.24.sup.(1) W.sub.24.sup.(23)/{square root over (2)}
25 u.sub.25 = [1 -j j -1].sup.T W.sub.25.sup.(1)
W.sub.25.sup.(12)/{square root over (2)} 26 u.sub.26 = [1 1 -j
j].sup.T W.sub.26.sup.(1) W.sub.26.sup.(34)/{square root over (2)}
27 u.sub.27 = [1 j j 1].sup.T W.sub.27.sup.(1)
W.sub.27.sup.(13)/{square root over (2)} 28 u.sub.28 = [1 -1 j
j].sup.T W.sub.28.sup.(1) W.sub.28.sup.(12)/{square root over (2)}
29 u.sub.29 = [1 -j -j 1].sup.T W.sub.29.sup.(1)
W.sub.29.sup.(13)/{square root over (2)} 30 u.sub.30 = [1 1 j
-j].sup.T W.sub.30.sup.(1) W.sub.30.sup.(12)/{square root over (2)}
31 u.sub.31 = [1 j -j -1].sup.T W.sub.31.sup.(1)
W.sub.31.sup.(14)/{square root over (2)} 32 u.sub.32 = [1
-e.sup.j2.pi.2/32 -e.sup.j40.pi./32 -e.sup.j44.pi./32].sup.T
W.sub.32.sup.(1) W.sub.32.sup.(12)/{square root over (2)} 33
u.sub.33 = [1 -e.sup.j2.pi.10/32 -e.sup.j8.pi./32
-e.sup.j28.pi./32].sup.T W.sub.33.sup.(1) W.sub.33.sup.(34)/{square
root over (2)} 34 u.sub.34 = [1 -e.sup.j2.pi.18/32
-e.sup.j40.pi./32 -e.sup.j12.pi./32].sup.T W.sub.34.sup.(1)
W.sub.34.sup.(14)/{square root over (2)} 35 u.sub.35 = [1
-e.sup.j2.pi.26/32 -e.sup.j8.pi./32 -e.sup.j50.pi./32].sup.T
W.sub.35.sup.(1) W.sub.35.sup.(13)/{square root over (2)} 36
u.sub.36 = [1 -e.sup.j2.pi.2/32 -e.sup.j24.pi./32
-e.sup.j28.pi./32].sup.T W.sub.36.sup.(1) W.sub.36.sup.(12)/{square
root over (2)} 37 u.sub.37 = [1 -e.sup.j2.pi.10/32
-e.sup.j56.pi./32 -e.sup.j12.pi./32].sup.T W.sub.37.sup.(1)
W.sub.37.sup.(34)/{square root over (2)} 38 u.sub.38 = [1
-e.sup.j2.pi.18/32 -e.sup.j24.pi.21/32 -e.sup.j60.pi./32].sup.T
W.sub.38.sup.(1) W.sub.38.sup.(34)/{square root over (2)} 39
u.sub.39 = [1 -e.sup.j2.pi.26/32 -e.sup.j56.pi./32
-e.sup.j44.pi./32].sup.T W.sub.39.sup.(1) W.sub.39.sup.(14)/{square
root over (2)} 40 u.sub.40 = [1 -e.sup.j2.pi.2/32 -e.sup.j56.pi./32
-e.sup.j60.pi./32].sup.T W.sub.40.sup.(1) W.sub.40.sup.(13)/{square
root over (2)} 41 u.sub.41 = [1 -e.sup.j2.pi.10/32
-e.sup.j24.pi./32 -e.sup.j44.pi./32].sup.T W.sub.41.sup.(1)
W.sub.41.sup.(23)/{square root over (2)} 42 u.sub.42 = [1
-e.sup.j2.pi.18/32 -e.sup.j56.pi./32 -e.sup.j28.pi./32].sup.T
W.sub.42.sup.(1) W.sub.42.sup.(24)/{square root over (2)} 43
u.sub.43 = [1 -e.sup.j2.pi.36/32 -e.sup.j24.pi./32
-e.sup.j12.pi./32].sup.T W.sub.43.sup.(1) W.sub.43.sup.(24)/{square
root over (2)} 44 u.sub.44 = [1 -e.sup.j2.pi.6/32 -e.sup.j56.pi./32
-e.sup.j4.pi./32].sup.T W.sub.44.sup.(1) W.sub.44.sup.(12)/{square
root over (2)} 45 u.sub.45 = [1 -e.sup.j2.pi.14/32
-e.sup.j24.pi./32 -e.sup.j52.pi./32].sup.T W.sub.45.sup.(1)
W.sub.45.sup.(13)/{square root over (2)} 46 u.sub.46 = [1
-e.sup.j2.pi.22/32 -e.sup.j56.pi./32 -e.sup.j56.pi./32].sup.T
W.sub.46.sup.(1) W.sub.46.sup.(12)/{square root over (2)} 47
u.sub.47 = [1 -e.sup.j2.pi.30/32 -e.sup.j24.pi./32
-e.sup.j20.pi./32].sup.T W.sub.47.sup.(1) W.sub.47.sup.(12)/{square
root over (2)} 48 u.sub.48 = [1 (-1 - j)/{square root over (2)} j
(-1 + j)/{square root over (2)}].sup.T W.sub.48.sup.(1)
W.sub.48.sup.(34)/{square root over (2)} 49 u.sub.49 = [1 (1 -
j)/{square root over (2)} -j (1 + j)/{square root over (2)}].sup.T
W.sub.49.sup.(1) W.sub.49.sup.(13)/{square root over (2)} 50
u.sub.50 = [1 (1 + j)/{square root over (2)} j (1 - j)/{square root
over (2)}].sup.T W.sub.50.sup.(1) W.sub.50.sup.(23)/{square root
over (2)} 51 u.sub.51 = [1 (-1 + j)/{square root over (2)} -j (-1 -
j)/{square root over (2)}].sup.T W.sub.51.sup.(1)
W.sub.51.sup.(12)/{square root over (2)} 52 u.sub.52 = [1 (-1 -
j)/{square root over (2)} -1 (-1 - j)/{square root over (2)}].sup.T
W.sub.52.sup.(1) W.sub.52.sup.(12)/{square root over (2)} 53
u.sub.53 = [1 (-1 - j)/{square root over (2)} 1 (-1 + j)/{square
root over (2)}].sup.T W.sub.53.sup.(1) W.sub.53.sup.(13)/{square
root over (2)} 54 u.sub.54 = [1 (1 + j)/{square root over (2)} -1
(1 + j)/{square root over (2)}].sup.T W.sub.54.sup.(1)
W.sub.54.sup.(12)/{square root over (2)} 55 u.sub.55 = [1 (-1 +
j)/{square root over (2)} 1 (1 - j)/{square root over (2)}].sup.T
W.sub.55.sup.(1) W.sub.55.sup.(14)/{square root over (2)} 56
u.sub.56 = [1 (-1 - j)/{square root over (2)} 1 (1 + j)/{square
root over (2)}].sup.T W.sub.56.sup.(1) W.sub.56.sup.(23)/{square
root over (2)} 57 u.sub.57 = [1 (-1 - j)/{square root over (2)} -1
(1 - j)/{square root over (2)}].sup.T W.sub.57.sup.(1)
W.sub.57.sup.(23)/{square root over (2)} 58 u.sub.58 = [1 (1 +
j)/{square root over (2)} 1 (-1 - j)/{square root over (2)}].sup.T
W.sub.58.sup.(1) W.sub.58.sup.(23)/{square root over (2)} 59
u.sub.59 = [1 (-1 + j)/{square root over (2)} -1 (-1 + j)/{square
root over (2)}].sup.T W.sub.59.sup.(1) W.sub.59.sup.(14)/{square
root over (2)} 60 u.sub.60 = [2 0 0 0].sup.T W.sub.60.sup.(1)
W.sub.60.sup.(12)/{square root over (2)} 61 u.sub.61 = [0 2 0
0].sup.T W.sub.61.sup.(2) W.sub.61.sup.(12)/{square root over (2)}
62 u.sub.62 = [0 0 2 0].sup.T W.sub.62.sup.(3)
W.sub.62.sup.(13)/{square root over (2)} 63 u.sub.63 = [0 0 0
2].sup.T W.sub.63.sup.(4) W.sub.63.sup.(23)/{square root over
(2)}
[0020] Referring now to FIG. 4, a diagram of cross polarized
antennas for which the codebook of FIG. 3 may be designed to
optimize performance in accordance with one or more embodiments
will be discussed. An example cross polarized (X-Pol) antenna array
400 is shown in FIG. 4 having two pairs of antennas, antenna 410,
antenna 412, antenna 414 and antenna 416, with the same spacing but
the two pairs have different antenna polarizations. The different
polarizations make the phase difference between the corresponding
elements of the two pairs randomly distributed between 0 and 360
degrees wherein .alpha., .beta..about.[0, 2.pi.]. Since a Discrete
Fourier Transform (DFT) based codebook is utilized in Release 8 and
Release 10 of the Third Generation Partnership Project (3GPP)
standard, in one or more embodiments codebook 200 of FIG. 3 may be
optimized for cross polarization of the antennas while maintaining
the backward compatibility as much as possible. For the vector
codebook, the 4.times.1 codebook, the DFT vector has three
properties. The magnitude of each entry is the same, the phase
difference between any two adjacent entries remains the same for
each vector; and the phase of each entry is picked from a finite
alphabet:
{ i 2 .pi. 32 } 32 i = 1 ##EQU00001##
The constant magnitude is for lowering the peak to average power
ratio of the power amplifier. The constant phase difference is
suitable for uniform linear arrays, which have evenly spaced
antenna elements. However, the constant phase difference may not
fit the cross polarized antenna array 400.
[0021] In one or more embodiments, the codebook design may be
optimized for cross polarized antenna array 400 as a likely
deployment scenario. Taking into account the phase structure of
cross polarized antenna array 400, we have the codebook structure
may be created as discussed, below, while maintaining the backward
compatibility as much as possible for the 3GPP standard in addition
to addressing performance for cross polarized antenna array 400.
Examples of suitable codewords for such a codebook 200 having at
least some Rank-1 DFT vectors 218 and at least some Rank-1 vectors
optimized for cross polarization 220 are shown by the
W.sub.n.sup.{k} terms in Table 1 and/or Table 2, above.
[0022] In general, one example process for design of such a
codebook may be as follows:
[0023] 1. The constant magnitude (or constant modulus) property of
the legacy codebook is kept for backward compatibility and low
PAPR.
[0024] 2. The 4.times.1 codeword is of a structure (e.sup.j0
e.sup.j.alpha. e.sup.j.beta. e.sup.j.beta.+.alpha.), where .alpha.
is for quantizing the phase difference between the two co-pol
antennas and .beta. is for quantizing the phase difference between
the two pairs of the cross polarized antennas 400.
[0025] 3. The .alpha. and .beta. are selected from a finite
alphabet, for example,
{ i 2 .pi. 32 } 32 i = 1. ##EQU00002##
[0026] 4. Although the .alpha. and .beta. of the input channel
vector are independently, randomly distributed over [0, 360
degrees], the .alpha. and .beta. of the quantization codebook can
be jointly designed. For example, letting .beta.=2.alpha. results
into a codeword structure of (e.sup.j0 e.sup.j.alpha.
e.sup.j2.alpha. e.sup.j3.alpha.). This codeword structure may be
suitable for a uniform linear array (ULA) of antennas, which also
may be a useful deployment scenario in one or more embodiments. For
covering the 2.pi. range of .beta., one more structure may be
needed, for example (e.sup.j0 e.sup.j.alpha.
e.sup.j2.alpha.+n.delta. e.sup.j3.alpha.n+.delta.), where .delta.
e.g.,
.delta. = .pi. 2 ##EQU00003##
is in the finite alphabet e.g.,
{ i 2 .pi. 32 } 32 i = 1 ##EQU00004##
and n is an integer taking values from 0, 1, . . . , N such that
N.delta..ltoreq.2.pi. e.g., N=4. In other words, the stepping
through of the .alpha. and .beta. over [0, 360 degrees] may be
synchronized in constructing the quantization codewords such that
codewords of (e.sup.j0 e.sup.j.alpha. e.sup.j2.alpha.
e.sup.j3.alpha.) structure may be generated without scarifying the
quantization performance of cross polarized antennas 400 and help
the quantization performance of a uniform linear array (ULA) of
antennas antenna as an additional benefit. It should be noted,
however, that this is merely one example of a structure of a
codebook 200 capable of accommodating cross polarized antennas 400
while also maintaining backwards compatibility with a legacy 3GPP
codebook, and the scope of the claimed subject matter is not
limited in this respect.
[0027] Referring now to FIG. 5, a flow diagram of a method to
perform a codeword search for a single user multiple-input,
multiple-output (SU-MIMO) system in accordance with one or more
embodiments will be discussed. It should be noted that although
FIG. 5 illustrates one particular embodiment of method 500,
alternative embodiments of method 500 may be realized for example
where method 500 includes more or fewer blocks than shown, and/or
in various other orders, and the scope of the claimed subject
matter is not limited in these respects. In one or more
embodiments, UE 112 may optimize a codeword search method if UE 112
has knowledge of the scheduling preference of eNB 110. If UE 112 is
only configured with one channel state information (CSI) reporting
process, eNB 110 needs a minimum of one bit for broadcasting a
signaling to indicate its scheduling preference. In Release 10 of
the Third Generation Partnership Project (3GPP) standard, it has
been standardized that UE 112 may be configured with two CSI
reporting processes. In such an arrangement, eNB 110 may configure
one CSI process for single user multiple-input, multiple-output
(SU-MIMO) CSI and the other CSI process for multi-user
multiple-input, multiple-output (MU-MIMO) CSI. Since one CSI
process may be dedicated to MU-MIMO, in accordance with one or more
embodiments, a codeword search process may be further optimized by
leveraging both the rank-1 and rank-2 codebooks.
[0028] For a CSI search method for SU-MIMO as shown in FIG. 5, UE
112 may perform a CSI search at block 510 to find a best precoding
matrix indicator (PMI) for each of rank-1 and rank-2. The PMI
search algorithm for a given rank may be described by the following
equation:
i r = arg max ( capacity ( v i , H , C ) ) v i .di-elect cons. C r
##EQU00005##
where C.sub.r is the codebook of rank, r, H is the measured channel
matrix of one subcarrier, i.sub.r is the best PMI for rank, r, and
C is the interference covariance matrix. After UE 112 determines
the best PMI for each rank at block 510, at block 512 UE 112 may
select the best rank, rank-1 or rank-2, using the following
equation:
r best = arg max ( capacity ( v i r , H , C ) ) 1 .ltoreq. r r max
##EQU00006##
At block 514, UE 112 reports the better or best rank and the best
PMI/CQI for the better or best rank accordingly. By utilizing
method 500 of FIG. 5, the capacity for SU-MIMO may be maximized or
nearly maximized, although the scope of the claimed subject matter
is not limited in this respect.
[0029] Referring now to FIG. 6, a flow diagram of a method to
perform a codeword search for a multi-user multiple-input,
multiple-output (MU-MIMO) system in accordance with one or more
embodiments will be discussed. It should be noted that although
FIG. 6 illustrates one particular embodiment of method 600,
alternative embodiments of method 600 may be realized for example
where method 600 includes more or fewer blocks than shown, and/or
in various other orders, and the scope of the claimed subject
matter is not limited in these respects. At block 610, UE 112 may
perform a CSI search to find a better or best rank for rank-1 and
rank-2 using each column of each codeword as a rank-1 precoder in
the following equation:
( l r , i r ) = arg max ( trace ( rv i ( : , l ) H Rv i ( : , l ) )
) v i .di-elect cons. C r , 1 .ltoreq. l .ltoreq. r
##EQU00007##
where C.sub.r is the codebook of rank r, R is the channel
covariance matrix of one subcarrier or one band, and i.sub.r is the
best PMI for rank r. After UE 112 determines a better or best PMI
for rank-1 and rank-2, UE 112 determines the better or best rank at
block 612 using the following equation:
r best = arg max ( trace ( rv i r ( : , l ) H Rv i r ( : , l r ) )
) r = 1 , 2 ##EQU00008##
At block 614 UE 112 then reports the better or best rank and the
best PMI/CQI for the better or best rank accordingly. The algorithm
of method 600 may minimize the quantization error of the principal
Eigen beam. It should be noted that it also may be possible to
apply the better or best rank search equation of block 510 of FIG.
5 to search for the best rank-1 vector for MU-MIMO instead of using
the equations of block 610 and 612 of method 600, although
performance may be suboptimal. Since the nesting property of the
codebooks of Release 8 and Release 10 of the Third Generation
Partnership Project (3GPP) standard reduces the codeword and/or
rank search complexity with a tradeoff of performance, the nesting
property optionally may be removed. Since the first column of each
rank-2 codeword does not need to be the same as its corresponding
rank-1 codeword, there are more rank-1 vectors available in rank-1
and rank-2 codebooks overall than before so that the quantization
error of rank-1 input may be reduced. Therefore, in order to
maximize the channel capacity using the MU-MIMO optimized search
method 600 of FIG. 6, the nesting constraint optionally need not be
imposed on the newly added 48 codewords in Table 1 and/or Table 2
as discussed, above, although the scope of the claimed subject
matter is not limited in this respect.
[0030] Referring now to FIG. 7, a block diagram of an information
handling system capable of utilizing a codebook and/or performing a
codebook search in accordance with one or more embodiments will be
discussed. Information handling system 700 of FIG. 7 may tangibly
embody any one or more of the elements described herein, above,
including for example eNB 110 and/or UE 112, with greater or fewer
components depending on the hardware specifications of the
particular device. Although information handling system 700
represents one example of several types of computing platforms,
information handling system 700 may include more or fewer elements
and/or different arrangements of elements than shown in FIG. 7, and
the scope of the claimed subject matter is not limited in these
respects.
[0031] In one or more embodiments, information handling system 700
may include an application processor 710 and a baseband processor
712. Application processor 710 may be utilized as a general-purpose
processor to run applications and the various subsystems for
information handling system 700. Application processor 710 may
include a single core or alternatively may include multiple
processing cores wherein one or more of the cores may comprise a
digital signal processor or digital signal processing (DSP) core.
Furthermore, application processor 710 may include a graphics
processor or coprocessor disposed on the same chip, or
alternatively a graphics processor coupled to application processor
710 may comprise a separate, discrete graphics chip. Application
processor 710 may include on board memory such as cache memory, and
further may be coupled to external memory devices such as
synchronous dynamic random access memory (SDRAM) 714 for storing
and/or executing applications during operation, and NAND flash 716
for storing applications and/or data even when information handling
system 700 is powered off. In one or more embodiments, instructions
to operate or configure the information handling system 700 and/or
any of its components or subsystems to operate in a manner as
described herein may be stored on a article of manufacture
comprising a non-transitory storage medium. In one or more
embodiments, the storage medium may comprise any of the memory
devices shown in and described herein, although the scope of the
claimed subject matter is not limited in this respect. Baseband
processor 712 may control the broadband radio functions for
information handling system 700. Baseband processor 712 may store
code for controlling such broadband radio functions in a NOR flash
718. Baseband processor 712 controls a wireless wide area network
(WWAN) transceiver 720 which is used for modulating and/or
demodulating broadband network signals, for example for
communicating via a 3GPP LTE or LTE-Advanced network or the
like.
[0032] In general, WWAN transceiver 720 may operate according to
any one or more of the following radio communication technologies
and/or standards including but not limited to: a Global System for
Mobile Communications (GSM) radio communication technology, a
General Packet Radio Service (GPRS) radio communication technology,
an Enhanced Data Rates for GSM Evolution (EDGE) radio communication
technology, and/or a Third Generation Partnership Project (3GPP)
radio communication technology, for example Universal Mobile
Telecommunications System (UMTS), Freedom of Multimedia Access
(FOMA), 3GPP Long Term Evolution (LTE), 3GPP Long Term Evolution
Advanced (LTE Advanced), Code division multiple access 2000
(CDMA2000), Cellular Digital Packet Data (CDPD), Mobitex, Third
Generation (3G), Circuit Switched Data (CSD), High-Speed
Circuit-Switched Data (HSCSD), Universal Mobile Telecommunications
System (Third Generation) (UMTS (3G)), Wideband Code Division
Multiple Access (Universal Mobile Telecommunications System)
(W-CDMA (UMTS)), High Speed Packet Access (HSPA), High-Speed
Downlink Packet Access (HSDPA), High-Speed Uplink Packet Access
(HSUPA), High Speed Packet Access Plus (HSPA+), Universal Mobile
Telecommunications System-Time-Division Duplex (UMTS-TDD), Time
Division-Code Division Multiple Access (TD-CDMA), Time
Division-Synchronous Code Division Multiple Access (TD-CDMA), 3rd
Generation Partnership Project Release 8 (Pre-4th Generation) (3GPP
Rel. 8 (Pre-4G)), UMTS Terrestrial Radio Access (UTRA), Evolved
UMTS Terrestrial Radio Access (E-UTRA), Long Term Evolution
Advanced (4th Generation) (LTE Advanced (4G)), cdmaOne (2G), Code
division multiple access 2000 (Third generation) (CDMA2000 (3G)),
Evolution-Data Optimized or Evolution-Data Only (EV-DO), Advanced
Mobile Phone System (1st Generation) (AMPS (1G)), Total Access
Communication System/Extended Total Access Communication System
(TACS/ETACS), Digital AMPS (2nd Generation) (D-AMPS (2G)),
Push-to-talk (PTT), Mobile Telephone System (MTS), Improved Mobile
Telephone System (IMTS), Advanced Mobile Telephone System (AMTS),
OLT (Norwegian for Offentlig Landmobil Telefoni, Public Land Mobile
Telephony), MTD (Swedish abbreviation for Mobiltelefonisystem D, or
Mobile telephony system D), Public Automated Land Mobile
(Autotel/PALM), ARP (Finnish for Autoradiopuhelin, "car radio
phone"), NMT (Nordic Mobile Telephony), High capacity version of
NTT (Nippon Telegraph and Telephone) (Hicap), Cellular Digital
Packet Data (CDPD), Mobitex, DataTAC, Integrated Digital Enhanced
Network (iDEN), Personal Digital Cellular (PDC), Circuit Switched
Data (CSD), Personal Handy-phone System (PHS), Wideband Integrated
Digital Enhanced Network (WiDEN), iBurst, Unlicensed Mobile Access
(UMA), also referred to as also referred to as 3GPP Generic Access
Network, or GAN standard), Zigbee, Bluetooth.RTM., and/or general
telemetry transceivers, and in general any type of RF circuit or
RFI sensitive circuit. It should be noted that such standards may
evolve over time, and/or new standards may be promulgated, and the
scope of the claimed subject matter is not limited in this
respect.
[0033] The WWAN transceiver 720 couples to one or more power amps
722 respectively coupled to one or more antennas 724 for sending
and receiving radio-frequency signals via the WWAN broadband
network. The baseband processor 712 also may control a wireless
local area network (WLAN) transceiver 726 coupled to one or more
suitable antennas 728 and which may be capable of communicating via
a Wi-Fi, Bluetooth.RTM., and/or an amplitude modulation (AM) or
frequency modulation (FM) radio standard including an IEEE
802.11a/b/g/n standard or the like. It should be noted that these
are merely example implementations for application processor 710
and baseband processor 712, and the scope of the claimed subject
matter is not limited in these respects. For example, any one or
more of SDRAM 814, NAND flash 716 and/or NOR flash 718 may comprise
other types of memory technology such as magnetic memory,
chalcogenide memory, phase change memory, or ovonic memory, and the
scope of the claimed subject matter is not limited in this
respect.
[0034] In one or more embodiments, application processor 710 may
drive a display 730 for displaying various information or data, and
may further receive touch input from a user via a touch screen 732
for example via a finger or a stylus. An ambient light sensor 734
may be utilized to detect an amount of ambient light in which
information handling system 700 is operating, for example to
control a brightness or contrast value for display 730 as a
function of the intensity of ambient light detected by ambient
light sensor 734. One or more cameras 736 may be utilized to
capture images that are processed by application processor 710
and/or at least temporarily stored in NAND flash 716. Furthermore,
application processor may couple to a gyroscope 738, accelerometer
740, magnetometer 742, audio coder/decoder (CODEC) 744, and/or
global positioning system (GPS) controller 746 coupled to an
appropriate GPS antenna 748, for detection of various environmental
properties including location, movement, and/or orientation of
information handling system 700. Alternatively, controller 746 may
comprise a Global Navigation Satellite System (GNSS) controller.
Audio CODEC 744 may be coupled to one or more audio ports 750 to
provide microphone input and speaker outputs either via internal
devices and/or via external devices coupled to information handling
system via the audio ports 750, for example via a headphone and
microphone jack. In addition, application processor 710 may couple
to one or more input/output (I/O) transceivers 752 to couple to one
or more I/O ports 754 such as a universal serial bus (USB) port, a
high-definition multimedia interface (HDMI) port, a serial port,
and so on. Furthermore, one or more of the I/O transceivers 752 may
couple to one or more memory slots 756 for optional removable
memory such as secure digital (SD) card or a subscriber identity
module (SIM) card, although the scope of the claimed subject matter
is not limited in these respects.
[0035] Referring now to FIG. 8, an isometric view of an information
handling system of FIG. 7 that optionally may include a touch
screen in accordance with one or more embodiments will be
discussed. FIG. 8 shows an example implementation of information
handling system 700 of FIG. 7 tangibly embodied as a cellular
telephone, smartphone, or tablet type device or the like. The
information handling system 700 may comprise a housing 810 having a
display 830 which may include a touch screen 832 for receiving
tactile input control and commands via a finger 816 of a user
and/or a via stylus 818 to control one or more application
processors 710. The housing 810 may house one or more components of
information handling system 700, for example one or more
application processors 710, one or more of SDRAM 714, NAND flash
716, NOR flash 718, baseband processor 712, and/or WWAN transceiver
720. The information handling system 700 further may optionally
include a physical actuator area 820 which may comprise a keyboard
or buttons for controlling information handling system via one or
more buttons or switches. The information handling system 700 may
also include a memory port or slot 756 for receiving non-volatile
memory such as flash memory, for example in the form of a secure
digital (SD) card or a subscriber identity module (SIM) card.
Optionally, the information handling system 700 may further include
one or more speakers and/or microphones 824 and a connection port
754 for connecting the information handling system 700 to another
electronic device, dock, display, battery charger, and so on. In
addition, information handling system 700 may include a headphone
or speaker jack 828 and one or more cameras 736 on one or more
sides of the housing 810. It should be noted that the information
handling system 700 of FIG. 8 may include more or fewer elements
than shown, in various arrangements, and the scope of the claimed
subject matter is not limited in this respect.
[0036] Although the claimed subject matter has been described with
a certain degree of particularity, it should be recognized that
elements thereof may be altered by persons skilled in the art
without departing from the spirit and/or scope of claimed subject
matter. It is believed that the subject matter pertaining to
cooperative multiple beam transmission and/or many of its attendant
utilities will be understood by the forgoing description, and it
will be apparent that various changes may be made in the form,
construction and/or arrangement of the components thereof without
departing from the scope and/or spirit of the claimed subject
matter or without sacrificing all of its material advantages, the
form herein before described being merely an explanatory embodiment
thereof, and/or further without providing substantial change
thereto. It is the intention of the claims to encompass and/or
include such changes.
* * * * *