CN102130754B - A kind of method and system for realizing cooperateing with precoding - Google Patents
A kind of method and system for realizing cooperateing with precoding Download PDFInfo
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- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
- H04B7/022—Site diversity; Macro-diversity
- H04B7/024—Co-operative use of antennas of several sites, e.g. in co-ordinated multipoint or co-operative multiple-input multiple-output [MIMO] systems
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
- H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
- H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
- H04B7/0613—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission
- H04B7/0615—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal
- H04B7/0619—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal using feedback from receiving side
- H04B7/0636—Feedback format
- H04B7/0639—Using selective indices, e.g. of a codebook, e.g. pre-distortion matrix index [PMI] or for beam selection
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- H04L25/00—Baseband systems
- H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
- H04L25/0202—Channel estimation
- H04L25/0224—Channel estimation using sounding signals
- H04L25/0228—Channel estimation using sounding signals with direct estimation from sounding signals
- H04L25/023—Channel estimation using sounding signals with direct estimation from sounding signals with extension to other symbols
- H04L25/0232—Channel estimation using sounding signals with direct estimation from sounding signals with extension to other symbols by interpolation between sounding signals
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- H04L25/00—Baseband systems
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- H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
- H04L25/03891—Spatial equalizers
- H04L25/03898—Spatial equalizers codebook-based design
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- H04L25/00—Baseband systems
- H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
- H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
- H04L25/03891—Spatial equalizers
- H04L25/03949—Spatial equalizers equalizer selection or adaptation based on feedback
- H04L25/03955—Spatial equalizers equalizer selection or adaptation based on feedback in combination with downlink estimations, e.g. downlink path losses
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- H04L5/00—Arrangements affording multiple use of the transmission path
- H04L5/14—Two-way operation using the same type of signal, i.e. duplex
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- H04L25/00—Baseband systems
- H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
- H04L25/0202—Channel estimation
- H04L25/024—Channel estimation channel estimation algorithms
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- H04L25/0248—Eigen-space methods
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- H04L25/00—Baseband systems
- H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
- H04L25/0202—Channel estimation
- H04L25/024—Channel estimation channel estimation algorithms
- H04L25/0258—Channel estimation using zero-forcing criteria
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L25/00—Baseband systems
- H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
- H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
- H04L25/0398—Restoration of channel reciprocity
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- H—ELECTRICITY
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- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W24/00—Supervisory, monitoring or testing arrangements
- H04W24/10—Scheduling measurement reports ; Arrangements for measurement reports
Abstract
The present invention is for the problem for cooperateing with precoding technique to exist between the descending base station of current TDD system, propose a kind of method and system for realizing cooperateing with precoding, on the one hand receiving terminal and the unmatched error of base station end code book under actual channel environment are greatly reduced in TDD system using the channel estimation methods based on linear interpolation, on the other hand the feedback quantity of the local precodings of CoMP is reduced using two sets of code book schemes, the synchronization between base station is strengthened simultaneously, and the communication quality of Cell Edge User is drastically increased while feedback quantity is reduced.
Description
Technical field
The present invention relates to the communications field, and in particular to one kind realizes cooperateing with the method and system of precoding (precoding).
Background technology
Several cells can simultaneously be combined using coordinate multipoint (CoMP) transmission technology in 3G LTE-Advanced systems
Node is covered to cell bound fraction, and the performance of cell edge is improved with this.CoMP technologies and traditional distributed day
Line technology is similar to, but the design of spaced antenna is based on for specific Practical Project form, rather than the concept of technological layer.
CoMP is defined from technical standpoint, and the antenna sites collaboration connected using optical fiber is together user service, and adjacent is several
Individual antenna station or node are simultaneously a user service, so as to improve the data transfer rate of user.Conventional network topology structure it is main
Problem is：The interface of base station has that interference and covering quality decline, and causes terminal in the poor-performing of switch area.
CoMP technologies can especially improve the performance of cell edge with respect to other 3G key technologies.It can make several cells simultaneously to small
Area joint portion is covered, and can thus improve the communication quality of cell edge.
Precoding is one of important technology of CoMP, at present using two kinds of methods for designing point of the precoding based on code book
It is not independent design and co-design.Precoding mechanism in four kinds of descending (DL) JP CoMP is respectively：The precoding of the overall situation,
The local precoding of MBSFN precodings, local precoding and weighting.Wherein, global precoding complexity highest, it is necessary to it is complete
Originally very huge and dimension is with CoMP cell size variation for office code, and codebook design is too complicated；MBSFN Precoding Designs are most simple,
But there is certain performance loss；Local precoding is proposed for balance complexity and performance, but because determines to prelist
Code operation needs different PMI, so also bringing along larger feedback overhead；The local precoding of weighting is to local precoding
Wave beam precoding is addition of, its basic thought is the weighted sum for obtaining local precoding, its performance is only less than global precoding, but
Be realize it is still excessively complicated, except feedback PMI, in addition it is also necessary to calculate and feedback weight vector.
In FDD system, downstream state information can be by user terminal to base station feedback code word, and direct base station selection is pre-
Coding codeword is realized.But feedback scheme can bring extra signaling consumption, particularly between base station exist very big distance
Base station between coordination technique, signaling and complexity are even more the problem that must take into consideration.TDD system has up-downgoing channel reciprocity
Advantage, base station obtains downlink channel condition by uplink channel estimation, so as to decomposite the precoding vector of needs, can be with
Avoid the problem that codeword feedback brings.But in actual TDD system, because transceiver internal channel can not be completely the same,
Up-downgoing channel often has certain difference.Therefore, directly obtaining downlink precoding from up channel can bring very big property
The loss of energy.Although precoding algorithms based on code book bring quantization loss, but because the number of code word in code book is limited
, and a certain distance is there is also between code word, accordingly even when the channel information that base station and terminal are obtained is variant, still
Very possible selection identical code word.
The content of the invention
In view of this, it is a primary object of the present invention to provide a kind of method and system for realizing cooperateing with precoding, to drop
Low receiving terminal and the unmatched error of base station end code word, improve the channel capacity of the precoding technique based on code book.
To reach above-mentioned purpose, the technical proposal of the invention is realized in this way：
A kind of method for realizing cooperateing with precoding, the method includes：
Estimate channel using uplink detection signal, optimal code word is selected using maximum capacity standard from code book, from upper
Synchronization code word index is extracted in row information to find out synchronization code word, to sending pre-encoding results after signal precoding；
Channel estimation is made according to each base station down detectable signal respectively, with the channel estimation based on linear interpolation from appointing in advance
The optimal code word of corresponding base station signal was selected in fixed code book, the synchronization code word index further according to a upper time of reception calculates decoding
Code word, and estimate that obtaining current time optimal synchronisation codewords indexes is sent to base station according to actual channel.
The code word uses two sets of precoding codebooks, and a set of code book is used for the local precodings of coordinate multipoint CoMP, another set of
Code book is used for synchronization among base stations codeword selection.
The method is further included：
Base station end initialization, user terminal is performed to be initially accessed and the operation of synchronization code word selection scheme.
The base station end initialization operation includes：The connection request of edge customer is detected, with cooperative base station end by letter
Number tunnel backhaul interactive information determines to be sent to the signal and resource information of user；
The user terminal is initially accessed operation to be included：It is initially accessed (random access procedure) with base station, is obtained newest descending
Channel information, determines base station synchronization codewords indexes information and is sent to base station according to channel estimation；
The synchronization code word selection scheme operation includes：The method for providing the selection of user terminal synchronization code word.
The method further include to upgrade in time and feedback code index information operation：
In each communication occasions user terminal according to channel estimation selection decoding code word, while being the hair of subsequent time base station end
Send to be elected and select synchronization code word and feed back；Base station end then updates synchronization code word information.
A kind of system for realizing cooperateing with precoding, the system includes transmission processe unit, reception processing unit；Wherein,
The transmission processe unit, for estimating channel using uplink detection signal, uses maximum capacity from code book
Standard selects optimal code word, synchronization code word index is extracted from uplink information to find out synchronization code word, after signal precoding
Send pre-encoding results；
The reception processing unit, for receiving the information from base station end, according to each base station down detectable signal point
Do not make channel estimation, the optimal of corresponding base station signal is selected from the code book made an appointment with the channel estimation based on linear interpolation
Code word, the synchronization code word index further according to a upper time of reception calculates decoding code word, and is estimated to obtain currently according to actual channel
Moment optimal synchronisation codewords indexes are simultaneously sent to base station.
The code word uses two sets of precoding codebooks, and a set of code book is used for the local precodings of coordinate multipoint CoMP, another set of
Code book is used for synchronization among base stations codeword selection.
The system further includes early stage processing unit, for perform base station end initialization, user terminal be initially accessed and
Synchronization code word selection scheme is operated.
When the early stage processing unit performs base station end initialization operation, it is used for：The connection request of edge customer is detected,
With the signal and resource information that cooperative base station end will be sent to user by the determination of backhaul interactive information；
When the early stage processing unit execution user terminal is initially accessed operation, it is used for：(Stochastic accessing is initially accessed with base station
Process), newest descending channel information is obtained, base station synchronization codewords indexes information is determined according to channel estimation and base station is sent to；
When the early stage processing unit performs the operation of synchronization code word selection scheme, it is used for：Provide the choosing of user terminal synchronization code word
The method selected.
The system further includes to update feedback unit, the unit upgrading in time and during feedback code index information,
For：
Channel estimation is done to select to decode code word in each communication occasions triggering user terminal, while being subsequent time base station end
Transmission selection synchronization code word and feed back；And trigger base station end and update synchronization code word information.
The present invention is for the problem for cooperateing with precoding technique to exist between the descending base station of current TDD system, it is proposed that Yi Zhongshi
The method and system of precoding is now cooperateed with, on the one hand TDD systems is greatly reduced using the channel estimation methods based on linear interpolation
Receiving terminal and the unmatched error of base station end code book under actual channel environment in system, are on the other hand reduced using two sets code book schemes
The feedback quantity of the local precodings of CoMP, while the synchronization between strengthening base station, and while feedback quantity is reduced greatly
Improve the communication quality of Cell Edge User.
Brief description of the drawings
Fig. 1 is the realization collaboration precoding general flow chart of the embodiment of the present invention；
Fig. 2 is two BTS channel models of the embodiment of the present invention；
Fig. 3 is the synchronization code word selection flow chart of the embodiment of the present invention；
Fig. 4 is the user terminal reception processing flow chart of the embodiment of the present invention；
Fig. 5 is the precoding algorithms time slot flow chart based on linear interpolation of the embodiment of the present invention；
Fig. 6 is the tdd frame structural representation of the embodiment of the present invention；
Fig. 7 compares for the performance of BER of different transmission algorithms under actual channel condition；
Fig. 8 compares for the performance of BER of different transmission algorithms under desirable channel conditions；
Fig. 9 is collaboration precoding between base station and the Performance comparision of global precoding algorithms；
Figure 10 is the system diagram of the realization collaboration precoding of the embodiment of the present invention.
Specific embodiment
In actual applications, under multiple cell edge customer environment, in order to transceiver inside is believed in reducing actual TDD system
The inconsistent codeword matching error brought in road, while strengthening the diversity gain that collaboration belt between base station comes, reduces feedback quantity, improves side
The speech quality of edge user, can combine and precoding technique is cooperateed between TDD system precoding technique and descending base station, propose a kind of
It is new based on two sets of local method for precoding of code book.It is simultaneously it that Cell Edge User can receive two or three base stations
Service, user terminal can be reduced under TDD system actual channel environment using the channel estimation technique based on linear interpolation, the technology
Receiving terminal and the unmatched error of base station end code word, and improve the channel capacity of the precoding technique based on code book.
On the other hand the present invention uses two sets of precoding codebooks, and a set of code book is used for the local precodings of CoMP, due to TDD systems
System up-downgoing channel reciprocity eliminates the PMI feedback overheads of the local precodings of CoMP, and another set of code book is used for synchronization among base stations
Codeword selection, synchronization among base stations are strengthened with a small amount of feedback quantity.
Overall operation thinking of the invention is as shown in figure 1, comprise the following steps：
1. base station end initialization：The connection request of edge customer k is detected, signal tunnel is passed through with cooperative base station end
(backhaul) interactive information determines to be sent to the signal X of user kkAnd it is shared code book, power configuration information, frequency, same
The resource informations such as step time slot.
2. user terminal is initially accessed：It is initially accessed (random access procedure) with base station, obtains newest descending channel information, root
Determine base station synchronization codewords indexes information according to channel estimation and be sent to base station.
3. synchronization code word selection scheme：The method for providing the selection of user terminal synchronization code word.
4. base station end transmission processe：Estimate channel using uplink detection signal, maximum capacity standard is used from code book
Select optimal code wordSynchronization code word index is extracted from uplink information to find out synchronization code wordTo signal precoding
After send pre-encoding results
5. user terminal receive information treatment：Receive from the B=2 information of base station end：
Channel estimation is made according to each base station down detectable signal respectively, with based on linear interpolation channel estimation (close to
Channel condition information used by each base coded) the B=2 optimum code of corresponding base station signal is selected from the code book made an appointment
Word, the synchronization code word index further according to a upper time of reception calculates decoding code word (such as：Using zero-forcing receiver), decode code word
For：
Estimate to obtain current time optimal synchronisation codewords indexes according to actual channel and be sent to base station (the same step of method
2)。
6. upgrade in time and feedback code index information：Estimated according to current time channel in each communication occasions user terminal
Meter selection decoding code word, while for the transmission of subsequent time base station end selects synchronization code word and feeds back.Base station end each moment is all
Update synchronization code word information.
Core of the invention is how to carry out channel estimation to reduce the difference of transmitting-receiving moment channel so that base station end and connect
Receiving end code book is tried one's best matching；Synchronization among base stations code word how is designed, CoMP edge customers are improved while feedback quantity to reduce
Performance.
Below in conjunction with accompanying drawing, method for precoding is cooperateed between the descending base station based on code book in detailed description TDD system.
Referring to Fig. 2, Fig. 2 is shown two BTS channel models, and the present invention uses TDD-CoMP systems, it is assumed that cooperation cell
Number is B, and each cell base station has NTIndividual transmission antenna, terminal has NRIndividual reception antenna, information to be sent is divided into NSIt is individual independent
Data flow, wherein NS≤NR≤NT。
In base station end, NSAfter the signal transactings such as the individual encoded modulation of independent data flow, then precoding is carried out (comprising base
Synchronization code word between standing) treatment, finally by being sent to terminal after modulation.Terminal receiver recovers former using corresponding processing method
Beginning signal.As shown in Figure 2.Cell base station b (b=1,2) and user UEkBetween channel gain matrix be：Base station b is to user UEkPre-coding matrix is：Base station synchronization code word square
Battle array be：The cooperative signal that user terminal is received is：
Wherein：Composite channel matrix
Synthesis pre-coding matrix
Synthesis synchronization code word matrix
Sending signal xk(NS× 1) common NSLayer data stream,It is the transmit power of each layer data stream, nkIt is Gauss white noise
Acoustic vector, its covariance matrix is：Symbol ()HIt is the conjugate transposition for seeking matrix,It is NRRank list
Position battle array.For statement is clear, the main citing B=2, N of the present inventionS=1 situation, but method proposed by the present invention equally applicable B, NS
Take the situation of other values.Realize that step is as follows：
1. base station end initialization
When edge customer has communication request, nearby base station (more than two) can detect the connection request of edge customer k,
Cooperative base station end determines to be sent to the signal x of user k by backhaul interactive informationkAnd shared code book, power configuration
The resource informations such as information, frequency, synchronization slot.After initialization is finished, detectable signal is sent to user, to determine channel status
Information is that subsequent time is descending sends the suitable synchronization code word of selection.
2. user terminal is initially accessed
It is initially accessed (random access procedure) with base station, obtains newest descending channel information, base is determined according to channel estimation
Synchronization code word index information of standing is sent to base station.Cooperateed between due to not accounting for base station in local precoding algorithms, therefore needed
Second set of code book (synchronization code word) is wanted to meet synchronization among base stations.The thought of second set of codebook design comes from single cell (NT=B
=2, NR=1) precoding codebook design under environment.Under single-cell environment, pre-encoding codeword is：
Code word W carries out Phase synchronization equivalent to the signal that two antennas of transmitting terminal send, similarly under CoMP environment
Code wordEquivalent to transmitting terminal NTThe signal that root antenna sends carries out Phase synchronization；Therefore by code wordAfter precoding, B base station is equivalent to the phase for having B different.There are 2 different phases, institute for B=2 base station
The task of B=2 synchronization among base stations can be completed with code word W, only code word W need to be extended to adapt to synchronization among base stations.
Extended method is as follows：
It is NT×NTDimension diagonal matrix.It is normalized after extension：
ForThe synchronization code word of generation, can be arbitrarily assigned to two base stations；For two base stations, W
Codebook size be 4, therefore synthesis synchronization code word matrixSize also be 4.
After user terminal calculates synchronization code word, codebook index information is fed back to two base stations, code word respectively 's
Distribution is solved by coordinating between base station.
3. synchronization code word selection scheme
The code word quilt of power system capacity can be maximized in code book from power system capacity as synchronization code word selection standard
It is optimal code word to be elected to be, and Fig. 3 is that synchronization code word selects flow chart, is mainly summarised as following operating process：
First, the corresponding code of maximum system capacity of each base station is chosen from first set code book (local precoding codebook)
Word, maximizes power system capacity Criterion of Selecting as follows：
Wherein,B=1,2 represent two base stations
Respective optimal code word.
Next, two channel matrixes of base station are synthesized：By two base stations
The optimal code word selected is merged into following form：
Synthesis pre-coding matrix
Finally, power system capacity criterion from synthesis synchronization code word matrix is maximized using followingMiddle choosing
Optimal synchronization code word is taken, Criterion of Selecting is：
Wherein,
4. base station end transmission processe
Base station end estimates channel using uplink detection signal, and optimal code word is selected using maximum capacity standard from code book(choosing method is with step 3 first step).Synchronization code word index is extracted from uplink information to find out synchronization code wordIt is right
Pre-encoding results are sent after signal precoding
5. user terminal receive information treatment
User terminal is received from the B=2 information of base station end：
Referring to Fig. 4, Fig. 4 is user terminal reception processing flow chart, and the flow includes following operation：
Branch one：Decoding receives signal
(1) makees channel estimation respectively according to each base station down detectable signal, estimates channel based on linear interpolation method, i.e.,
Channel condition information used by the channel for estimating close to each base coded.Referring to Fig. 5, Fig. 5 is based on the pre- of linear interpolation
Encryption algorithm time slot flow chart, the time slot map is that entirety realizes that flow chart clearly expresses the principle of linear interpolation method.t0
Represent some moment in communication process, TfThe frame length of TDD is represented, Δ T represents time interval between downstream transmission.In figure
Give the process that uplink and downlink are transmitted twice：
First, in t0-TfMoment, terminal receives base station down detectable signal and carries out channel estimation, obtains current channel
Status informationUsing the Channel assignment synchronization code word and feedback synchronization codewords indexes estimated.In t0- Δ T moment, base station pair
After reception signal carries out channel estimation, current channel condition information is obtainedUsing the channel estimated and the synchronization for solving
Codewords indexes (user feedback) select downlink precoding matrixBy signalIt is sent to terminal.
Then, in t0Moment, terminal receives base station down precoded signalObtained after carrying out channel estimationOne
Aspect carries out linear EV model, code word selection, signal interpretation using the channel information, obtains respectivelyWithOn the other hand it is based on channel informationSelection synchronization code word and feedback synchronization codewords indexes.Passing
In the TDD pre-coding systems of system, base station can be according to channel estimationObtain solution pre-coding matrixThen soft-decision is utilized
Solve transmission data vector：
Wherein,
Under the hypothesis of ideal communication channel, the channel conditions of uplink downlink (With) essentially identical, therefore channel
The pre-coding matrix at two ends is conciliate pre-coding matrix and is matched each other.But in systems in practice, channel is time-varying.Up-downgoing chain
Small difference is likely to the mismatch for causing pre-coding matrix to conciliate pre-coding matrix between road, causes systematic function seriously to decline
Fall.Fig. 6 more clearly gives tdd frame topology example.Wherein, TsTime slot is represented, ↓ descending time slot is represented, when ↑ expression is up
Gap.
Linear interpolation method based on channel estimation is estimated that the down channel in previous frame.When in t0Moment obtains
After channel condition information, the down channel that terminal is estimatedIt is represented by
Wherein,
ThisCan be fromMiddle acquisition.(5-2) formula is converted to：
(2) is according to estimation channelB=2 is selected from the code book made an appointment
The optimal decoding code word of corresponding base station signal, has had many texts on the codebook quantification in FDD system and codeword selection method
Chapter has done substantial amounts of research.The packing of Jim Glassman subspace is a kind of technology for maximizing the minimum range between code word, a lot
Research Literature is used.Consider the complexity of maximum likelihood receiver, can be using the linear receiver of suboptimum.
Receiver is by using NR×NTDimension matrixObtain ykEstimate：
When ZF (Zero Forcing, ZF) receiver is used in systems：
When using Minimum Mean Square Error receiver (Minimum Mean Square Error, MMSE)：
Mean squared error criterion (Mean Square Error, MSE) can be obtained as follows：
Wherein,
(3) the synthesis synchronization code word that was obtained according to a upper time of receptionCalculate decoding code word.The present invention is below
Will be using zero-forcing detector in emulation, decoding code word is：
Decoded signal is：
Branch two：Synchronization code word selection and feedback synchronization codewords indexes
Estimated to obtain current time optimal synchronisation code word according to actual channel, and synchronization code word index is sent to base station
(method is with step 2).
6. upgrade in time and feedback code index information
In each communication occasions user terminal according to current time channel estimation selection decoding code word, while being subsequent time base
The transmission selection at end of standing and is fed back synchronization code word.Base station end each moment will update synchronization code word information.
7. simulation performance
The present invention is using Monte Carlo emulation cooperateing with method for precoding between the base station based on linear interpolation for proposing
Performance is verified that the performance to following 8 kinds of transmission mechanisms is compared：
Under actual channel condition precoding is cooperateed between the base station based on linear interpolation：Base station is according to uplink channel estimation and end
Hold synchronization code word index (2bit feedbacks) of feedback that optimal code word is selected from local code book, carry out precoding processing；Terminal root
Estimate to estimate uplink channel status information with the method based on linear interpolation according to down channel, select optimal from local code book
Code word carries out solution precoding processing.
Precoding is cooperateed with actual channel condition between base station：The synchronous code that base station is fed back according to uplink channel estimation and terminal
Word indexing (2bit feedbacks) selects optimal code word from local code book, carries out precoding processing；Terminal is estimated according to down channel
Optimal code word is selected from local code book, solution precoding processing is carried out.
Local precoding based on linear interpolation under actual channel condition：Base station is according to uplink channel estimation from local code book
The middle optimal code word of selection, carries out precoding processing；Terminal is estimated to be estimated with the method based on linear interpolation according to down channel
Uplink channel status information, selects optimal code word from local code book, carries out solution precoding processing.
Non- code book SVD decomposes precoding (0bit feedbacks) under actual channel condition：Each base station and terminal are respectively according to up and down
Row channel estimation, SVD is carried out to channel matrix decomposes to conciliate pre-coding matrix to obtain precoding, does not cooperate between base station.
Precoding is cooperateed with desirable channel conditions between base station：The synchronous code that base station is fed back according to uplink channel estimation and terminal
Word indexing (2bit feedbacks) selects optimal code word from local code book, carries out precoding processing；Terminal is estimated according to down channel
Optimal code word is selected from local code book, solution precoding processing is carried out.
Global precoding under desirable channel conditions：The code book index (8bit feedbacks) that base station is fed back according to terminal is from all-key sheet
Middle selection code word carries out precoding processing；Terminal is estimated to select optimal code word from all-key sheet according to down channel, carries out solving pre-
Coded treatment.
Non- code book SVD decomposes precoding (0bit feedbacks) under desirable channel conditions：Each base station and terminal are respectively according to up and down
Row channel estimation, SVD is carried out to channel matrix decomposes to conciliate pre-coding matrix to obtain precoding, does not cooperate between base station.
Local precoding under desirable channel conditions：Base station selects optimum code according to uplink channel estimation from local code book
Word, carries out precoding processing；Terminal is estimated to select optimal code word from local code book according to down channel, carries out Xie Yubianmachu
Reason.
For real system channel time-varying model, present invention assumes that adjacent moment channel matrix mean square error (MSE) is α2,
Channel Modeling is as follows：
α=0.99 is used in present invention emulation.
Fig. 7 is that two base station models difference transmission algorithm performance of BER compare under actual channel condition, can be with from figure
Find out and cooperate between the base station based on linear interpolation that precoding algorithms are optimal algorithms because with local precoding algorithms phase
Than cooperateing with precoding algorithms to increased synchronization code word feedback between base station, equivalent to two channel informations between base station and user
Global optimization has been carried out, the mutual interference between the antenna data stream of different base station has preferably been eliminated；Precoding is cooperateed with between base station
Algorithm is compared, and linear interpolation algorithm enhances the matching degree that pre-coding matrix is conciliate in precoding, therefore the base based on linear interpolation
It is best that precoding algorithms are cooperateed between standing.In low signal-to-noise ratio, the precoding algorithms that non-code book SVD is decomposed are better than based on linear
The local precoding algorithms of interpolation, this is because in the case where sending signal power is relatively low, the received signal to noise ratio of terminal is more
It is important, therefore it is subject to the non-code book SVD of codebook quantification loss influence to decompose precoding algorithms just with some superiority；With
The increase of sending signal power, between multiple antennas data flow interference gradually substitution noise turn into influence systematic function it is main because
Element, and the linear interpolation algorithm for being based on code book can strengthen the matching degree that pre-coding matrix is conciliate in precoding, preferably eliminate not
With the mutual interference between antenna data stream, therefore the linear interpolation algorithm based on code book is better than non-code book SVD decomposition algorithms, and this is also
The present invention is using the main cause based on code book algorithm.
Fig. 8 is that two base station models difference transmission algorithm performance of BER compare under desirable channel conditions, can be with from figure
Find out and cooperate between base station that precoding is equally optimal algorithm, it is better than local precoding algorithms and non-code book SVD decomposition algorithms
Reason is that of obtaining than their more channel informations.The reason for cooperateing with precoding algorithms to be better than global precoding algorithms between base station
It is them under the conditions of channel information as much is obtained, the former uses two sets of code books, and code book total size is equivalent to 16 × 16 × 4
=210, and the codebook size of the latter is 256=28, from feedback quantity due between base station cooperate with precoding need to only feed back second
The code word of code book is covered, therefore feedback quantity is 2bit, global precoding algorithms need 8bit feedback quantities；Come from algorithm complex
See, due to select cooperateing with precoding algorithms complexity to be more than global precoding algorithms between code word, base station from two sets of code books.But
TDD system has the advantage of up-downgoing channel reciprocity, and base station obtains downlink channel condition information by uplink channel estimation,
So as to decomposite the precoding vector of needs.Global precoding algorithms are actually to abandon this advantage, the method for the present invention
This advantage is combined closely with TDD system by way of using two sets of code books, and its performance is completely superior to global precoding.
Fig. 9 is collaboration precoding between base station and the Performance comparision of global precoding algorithms.It can be seen that preferable letter
Non- code book SVD decomposition algorithms are better than local precoding algorithms under the conditions of road, because non-code book SVD decomposes calculation under desirable channel conditions
Method is not influenceed by channel variation, and the matching that pre-coding matrix is conciliate in precoding is better than having codebook quantification to lose local precoding calculation
Method, it can be seen that under actual channel condition, importance of the linear interpolation algorithm to the precoding algorithms based on code book.
In order to ensure the smooth realization of various embodiments above, setting as shown in Figure 10 can be carried out.Referring to Figure 10, Figure 10
It is the system diagram of the realization collaboration precoding of the embodiment of the present invention, the system includes the early stage processing unit that can be connected, sends
Processing unit, reception processing unit, also the renewal feedback unit including can be connected with above three unit.
In actual applications, early stage processing unit be able to carry out foregoing base station end initialization, user terminal be initially accessed with
And the operation such as synchronization code word selection scheme；Transmission processe unit can estimate channel using uplink detection signal, be adopted from code book
Optimal code word is selected with maximum capacity standard, synchronization code word index is extracted from uplink information to find out synchronization code word, it is right
Pre-encoding results are sent after signal precoding；Reception processing unit can receive the information from base station end, according to each base station
Downlink detecting signal makees channel estimation respectively, selects corresponding from the code book made an appointment with the channel estimation based on linear interpolation
The optimal code word of base station signal, the synchronization code word index further according to a upper time of reception calculates decoding code word, and according to actual letter
Estimate to obtain current time optimal synchronisation codewords indexes and be sent to base station in road.
Updating feedback unit can upgrade in time and feedback code index information：User terminal is triggered in each communication occasions
Channel estimation is done to select to decode code word, while for the transmission of subsequent time base station end selects synchronization code word and feeds back；And touch
Hair base station end updates synchronization code word information.
Visible in sum, either method or system, of the invention to realize cooperateing with the technology of precoding to be related to TDD system
Method for precoding is cooperateed between descending base station, using the channel estimation methods of linear interpolation, TDD system actual channel environment is reduced
Lower receiving terminal and the unmatched error of base station end code word, improve the channel capacity of the precoding technique based on code book.The opposing party
The face present invention uses two sets of precoding codebooks, and a set of code book is used for the local precodings of CoMP, because TDD system up-downgoing channel is mutual
Favour eliminates the PMI feedback overheads of the local precodings of CoMP, and another set of code book is used for synchronization among base stations codeword selection, with a small amount of
Feedback quantity strengthens synchronization among base stations.
The above, only presently preferred embodiments of the present invention is not intended to limit the scope of the present invention.
Claims (8)
1. it is a kind of realize cooperate with precoding method, it is characterised in that the method includes：
Channel is estimated in base station using uplink detection signal, and optimal code word is selected using maximum capacity standard from code book, from upper
Synchronization code word index is extracted in row information to find out synchronization code word, to sending pre-encoding results after signal precoding；
User terminal makees channel estimation respectively according to each base station down detectable signal, with the channel estimation based on linear interpolation from advance
The optimal code word of corresponding base station signal was selected in the code book of agreement, the synchronization code word index further according to a upper time of reception calculates solution
Code code word, and estimate that obtaining current time optimal synchronisation codewords indexes is sent to base station according to actual channel；
The channel estimation based on linear interpolation is used to obtain the channel condition information used by each base coded；
Methods described uses two sets of precoding codebooks, and a set of code book is for the local precodings of coordinate multipoint CoMP, another set of code book
For synchronization among base stations codeword selection.
2. method according to claim 1, it is characterised in that the method is further included：
Base station end initialization, user terminal is performed to be initially accessed and the operation of synchronization code word selection scheme.
3. method according to claim 2, it is characterised in that
The base station end initialization operation includes：The connection request of edge customer is detected, signal tunnel is passed through with cooperative base station end
Road backhaul interactive information determines to be sent to the signal and resource information of user；
The user terminal is initially accessed operation to be included：It is initially accessed with base station, obtains newest descending channel information, is estimated according to channel
Meter determines base station synchronization codewords indexes information and is sent to base station；It is random access procedure that the base station is initially accessed；
The synchronization code word selection scheme operation includes：The method for providing the selection of user terminal synchronization code word.
4. the method according to any one of claims 1 to 3, it is characterised in that the method further include to upgrade in time with
And the operation of feedback code index information：
In each communication occasions user terminal according to channel estimation selection decoding code word, while for the transmission of subsequent time base station end is selected
Select synchronization code word and feed back；Base station end then updates synchronization code word information.
5. it is a kind of realize cooperate with precoding system, it is characterised in that the system include transmission processe unit, reception processing list
Unit；Wherein,
The transmission processe unit, for estimating channel using uplink detection signal, uses maximum capacity standard from code book
Optimal code word is selected, synchronization code word index is extracted from uplink information to find out synchronization code word, to being sent after signal precoding
Pre-encoding results；
The reception processing unit, for receiving the information from base station end, makees respectively according to each base station down detectable signal
Channel estimation, the optimum code of corresponding base station signal is selected with the channel estimation based on linear interpolation from the code book made an appointment
Word, the synchronization code word index further according to a upper time of reception calculates decoding code word, and when estimating to obtain current according to actual channel
Carve optimal synchronisation codewords indexes and be sent to base station；
The channel estimation based on linear interpolation is used to obtain the channel condition information used by each base coded；
The system uses two sets of precoding codebooks, and a set of code book is for the local precodings of coordinate multipoint CoMP, another set of code book
For synchronization among base stations codeword selection.
6. system according to claim 5, it is characterised in that the system further includes early stage processing unit, for holding
The initialization of row base station end, user terminal are initially accessed and the operation of synchronization code word selection scheme.
7. system according to claim 6, it is characterised in that
When the early stage processing unit performs base station end initialization operation, it is used for：The connection request of edge customer is detected, with association
Make base station end to determine to be sent to the signal and resource information of user by backhaul interactive information；
When the early stage processing unit execution user terminal is initially accessed operation, it is used for：It is initially accessed with base station, is obtained newest descending
Channel information, determines base station synchronization codewords indexes information and is sent to base station according to channel estimation；Wherein, the base station initially connects
It is random access procedure to enter；
When the early stage processing unit performs the operation of synchronization code word selection scheme, it is used for：Provide the selection of user terminal synchronization code word
Method.
8. the system according to any one of claim 5 to 7, it is characterised in that the system further includes to update feedback
Unit, the unit is upgrading in time and during feedback code index information, is being used for：
Channel estimation is done to select to decode code word, while being the hair of subsequent time base station end in each communication occasions triggering user terminal
Send to be elected and select synchronization code word and feed back；And trigger base station end and update synchronization code word information.
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| CN103023607B (en) * | 2011-09-23 | 2017-05-10 | 中兴通讯股份有限公司 | Method and system for cooperative transmission of data |
| CN103580782B (en) * | 2012-07-24 | 2017-10-17 | 华为技术有限公司 | The base band processing device and wireless communication system of wireless communication system |
| WO2015024157A1 (en) * | 2013-08-19 | 2015-02-26 | 富士通株式会社 | Information transmission method, user equipment and communication system |
| WO2015024159A1 (en) * | 2013-08-19 | 2015-02-26 | 富士通株式会社 | Method, base station, and user equipment for transmitting information |
| HUE055450T2 (en) * | 2018-04-06 | 2021-11-29 | Ericsson Telefon Ab L M | Power control for new radio uplink single-user multiple-input-multiple- output communication |
| WO2020231523A1 (en) * | 2019-05-13 | 2020-11-19 | Google Llc | Parallel beamforming training with coordinated base stations |
| WO2021007810A1 (en) * | 2019-07-17 | 2021-01-21 | Oppo广东移动通信有限公司 | Precoding method and communication device |
| CN111106838B (en) * | 2019-12-31 | 2021-08-31 | 华中科技大学 | Communication synchronization method, device and system |
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| CN1972257A (en) * | 2005-11-21 | 2007-05-30 | 上海原动力通信科技有限公司 | Method and apparatus for implementing symmetry of channel in broadband orthogonal frequency division multiplexing system |
| WO2010075640A1 (en) * | 2008-12-31 | 2010-07-08 | 上海贝尔股份有限公司 | Multiple base station unite pre-coding method, mobile terminal and base station based on codebook |
| WO2010123313A2 (en) * | 2009-04-24 | 2010-10-28 | Samsung Electronics Co., Ltd. | Techniques for channel state information feedback in wireless communication system |
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| CN1972257A (en) * | 2005-11-21 | 2007-05-30 | 上海原动力通信科技有限公司 | Method and apparatus for implementing symmetry of channel in broadband orthogonal frequency division multiplexing system |
| WO2010075640A1 (en) * | 2008-12-31 | 2010-07-08 | 上海贝尔股份有限公司 | Multiple base station unite pre-coding method, mobile terminal and base station based on codebook |
| WO2010123313A2 (en) * | 2009-04-24 | 2010-10-28 | Samsung Electronics Co., Ltd. | Techniques for channel state information feedback in wireless communication system |
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