DESCRIPTION
Orthogonal Cover Code Generating Apparatus, Demodulation Reference
Signal Generating Apparatus, and Methods thereof
Field of the Invention
The present invention relates to transmission technologies in the wireless
communication system, and more particularly, to an orthogonal cover code
generating apparatus, a demodulation reference signal generating apparatus,
and methods thereof used in Long Term Evolution and Long Term
Evolution-Advanced systems.
Background of the Invention
The Long Term Evolution-Advanced (LTE-Advanced) next-generation wireless
communication system of 3GPP requires the downlink to provide a peak rate
of 1Gps and a peak spectral efficiency of 30bps/Hz, and this brings about
challenges to the physical layer transmission scheme of the system. A multiple
input multiple output (MIMO) multi-antenna system supports transmission of
parallel data streams, thereby greatly enhancing the system throughput. Under
general circumstances, independent forward error-correcting code encoding is
firstly performed in parallel data streams transmitted in the multi-antenna
system, and the encoded codeword is then mapped to one or more data
transmission layers. When the codeword is mapped to plural transmission
layers, it suffices to convert the serial data output from the encoder into
corresponding plural layers. In one transmission, the number of all layers
supported by the system is also referred to as the rank of the transmission.
The process of converting the data of each layer into the data of each physical
antenna is referred to as the pre-coding process of signals. LTE-Advanced
Rel-10 supports the pre-coding technique with the maximum rank of 8.
In order for the receiving terminal to perform MIMO decoding and the
associated demodulation, it is necessary for the transmitting side to transmit a
pilot sequence, namely a demodulation reference signal (hereinafter referred
to as "DMRS"), for estimating channels. Design of DMRSs requires that
corresponding DMRSs of data transmission layers be orthogonal to one
another, that is, to ensure that equivalent channels to the pre-coded channels
of the transmission antennas are free of interference. In the Rel-10 system,
corresponding DMRSs of the data transmission layers are differentiated by the
frequency division multiplexing (FDM) and/or code division multiplexing (CDM)
mode(s). Code division multiplexing is realized by spectrum-spreading
sequences with ideal correlation via an orthogonal cover code (hereinafter
referred to as "OCC") sequence. The OCC sequence is usually a Walsh
sequence or a discrete Fourier transform (DFT) sequence.
As the inventors found during the process of the present invention, if an OCC
sequence is mapped (spectrum-spread) in a time domain, it is usually
presumed that channels on the physical resources corresponding to the cover
code sequence are identical. Assume that the spread factor of a
spectrum-spread sequence is M, it is then considered that channel responses
of M number of OFDM symbols are identical. Such assumption is true only in a
low-speed motion environment. With the increase in motion speed of a mobile
station, the change in channel responses of the M number of OFDM symbols
accordingly increases, and orthogonality of the spectrum-spread code is
damaged, whereby data transmission layers interfere with one another, and
the precision in channel estimation is lowered.
Moreover, in the Rel-10 system, DMRSs are subjected to the same pre-coding
treatment as the data, and mapped to transmission antennas. The pre-coding
treatment enables the DMRSs corresponding to the code-division multiplexed
data transmission layers to be linearly stacked, and when DMRSs
corresponding to M number of data transmission layers are stacked in the
same direction, a signal with an amplitude of M is obtained; whereas when
DMRSs corresponding to M number of data transmission layers are stacked in
opposite directions, they counteract one another to obtain a signal with an
amplitude of zero. If such power imbalance of each transmission antenna
occurs in the entire frequency domain bandwidth, efficiency of transmission
power will be markedly lowered.
As should be noted, the above introduction of the background is presented
merely to facilitate clear and comprehensive explanation of the technical
solutions of the present invention, and to make it easy for persons skilled in the
art to comprehend. It should not be considered that these solutions are publicly
known to persons skilled in the art only because they have been enunciated in
the Background of the Related Art section of the present invention.
Reference documents of the present invention are listed below and herein
incorporated by reference, as if they were described in detail in the Description
of the present application.
1. [Patent Document 1] : Hooli Kari, Pajukoski Ka, et al., Method,
apparatuses, system and related computer product for resource allocation
(WO 2009056464 A1)
2. [Patent Document 2] ; Che Xiangguang, Guo Chunyan, et al., Variable
transmission structure for reference signals in uplink messages (WO
2009022293 A2)
3. [Patent Document 3] : Cho Joon-young, Zhang Jianzhong, et al.,
Apparatus and method for allocating code resource to uplink ACK/NACK
channels in a cellular wireless communication system (US 2009046646 A1)
4. [Patent Document 4] : Yang Yunsong, Kwon Younghoon, System and
method for adaptively controlling feedback information (US 20090209264 A1)
5. [Patent Document 5] :Pajukoski Kari P, Tiirola Esa, Providing improved
scheduling request signaling with ACK/NACK or CQI (US 20090100917)
6. [Patent Document 6] : Li Don, Yang Guang, Multi-channel spread
spectrum system (US 20020015437 A1).
Summary of the Invention
Embodiments of the present invention are proposed in view of the
aforementioned problems in the prior art to remove or alleviate one or more
defects in the related art and at least to provide one advantageous choice. To
achieve the above objectives, the present invention proposes the following
aspects.
Aspect 1. A Demodulation Reference Signal (DMRS) generator for generating
a DMRS, which generator comprises a non-correlation sequence generator
configured to generate a non-correlation sequence for pilot of a first resource
block; a first spectrum spreading unit configured to spread spectrums of
elements in the non-correlation sequence for pilot of the first resource block to
be mapped to a first frequency resource of the first resource block, by using a
first group of Orthogonal Cover Codes (OCCs); a second spectrum spreading
unit configured to spread spectrums of elements in the non-correlation
sequence for pilot of the first resource block to be mapped to a second
frequency resource of the first resource block, by using a second group of
OCCs; the first and second frequency resources are adjacent frequency
resources with respect to a first group of data streams, and the first and
second groups of OCCs are mirrors in column to each other; and a mapping
unit configured to map the elements with their spectrums spread by the first
and second spectrum spreading units to the first and second frequency
resources of the first resource block, respectively.
Aspect 2. The DMRS generator according to Aspect 1, wherein the DMRS
generator further comprises a third spectrum spreading unit configured to
spread spectrums of elements in the non-correlation sequence for pilot of the
first resource block to be mapped to a third frequency resource, by using a
third group of OCCs; a fourth spectrum spreading unit configured to spread
spectrums of elements in the non-correlation sequence for pilot of the first
resource block to be mapped to a fourth frequency resource, by using a fourth
group of OCCs; the third and fourth frequency resources are adjacent
frequency resources with respect to a second group of data streams, and the
third and fourth groups of OCCs are mirrors in column to each other; wherein
the mapping unit further maps the elements with their spectrums spread by the
third and fourth spectrum spreading units to the third and fourth frequency
resources, respectively.
Aspect 3. The DMRS generator according to Aspect 2, wherein one of the third
and fourth groups of OCCs is formed by performing a column vector cyclic shift
to one of the first and second groups of OCCs.
Aspect 4. The DMRS generator according to Aspect 3, wherein the same
column vector has different column serial numbers in the first to fourth groups
of OCCs.
Aspect 5. The DMRS generator according to Aspect 1, wherein the
non-correlation sequence generator generates a non-correlation sequence for
pilot of a second resource block, the second resource block being adjacent to
the first resource block; the first spectrum spreading unit spreads spectrums of
elements in the non-correlation sequence for pilot of the second resource
block to be mapped to a first frequency resource of the second resource block,
by using the first group of OCGs; the second spectrum spreading unit spreads
spectrums of elements in the non-correlation sequence for pilot of the second
resource block to be mapped to a second frequency resource of the second
resource block, by using the second group of OCCs; the first and second
frequency resources of the second resource block are adjacent frequency
resources with respect to the first group of data streams; the mapping unit
further maps the elements in the non-correlation sequence for pilot of the
second resource block with their spectrums spread by the first and second
spectrum spreading units to the first and second frequency resources of the
second resource block, respectively, wherein the first frequency resource of
the second resource block corresponds to the first frequency resource or the
second frequency resource of the first resource block, and the second
frequency resource of the second resource block corresponds to the second
frequency resource or the first frequency resource of the first frequency block,
such that the elements in the non-correlation sequence for pilot of the first
resource block and/or the elements in the non-correlation sequence for pilot of
the second resource block to be mapped to the adjacent frequency resources
with respect to the first group of data streams are spectrum-spread by the first
group of OCCs and the second group of OCCs, respectively, in the first
resource block and the second resource block.
Aspect 6. The DMRS generator according to Aspect 1, wherein the
non-correlation sequence generator further generates a non-correlation
sequence for pilot of a second resource block, the second resource block
being adjacent to the first resource block; the first spectrum spreading unit
spreads spectrums of elements in the non-correlation sequence for pilot of the
second resource block to be mapped to a first frequency resource of the
second resource block, by using the third group of OCCs; the second
spectrum spreading unit spreads spectrums of elements in the non-correlation
sequence for pilot of the second resource block to be mapped to a second
frequency resource of the second resource block, by using the fourth group of
OCCs; the first and second frequency resources of the second resource block
are adjacent frequency resources with respect to the first group of data
streams; the fourth and third groups of OCCs are mirrors in column to each
other; the mapping unit maps the elements in the non-correlation sequence for
pilot of the second resource block with their spectrums spread by the first and
second spectrum spreading units to the first and second frequency resources
of the second resource block, respectively, wherein the first frequency
resource of the second resource block corresponds to the first frequency
resource or the second frequency resource of the first resource block, and the
second frequency resource of the second resource block corresponds to the
second frequency resource or the first frequency resource of the first
frequency block, such that the elements in the non-correlation sequence for
pilot of the first resource block and/or the elements in the non-correlation
sequence for pilot of the second resource block to be mapped to the adjacent
frequency resources with respect to the first group of data streams are
spectrum-spread by the first group of OCCs and the second group of OCCs,
respectively, and such that the elements in the non-correlation sequence for
pilot of the first resource block and/or the elements in the non-correlation
sequence for pilot of the second resource block to be mapped to the adjacent
frequency resources with respect to the second group of data streams are
spectrum-spread by the third group of OCCs and the fourth group of OCCs,
respectively, in the first resource block and the second resource block; one of
the fourth and third groups of OCCs is formed by performing a column vector
cyclic shift to one of the first and second groups of OCCs.
Aspect 7. The DMRS generator according to Aspect 6, wherein the same
column vector has different column serial numbers in the first to fourth groups
of OCCs.
Aspect 8. The DMRS generator according to Aspect 2, wherein the
non-correlation sequence generator generates a non-correlation sequence for
pilot of a second resource block, the second resource block being adjacent to
the first resource block; the first spectrum spreading unit spreads spectrums of
elements in the non-correlation sequence for pilot of the second resource
block to be mapped to a first frequency resource of the second resource block,
by using a fifth group of OCCs; the second spectrum spreading unit spreads
spectrums of elements in the non-correlation sequence for pilot of the second
resource block to be mapped to a second frequency resource of the second
resource block, by using a sixth group of OCCs; the first and second frequency
resources of the second resource block are adjacent frequency resources with
respect to the first group of data streams; the sixth and fifth groups of OCCs
are mirrors in column to each other; the third spectrum spreading unit spreads
spectrums of elements in the non-correlation sequence for pilot of the second
resource block to be mapped to a third frequency resource of the second
resource block, by using a seventh group of OCCs; the fourth spectrum
spreading unit spreads spectrums of elements in the non-correlation sequence
for pilot of the second resource block to be mapped to a fourth frequency
resource of the second resource block, by using an eighth group of OCCs; the
third and fourth frequency resources of the second resource block are adjacent
frequency resources with respect to the second group of data streams; the
seventh and eighth groups of OCCs are mirrors in column to each other; the
mapping unit further maps the elements in the non-correlation sequence for
pilot of the second resource block with their spectrums spread by the first to
fourth spectrum spreading units to the first to fourth frequency resources of the
second resource block, respectively.
Aspect 9. The DMRS generator according to Aspect 8, wherein the same
column vector has different column serial numbers in the fifth to eighth groups
of OCCs; one of the fifth and sixth groups of OCCs is formed by performing a
column vector cyclic shift to one of the first and second groups of OCCs by a
first displacement, and one of the seventh and eighth groups of OCCs is
formed by performing a column vector cyclic shift to one of the first and second
groups of OCCs by a second displacement.
Aspect 10. The DMRS generator according to Aspect 1, wherein the first and
second groups of OCCs are both Walsh code sequences or Fourier transform
sequences.
Aspect 11. A Demodulation Reference Signal (DMRS) generation method for
generating a DMRS, which method comprises a non-correlation sequence
generating step for generating a non-correlation sequence for pilot of a first
resource block; a first spectrum spreading step for spreading spectrums of
elements in the non-correlation sequence for pilot of the first resource block to
be mapped to a first frequency resource of the first resource block, by using a
first group of Orthogonal Cover Codes (OCCs); a second spectrum spreading
step for spreading spectrums of elements in the non-correlation sequence for
pilot of the first resource block to be mapped to a second frequency resource
of the first resource block, by using a second group of OCCs; the first and
second frequency resources are adjacent frequency resources with respect to
a first group of data streams, and the first and second groups of OCCs are
mirrors in column to each other; and a mapping step for mapping the elements
with their spectrums spread by the first and second spectrum spreading steps
to the first and second frequency resources of the first resource block,
respectively.
Aspect 12. The DMRS generation method according to Aspect 11, wherein the
DMRS generation method further comprises a third spectrum spreading step
for spreading spectrums of elements in the non-correlation sequence for pilot
of the first resource block to be mapped to a third frequency resource, by using
a third group of OCCs; a fourth spectrum spreading step for spreading
spectrums of elements in the non-correlation sequence for pilot of the first
resource block to be mapped to a fourth frequency resource, by using a fourth
group of OCCs; the third and fourth frequency resources are adjacent
frequency resources with respect to a second group of data streams, and the
third and fourth groups of OCCs are mirrors in column to each other; wherein
the mapping step further maps the elements with their spectrums spread by
the third and fourth spectrum spreading steps to the third and fourth frequency
resources, respectively.
Aspect 13. The DMRS generation method according to Aspect 12, wherein
one of the third and fourth groups of OCCs is formed by performing a column
vector cyclic shift to one of the first and second groups of OCCs.
Aspect 14. The DMRS generation method according to Aspect 13, wherein the
same column vector has different column serial numbers in the first to fourth
groups of OCCs.
Aspect 15. The DMRS generation method according to Aspect 11, wherein the
non-correlation sequence generating step generates a non-correlation
sequence for pilot of a second resource block, the second resource block
being adjacent to the first resource block; the first spectrum spreading step
spreads spectrums of elements in the non-correlation sequence for pilot of the
second resource block to be mapped to a first frequency resource of the
second resource block, by using the first group of OCCs; the second spectrum
spreading step spreads spectrums of elements in the non-correlation
sequence for pilot of the second resource block to be mapped to a second
frequency resource of the second resource block, by using the second group
of OCCs; the first and second frequency resources of the second resource
block are adjacent frequency resources with respect to the first group of data
streams; the mapping step further maps the elements in the non-correlation
sequence for pilot of the second resource block with their spectrums spread by
the first and second spectrum spreading steps to the first and second
frequency resources of the second resource block, respectively, wherein the
first frequency resource of the second resource block corresponds to the first
frequency resource or the second frequency resource of the first resource
block, and the second frequency resource of the second resource block
corresponds to the second frequency resource or the first frequency resource
of the first frequency block, such that the elements in the non-correlation
sequence for pilot of the first resource block and/or the elements in the
non-correlation sequence for pilot of the second resource block to be mapped
to the adjacent frequency resources with respect to the first group of data
streams are spectrum-spread by the first group of OCCs and the second group
of OCCs, respectively, in the first resource block and the second resource
block.
Aspect 16. The DMRS generation method according to Aspect 11, wherein the
non-correlation sequence generating step further generates a non-correlation
sequence for pilot of a second resource block, the second resource block
being adjacent to the first resource block; the first spectrum spreading step
spreads spectrums of elements in the non-correlation sequence for pilot of the
second resource block to be mapped to a first frequency resource of the
second resource block, by using the third group of OCCs; the second
spectrum spreading step spreads spectrums of elements in the non-correlation
sequence for pilot of the second resource block to be mapped to a second
frequency resource of the second resource block, by using the fourth group of
OCCs; the first and second frequency resources of the second resource block
are adjacent frequency resources with respect to the first group of data
streams; the fourth and third groups of OCCs are mirrors in column to each
other; the mapping step maps the elements in the non-correlation sequence
for pilot of the second resource block with their spectrums spread by the first
and second spectrum spreading steps to the first and second frequency
resources of the second resource block, respectively, wherein the first
frequency resource of the second resource block corresponds to the first
frequency resource or the second frequency resource of the first resource
block, and the second frequency resource of the second resource block
corresponds to the second frequency resource or the first frequency resource
of the first frequency block, such that the elements in the non-correlation
sequence for pilot of the first resource block and/or the elements in the
non-correlation sequence for pilot of the second resource block to be mapped
to the adjacent frequency resources with respect to the first group of data
streams are spectrum-spread by the first group of OCCs and the second group
of OCCs, respectively, and such that the elements in the non-correlation
sequence for pilot of the first resource block and/or the elements in the
non-correlation sequence for pilot of the second resource block to be mapped
to the adjacent frequency resources with respect to the second group of data
streams are spectrum-spread by the third group of OCCs and the fourth group
of OCCs, respectively, in the first resource block and the second resource
block; one of the fourth and third groups of OCCs is formed by performing a
column vector cyclic shift to one of the first and second groups of OCCs.
Aspect 17. The DMRS generation method according to Aspect 16, wherein the
same column vector has different column serial numbers in the first to fourth
groups of OCCs.
Aspect 18. The DMRS generation method according to Aspect 12, wherein the
non-correlation sequence generating step generates a non-correlation
sequence for pilot of a second resource block, the second resource block
being adjacent to the first resource block; the first spectrum spreading step
spreads spectrums of elements in the non-correlation sequence for pilot of the
second resource block to be mapped to a first frequency resource of the
second resource block, by using a fifth group of OCCs; the second spectrum
spreading step spreads spectrums of elements in the non-correlation
sequence for pilot of the second resource block to be mapped to a second
frequency resource of the second resource block, by using a sixth group of
OCCs; the first and second frequency resources of the second resource block
are adjacent frequency resources with respect to the first group of data
streams; the sixth and fifth groups of OCCs are mirrors in column to each other;
the third spectrum spreading step spreads spectrums of elements in the
non-correlation sequence for pilot of the second resource block to be mapped
to a third frequency resource of the second resource block, by using a seventh
group of OCCs; the fourth spectrum spreading step spreads spectrums of
elements in the non-correlation sequence for pilot of the second resource
block to be mapped to a fourth frequency resource of the second resource
block, by using an eighth group of OCCs; the third and fourth frequency
resources of the second resource block are adjacent frequency resources with
respect to the second group of data streams; the seventh and eighth groups of
OCCs are mirrors in column to each other; the mapping step further maps the
elements in the non-correlation sequence for pilot of the second resource
block with their spectrums spread by the first to fourth spectrum spreading
steps to the first to fourth frequency resources of the second resource block,
respectively.
Aspect 19. The DMRS generation method according to Aspect 18, wherein the
same column vector has different column serial numbers in the fifth to eighth
groups of OCCs; one of the fifth and sixth groups of OCCs is formed by
performing a column vector cyclic shift to one of the first and second groups of
OCCs by a first displacement, and one of the seventh and eighth groups of
OCCs is formed by performing a column vector cyclic shift to one of the first
and second groups of OCCs by a second displacement.
Aspect 20. The DMRS generation method according to Aspect 11, wherein the
first and second groups of OCCs are both Walsh code sequences or Fourier
transform sequences.
Aspect 21. An orthogonal cover code (OCC) generating apparatus, which
comprises a basic orthogonal code acquiring device configured to acquire a
group of basic orthogonal codes; a column cyclic shift unit configured to
perform a column vector cyclic shift to the basic orthogonal codes generated
by the basic orthogonal code acquiring device; and a mirror unit configured to
perform a mirroring in column on the basic orthogonal codes generated by the
basic orthogonal code acquiring device, so as to obtain a first basic orthogonal
code group pair, and further configured to perform a mirroring in column on the
basic orthogonal codes having undergone the cyclic shift by the column cyclic
shift unit, so as to obtain a second OCC group pair.
Aspect 22. The OCC generating apparatus according to Aspect 21, wherein
displacement of the column vector cyclic shift is variable.
Aspect 23. The OCC generating apparatus according to Aspect 21, wherein
the OCC generating apparatus further comprises a group pair group acquiring
unit configured to control the column cyclic shift unit and the mirror unit, so as
to obtain a group of column serial number distinguishable OCC group pairs
where the same column has different column serial numbers in different OCC
groups.
According to the methods and apparatuses for generating OCCs proposed in
the present invention, pilot randomization may be enhanced, the problem of
pilot power imbalance may be removed, the requirement on orthogonality at
the two dimensions of both the time and frequency may be satisfied, and more
robust channel estimation properties may be provided.
With reference to the following description and the drawings, the above and
further aspects and features of the present invention will come to be clearer. In
the following description and the accompanying drawings, specific
embodiments for emboding the invention are disclosed in greater detail, and
modes of execution applicable to the principles of the present invention are
pointed out. As should be noted, the present invention is not restricted in scope
thereby. The present invention includes various variations, modifications and
equalities within the spirits and provisos of the claims attached herewith.
Features described and/or illustrated with respect to one embodiment can be
employed in one or more other embodiments, combined with features of other
embodiments, or replace features of other embodiments in identical or similar
ways.
As should be stressed, the terms of "comprise/include" and
"comprising/including", as used in this disclosure, indicates the existence of
features, integral, steps or component parts, and does not exclude the
existence or addition of one or more other features, integral, steps or
component parts.
Brief Description of the Drawings
The aforementioned as well as other objectives, features and advantages of
the present invention will become more apparent by virtue of the subsequent
description with reference to the drawings, in which:
Fig. 1A is a schematic diagram illustrating a demodulation reference signal
(DMRS) generating apparatus according to one embodiment of the present
invention;
Fig. 1B is a schematic diagram illustrating a DMRS generating apparatus
according to one embodiment of the present invention;
Figs. 2 and 3 illustrate one advantage of the DMRS generating apparatus
according to the present invention;
Fig. 4 is a schematic diagram illustrating the flow of generating orthogonal
cover code (OOC) group pairs by the method according to the present
invention;
Fig. 5A is a flow chart illustrating a DMRS generation method according to one
embodiment of the present invention;
Fig. 5B is a schematic diagram illustrating the flow of a DMRS generation
method according to another embodiment of the present invention;
Fig. 6 is a schematic diagram illustrating an example of downlink DMRS
resources generated by using the DMRS generation method according to the
present invention;
Fig. 7 is a schematic diagram illustrating another example of downlink DMRS
resources generated by using the DMRS generation method according to the
present invention;
Fig. 8 is a schematic diagram illustrating power distribution of four groups of
pre-coded OCC sequences (column serial number distinguishable OCC group
pairs) generated according to the present invention mapped to the first
transmission antenna;
Figs. 9 and 10 illustrate the spectrum spreading treatment of the second
resource block according to one embodiment of the present invention;
Figs. 11 and 12 illustrate the spectrum spreading treatment of the second
resource block according to another embodiment of the present invention;
Fig. 13 is a schematic diagram illustrating an OCC generating apparatus
according to one embodiment of the present invention;
Fig. 14 is a block diagram exemplarily illustrating a computer capable of
implementing the method and apparatus according to the embodiments of the
present invention; and
Fig. 15 is a block diagram exemplarily illustrating the function of a transmitter
that employs the DMRS generating apparatus and generation method
according to the embodiments of the present invention.
Detailed Description of the Embodiments
Preferred embodiments of the present invention are described in greater detail
below with reference to the drawings. Details and functions unnecessary to the
present invention are not mentioned in the description to avoid confused
comprehension of the present invention.
Fig. 1A is a schematic diagram illustrating a demodulation reference signal
(DMRS) generating apparatus according to one embodiment of the present
invention. As shown in Fig. 1A, the DMRS generating apparatus 100 according
to one embodiment of the present invention includes a non-correlation
sequence generating unit 101, a first spectrum spreading unit 102, a second
spectrum spreading unit 103 and a mapping unit 104.
The non-correlation sequence generating unit 101 is configured to generate a
non-correlation sequence for pilot, which sequence should have ideal
correlation (relatively small or even zero). The non-correlation sequence in this
context is for instance a Zadoff-Chu sequence or a PN code sequence. Any
methods already known or to be known to persons skilled in the art can be
used to generate the non-correlation sequence such as the Zadoff-Chu
sequence or the PN code sequence, and are not extensively described here.
For example, the non-correlation sequence generating unit 101 generates a
non-correlation sequence (a, c) for a certain resource block.
The first spectrum spreading unit 102 is configured to spread spectrums of
elements (a, for instance) in the non-correlation sequence for pilot to be
mapped to a first frequency resource by using a first group of orthogonal cover
codes (OCCs).
The second spectrum spreading unit 103 is configured to spread spectrums of
elements (c, for instance) in the non-correlation sequence for pilot to be
mapped to a second frequency resource by using a second group of OCCs.
The second frequency resource and the first frequency resource are adjacent
frequency resources with respect to a first group of data streams, and the
second group of OCCs and the first group of OCCs are mirrors in column to
each other. The first group of OCCs and the second group of OCCs can be
referred to as OCC group pairs.
The mapping unit 104 is configured to map the elements in the non-correlation
sequence for pilot with their spectrums spread by the first and second
spectrum spreading units to corresponding frequency resources, namely to the
first and second frequency resources, respectively.
In one embodiment, the first group of OCCs and the second group of OCCs
are Walsh codes. In another embodiment, the first group of OCCs and the
second group of OCCs are discrete Fourier transform (DFT) sequences. Any
other known OCC sequences may as well be used for the first group of OCCs
and the second group of OCCs. To facilitate description, the Walsh codes are
only taken as example for description.
Figs. 2 and 3 illustrate one advantage of the DMRS generating apparatus
according to the present invention. When four pilot signals are used, as shown
in Fig. 2, only one group of OCCs having a spectrum-spreading length of 4 (a,
-a, a, -a or c, -c, c, -c) at the time domain is used in the related art. As shown in
Fig. 3, when the DMRS generating apparatus according to the embodiment of
the present invention is used, it is possible to map the four pilot signals to two
subcarriers respectively, so as to reduce the spectrum-spreading length to 2 at
the time domain, thereby reducing the requirement on motion speed of the
mobile station.
On the other hand, it is also possible to make the power distribution more
uniform, and this will be described below. The present invention does not aim
to solve all technical problems existent in the related art in one embodiment,
and it is unnecessary to contain all technical advantages mentioned in the
invention in one embodiment.
Described below is the generation of the OCC sequences.
Fig. 4 is a schematic diagram illustrating the flow of generating OOC group
pairs by the method according to the present invention. Altogether eight groups
of OCC sequences are generated in the example illustrated in Fig. 4, each
OCC sequence includes four orthogonal sequences, and each orthogonal
sequence has a length of 4. The OCC sequences generated in this illustrated
example are Walsh sequences. As should be noted, the numbers 4 and 8 in
this context are used merely for the purpose of clarity of the description, rather
than to restrict the protection scope of the present invention.
As shown in Fig. 4, the following steps are specifically included.
Step S401 - generating a group of OCC sequence. The circumstance
illustrated in Fig. 4 is represented by a matrix Ci=[Ci,i;Cii2;Ci,3;Cii4]. This
group of OCC sequence (OCC group) includes four orthogonal sequences
orthogonal to one another and each having a length of 4:

For example, in Fig. 4 there are

and so on so forth.
Step S402 - subjecting the group of OCC sequence C1 to a column mirror
treatment to obtain a new group of OCC sequence C2=[ C2,1; C2,2; C2,3;C2,4]
=[C1,4; C1,3; C1,2; C1,1].
Thus obtained is a pair of OCC groups (OCC group pair)used in cooperation
with each other.
Further, when more cooperatively used pairs of OCC groups are required, the
method can also include the following steps.
Step S403 - subjecting the group of orthogonal sequence C1 to a column
vector cyclic shift treatment to obtain a new group of OCC sequence
C3=[C3,1;C3,2;C3,3;C3,4]; and then
Step S404 - subjecting the group of OCC sequence C3 to a column mirror
treatment to obtain another new group of OCC sequence C4=[ C4,1; C4,2;
C4,3;C4,4].
Cyclic displacement p in the column vector cyclic shift treatment is variable.
For instance, under the circumstance shown in Fig. 4, the cyclic displacement
p may be equal to 1, 2 and 3. Accordingly, when more cooperative group pairs
are required, Steps S403 and S404 can be repeated for several times, and the
cyclic displacement p is varied each time.
Fig. 4 illustrates the resultant C3 and C4 when p=2. Fig. 4 also illustrates the
resultant another pair of OCC groups C5 and C6 when p=3, as well as still
another pair of OCC groups C7 and C8 when p=1.
Preferably, when it is required to select two pairs of OCC groups, the same
column vector of the OCC sequences can be made different in column serial
numbers in every two pairs of OCC groups, namely to form a group of column
serial number distinguishable cover code vector group pairs. Taking for
example the all-1 column vectors in the illustrated example , it corresponds to
the first, the fourth, the third and the second columns in C1- C4, respectively,
while corresponds to the fourth, the first, the second and the third columns in
C5~ Cs, respectively, and the matrices of these eight groups of OCC
sequences are not equal to one another, so that C1 -C4 can be used together,
and C5~ C8 can be used together. The C1~ C4 in this context make up a group
of column serial number distinguishable cover code vector group pairs, and
C5~ C8 make up a group of column serial number distinguishable cover code
vector group pairs. Likewise, the all-1 column vectors in C1, C2, C7 and C8 are
respectively in the first, the fourth, the second and the third columns, while the
all-1 column vectors in C3, C4, C5 and C6 are respectively in the third, the
second, the fourth and the first columns, so that C3, C4, C5 and C6 can be used
together, and C1, C2, C7 and C8 can be used together. C3, C4, C5 and C6 also
make up a group of column serial number distinguishable cover code vector
group pairs, and C1, C2, C7 and C8 also make up a group of column serial
number distinguishable cover code vector group pairs. The advantage in using
the groups of column serial number distinguishable cover code vector group
pairs rests in enabling uniform power distribution on each pilot-transmitting
frequency resource, and this will be described later.
It is possible to select the groups of column serial number distinguishable
cover code vector group pairs by a certain method after all of OCC group pairs
have been obtained, and it is also possible to select suitable OCC group pairs
and discard unsuitable pairs of OCC groups by adding a determining step after
performing each round of cyclic shift to determine whether a group of column
serial number distinguishable cover code vector group pairs is made up.
In the eight groups of OCC sequences as generated, vectors formed by
elements in each of the pairs of OCC groups (pairs of OCC sequence matrix
groups) C1 with C2, C3 with C4, C5 with C6 and C7 with C8 satisfy the
relationship of being orthogonal to one another. Taking C1 with C2 for example,
[C11,C12,C21,C22] are orthogonal to each other, [C13,C14, C23,C24] are also
orthogonal, and so on. As can be seen, pairs of OCC groups obtained as thus
can achieve orthogonality of the two dimensions of both frequency and time.
Fig. 1B is a schematic diagram illustrating a DMRS generating apparatus
according to another embodiment of the present invention. As shown in Fig. 1B,
the DMRS generating apparatus 100' according to another embodiment of the
present invention further includes, in addition to the non-correlation sequence
generating unit 101, the first spectrum spreading unit 102, the second
spectrum spreading unit 103 and the mapping unit 104 as shown in Fig. 1A, a
third spectrum spreading unit 105 and a fourth spectrum spreading unit 106.
In the DMRS generating apparatus 100' according to this embodiment, the
non-correlation sequence generator generates a non-correlation sequence for
pilot, for instance a non-correlation sequence (a, b, c, d) for pilot.
The first spectrum spreading unit 102 is configured to spread spectrums of
elements (a, for instance) in the non-correlation sequence for pilot to be
mapped to a first frequency resource by using a first group of OCCs (C1, for
instance).
The second spectrum spreading unit 103 is configured to spread spectrums of
elements (c, for instance) in the non-correlation sequence for pilot to be
mapped to a second frequency resource by using a second group of OCCs (C2,
for instance). The second frequency resource and the first frequency resource
are adjacent frequency resources with respect to a first group of data streams,
and the second group of OCCs and the first group of OCCs are mirrors in
column to each other. The first group of OCCs and the second group of OCCs
can be referred to as OCC group pairs. The first group of data streams is for
instance data streams of the first, the second, the fifth and the sixth layers. In
this disclosure, when it says that both the second frequency resource and the
first frequency resource are frequency resources with respect to the first group
of data streams, it means that pilots carried by the two frequency resources
are used for the first group of data streams.
The third spectrum spreading unit 105 is configured to spread spectrums of
elements (b, for instance) in the non-correlation sequence for pilot to be
mapped to a third frequency resource by using a third group of OCCs (C3, for
instance).
The fourth spectrum spreading unit 106 is configured to spread spectrums of
elements (d, for instance) in the non-correlation sequence for pilot to be
mapped to a fourth frequency resource by using a fourth group of OCCs (C4,
for instance). The third frequency resource and the fourth frequency resource
are adjacent frequency resources with respect to a second group of data
streams, and the third group of OCCs and the fourth group of OCCs are
mirrors in column to each other. In this disclosure, when it says that both the
third frequency resource and the fourth frequency resource are frequency
resources with respect to the second group of data streams, it means that
pilots carried by the two frequency resources are used for the second group of
data streams. The second group of data streams is for instance data streams
of the third, the fourth, the seventh and the eighth layers.
Preferably, the first group of OCCs and the second group of OCCs as well as
the third group of OCCs and the fourth group of OCCs make up groups of
column serial number distinguishable OCC group pairs, like the
above-illustrated circumstances in which C1, C2 are combined with C3 and C4.
However, this is not necessarily so, as it is also possible to combine C1, C2 with
C5 and C6, for instance.
Fig. 5A is a flow chart illustrating a DMRS generation method according to one
embodiment of the present invention.
As shown in Fig. 5A, firstly in Step S501 the non-correlation sequence
generating unit 101 generates a non-correlation sequence for pilot. The
non-correlation sequence for pilot in this context is for instance a Zadoff-Chu
sequence or a PN code sequence. Any methods already known or to be
known to persons skilled in the art can be used to generate the non-correlation
sequence such as the Zadoff-Chu sequence or the PN code sequence, and
are not extensively described here.
In Step S502, the first spectrum spreading unit 102 spreads spectrums of
elements in the non-correlation sequence to be mapped to a first frequency
resource by using a first group of OCCs.
In Step S503, the second spectrum spreading unit 103 spreads spectrums of
elements in the non-correlation sequence to be mapped to a second frequency
resource by using a second group of OCCs. The second frequency resource
and the first frequency resource are adjacent frequency resources with respect
to the same group of data streams, and the second group of OCCs and the
first group of OCCs are mirrors in column to each other. The first group of
OCCs and the second group of OCCs can be referred to as OCC group pair.
Thereafter in Step S504, the mapping unit 104 maps the elements in the
non-correlation sequence for pilot with their spectrums spread by the first and
second spectrum spreading units to corresponding frequency resources,
namely to the first and second frequency resources, respectively.
As easily conceivable, Steps S502 and S503 can be performed either
successively or concurrently.
Fig. 5B is a schematic diagram illustrating a DMRS generation method
according to another embodiment of the present invention.
As shown in Fig. 5B, according to the DMRS generation method of an
embodiment of the present invention, firstly in Step S501, a non-correlation
sequence for pilot is generated, which sequence should have ideal correlation
(relatively small or even zero). The non-correlation sequence in this context is
for instance a Zadoff-Chu sequence or a PN code sequence.
Then in Step S502, the first spectrum spreading unit spreads spectrums of
elements in the non-correlation sequence for pilot to be mapped to a first
frequency resource by using a first group of OCCs.
In Step S503, the second spectrum spreading unit spreads spectrums of
elements in a plurality of first non-correlation sequences to be mapped to a
second frequency resource by using a second group of OCCs. The second
frequency resource and the first frequency resource are adjacent frequency
resources with respect to a first group of data streams, and the second group
of OCCs and the first group of OCCs are mirrors in column to each other.
Unlike the DMRS generation method shown in Fig. 5A, the DMRS generation
method shown in Fig. 5B further includes Steps S505 and S506.
In Step S505, the third spectrum spreading unit spreads spectrums of
elements in the non-correlation sequence for pilot to be mapped to a third
frequency resource by using a third group of OCCs.
In Step S506, the fourth spectrum spreading unit spreads spectrums of
elements in the non-correlation sequence for pilot to be mapped to a fourth
frequency resource by using a fourth group of OCCs. The fourth frequency
resource and the third frequency resource are adjacent frequency resources
with respect to the second group of data streams, and the fourth group of
OCCs and the third group of OCCs are mirrors in column to each other.
And preferably, the groups of group pairs formed by the fourth group of OCCs
and the third group of OCCs as well as by the first group of OCCs and the
second group of OCCs make up groups of column serial number
distinguishable OCC group pairs.
In Step S504, the mapping unit 104 maps the elements in the non-correlation
sequence for pilot with their spectrums spread by the first to fourth spectrum
spreading units to corresponding frequency resources, namely to the first to
fourth frequency resources, respectively.
As easily conceivable, Steps S502, S503, S505 and S506 can be performed
either successively or concurrently.
Fig. 6 is a schematic diagram illustrating an example of downlink DMRS
resources generated by using the DMRS generation method according to the
present invention.
Fig. 6 illustrates a circumstance in which there are two data streams. Assume
that the pilots occupy twelve subcarriers (also referred to as "resource
elements", RE) in physical resource blocks (PRB) of the sixth and seventh
OFDM symbols and the thirteenth and fourteenth OFDM symbols in each
subframe of the LTE-A system. The pilots of the first and second layers occupy
the same PRB, and are differentiated via OCCs each having a length of 2.
Under such a circumstance, after the non-correlation sequence for pilot (such
as a, b, c) is generated, the first group of OCCs is used to spread spectrums of
elements (a, for instance) in the non-correlation sequence for pilot to be
mapped to a first subcarrier with respect to the first group of data streams (data
streams of the first and second layers), the second group of OCCs is used to
spread spectrums of elements (b, for instance) in the non-correlation sequence
for pilot to be mapped to a sixth subcarrier (which is also with respect to the
first group of data streams), and the first group of OCCs is used to spread
spectrums of elements (c, for instance) in the non-correlation sequence for
pilot to be mapped to an eleventh subcarrier (which is also with respect to the
first group of data streams). Mapping is performed thereafter.
The first group of OCCs and the second group of OCCs are mirrors in column
to each other, that is, they form a pair of OCC groups.
In this context, although the first, the sixth and the eleventh subcarriers as
exemplarily illustrated are not physically adjacent, because they are used for
pilots with respect to the same data streams, they are adjacent insofar as they
are with respect to the same data streams, so they are referred to as adjacent
frequency resources with respect to the first group of data streams.
Fig. 7 is a schematic diagram illustrating another example of downlink DMRS
resources generated by using the DMRS generation method according to the
present invention.
Fig. 7 illustrates a circumstance in which there are four data streams. Assume
that the pilots occupy twenty-four subcarriers (also referred to as "resource
elements", RE) in physical resource blocks (PRB) of the sixth and seventh
OFDM symbols and the thirteenth and fourteenth OFDM symbols in each
subframe of the LTE-A system. The pilots of the first and second layers occupy
the same PRB, and are differentiated via OCCs each having a length of 2. The
pilots of the third and fourth layers occupy the same PRB, and are
differentiated via OCCs each having a length of 2.
Under such a circumstance, after the non-correlation sequence for pilot is
generated, the first group of OCCs (C1( for instance) is used to spread
spectrums of elements in the non-correlation sequence for pilot to be mapped
to a 0th subcarrier with respect to the first and second layers, the second group
of OCCs (C2, for instance) is used to spread spectrums of elements in the
non-correlation sequence for pilot to be mapped to a fifth subcarrier with
respect to the first and second layers, and the first group of OCCs is used to
spread spectrums of elements in the non-correlation sequence for pilot to be
mapped to a tenth subcarrier with respect to the first and second layers. The
third group of OCCs (C3, for instance) is used to spread spectrums of elements
in the non-correlation sequence for pilot to be mapped to a first subcarrier with
respect to the third and fourth layers, the fourth group of OCCs (C4, for
instance) is used to spread spectrums of elements in the non-correlation
sequence for pilot to be mapped to a sixth subcarrier with respect to the third
and fourth layers, and the third group of OCCs is used to spread spectrums of
elements in the non-correlation sequence for pilot to be mapped to an eleventh
subcarrier with respect to the third and fourth layers. Mapping is performed
thereafter.
The first group of OCCs and the second group of OCCs are mirrors in column
to each other, that is, they form a pair of OCC groups. The third group of OCCs
and the fourth group of OCCs are mirrors in column to each other, that is, they
also form a pair of OCC groups. The first and second layers can be
differentiated from the third and fourth layers in the form of FDM, that is, they
are differentiated by frequencies.
As should be noted, the pair of OCC groups formed by the first group of OCCs
and the second group of OCCs can either be identical with or different from the
pair of OCC groups formed by the third group of OCCs and the fourth group of
OCCs.
When there are more than four data streams, the method can also be carried
out in the similar way as shown in Fig. 7. That is to say, frequency resources
that carry pilots are divided into two groups with respect to different data
streams, and elements in the non-correlation sequence for pilot mapped to
each of the groups are spectrum-spread by different groups of OCCs. Different
groups are differentiated by frequencies.
For instance, also in the pattern of pilot resources illustrated in Fig. 7, after the
non-correlation sequence for pilot is generated, the first group of OCCs is used
to spread spectrums of elements in the non-correlation sequence for pilot to be
mapped to the 0th subcarrier with respect to the first to fourth layers, the
second group of OCCs is used to spread spectrums of elements in the
non-correlation sequence for pilot to be mapped to the fifth subcarrier with
respect to the first to fourth layers, and the first group of OCCs is used to
spread spectrums of elements in the non-correlation sequence for pilot to be
mapped to the tenth subcarrier with respect to the first to fourth layers. The
third group of OCCs is used to spread spectrums of elements in the
non-correlation sequence for pilot to be mapped to the first subcarrier with
respect to the fifth to eighth layers, the fourth group of OCCs is used to spread
spectrums of elements in the non-correlation sequence for pilot to be mapped
to the sixth subcarrier with respect to the fifth to eighth layers, and the third
group of OCCs is used to spread spectrums of elements in the non-correlation
sequence for pilot to be mapped to the eleventh subcarrier with respect to the
fifth to eighth layers. Mapping is performed thereafter.
The first group of OCCs and the second group of OCCs are mirrors in column
to each other, that is, they form a pair of OCC groups. The third group of OCCs
and the fourth group of OCCs are mirrors in column to each other, that is, they
also form a pair of OCC groups. The first to fourth layers can be differentiated
from the fifth and eighth layers in the form of FDM, that is, they are
differentiated by frequencies. At this time, the length of the OCCs should be 4.
As should be noted under such a circumstance, the pair of OCC groups
formed by the first group of OCCs and the second group of OCCs can either
be identical with or different from the pair of OCC groups formed by the third
group of OCCs and the fourth group of OCCs. However, groups of column
serial number distinguishable OCC group pairs are preferably used. The first to
fourth layers make up the first group of data streams, and the fifth to eighth
layers make up the second group of data streams. But the above is merely
taken as examples, as the first group of data streams may as well be data
streams of the first, the second, the fifth and the sixth layers, and the second
group of data streams may as well be data streams of the third, the fourth, the
seventh and the eighth layers.
As can be seen from Fig. 6 and Fig. 7, the OCC sequences are
spectrum-spread at the time domain, that is, DMRSs corresponding to the
same subcarrier on the sixth, the seventh, the thirteenth and the fourteenth
OFDM symbols constitute spectrum-spread codes each having a length of 4.
Moreover, DMRSs corresponding to the kth and the k+6th subcarriers on the
sixth, the seventh, the thirteenth and the fourteenth OFDM symbols also
constitute spectrum-spread codes each having a length of 4; that is to say,
orthogonality is provided in the two dimensions of time and frequency.
Fig. 8 is a schematic diagram illustrating power distribution of four groups of
pre-coded OCC sequences (groups of column serial number distinguishable
OCC group pairs) generated according to the present invention mapped to the
first transmission antenna. As can be seen from Fig. 8, if the row vectors in the
pre-coding matrices are all 1, after column vectors of the four groups of OCC
sequence matrices Ci~C4 are respectively multiplied with and added to the
row vectors of the pre-coding matrices, DMRSs corresponding to the sixth, the
seventh, the thirteenth and the fourteenth OFDM symbols are respectively 4a,
0, 0, 0 on the kth subcarrier; DMRSs corresponding to the sixth, the seventh,
the thirteenth and the fourteenth OFDM symbols are respectively 0, 0, 4c, 0 on
the k-1th subcarrier; DMRSs corresponding to the sixth, the seventh, the
thirteenth and the fourteenth OFDM symbols are respectively 0, 0, 0, 4d on the
k-6th subcarrier; and DMRSs corresponding to the sixth, the seventh, the
thirteenth and the fourteenth OFDM symbols are respectively 0, 4b, 0, 0 on the
k-7th subcarrier. As it is not difficult to see, power of the DMRSs is uniformly
distributed on the four OFDM symbols, and the problem of power imbalance is
avoided.
Figs. 9 and 10 illustrate the spectrum spreading treatment of the second
resource block according to one embodiment of the present invention.
According to one embodiment of the present invention, as shown in Figs. 9
and 10, as for an adjacent resource block (the second resource block in Figs. 9
and 10, for instance), demodulation reference signals can be generated by the
same mode as the original resource block (the first resource block in Figs. 9
and 10, for instance); moreover, the groups of OCCs as applied between the
two resource blocks are made to be mirrors in column to each other with
respect to the adjacent frequency resources of the same data streams, namely
to form a pair of OCC groups. For instance, as shown in Fig. 10, with respect to
the tenth subcarrier of the first resource block and the 0th subcarrier of the
second resource block, the groups of OCCs C1 and C2 as mirrors in column to
each other are used; with respect to the eleventh subcarrier of the first
resource block and the first subcarrier of the second resource block, the
groups of OCCs C3 and C4 as mirrors in column to each other are used. For
further instance, as shown in Fig. 9, with respect to the eleventh subcarrier of
the first resource block and the first subcarrier of the second resource block,
the groups of OCCs C1 and C2 as mirrors in column to each other are used.
As should be noted, as shown in Figs. 9 and 10, the first frequency resource
and the second frequency resource may indicate different subcarriers at
different resource blocks.
Figs. 11 and 12 illustrate the spectrum spreading treatment of the second
resource block according to another embodiment of the present invention.
According to another embodiment of the present invention, as shown in Figs.
11 and 12, with respect to adjacent resource blocks, two groups of OCCs as
mirrors in column to each other are used. As shown in Fig. 11, different pairs of
OCC groups are used in the second resource block for frequency resources
(the first, the sixth and the eleventh subcarriers in the second resource block,
for instance) corresponding to the frequency resources (the first, the sixth and
the eleventh subcarriers in the first resource block, for instance) in the original
resource block. Preferably, the two pairs of OCC groups form a group of
column serial number distinguishable OCC group pairs. For further instance as
shown in Fig. 12, different pairs of OCC groups are used in the second
resource block for frequency resources corresponding to the frequency
resources in the original resource block. The pairs of OCC groups used in the
adjacent resource block also form a group of column serial number
distinguishable OCC group pairs. One group of OCCs in the group of column
serial number distinguishable OCC group pairs used in the second resource
block is obtained by performing column vector cyclic shift on one group of
OCCs in the group of column serial number distinguishable OCC group pairs
used in the first resource block.
Fig. 13 is a schematic diagram illustrating an OCC generating apparatus
according to one embodiment of the present invention.
As shown in Fig. 13, the OCC generating apparatus according to the present
invention includes a basic orthogonal code acquiring unit 1301, a mirror unit
1302, a column cyclic shift unit 1303 and a group pair group acquiring unit
1304.
The basic orthogonal code acquiring unit 1301 is configured to acquire a group
of basic orthogonal codes, such as the Walsh codes or DFT codes as
previously mentioned.
The column cyclic shift unit 1303 is configured to perform a column vector
cyclic shift to the basic orthogonal codes generated by the basic orthogonal
code acquiring unit 1301. Displacement of the column vector cyclic shift is
variable.
The mirror unit 1302 is configured to perform a mirroring in column on the
basic orthogonal codes generated by the basic orthogonal code acquiring unit
1301, so as to obtain a first basic orthogonal code group pair, and further to
perform a mirroring in column on the basic orthogonal codes having
undergone the cyclic shift by the column cyclic shift unit 1303, so as to obtain a
second, a third, or more OCC group pairs.
The group pair group acquiring unit 1304 is configured to control the column
cyclic shift unit 1303 and the mirror unit 1302, so as to obtain a group of
column serial number distinguishable OCC group pairs.
As should be noted, the group pair group acquiring unit 1304 can be dispensed
with in certain applications.
Under certain circumstances, the column cyclic shift unit 1303 can also be
dispensed with.
Various constituent modules, units and subunits in the above apparatus may
be configured through software, firmware, hardware or combinations thereof.
The specific configuring means or manners are well known by a person skilled
in the art, and herein are not repeated. In case of the implementation through
software or firmware, programs constructing the software shall be installed
from a storage medium or network to a computer with dedicated hardware
structure (e.g., a general computer as illustrated in Fig. 14), and the computer
can perform various functions when being installed with various programs.
Fig. 14 is a block diagram illustrating a computer capable of implementing the
method and apparatus according to the embodiments of the present invention.
In Fig. 14, a Central Processing Unit (CPU) 1401 performs various processing
according to programs stored in a Read Only Memory (ROM) 1402 or
programs loaded from a storage section 1408 to a Random Access Memory
(RAM) 1403. Data required by the CPU 1401 to perform various processing
shall be stored in the RAM 1403 as necessary. The CPU 1401, the ROM 1402
and the RAM 1403 are connected to each other via a bus 1404. An
Input/Output (I/O) interface 1405 may also be connected to the bus 1404 as
necessary.
As necessary, the following components may be connected to the I/O interface
1405: an input section 1406 (including keypad, mouse, etc.), an output section
1407 (including display such as Cathode-Ray Tube (CRT) and Liquid Crystal
Display (LCD), and loudspeaker, etc.), a storage section 1408 (including hard
disk, etc.) and a communication section 1409 (including network interface card
such as LAN card, modem, etc.). The communication section 1409 for
example performs a communication processing through a network such as
Internet. A driver 1410 may also be connected to the I/O interface 1405 as
necessary. A detachable medium 1411 such as magnetic disk, optical disk,
magneto-optical disk, semiconductor memory, etc. may be mounted on the
driver 1410 as necessary, so that the computer program read therefrom will be
installed into the storage section 1408 upon request.
In case the above series of processing is implemented through software,
programs constructing the software shall be installed from a network such as
the Internet or a storage medium such as the detachable medium 1411.
A person skilled in the art shall appreciate that the storage medium is not
limited to the detachable medium 1411 as illustrated in Fig. 14 which stores
programs and is distributed independently from the device to provide the
programs to the subscriber. The detachable medium 1411 for example
includes magnetic disk (including floppy disk (registered trademark)), compact
disk (including Compact Disk Read Only Memory (CD-ROM) and Digital
Versatile Disk (DVD)), magnetic optical disk (including Mini Disk (MD)
(registered trademark)) and semiconductor memory. Or the storage medium
may be the ROM 1402, the hard disk in the storage section 1408, etc. in which
programs are stored and distributed to the subscriber together with the device
containing them.
The present invention further provides a program product that stores machine
readable instruction codes capable of executing the above method according
to the embodiments of the present invention when being read and executed by
a machine.
Accordingly, a storage medium for loading the program product that stores the
machine readable instruction codes is also included in the disclosure of the
present invention. The storage medium includes, but is not limited to, floppy
disk, optical disk, magneto-optical disk, memory card, memory stick, etc.
Fig. 15 is a block diagram exemplarily illustrating the function of a transmitter
that employs the DMRS generating apparatus and generation method
according to the embodiments of the present invention. A power source, a
storage unit, a data generating module and the like which are not of direct
relevance to understanding the technical solution of present invention are
omitted in this block diagram.
As shown in Fig. 15, data is encoded as to channels at a channel encoding unit
1501, and is then modulated at a modulating unit 1502. The modulated data is
mapped as to resources at a resource mapping unit 1503. At the same time,
DMRSs are generated by a DMRS generating unit 1506 by using the DMRS
generating apparatus or generation method according to the present invention
and are mapped. As should be noted, in the above description the DMRS
generating apparatus also has a mapping unit, which is actually the same one
as the resource mapping unit 1503, that is to say, data and DMRSs are
mapped at the same time. Thereafter, the data mapped to a physical channel
is pre-coded at a pre-coding unit 1504, receives OFDM modulation at an
OFDM modulating unit 1505, and is then sent out via an antenna.
Description of the present invention is given for purposes of exemplification
and illustration, and is not exhaustive or restrictive of the present invention
within the form disclosed herein. Many modifications and variations are
apparent to persons ordinarily skilled in the art. The selection and description
of the embodiments are directed to better explanation of the principles and
practical applications of the present invention, and to enabling persons
ordinarily skilled in the art to so comprehend the present invention as to design
various embodiments with various modifications adapted to particular
purposes of use.
We Claim:
1. A Demodulation Reference Signal (DMRS) generator for generating a
DMRS, comprising:
a non-correlation sequence generator configured to generate a
non-correlation sequence for pilot of a first resource block;
a first spectrum spreading unit configured to spread spectrums of
elements in the non-correlation sequence for pilot of the first resource block to
be mapped to a first frequency resource of the first resource block, by using a
first group of Orthogonal Cover Codes (OCCs);
a second spectrum spreading unit configured to spread spectrums of
elements in the non-correlation sequence for pilot of the first resource block to
be mapped to a second frequency resource of the first resource block, by
using a second group of OCCs; the first and second frequency resources are
adjacent frequency resources with respect to a first group of data streams, and
the first and second groups of OCCs are mirrors in column to each other;
a third spectrum spreading unit configured to spread spectrums of
elements of in the non-correlation sequence for pilot of the first resource block
to be mapped to a third frequency resource of the first resource block, by using
a third group of OCCs;
a fourth spectrum spreading unit configured to spread spectrums of
elements in the non-correlation sequence for pilot of the first resource block to
be mapped to a fourth frequency resource of the first resource block, by using
a fourth group of OCCs; the third and fourth frequency resources are adjacent
frequency resources with respect to a second group of data streams, and the
third and fourth groups of OCCs are mirrors in column to each other; and
a mapping unit configured to map the elements with their spectrums
spread by the first and second spectrum spreading units to the first and second
frequency resources of the first resource block, respectively, and map the
elements with their spectrums spread by the third and fourth spectrum
spreading units to the third and fourth frequency resources of the first resource
block, respectively.
2. The DMRS generator according to claim 1, wherein one of the third and
fourth groups of OCCs is formed by performing a column vector cyclic shift to
one of the first and second groups of OCCs, and the same column vector has
different column serial numbers in the first to fourth groups of OCCs.
3. The DMRS generator according to claim 1, wherein
the non-correlation sequence generator generates a non-correlation
sequence for pilot of a second resource block, the second resource block
being adjacent to the first resource block;
the first spectrum spreading unit spreads spectrums of elements in the
non-correlation sequence for pilot of the second resource block to be mapped
to a first frequency resource of the second resource block, by using a fifth
group of OCCs;
the second spectrum spreading unit spreads spectrums of elements in the
non-correlation sequence for pilot of the second resource block to be mapped
to a second frequency resource of the second resource block, by using a sixth
group of OCCs; the first and second frequency resources of the second
resource block are adjacent frequency resources with respect to the first group
of data streams, and the fifth and sixth groups of OCCs are mirrors in column
to each other;
the third spectrum spreading unit spreads spectrums of elements in the
non-correlation sequence for pilot of the second resource block to be mapped
to a third frequency resource of the second resource block, by using a seventh
group of OCCs;
the fourth spectrum spreading unit spreads spectrums of elements in the
non-correlation sequence for pilot of the second resource block to be mapped
to a fourth frequency resource of the second resource block, by using an
eighth group of OCCs; the third and fourth frequency resources of the second
resource block are adjacent frequency resources with respect to the second
group of data streams, and the seventh and eighth groups of OCCs are mirrors
in column to each other;
the mapping unit further maps the elements in the non-correlation
sequence for pilot of the second resource block with their spectrums spread by
the first to fourth spectrum spreading units to the first to fourth frequency
resources of the second resource block, respectively.
4. The DMRS generator according to claim 1, wherein
the same column vector has different column serial numbers in the fifth to
eighth groups of OCCs, one of the fifth and sixth groups of OCCs is formed by
performing a column vector cyclic shift to one of the first and second groups of
OCCs by a first displacement, and one of the seventh and eighth groups of
OCCs is formed by performing a column vector cyclic shift to one of the first
and second groups of OCCs by a second displacement.
5. A DMRS generation method for generating a DMRS, comprising:
a non-correlation sequence generating step for generating a
non-correlation sequence for pilot of a first resource block;
a first spectrum spreading step for spreading spectrums of elements in the
non-correlation sequence for pilot of the first resource block to be mapped to a
first frequency resource of the first resource block, by using a first group of
Orthogonal Cover Codes (OCCs);
a second spectrum spreading step for spreading spectrums of elements in
the non-correlation sequence for pilot of the first resource block to be mapped
to a second frequency resource of the first resource block, by using a second
group of OCCs; the first and second frequency resources are adjacent
frequency resources with respect to a first group of data streams, and the first
and second groups of OCCs are mirrors in column to each other;
a third spectrum spreading step for spreading spectrums of elements in
the non-correlation sequence for pilot of the first resource block to be mapped
to a third frequency resource of the first resource block, by using a third group
of OCCs;
a fourth spectrum spreading step for spreading spectrums of elements in
the non-correlation sequence for pilot of the first resource block to be mapped
to a fourth frequency resource in the first resource block, by using a fourth
group of OCCs; the third and fourth frequency resources are adjacent
frequency resources with respect to a second group of data streams, and the
third and fourth groups of OCCs are mirrors in column to each other; and
a mapping step for mapping the elements with their spectrums spread by
the first and second spectrum spreading steps to the first and second
frequency resources of the first resource block, respectively, and map the
elements with their spectrums spread by the third and fourth spectrum
spreading steps to the third and fourth frequency resources of the first
resource block, respectively.
6. The DMRS generation method according to claim 5, wherein one of the
third and fourth groups of OCCs is formed by performing a column vector
cyclic shift to one of the first and second groups of OCCs, and the same
column vector has different column serial numbers in the first to fourth groups
of OCCs.
7. The DMRS generation method according to claim 5, wherein
the non-correlation sequence generation step generates a non-correlation
sequence for pilot of a second resource block, the second resource block
being adjacent to the first resource block;
the first spectrum spreading step spreads spectrums of elements in the
non-correlation sequence for pilot of the second resource block to be mapped
to a first frequency resource of the second resource block, by using a fifth
group of OCCs;
the second spectrum spreading step spreads spectrums of elements in
the non-correlation sequence for pilot of the second resource block to be
mapped to a second frequency resource of the second resource block, by
using a sixth group of OCCs; the first and second frequency resources of the
second resource block are adjacent frequency resources with respect to the
first group of data streams, and the fifth and sixth groups of OCCs are mirrors
in column to each other;
the third spectrum spreading step spreads spectrums of elements in the
non-correlation sequence for pilot of the second resource block to be mapped
to a third frequency resource of the second resource block, by using a seventh
group of OCCs;
the fourth spectrum spreading step spreads spectrums of elements in the
non-correlation sequence for pilot of the second resource block to be mapped
to a fourth frequency resource of the second resource block, by using an
eighth group of OCCs; the third and fourth frequency resources of the second
resource block are adjacent frequency resources with respect to the second
group of data streams, and the seventh and eighth groups of OCCs are mirrors
in column to each other;
the mapping step further maps the elements in the non-correlation
sequence for pilot of the second resource block with their spectrums spread by
the first to fourth spectrum spreading units to the first to fourth frequency
resources of the second resource block, respectively.
8. The DMRS generation method according to claim 7, wherein
the same column vector has different column serial numbers in the fifth to
eighth groups of OCCs, one of the fifth and sixth groups of OCCs is formed by
performing a column vector cyclic shift to one of the first and second groups of
OCCs by a first displacement, and one of the seventh and eighth groups of
OCCs is formed by performing a column vector cyclic shift to one of the first
and second groups of OCCs by a second displacement.
9. The DMRS generation method according to claim 5, wherein the first
and second groups of OCCs are both Walsh code sequences or Fourier
transform sequences.
10. An OCC generating apparatus, comprising:
a basic orthogonal code acquiring device configured to acquire a group of
basic orthogonal codes;
a mirror unit configured to perform a mirroring in column on the basic
orthogonal codes generated by the basic orthogonal code acquiring device, so
as to obtain a first basic orthogonal code group pair, and further to perform a
mirroring in column on the basic orthogonal codes having undergone the cyclic
shift by the column cyclic shift unit, so as to obtain a second OCC group pair;
a column cyclic shift unit is configured to perform a column vector cyclic
shift to the basic orthogonal codes generated by the basic orthogonal code
acquiring device, wherein the displacement of the column vector cyclic shift is
variable; and
a group pair group acquiring unit configured to control the column cyclic
shift unit and the mapping unit, so as to obtain a group of column serial number
distinguishable OCC group pairs where the same column has different column
serial numbers in different OCC groups.