U.S. patent application number 13/016572 was filed with the patent office on 2011-05-12 for method and computer program product for precoding.
This patent application is currently assigned to Huawei Technologies Co., Ltd.. Invention is credited to Qiang Wu, Yongxing Zhou.
Application Number | 20110110448 13/016572 |
Document ID | / |
Family ID | 43543946 |
Filed Date | 2011-05-12 |
United States Patent
Application |
20110110448 |
Kind Code |
A1 |
Zhou; Yongxing ; et
al. |
May 12, 2011 |
Method and Computer Program Product for Precoding
Abstract
A method and a computer program product for precoding are
provided. The precoding method includes selecting, by a processor,
a codeword for precoding data from a codebook, wherein the codebook
includes 1 2 [ 0 1 0 1 0 0 0 0 1 1 0 0 ] , 1 2 [ 0 1 0 1 0 0 0 0 1
- 1 0 0 ] , 1 2 [ 1 0 0 0 1 0 1 0 0 0 0 1 ] , 1 2 [ 1 0 0 0 1 0 - 1
0 0 0 0 1 ] , 1 2 [ 1 0 0 1 0 0 0 1 0 0 0 1 ] , 1 2 [ 1 0 0 - 1 0 0
0 1 0 0 0 1 ] , 1 2 [ 0 1 0 0 0 1 1 0 0 1 0 0 ] , 1 2 [ 0 1 0 0 0 1
1 0 0 - 1 0 0 ] , 1 2 [ 1 0 0 0 0 1 0 1 0 1 0 0 ] , 1 2 [ 1 0 0 0 0
1 0 1 0 - 1 0 0 ] , 1 2 [ 0 1 0 1 0 0 1 0 0 0 0 1 ] , and 1 2 [ 0 1
0 1 0 0 - 1 0 0 0 0 1 ] . ##EQU00001##
Inventors: |
Zhou; Yongxing; (Long Beach,
CA) ; Wu; Qiang; (Shenzhen, CN) |
Assignee: |
Huawei Technologies Co.,
Ltd.
Shenzhen
CN
|
Family ID: |
43543946 |
Appl. No.: |
13/016572 |
Filed: |
January 28, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12983103 |
Dec 31, 2010 |
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13016572 |
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PCT/CN2010/075788 |
Aug 9, 2010 |
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12983103 |
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Current U.S.
Class: |
375/260 ;
341/106 |
Current CPC
Class: |
H04W 72/042 20130101;
Y02D 30/70 20200801; H04L 25/03929 20130101; H04B 17/318 20150115;
Y02D 70/444 20180101; Y02D 70/1264 20180101; H04B 7/0465 20130101;
H04B 7/043 20130101; Y02D 70/1262 20180101 |
Class at
Publication: |
375/260 ;
341/106 |
International
Class: |
H04L 27/28 20060101
H04L027/28; H03M 7/00 20060101 H03M007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 7, 2009 |
CN |
200910091108.5 |
Aug 14, 2009 |
CN |
200910165292.3 |
Claims
1. A method for precoding, comprising: using a processor to select
a codeword for precoding data from a codebook, wherein the codebook
comprises 1 2 [ 0 1 0 1 0 0 0 0 1 1 0 0 ] , 1 2 [ 0 1 0 1 0 0 0 0 1
- 1 0 0 ] , 1 2 [ 1 0 0 0 1 0 1 0 0 0 0 1 ] , 1 2 [ 1 0 0 0 1 0 - 1
0 0 0 0 1 ] , 1 2 [ 1 0 0 1 0 0 0 1 0 0 0 1 ] , 1 2 [ 1 0 0 - 1 0 0
0 1 0 0 0 1 ] , 1 2 [ 0 1 0 0 0 1 1 0 0 1 0 0 ] , 1 2 [ 0 1 0 0 0 1
1 0 0 - 1 0 0 ] , 1 2 [ 1 0 0 0 0 1 0 1 0 1 0 0 ] , 1 2 [ 1 0 0 0 0
1 0 1 0 - 1 0 0 ] , 1 2 [ 0 1 0 1 0 0 1 0 0 0 0 1 ] , and 1 2 [ 0 1
0 1 0 0 - 1 0 0 0 0 1 ] . ##EQU00038##
2. The method for precoding of claim 1, wherein the data is uplink
data.
3. The method for precoding of claim 1, wherein the method is
applied in a Long Term Evolution-Advanced (LTE-A) system.
4. A computer program product for storing instructions operable in
a base station, comprising: a non-transitory computer-readable
medium comprising code for selecting a codeword for precoding data
from a codebook, wherein the codebook comprises 1 2 [ 0 1 0 1 0 0 0
0 1 1 0 0 ] , 1 2 [ 0 1 0 1 0 0 0 0 1 - 1 0 0 ] , 1 2 [ 1 0 0 0 1 0
1 0 0 0 0 1 ] , 1 2 [ 1 0 0 0 1 0 - 1 0 0 0 0 1 ] , 1 2 [ 1 0 0 1 0
0 0 1 0 0 0 1 ] , 1 2 [ 1 0 0 - 1 0 0 0 1 0 0 0 1 ] , 1 2 [ 0 1 0 0
0 1 1 0 0 1 0 0 ] , 1 2 [ 0 1 0 0 0 1 1 0 0 - 1 0 0 ] , 1 2 [ 1 0 0
0 0 1 0 1 0 1 0 0 ] , 1 2 [ 1 0 0 0 0 1 0 1 0 - 1 0 0 ] , 1 2 [ 0 1
0 1 0 0 1 0 0 0 0 1 ] , and 1 2 [ 0 1 0 1 0 0 - 1 0 0 0 0 1 ] .
##EQU00039##
5. The computer program product of claim 4, wherein the base
station is applied in a Long Term Evolution-Advanced (LTE-A)
system.
6. The computer program product of claim 4, wherein the data is
uplink data.
7. A computer program product for storing instructions operable in
a user equipment, comprising: a non-transitory computer-readable
medium comprising code for precoding data using a codeword from a
codebook, wherein the codebook comprises 1 2 [ 0 1 0 1 0 0 0 0 1 1
0 0 ] , 1 2 [ 0 1 0 1 0 0 0 0 1 - 1 0 0 ] , 1 2 [ 1 0 0 0 1 0 1 0 0
0 0 1 ] , 1 2 [ 1 0 0 0 1 0 - 1 0 0 0 0 1 ] , 1 2 [ 1 0 0 1 0 0 0 1
0 0 0 1 ] , 1 2 [ 1 0 0 - 1 0 0 0 1 0 0 0 1 ] , 1 2 [ 0 1 0 0 0 1 1
0 0 1 0 0 ] , 1 2 [ 0 1 0 0 0 1 1 0 0 - 1 0 0 ] , 1 2 [ 1 0 0 0 0 1
0 1 0 1 0 0 ] , 1 2 [ 1 0 0 0 0 1 0 1 0 - 1 0 0 ] , 1 2 [ 0 1 0 1 0
0 1 0 0 0 0 1 ] , and 1 2 [ 0 1 0 1 0 0 - 1 0 0 0 0 1 ] .
##EQU00040##
8. The computer program product of claim 7, wherein the user
equipment is applied in a Long Term Evolution-Advanced (LTE-A)
system.
9. The computer program product of claim 7, wherein the data is
uplink data.
Description
[0001] This application is a continuation of U.S. patent
application Ser. No. 12/983,103, filed on Dec. 31, 2010, which is a
continuation of co-pending International Application No.
PCT/CN2010/075788, filed on Aug. 9, 2010, which designated the
United States and was not published in English, and which claims
priority to Chinese Application No. 200910091108.5, filed on Aug.
7, 2009, and Chinese Application No. 200910165292.3, filed on Aug.
14, 2009. All of these applications are incorporated herein by
reference.
TECHNICAL FIELD
[0002] The present invention relates to the field of communication
technology, and in particular, to a method and a computer program
product for precoding.
BACKGROUND
[0003] The Long Term Evolution-Advanced (LTE-A) is a subsequent
evolution of the LTE technology. In the LTE-A, the Single Carrier
Frequency Division Multiple Access (SC-FDMA) in the LTE continues
to be adopted as a coding mode for the uplink data. The LTE-A can
at most support four antennas to transmit data at the same time, so
precoding of the uplink data by adopting a codebook becomes
possible.
[0004] In the process of implementing the present invention, the
inventors find that the prior art at least has the following
problems. In a case of a high signal-to-noise ratio, if data to be
transmitted is being precoded by adopting an existing codebook
structure, a loss occurs to a transmit performance of the transmit
antenna, and if a transmit power of the transmit antenna is
restricted, the power amplification of the transmit antenna can not
be completely used for full power transfer.
SUMMARY OF THE INVENTION
[0005] The embodiments of the present invention provide a method
and a computer program product for precoding, so as to solve the
problems of the loss of the transmit performance of the transmit
antenna and the incapability of full power transmission if the
transmit power is restricted.
[0006] An embodiment of the present invention provides a method for
precoding, where the method includes obtaining a total uplink power
of a User Equipment (UE); and if the total uplink power is smaller
than or equal to 3/4 of a rated total transmit power of antennas,
selecting a codeword from a first codebook with imbalanced power
between layers and a second codebook with balanced power between
layers, so the UE precodes data to be transmitted according to the
selected codeword.
[0007] Correspondingly, an embodiment of the present invention
provides a BS, where the BS includes an obtaining module, adapted
to obtain a total uplink power of a UE; and a first processing
module, adapted to select a codeword from a first codebook with
imbalanced power between layers and a second codebook with balanced
power between layers if the total uplink power obtained by the
obtaining module is smaller than equal to 3/4 of a rated total
transmit power of antennas, so the UE precodes data to be
transmitted according to the selected codeword.
[0008] In the embodiments of the precoding method and the
corresponding BS according to the present invention, the BS can
select a codeword from a corresponding codebook for precoding data
to be transmitted according to a relationship between the total
uplink power reported by the UE and the maximal rated total power
of the antenna of the BS, so the UE precodes data to be transmitted
according to the selected codeword. As in the method in this
embodiment, the codebook structure adopts a first codebook with
imbalanced power between layers and a second codebook with balanced
structures between layers, if the codeword is being selected from
the second codebook for precoding, loss of an antenna performance
at a high signal-to-noise ratio is reduced, and if the codeword is
selected from the first codebook for precoding, loss of the power
amplification of the antenna can be reduced if the transmit power
of the antenna is restricted.
[0009] In view of the problem in prior art that cubic metric (CM)
characteristics are unable to be preserved, an embodiment of the
present invention further provides another precoding method, where
the method includes allocating a sub-carrier resource to a UE; and
if the sub-carrier resource is continuously allocated, selecting a
cubic metric preserving (CMP) codebook for precoding data to be
transmitted; otherwise, selecting a cubic metric friendly (CMF)
codebook for precoding data to be transmitted.
[0010] Correspondingly, an embodiment of the present invention
further provides a BS, where the BS includes an allocation module,
adapted to allocate a sub-carrier resource to the UE; and a second
processing module, adapted to select a CMP codebook for precoding
data to be transmitted if the sub-carrier resource is continuously
allocated; otherwise, select a CMF codebook for precoding data to
be transmitted.
[0011] In the embodiments of the precoding method and the
corresponding BS according to the present invention, the BS can
select a codeword from different codebooks respectively for
precoding data to be transmitted according to different types of
the sub-carrier resource allocated by the UE, such that the CM
characteristics are guaranteed by selecting the codeword in the CMP
codebook if the sub-carrier resource is continuously allocated.
[0012] As a code distance of the codebook structure in the prior
art is too small and complexity is relatively high, an embodiment
of the present invention provides a codebook, where the codebook
includes at least one codeword of
1 2 [ 0 1 0 1 0 0 0 0 1 1 0 0 ] , 1 2 [ 0 1 0 1 0 0 0 0 1 - 1 0 0 ]
, 1 2 [ 1 0 0 0 1 0 1 0 0 0 0 1 ] , 1 2 [ 1 0 0 0 1 0 - 1 0 0 0 0 1
] , 1 2 [ 1 0 0 1 0 0 0 1 0 0 0 1 ] , 1 2 [ 1 0 0 - 1 0 0 0 1 0 0 0
1 ] , 1 2 [ 0 1 0 0 0 1 1 0 0 1 0 0 ] , 1 2 [ 0 1 0 0 0 1 1 0 0 - 1
0 0 ] , 1 2 [ 1 0 0 0 0 1 0 1 0 1 0 0 ] , 1 2 [ 1 0 0 0 0 1 0 1 0 -
1 0 0 ] , 1 2 [ 0 1 0 1 0 0 1 0 0 0 0 1 ] , and 1 2 [ 0 1 0 1 0 0 -
1 0 0 0 0 1 ] . ##EQU00002##
[0013] As fewer codewords are used in the codebook, an average code
distance is increased, and the Quadrature Phase Shift Keying (QPSK)
character set is not used in the codebook, so the complexity is
relatively reduced.
[0014] In view of that in the prior art the CM characteristics are
unable to be preserved in the codebook structure, an embodiment of
the present invention further provides another codebook, where the
codebook includes at least one codeword of
1 5 [ 0.5 1 0 - 0.5 1 0 0.5 0 1 0.5 j 0 - j ] , 1 5 [ 0.5 1 0 0.5 j
0 1 - 0.5 j j 0 - 0.5 j 0 1 ] , 1 5 [ 0.5 1 0 - 0.5 1 0 0.5 j 0 1
0.5 0 j ] , 1 5 [ 0.5 1 0 - 0.5 j 0 1 - 0.5 1 0 - 0.5 0 j ] , 1 5 [
0.5 1 0 0.5 j - j 0 - 0.5 0 1 0.5 0 1 ] , 1 5 [ 0.5 1 0 0.5 j - j 0
0.5 j 0 1 0.5 j 0 - 1 ] , 1 5 [ 0.5 1 0 - 0.5 0 1 - 0.5 j 0 - j -
0.5 1 0 ] , 1 5 [ 0.5 1 0 0.5 - 1 0 0.5 j 0 1 - 0.5 0 - j ] , 1 5 [
0.5 1 0 - 0.5 0 1 - 0.5 0 - 1 - 0.5 j j 0 ] , 1 5 [ 0.5 1 0 0.5 0 1
0.5 j - j 0 - 0.5 0 1 ] , 1 5 [ 0.5 1 0 - 0.5 j 0 1 - 0.5 j 0 - 1
0.5 j - j 0 ] , 1 5 [ 0.5 1 0 0.5 0 1 0.5 - 1 0 - 0.5 j 0 j ] , 1 5
[ 0.5 1 0 - 0.5 j j 0 - 0.5 j 0 1 0.5 j 0 1 ] , 1 5 [ 0.5 1 0 - 0.5
0 1 0.5 0 1 0.5 j - j 0 ] , and 1 5 [ 0.5 1 0 - 0.5 j j 0 - 0.5 0 1
- 0.5 0 - 1 ] . ##EQU00003##
[0015] In the codebook, by introducing imbalanced power between
layers, a power of a column with all elements being non-zero is
further reduced, so the CM value is reduced and the CM
characteristics are improved.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] To illustrate the technical solutions according to the
embodiments of the present invention more clearly, the accompanying
drawings for describing the embodiments are introduced briefly in
the following. Apparently, the accompanying drawings in the
following description are only some embodiments of the present
invention, and persons of ordinary skill in the art can derive
other drawings from the accompanying drawings without creative
efforts.
[0017] FIG. 1 is a flow chart of an embodiment of a precoding
method according to the present invention;
[0018] FIG. 2 is a flow chart of another embodiment of the
precoding method according to the present invention;
[0019] FIG. 3 is a comparison diagram between simulation results of
a codebook of the present invention and a codebook as shown in
expression (1);
[0020] FIG. 4 is a schematic structural view of an embodiment of a
BS according to the present invention;
[0021] FIG. 5 is a schematic structural view of another embodiment
of the BS according to the present invention;
[0022] FIG. 6 is a schematic structural view of yet another
embodiment of the BS according to the present invention; and
[0023] FIG. 7 is a schematic structural view of yet another
embodiment of the BS according to the present invention.
DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
[0024] The technical solution of the embodiments of the present
invention will be clearly and completely described in the following
with reference to the accompanying drawings. It is obvious that the
embodiments to be described are only a part rather than all of the
embodiments of the present invention. All other embodiments
obtained by persons skilled in the art based on the embodiments of
the present invention without creative efforts shall fall within
the protection scope of the present invention.
[0025] FIG. 1 is a flow chart of an embodiment of a precoding
method according to the present invention. As shown in FIG. 1, the
precoding method in this embodiment includes the following
steps.
[0026] In Step 101, a total uplink power of a UE is obtained.
[0027] For example, a BS, for example, an eNodeB, can obtain the
total uplink power of the UE, in which the total uplink power can
be a total power after the uplink power control. The eNodeB can
determine a transmit power that the antenna needs to transmit data
to the UE according to the total uplink power of the UE, that is,
select which codebook structure for precoding data to be
transmitted.
[0028] In Step 102, if the total uplink power is greater than 3/4
of a rated total transmit power of antennas, a codeword is selected
from a first codebook with imbalanced power between layers;
otherwise, a codeword is selected from the first codebook and a
second codebook with balanced power between layers, so the UE
precodes data to be transmitted according to the selected
codeword.
[0029] In the prior art, a codebook used for 3-layer transfer
(rank=3) of four transmit antennas mainly includes the following
three types.
[0030] A first codebook structure is as shown in expression
(1).
1 2 [ 0 1 0 1 0 0 0 0 1 x 0 0 ] , 1 2 [ 1 0 0 0 1 0 x 0 0 0 0 1 ] ,
1 2 [ 1 0 0 x 0 0 0 1 0 0 0 1 ] , 1 2 [ 0 1 0 0 0 1 1 0 0 x 0 0 ] (
1 ) ##EQU00004##
[0031] .chi..di-elect cons.{+1, -1, +j, -j}. The 3 columns of the
codebook stand for 3-layer transfer, and 4 rows stand for 4
transmit antennas.
[0032] As .di-elect cons. has 4 values, 16 codewords in total exist
in the codebook, and in the expression (1) 8 codewords are a
Quadrature Phase Shift Keying (QPSK) character set, that is,
codewords with x=+j or -j. The rest 8 codewords are a Binary Phase
Shift Keying (BPSK) character set, that is, codewords with x=+1 or
-1.
[0033] For a codebook structure as shown in expression (1), the
transfer power of four transmit antennas corresponding to the first
column is larger than the transfer power in the other two layers,
and the transfer power in each layer is imbalanced. In a case of a
high signal-to-noise ratio, loss occurs to the transmit performance
of the transmit antenna of the codebook structure. Meanwhile, as in
the codebook in expression (1), the QPSK character set occupies
half of the character set, the calculation complexity during the
precoding is also large.
[0034] The second codebook structure is as shown in expression
(2).
1 3 [ 1 / 2 0 0 0 1 0 1 / 2 0 0 0 0 1 ] , 1 3 [ 0 1 0 1 / 2 0 0 0 0
1 1 / 2 0 0 ] , 1 3 [ 1 / 2 0 0 1 / 2 0 0 0 1 0 0 0 1 ] , 1 3 [ 0 1
0 0 0 1 1 / 2 0 0 1 / 2 0 0 ] , 1 3 [ 1 / 2 0 0 0 1 0 - 1 / 2 0 0 0
0 1 ] , 1 3 [ 0 1 0 1 / 2 0 0 0 0 1 - 1 / 2 0 0 ] , 1 3 [ 1 / 2 0 0
- 1 / 2 0 0 0 1 0 0 0 1 ] , 1 3 [ 0 1 0 0 0 1 1 / 2 0 0 - 1 / 2 0 0
] , 1 3 [ 1 / 2 0 0 0 1 0 1 / 2 j 0 0 0 0 1 ] , 1 3 [ 0 1 0 1 / 2 0
0 0 0 1 1 / 2 j 0 0 ] , 1 3 [ 1 / 2 0 0 1 / 2 j 0 0 0 1 0 0 0 1 ] ,
1 3 [ 0 1 0 0 0 1 1 / 2 0 0 1 / 2 j 0 0 ] , 1 3 [ 1 / 2 0 0 0 1 0 -
1 / 2 j 0 0 0 0 1 ] , 1 3 [ 0 1 0 1 / 2 0 0 0 0 1 - 1 / 2 j 0 0 ] ,
1 3 [ 1 / 2 0 0 - 1 / 2 j 0 0 0 1 0 0 0 1 ] , 1 3 [ 0 1 0 0 0 1 1 /
2 0 0 - 1 / 2 j 0 0 ] ( 2 ) ##EQU00005##
[0035] For the codebook structures as shown in expression (2), the
transmit power of the first transmit antenna and the transmit power
of the third transmit antenna are only half of that of the second
transmit antenna and the fourth transmit antenna, and if the
transmit power of the transmit antennas are restricted, the power
amplification of the four transmit antennas is unable to be
completely used for full power transfer, that is, the power
amplification of all antennas are imbalanced.
[0036] A third codebook structure is as shown in expression
(3).
[ 1 1 0 - 1 1 0 1 0 1 j 0 - j ] .LAMBDA. , [ 1 1 0 - 1 1 0 - 1 0 1
- j 0 - j ] .LAMBDA. , [ 1 1 0 - 1 1 0 j 0 1 1 0 j ] .LAMBDA. , [ 1
1 0 - 1 1 0 - j 0 1 - 1 0 j ] .LAMBDA. , [ 1 1 0 j - j 0 1 0 1 - 1
0 1 ] .LAMBDA. , [ 1 1 0 j - j 0 1 0 1 - 1 0 1 ] .LAMBDA. , [ 1 1 0
j - j 0 1 0 1 - 1 0 1 ] .LAMBDA. , [ 1 1 0 j - j 0 1 0 1 - 1 0 1 ]
.LAMBDA. , [ 1 1 0 j - j 0 1 0 1 - 1 0 1 ] .LAMBDA. , [ 1 1 0 j - j
0 1 0 1 - 1 0 1 ] .LAMBDA. , [ 1 1 0 j - j 0 1 0 1 - 1 0 1 ]
.LAMBDA. , [ 1 1 0 j - j 0 1 0 1 - 1 0 1 ] .LAMBDA. , [ 1 1 0 j - j
0 1 0 1 - 1 0 1 ] .LAMBDA. , [ 1 1 0 j - j 0 1 0 1 - 1 0 1 ]
.LAMBDA. , [ 1 1 0 j - j 0 1 0 1 - 1 0 1 ] .LAMBDA. , [ 1 1 0 j - j
0 1 0 1 - 1 0 1 ] .LAMBDA. ( 3 ) ##EQU00006##
.LAMBDA. is a normalized matrix.
[0037] For the codebook structure as shown in expression (3), as
data of the carrier overlap exists among all antennas, the CM
characteristics of the SC-FDMA are unable to be preserved.
[0038] Different from the precoding data to be transmitted by
adopting an existing codebook structure, the codebook structure
adopted in this embodiment can include two parts and K codewords in
total. M codewords belong to the first codebook with imbalanced
power between layers, and other (K-M) codewords belong to the
second codebook with balanced power between layers.
[0039] In another embodiment of the precoding method according to
the present invention, the first codebook includes at least one
codeword of
1 2 [ 1 0 0 0 1 0 x 0 0 0 0 1 ] , 1 2 [ 0 1 0 1 0 0 0 0 1 x 0 0 ] ,
1 2 [ 1 0 0 x 0 0 0 1 0 0 0 1 ] , 1 2 [ 0 1 0 0 0 1 1 0 0 x 0 0 ] ,
1 2 [ 1 0 0 0 0 1 0 1 0 x 0 0 ] , and 1 2 [ 0 1 0 1 0 0 x 0 0 0 0 1
] , ##EQU00007##
in which .chi..di-elect cons.{+1, -1, +j, -j}.
[0040] It can be seen from the structure of the first codebook that
the transmit power in the first layer is twice as much as that in
the second layer and that in the third layer, that is, the power
between layers in the first codebook is imbalanced.
[0041] The second codebook includes at least one codeword of
[ 1 0 0 0 1 0 x 0 0 0 0 1 ] H , [ 0 1 0 1 0 0 0 0 1 x 0 0 ] H , [ 1
0 0 x 0 0 0 1 0 0 0 1 ] H , [ 0 1 0 0 0 1 1 0 0 x 0 0 ] H , [ 1 0 0
0 0 1 0 1 0 x 0 0 ] H , and [ 0 1 0 1 0 0 x 0 0 0 0 1 ] H , in
which H = [ 1 6 0 0 0 1 3 0 0 0 1 3 ] , ##EQU00008##
and .chi..di-elect cons.{+1, -1, +j, -j}.
[0042] It can be seen from the structure of the second codebook
that the three layers have an equal transmit power, that is, the
power of different layers in the second codebook is balanced.
[0043] In this embodiment, it is assumed that the rated transmit
power of the antenna is 1, the rated total transmit power of the
four antennas is 4, so the eNodeB can learn whether the total
uplink power of the UE is greater than
4 .times. 3 4 = 3. ##EQU00009##
If the total uplink power of the UE is greater than 3, for the
second codebook, as the power of different layers is balanced, the
transmit power of each layer is greater than 1. For example, the
eNodeB learns that the total uplink power of the UE is 4, so each
layer of the second codebook has a transmit power of
4 3 .apprxeq. 1.33 , ##EQU00010##
which exceeds the rated transmit power 1 of the each transmit
antenna in each layer. For the first codebook, as the power of
different layers is imbalanced, full power can be adopted in all
three layers for data transmission, that is, the transmit power in
the first layer is 2, and the transmit power in both the second
layer and the third layer is 1. If the eNodeB learns that the total
uplink power of the UE is smaller than or equal to
4 .times. 3 4 = 3 , ##EQU00011##
as the transmit power of each antenna in the first codebook and the
second codebook can be smaller than the rated transmit power 1, the
eNodeB can select the codebook in the first codebook, and can also
select the codebook in the second codebook.
[0044] Therefore, if the eNodeB learns that the total uplink power
of the UE is greater than 3/4 of the rated total transmit power of
the antennas, the eNodeB may select a codeword from the first
codebook, and if the eNodeB learns that the total uplink power is
smaller than or equal to 3/4 of the rated total transmit power of
the antennas, the eNodeB may select a codeword from a codebook
formed by the first codebook and the second codebook.
[0045] For the method in which the eNodeB selects a codeword from a
codebook formed by a first codebook and a second codebook for
precoding data to be transmitted by using the selected codeword,
any method in the prior art can be adopted, the description of
which is omitted.
[0046] In yet another embodiment of the precoding method according
to the present invention, the first codebook and the second
codebook have 16 codewords in total, in which the first codebook
has 8 codewords. Therefore, in this embodiment, the codebook
including the first codebook and the second codebook may be:
TABLE-US-00001 Index 0 to 3 1 2 [ 1 0 0 0 0 1 0 1 0 1 0 0 ]
##EQU00012## 1 2 [ 1 0 0 0 0 1 0 1 0 - 1 0 0 ] ##EQU00013## 1 2 [ 1
0 0 0 0 1 0 1 0 j 0 0 ] ##EQU00014## 1 2 [ 1 0 0 0 0 1 0 1 0 - j 0
0 ] ##EQU00015## Index 4 to 7 1 2 [ 0 1 0 1 0 0 1 0 0 0 0 1 ]
##EQU00016## 1 2 [ 0 1 0 1 0 0 - 1 0 0 0 0 1 ] ##EQU00017## 1 2 [ 0
1 0 1 0 0 j 0 0 0 0 1 ] ##EQU00018## 1 2 [ 0 1 0 1 0 0 - j 0 0 0 0
1 ] ##EQU00019## Index 8 to 11 [ 1 0 0 0 1 0 1 0 0 0 0 1 ] .LAMBDA.
##EQU00020## [ 1 0 0 0 1 0 - 1 0 0 0 0 1 ] .LAMBDA. ##EQU00021## [
0 1 0 1 0 0 0 0 1 1 0 0 ] .LAMBDA. ##EQU00022## [ 0 1 0 1 0 0 0 0 1
- 1 0 0 ] .LAMBDA. ##EQU00023## Index 12 to 15 [ 1 0 0 1 0 0 0 1 0
0 0 1 ] .LAMBDA. ##EQU00024## [ 1 0 0 - 1 0 0 0 1 0 0 0 1 ]
.LAMBDA. ##EQU00025## [ 0 1 0 0 0 1 1 0 0 1 0 0 ] .LAMBDA.
##EQU00026## [ 0 1 0 0 0 1 1 0 0 - 1 0 0 ] .LAMBDA.
##EQU00027##
[0047] In yet another embodiment of the precoding method according
to the present invention, on the basis of the embodiment as shown
in FIG. 1, the precoding method further includes the following
steps. A first codebook and a second codebook are selected from the
codebook so as to maximize a minimal chordal distance of the
codewords of the first codebook and the second codebook, and an
antenna performance corresponding to a codeword in the first
codebook is different from an antenna performance corresponding to
a codeword in the second codebook, so that if the total uplink
power is greater than 3/4 of a rated total transmit power of
antennas, a codeword is selected from a codebook formed by the
first codebook and the second codebook. The step and Step 101 may
have no specific order.
[0048] Specifically, the eNodeB can use many codewords for
precoding, and the large amount of codewords form a codebook.
However, in this embodiment, a first codebook and a second codebook
are selected from the codebook by using two rules. It is assumed
that the selected first codebook and the selected second codebook
have K codewords in total, so one principle of selecting the K
codewords is so as to maximize a minimal chordal distance of the K
selected codewords. A chordal distance of any two codewords u.sub.i
and u.sub.j is defined as:
d ( u i , u j ) = 1 2 u i , u i H - u j u j H F , in which u i F =
u j F = 1. ##EQU00028##
[0049] Thus, the equation can be adopted to calculate a chordal
distance of any two codewords, and a codeword is selected according
to the calculated chordal distance, so as to construct the first
codebook and the second codebook respectively.
[0050] A principle of selecting the K codewords is that if the
influences of power allocation matrix are not considered, the
corresponding codewords in the first codebook and the second
codebook are same. In the process of selecting the codewords in the
whole codebook, this situation of same codewords needs to be
avoided.
[0051] For example, if
1 2 [ 1 0 0 0 1 0 1 0 0 0 0 1 ] ##EQU00029##
is selected as a codeword in the first codebook,
[ 1 0 0 0 1 0 1 0 0 0 0 1 ] .times. [ 1 6 0 0 0 1 3 0 0 0 1 3 ]
##EQU00030##
is not allowed to be a codeword in the second codebook, and vice
versa, that is, the antenna performance corresponding to the
codeword in the first codebook is different from the antenna
performance corresponding to the codeword in the second
codebook.
[0052] In the embodiments of the precoding method according to the
present invention, the BS can select a codeword from a
corresponding codebook for precoding data to be transmitted
according to a relationship between the total uplink power reported
by the UE and the maximal rated total power of the antenna of the
BS. As in the method in this embodiment, the codebook structure
adopts the first codebook with imbalanced power between layers and
the second codebook with balanced structures between layers, if a
codeword is selected from the second codebook for precoding, loss
of the antenna performance at a high signal-to-noise ratio can be
reduced, and if a codeword is selected from the first codebook for
precoding, the loss of the power amplification of the antenna can
be reduced if the transmit power of the antennas is restricted.
[0053] FIG. 2 is a flow chart of another embodiment of a precoding
method according to the present invention. As shown in FIG. 2, the
method in this embodiment includes the following steps.
[0054] In Step 201, a sub-carrier resource is allocated to a
UE.
[0055] For example, an eNodeB can allocate a sub-carrier resource
to the UE, in which the sub-carrier resource is used for data
transmission between the UE and the eNodeB. The eNodeB may allocate
a continuous sub-carrier resource to the UE and may also allocate
discontinuous sub-carrier resource to the UE.
[0056] In Step 202, if the sub-carrier resource is continuously
allocated, a CMP codebook is selected for precoding data to be
transmitted; otherwise, a CMF codebook is selected for precoding
data to be transmitted.
[0057] The eNodeB can correspondingly select different codebooks
for precoding data to be transmitted according to whether the
sub-carrier resource allocated by the UE is continuously allocated
or discontinuously allocated. If the eNodeB learns that the
sub-carrier resource allocated to the UE is continuously allocated,
transmitted data of the sub-carriers do not need overlap, so if
this resource allocation mode is adopted for data transmission, the
eNodeB can select a CMP codebook. If the eNodeB learns that the
sub-carrier resource allocated to the UE is discontinuously
allocated, transmitted data of the sub-carriers do need overlap, so
if this resource allocation mode is adopted for data transmission,
the eNodeB can select a CMF codebook. The CMF codebook refers to a
codebook that incompletely preserves CM characteristics. For any
codeword in a CMP codebook, each row only has one non-zero element.
For any codeword in a CMF codebook, in some rows, more than one
non-zero elements exist, but in the rows, not all elements are
non-zero. For example, one row only has two non-zero elements, and
others are still zero. Therefore, compared with the CMP codebook,
some CMs are added in the CMF codebook. However, not many CMs are
added. Therefore, compared with a codebook in which the CM
characteristic design is completely not considered, the CMF
codebook has better CM characteristics.
[0058] In a precoding method according to an embodiment of the
present invention, the CMP codebook includes at least one codeword
of
1 2 [ 0 1 0 1 0 0 0 0 1 x 0 0 ] , 1 2 [ 1 0 0 0 1 0 x 0 0 0 0 1 ] ,
1 2 [ 1 0 0 x 0 0 0 1 0 0 0 1 ] , and 1 2 [ 0 1 0 0 0 1 1 0 0 x 0 0
] , ##EQU00031##
in which .chi..di-elect cons.{+1, -1, +j, -j}; or includes at least
one codeword of
1 3 [ 1 2 0 0 0 1 0 1 2 0 0 0 0 1 ] , 1 3 [ 0 1 0 1 2 0 0 0 0 1 1 2
0 0 ] , 1 3 [ 1 2 0 0 1 2 0 0 0 1 0 0 0 1 ] , 1 3 [ 0 1 0 0 0 1 1 2
0 0 1 2 0 0 ] , 1 3 [ 1 2 0 0 0 1 0 - 1 2 0 0 0 0 1 ] , 1 3 [ 0 1 0
1 2 0 0 0 0 1 - 1 2 0 0 ] , 1 3 [ 1 2 0 0 - 1 2 0 0 0 1 0 0 0 1 ] ,
1 3 [ 0 1 0 0 0 1 1 2 0 0 - 1 2 0 0 ] , 1 3 [ 1 2 0 0 0 1 0 1 2 j 0
0 0 0 1 ] , 1 3 [ 0 1 0 1 2 0 0 0 0 1 1 2 j 0 0 ] , 1 3 [ 1 2 0 0 1
2 j 0 0 0 1 0 0 0 1 ] , 1 3 [ 0 1 0 0 0 1 1 2 0 0 1 2 j 0 0 ] , 1 3
[ 1 2 0 0 0 1 0 - 1 2 j 0 0 0 0 1 ] , 1 3 [ 0 1 0 1 2 0 0 0 0 1 - 1
2 j 0 0 ] , 1 3 [ 1 2 0 0 - 1 2 j 0 0 0 1 0 0 0 1 ] , and
##EQU00032## 1 3 [ 0 1 0 0 0 1 1 2 0 0 - 1 2 j 0 0 ] .
##EQU00032.2##
[0059] The CMF codebook includes at least one codeword of
[ 1 1 0 - 1 1 0 1 0 1 j 0 - j ] .LAMBDA. , [ 1 1 0 - 1 1 0 - 1 0 1
- j 0 - j ] .LAMBDA. , [ 1 1 0 - 1 1 0 j 0 1 1 0 j ] .LAMBDA. , [ 1
1 0 - 1 1 0 - j 0 1 - 1 0 j ] .LAMBDA. , [ 1 1 0 j - j 0 1 0 1 - 1
0 1 ] .LAMBDA. , [ 1 1 0 j - j 0 1 0 1 - 1 0 1 ] .LAMBDA. , [ 1 1 0
j - j 0 1 0 1 - 1 0 1 ] .LAMBDA. , [ 1 1 0 j - j 0 1 0 1 - 1 0 1 ]
.LAMBDA. , [ 1 1 0 j - j 0 1 0 1 - 1 0 1 ] .LAMBDA. , [ 1 1 0 j - j
0 1 0 1 - 1 0 1 ] .LAMBDA. , [ 1 1 0 j - j 0 1 0 1 - 1 0 1 ]
.LAMBDA. , [ 1 1 0 j - j 0 1 0 1 - 1 0 1 ] .LAMBDA. , [ 1 1 0 j - j
0 1 0 1 - 1 0 1 ] .LAMBDA. , [ 1 1 0 j - j 0 1 0 1 - 1 0 1 ]
.LAMBDA. , [ 1 1 0 j - j 0 1 0 1 - 1 0 1 ] .LAMBDA. , and [ 1 1 0 j
- j 0 1 0 1 - 1 0 1 ] .LAMBDA. , ##EQU00033##
in which .LAMBDA. is a normalized matrix.
[0060] In the embodiment of the precoding method according to the
present invention, the BS selects a codeword in different codebooks
respectively for precoding data to be transmitted according to
different types of sub-carrier resources allocated by the UE, such
that the CM characteristics are guaranteed by selecting the
codeword in the CMP codebook if the sub-carrier resource is
continuously allocated.
[0061] An embodiment of the present invention provides a codebook,
which includes at least one codeword of
1 2 [ 0 1 0 1 0 0 0 0 1 1 0 0 ] , 1 2 [ 0 1 0 1 0 0 0 0 1 - 1 0 0 ]
, 1 2 [ 1 0 0 0 1 0 1 0 0 0 0 1 ] , 1 2 [ 1 0 0 0 1 0 - 1 0 0 0 0 1
] , 1 2 [ 1 0 0 1 0 0 0 1 0 0 0 1 ] , 1 2 [ 1 0 0 - 1 0 0 0 1 0 0 0
1 ] , 1 2 [ 0 1 0 0 0 1 1 0 0 1 0 0 ] , 1 2 [ 0 1 0 0 0 1 1 0 0 - 1
0 0 ] , 1 2 [ 1 0 0 0 0 1 0 1 0 1 0 0 ] , 1 2 [ 1 0 0 0 0 1 0 1 0 -
1 0 0 ] , 1 2 [ 0 1 0 1 0 0 1 0 0 0 0 1 ] , and 1 2 [ 0 1 0 1 0 0 -
1 0 0 0 0 1 ] . ##EQU00034##
[0062] In this embodiment the codebook is a BPSK CMP codebook, in
the codebook in this embodiment, all codewords are BPSK characters,
and the number is at most 12, so compared with the codebook as
shown in expression (1), for the codebook in this embodiment, the
complexity of the precoding using the codebook is relatively
reduced.
[0063] Furthermore, in this embodiment, the codebook further
includes at least one codeword of
1 2 [ 0 1 0 1 0 0 0 0 1 j 0 0 ] , 1 2 [ 0 1 0 1 0 0 0 0 1 - j 0 0 ]
, 1 2 [ 1 0 0 0 1 0 j 0 0 0 0 1 ] , and 1 2 [ 1 0 0 0 1 0 - j 0 0 0
0 1 ] . ##EQU00035##
[0064] Therefore, the codebook in this embodiment includes at least
one codeword of the following codebook structures:
1 2 [ 0 1 0 1 0 0 0 0 1 1 0 0 ] , 1 2 [ 0 1 0 1 0 0 0 0 1 - 1 0 0 ]
, 1 2 [ 0 1 0 1 0 0 0 0 1 j 0 0 ] , 1 2 [ 0 1 0 1 0 0 0 0 1 - j 0 0
] , 1 2 [ 1 0 0 0 1 0 1 0 0 0 0 1 ] , 1 2 [ 1 0 0 0 1 0 - 1 0 0 0 0
1 ] , 1 2 [ 1 0 0 0 1 0 j 0 0 0 0 1 ] , 1 2 [ 1 0 0 0 1 0 - j 0 0 0
0 1 ] , 1 2 [ 1 0 0 1 0 0 0 1 0 0 0 1 ] , 1 2 [ 1 0 0 - 1 0 0 0 1 0
0 0 1 ] , 1 2 [ 0 1 0 0 0 1 1 0 0 1 0 0 ] , 1 2 [ 0 1 0 0 0 1 1 0 0
- 1 0 0 ] , 1 2 [ 1 0 0 0 0 1 0 1 0 1 0 0 ] , 1 2 [ 1 0 0 0 0 1 0 1
0 - 1 0 0 ] , 1 2 [ 0 1 0 1 0 0 1 0 0 0 0 1 ] , and 1 2 [ 0 1 0 1 0
0 - 1 0 0 0 0 1 ] . ##EQU00036##
[0065] Compared with the codebook as shown in expression (1), the
codebook provided in this embodiment has a greater average code
distance, in the codebook only 4 codewords are a QPSK character
set, and the rest 12 codewords are a BPSK character set, so
compared with the codebook as shown in expression (1), for the
codebook in this embodiment, the complexity of precoding using the
codebook is reduced to a certain degree. FIG. 3 is a comparison
diagram between simulation results of a codebook of the present
invention and a codebook as shown in expression (1). As shown in
FIG. 3, through the link simulation, in a case of the same
signal-to-noise ratio, the codebook in this embodiment (that is,
the codebook as shown by curve 1 in FIG. 3) has a certain gain in
terms of throughput compared with the codebook as shown in
expression (1) (that is, the codebook as shown by curve 2 in FIG.
3) and the codebook as shown by curve 3 in FIG. 3, so as to
transfer more data.
[0066] An embodiment of the present invention further provides
another codebook, which includes at least one codeword of
1 5 [ 0.5 1 0 - 0.5 1 0 0.5 0 1 0.5 j 0 - j ] , 1 5 [ 0.5 1 0 0.5 j
0 1 - 0.5 j j 0 - 0.5 j 0 1 ] , 1 5 [ 0.5 1 0 - 0.5 1 0 0.5 j 0 1
0.5 0 j ] , 1 5 [ 0.5 1 0 0.5 j 0 1 0.5 0 j - 0.5 1 0 ] , 1 5 [ 0.5
1 0 - 0.5 j 0 1 - 0.5 1 0 - 0.5 0 j ] , 1 5 [ 0.5 1 0 0.5 j - j 0 -
0.5 0 1 0.5 0 1 ] , 1 5 [ 0.5 1 0 0.5 j - j 0 0.5 j 0 1 0.5 j 0 - 1
] , 1 5 [ 0.5 1 0 - 0.5 0 1 - 0.5 j 0 - j - 0.5 1 0 ] , 1 5 [ 0.5 1
0 0.5 - 1 0 0.5 j 0 1 - 0.5 0 - j ] , 1 5 [ 0.5 1 0 - 0.5 0 1 - 0.5
0 - 1 - 0.5 j j 0 ] , 1 5 [ 0.5 1 0 0.5 0 1 0.5 j - j 0 - 0.5 0 1 ]
, 1 5 [ 0.5 1 0 - 0.5 j 0 1 - 0.5 j 0 - 1 0.5 j - j 0 ] , 1 5 [ 0.5
1 0 0.5 0 1 0.5 - 1 0 - 0.5 j 0 j ] , 1 5 [ 0.5 1 0 - 0.5 j j 0 -
0.5 j 0 1 0.5 j 0 1 ] , 1 5 [ 0.5 1 0 - 0.5 0 1 0.5 0 1 0.5 j - j 0
] , and 1 5 [ 0.5 1 0 - 0.5 j j 0 - 0.5 0 1 - 0.5 0 - 1 ] .
##EQU00037##
[0067] In the codebook in this embodiment, imbalanced power between
layers is introduced, so a power of a column with all elements
being non-zero is further reduced so as to reduce a CM value, and
after adjustment, a power ratio among all layers is 2:2:1, that is,
two strong layers and one weak layer. A power ratio among all
layers in the CMF codebook with balanced power between layers as
shown in expression (3) is 1:1:1, so compared with the CMF codebook
with balanced power between layers as shown in expression (3), for
the codebook in this embodiment the CM value can be decreased, and
as indicated through experiments, the CM value is decreased by 0.2
dB.
[0068] FIG. 4 is a schematic structural view of an embodiment of a
BS according to the present invention. As shown in FIG. 4, in this
embodiment, the BS includes an obtaining module 11 and a first
processing module 12. The obtaining module 11 is adapted to obtain
a total uplink power of a UE. The first processing module 12 is
adapted to select a codeword from a first codebook with imbalanced
power between layers if the total uplink power is greater than 3/4
of a rated total transmit power of antennas; otherwise, select a
codeword from the first codebook and a second codebook with
balanced power between layers, so as for precoding data to be
transmitted according to the selected codeword.
[0069] The BS in this embodiment has the same principles as those
in the embodiment of the precoding method as shown in FIG. 1, the
description of which is omitted here.
[0070] FIG. 5 is a schematic structural view of another embodiment
of the BS according to the present invention. As shown in FIG. 5,
on the basis of the embodiment as shown in FIG. 4, in this
embodiment the BS further includes a selection module 13. The
selection module 13 is adapted to select a first codebook and a
second codebook from the codebook so as to maximize a minimal
chordal distance of codewords of the first codebook and the second
codebook, and an antenna performance corresponding to a codeword in
the first codebook is different from an antenna performance
corresponding to a codeword in the second codebook, such that if
the total uplink power is greater than 3/4 of a rated total
transmit power of antennas, the first processing module 12 selects
a codeword from a codebook formed by the first codebook and the
second codebook. In this embodiment, the process that the selection
module 13 selects the first codebook and the second codebook from
the codebook can be performed before the process that the obtaining
module 11 obtains the total uplink power of the UE.
[0071] FIG. 6 is a schematic structural view of yet another
embodiment of the BS according to the present invention. As shown
in FIG. 6, a difference between this embodiment and the embodiment
of the BS as shown in FIG. 5 is that for the BS as shown in FIG. 6,
a process that a selection module 13 of the BS selects the first
codebook and the second codebook from the codebook can be performed
after the process that the obtaining module 11 obtains the total
uplink power of the UE.
[0072] The BS in the embodiment can select a codeword from a
corresponding codebook according to a relationship between the
total uplink power reported by the UE and the maximal rated total
power of the antenna of the BS, so as for precoding data to be
transmitted. As in the method in this embodiment, the codebook
structure adopts the first codebook with imbalanced power between
layers and the second codebook with balanced structures between
layers, if a codeword is selected from the second codebook for
precoding, the loss of the antenna performance at a high
signal-to-noise ratio can be reduced, and if a codeword is selected
from the first codebook for precoding, the loss of the power
amplification of the antenna can be reduced if the transmit power
of the antenna is restricted.
[0073] FIG. 7 is a schematic structural view of further another
embodiment of the BS according to the present invention. As shown
in FIG. 7, in this embodiment, the BS includes an allocation module
14 and a second processing module 15. The allocation module 14 is
adapted to allocate a sub-carrier resource to a UE. The second
processing module 15 is adapted to select a CMP codebook for
precoding data to be transmitted if the sub-carrier resource is
continuously allocated; otherwise, select a CMF codebook for
precoding data to be transmitted.
[0074] In this embodiment, the BS can select a codeword in
different codebooks respectively for precoding data to be
transmitted according to different types of sub-carrier resources
allocated by the UE, so the CM characteristic are guaranteed by
selecting the codeword in the CMP codebook if the sub-carrier
resource is continuously allocated.
[0075] Finally, it should be noted that the above embodiments are
merely provided for describing the technical solutions of the
present invention, but not intended to limit the present invention.
It should be understood by persons of ordinary skill in the art
that although the present invention has been described in detail
with reference to the embodiments, modifications or equivalent
replacements can be made to the technical solutions described in
the present invention, as long as such modifications or
replacements do not depart from the spirit and scope of the present
invention.
[0076] Those of ordinary skill in the art should understand that
all or a part of the steps of the method according to the
embodiments may be implemented by a program instructing relevant
hardware. The program may be stored in a computer readable storage
medium such as a read-only memory (ROM), a magnetic disk or an
optical disk.
[0077] The principle and implementation of the present invention
are described herein through specific examples. The description
about the embodiments of the present invention is merely provided
for ease of understanding of the method and core ideas of the
present invention. Persons of ordinary skill in the art can make
variations to the present invention in terms of the specific
implementations and application scopes according to the ideas of
the present invention. Therefore, the specification shall not be
construed as a limit to the present invention.
[0078] It should be noted that in the above device embodiments of
the UE and BS, the units are divided according to logical
functions, but the present invention is not limited to the
division, as long as corresponding functions can be realized; and
specific names of the units are merely provided for the purpose of
distinguishing the units from one another, but not intended to
limit the scope of the present invention.
[0079] It should be understood that the above descriptions are
merely preferred embodiments of the present invention, but not
intended to limit the scope of the present invention. Any
modification or replacement made without departing from the
technical scope of the present invention should fall within the
scope of the present invention as defined in the claims.
* * * * *