CN101719816A - Method for realizing low feedback velocity of self-adaptive MIMO-SCFDE system - Google Patents
Method for realizing low feedback velocity of self-adaptive MIMO-SCFDE system Download PDFInfo
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Abstract
The invention provides a method for realizing low feedback velocity of a self-adaptive MIMO-SCFDE system, comprising the following steps: (1) an available subchannel is selected by a receiving end, an optimum order of a channel matrix is determined, information symbols are transmitted only on the available frequency domain subchannel to generate subchannel identification information and channel order information which is transmitted to a transmitting end through a feedback channel; (2) the transmitting end forms S original equivalent time domain data frames, converts the S original equivalent time domain data frames into equivalent frequency domain symbols, maps the equivalent frequency domain symbols onto the available frequency domain channel after precoding equivalent frequency domain symbols to generate N-dimensional frequency domain vector, and transmits the N-dimensional frequency domain vector by transmitting antenna; (3) the receiving end selects the signals transmitted on the available frequency domain subchannel for balancing, and judges the transmitted information after the equivalent time domain is converted. By selecting frequency domain subchannel transmission information with balanced amplification and small noise, the invention ensures that the error ratio performance can not excessively deteriorate, and deals with MIMO channel order deficiency by adopting simple precoding matrix.
Description
Technical field
The present invention relates to many antennas broadband wireless communications transmission method, belong to the broadband wireless communication technique field.
Background technology
Along with the develop rapidly of science and technology, the communication technology is very important day by day to the influence of the people's the daily life and the national economic development.Broadband wireless communication technique particularly, be subjected to extensive concern as OFDM (hereinafter to be referred as OFDM:Orthogonal FrequencyDivision Multiplexing) and multiple-input and multiple-output (hereinafter to be referred as MIMO:Multiple-input Multiple-output), and the two become the key technology of future wireless in conjunction with MIMO-OFDM.
MIMO utilizes the uncorrelated characteristic of channel between the different antennae, obtains the high channel capacity, thereby improves the availability of frequency spectrum and reliability.OFDM based on the piecemeal transmission can resist multipath fading effectively, because the subcarrier spectrum main lobe is overlapping, has higher spectrum efficiency; Cyclic Prefix (hereinafter to be referred as CP:Cyclic Prefix) can well absorb inter-frame-interference; And can take simple frequency-domain equilibrium method to eliminate because the channel disturbance that the time delay expansion is introduced; Modulated process can be finished with invert fast fourier transformation (hereinafter to be referred as IFFT:Inverse Fast Fourier Transform), and demodulating process can be with fast fourier transform (hereinafter to be referred as FFT:Fast Fourier Transform)) finish.Single carrier frequency domain equalization (hereinafter to be referred as SCFDE:Single Carrier with Frequency Domain Equalization), be similar to the piecemeal transmission technology of OFDM, though the high peak-to-average power ratio (PAPR that can effectively resist multipath fading equally and not have OFDM to make a start, Peak-to-averagePower Ratio), still be subjected to degree of concern far away from OFDM.
The subject matter that mobile MIMO broadband wireless channel faces is: the time, frequently, empty selectivity.When utilizing the adaptive technique of channel condition information (hereinafter to be referred as CSI:Channel State Information) to resist effectively, frequently, empty selectivity, thereby more reliably more effectively communicate.Mimo channel for frequency selective fading, existing self-adaption MIMO-OFDM, no matter be Adaptive Modulation or power division, still effectively resist the precoding technique that lacks the order mimo channel, usually all need a large amount of CSI feedback informations to select to send strategy for making a start, particularly under mobile condition, a large amount of feedback informations needs passback continually, bring very big burden to whole communication system, have a strong impact on the efficient of communication system.
Summary of the invention
The present invention is directed to the big problem of back information amount that existing self-adaption MIMO-OFDM technology exists, a kind of method that can realize low feedback velocity of self-adaptive MIMO-SCFDE system is provided.
The method of realization low feedback velocity of self-adaptive MIMO-SCFDE system of the present invention may further comprise the steps:
(1) for N
T* N
RAdaptive MIMO systems, N
TThe expression number of transmit antennas, N
RExpression reception antenna number, receiving end is selected available M according to non-ideal factor (non-ideal factor comprises the nonlinear characteristic of synchronous error, channel estimation errors and the device etc.) performance loss that causes of channel condition information, system, the modulation system that is adopted and desired system errored bit performance from whole N frequency domain subchannel
SThe best order S of individual subchannel and definite channel matrix, have only the available frequency domain subchannel to upload the transmission information symbol, and other frequency domain subchannels do not transmit information symbol for the forbidding subchannel, generate subchannel identification information and channel sequence information then, and this subchannel identification information and channel sequence information sent to via feedback channel make a start;
(2) make a start according to the modulation system that is adopted and subchannel identification information and channel sequence information, form S original equivalent time domain Frame, through M
SPoint FFT (fast fourier transform), the equivalent time domain sign reversing of initial data frame is become equivalent frequency domain symbol, and the frequency domain subchannel mapping matrix according to subchannel label information and channel sequence information and receiving-transmitting sides agreement should be mapped to M after the precoding of equivalence frequency domain symbol then
SOn the individual available frequency domain subchannel, generate N
TIndividual N dimension frequency domain vector utilizes N point IFFT (invert fast fourier transformation) to change back to time domain again, and the while was by N after serial to parallel conversion added CP
TIndividual transmitting antenna sends;
(3) receiving end is with N
RAfter the Frame that individual reception antenna receives removes CP, utilize FFT to transform to frequency domain, select M according to subchannel identification information and frequency domain subchannel inverse mapping matrix
SIndividual available frequency domain subchannel is to the signal of last transmission, generates balanced matrix according to channel sequence information and channel condition information then and carries out equilibrium, and conversion rules out transmission information after returning equivalent time domain.
For the ease of better understanding, symbol used among the present invention is carried out the part explanation.Lowercase is represented time domain and equivalent time domain symbol, and capitalization is represented frequency domain and equivalent frequency domain symbol; Represent the n moment or m equivalence constantly for the subscript of lowercase (being time domain and equivalent time domain symbol), n=0,1 ..., N-1, m=0,1 ..., M
S-1; The subscript of capitalization (being frequency domain and equivalent frequency domain symbol) is represented k frequency domain subchannel or q equivalent frequency domain subchannel, k=0, and 1 ..., N-1, q=0,1 ..., M
S-1; Capital M in the subscript
SRepresent that this vector is the symbol of equivalent time domain or equivalent frequency domain, N represents that this vector is the symbol of time domain or frequency domain; Lowercase l, i in the subscript represent l root reception antenna and i transmit antennas respectively, if l and i occur simultaneously, l is preceding, i after, expression by i transmitting antenna to l reception antenna, i=1,2 ... N
T, l=1,2 ..., N
R, subscript d represents to make a start before the precoding or d the data flow of receiving end after balanced, d=1, and 2 ..., S.Making a start,
Expression M
STie up original equivalent time domain Frame, corresponding original equivalent frequency domain data frame
For
M
SPoint FFT, wherein
σ
x 2Be the average power of information symbol, d=1,2 ..., S; Because the best order of channel matrix is S, thus only transmit S road independent data stream,
Corresponding to d data flow.
With
Be respectively the original equivalent frequency domain symbol that on original equivalent time domain symbol that transmits in m the equivalence constantly and the individual equivalent frequency domain subchannel of q, transmits, m=0,1 ..., M
S-1, q=0,1 ..., M
S-1; Generate N according to channel sequence information
TThe pre-coding matrix Q of * S; On q equivalent frequency domain subchannel, utilize matrix to follow multiplication of vectors computing precoding to incite somebody to action
Be transformed to
Generate N * M according to frequency domain subchannel identification information then
SThe frequency domain subchannel mapping matrix P of dimension, and will
Be mapped to i transmit antennas frequency domain data frame to be sent
It is i transmit antennas time domain data frame to be sent that time domain is returned in conversion
I=1,2 ..., N
T 
It is the symbolic vector to be sent on k the frequency domain subchannel.H
L, i kBe k frequency domain subchannel gains between i transmit antennas and l root reception antenna; A
kBe the channel matrix of k frequency domain subchannel, wherein the capable i column element of l is H
L, i k, i=1,2 ..., N
T, l=1,2 ..., N
R, k=0,1 ..., N-1.After receiving terminal removed CP, l root reception antenna received
L=1,2 ..., N
R, wherein
Be the useful signal part, corresponding frequency domain form is
Be the reception noise vector,
σ wherein
w 2Be noise variance.Useful signal part and noise section in the signal that n each reception antenna of sampling time receives are respectively
With
N=0,1 ..., N-1; On k the frequency domain subchannel, signal component is
Wherein
Noise component(s) is
K=0,1 ..., N-1; According to the subchannel identification information, select the symbol that transmits on the available frequency domain subchannel
Wherein
K wherein
q∈ 0,1 ..., N-1} is the label of available frequency domain subchannel, q=0, and 1 ..., M
S-1; To M
SThe signal that is subjected to noise pollution on the individual available frequency domain subchannel carries out the ZF equilibrium, is equivalent to
M-P contrary
The difference premultiplication
With
Obtain
With
M
SObtain behind the some IFFT
With
D=1,2 ..., S; Balanced back m equivalence noise component(s) constantly is
M=0,1 ..., M
S-1.
For the adaptive M IMIO-SCFDE system that uses the ZF equilibrium, signal to noise ratio snr before the time domain equalization of n sampling time
Pre nAs follows:
And can calculate signal to noise ratio snr after m the equivalence equivalent time domain equilibrium constantly
Post m, as follows:
In fact, signal to noise ratio is the signal to noise ratio of n sampling time in the balanced preceding frame before the time domain equalization, and signal to noise ratio can be regarded as m equivalent judgement signal to noise ratio constantly in the frame of balanced back after the equivalent time domain equilibrium.According to signal to noise ratio after the equivalent time domain equilibrium, it is σ that the self-adaptive MIMO-SCFDE of low feedback velocity can be regarded average symbol power as
x 2M
SCircuit-switched data stream is parallel by having the same noise variance to be
Awgn channel.After modulation system is determined, just can utilize the errored bit computing formula under the existing AWGN to obtain in the errored bit performance of the self-adaptive MIMO-SCFDE of not considering low feedback velocity under the non-ideal factor situation, in addition also need the conversion of Eb/N0 and signal to noise ratio, for example adopt the 2PSK modulation, the bit error rate of then precoding adaptive M IMIO-SCFDE system is
The detailed implementation procedure in (1) step is as follows in the step of the invention described above:
After receiving-transmitting sides was set up communication, receiving end channel estimating mode was according to a preconcerted arrangement obtained the channel condition information of current channel, and wherein channel condition information is the channel matrix of all frequency domain subchannels, and wherein the channel matrix on each frequency domain subchannel is A
k, k=0,1 ..., N-1; The criterion that reaches the selection of available frequency domain subchannel of determining of the best order of channel matrix is, the performance loss that causes when the non-ideal factor that adopts certain modulation system and taking into account system, under the desired errored bit performance of system, transmit information symbol as much as possible, promptly allow the product M of selected available frequency domain number of subchannels under the best order of channel matrix and this order as far as possible
S* S or spectrum efficiency
Maximum; The best order S of channel matrix and available frequency domain subchannel k
q∈ 0,1 ..., the selection of N-1} is as follows:
Satisfying
Down, maximization M
S* S, wherein: M
SBe available subchannels number, M
S∈ 0,1 ..., N}, S ∈ 1,2 ..., N
T, q=0,1 ..., M
S-1, σ
x 2Be the average power of information symbol, σ
w 2Be noise variance, SNR
ReqFor adopting behind certain modulation system and the taking into account system non-ideal factor signal to noise ratio after the pairing equivalent time domain equilibrium of desired system errored bit performance;
Determine the best order S of channel matrix and select M
SBehind the individual available frequency domain subchannel, generate frequency domain subchannel identification information, D={D (k), k=0,1 ..., N-1}, wherein D (k
q)=1 expression k
qIndividual subchannel is an available subchannels, k
q∈ 0,1 ..., N-1}, q=0,1 ..., M
S-1, k subchannel of D (k)=0 expression is unavailable subchannel, k ≠ k
qWhen appointing the column selection of pre-coding matrix before the receiving-transmitting sides communication,, also need to generate log2 (N such as preceding S row
T) the channel sequence information B of bit, such as working as N
T=4 o'clock B={00,01,10, the best order that 11} identifies selected channel matrix successively is 1,2,3,4, otherwise also needs the selection of extra feedback information sign S row except the best order information that feeds back to channel; Then this subchannel identification information and channel sequence feedback information are postbacked end.
The detailed implementation procedure in (2) step is as follows in the described step of the present invention:
Make a start and carry out sign map, form S frame M waiting for transmission according to the modulation system that is adopted
SIndividual equivalent time domain symbol
D=1,2 ..., S is through M
SPoint FFT obtains
The subchannel label information D={D (k) that makes a start and obtain according to feedback, k=0,1 ..., N-1} and channel sequence information B generate frequency domain subchannel mapping matrix P and pre-coding matrix Q, wherein
And the element among the P is (k only
q+ 1, be that other elements of 1 these row is 0 q+1), k
qRepresent k
qIndividual available frequency domain subchannel, k
q∈ 0,1 ..., N-1}, q=0,1 ..., M
S-1, pre-coding matrix Q is the S row of unit matrix, when being chosen at receiving-transmitting sides and appointing before communication of S row, according to channel sequence information, generates Q, and on q equivalent frequency domain subchannel, precoding is with original equivalent frequency domain symbol
Be transformed to
Frequency domain subchannel mapping matrix P incites somebody to action then
Be mapped to M
SIndividual available frequency domain subchannel k
qOn, generate the N dimensional vector
Wherein
Other
I=1,2 ... N
T, to X
N, iBeing N point IFFT obtains
Add and carry out the D/A conversion behind the CP and carry out carrier modulation again and send simultaneously by each transmitting antenna.
It should be noted that promptly advanced line frequency territory subchannel shines upon precoding again if with precoding in this system and frequency domain subchannel mapping switch, systematic function is constant.And no matter precoding and frequency domain subchannel shine upon who preceding who after because pre-coding matrix is a few row of unit matrix, carry out a day line options so precoding at this moment can be regarded as.
The detailed implementation procedure in (3) step is as follows in the described step of the present invention:
Receiving end is with N
RAfter the Frame that individual reception antenna receives removes CP, utilize FFT to transform to frequency domain, select M according to subchannel identification information and frequency domain subchannel inverse mapping matrix
SIndividual available frequency domain subchannel is to the signal of last transmission, generates balanced matrix according to channel sequence information and channel condition information then and carries out equilibrium, and conversion rules out transmission information after returning equivalent time domain;
Because the effect of CP, on discrete time-domain, the linear convolution of signal and channel impulse response can convert the product on the discrete frequency domain to, so on k frequency domain subchannel,
And work as k=k
qThe time,
Otherwise X
N kDo not carry information, k
q∈ 0,1 ..., N-1}, q=0,1 ..., M
S-1, k=0,1 ..., N-1;
After receiving terminal removed CP, l root reception antenna received the useful signal part
With the reception noise vector
Being N point FFT obtains frequency domain form and is respectively
With
Then, receiving end generates available frequency domain subchannel inverse mapping matrix P according to the subchannel identification information earlier
T, utilize frequency domain subchannel inverse mapping matrix P
T, select the symbol that on available subchannels, transmits
L=1,2 ..., N
R, promptly only be retained in k
qThe symbol of individual sub-channel
k
q∈ 0,1 ..., N-1}, q=0,1 ..., M
S-1; The A that utilizes estimation to obtain
kWith the pre-coding matrix Q that obtains according to channel sequence information, the symbol of electing is carried out equilibrium (adopting the balanced and balanced dual mode of MMSE of ZF among the present invention), at k
qOn the individual available subchannels, the signal after the equilibrium is
k
q∈ 0,1 ..., N-1}, q=0,1 ..., M
S-1, wherein
Be balanced matrix, when adopting ZF balanced,
When adopt the least mean-square error equilibrium (hereinafter to be referred as the MMSE equilibrium: in the time of Minimum Mean Square Error equalization),
Equivalent frequency domain symbol after the equilibrium is carried out M
SObtain the estimation of d data flow behind the some IFFT
Adjudicate, d=1,2 ..., S.
It should be noted that the MMSE equilibrium is used for self-adaptive MIMO-SCFDE Adaptable System of the present invention, the errored bit performance generally is better than adopting the ZF equilibrium, but amount of calculation can increase.
The present invention makes the errored bit performance can excessively not worsen by selecting the balanced little frequency domain subchannel transmission information of noise of amplifying; The BER of system (Bit Error Rate, BER, bit error rate) has simple controllable when adopting zero forcing equalization; The present invention simultaneously adopts a kind of simple pre-coding matrix to resist the scarce order of channel, and the availability of frequency spectrum can be higher than the self-adaptive MIMO-SCFDE system that does not adopt precoding usually, has low feedback velocity.
Description of drawings
Fig. 1 is a self-adaptive MIMO-SCFDE system block diagram of realizing the inventive method.
Fig. 2 has provided and has adopted the self-adaptive MIMO-SCFDE system of the inventive method and the errored bit curve comparison diagram of other system.
Among the figure: 1, information source module, 2, the bit mapping block, 3, FFT module (M
sPoint), available frequency domain subchannel mapping block 4, precoding module, 5,, 6, IFFT module (N point), 7, add Cyclic Prefix (CP) module, 8, the D/A module, 9, intermediate frequency and rf modulations module, 10, channel, 11, radio frequency and intermediate frequency demodulation module, 12, A/D module, 13, go the CP module, 14, FFT module (N point), 15, available frequency domain subchannel inverse mapping module, 16, balance module, 17, IFFT module (M
sPoint), synchronization module 18, judgement and symbol inverse mapping module, 19, channel estimating, 20, available frequency domain subchannel and pre-coding matrix order select and subchannel identification information and channel sequence information generating module, 21.
Embodiment
What embodiment provided is the base band simulation result, does not consider the influence of synchronous error, promptly is ideal synchronisation synchronously.And channel estimating is desirable, does not promptly consider channel estimation errors.Fig. 1 has provided the self-adaptive MIMO-SCFDE system block diagram that uses method proposed by the invention, and wherein each module effect is as follows:
Information source module 1: the bit information that generation will be transmitted.
Bit mapping block 2: when modulation system is selected QAM or PSK, bit information is mapped on the planisphere corresponding points, in the present embodiment, has adopted the QPSK modulation.
FFT module (M
sPoint) 3: original equivalent time domain Frame is transformed to equivalent frequency domain.
Precoding module 4: send the available frequency domain subchannel of returning and the pre-coding matrix order is selected and the channel sequence information generation pre-coding matrix of subchannel identification information and channel sequence information generating module 20 according to feedback channel, and original equivalent frequency domain information symbol is carried out precoding.In the present embodiment, receiving-transmitting sides realizes appointing that the column selection mode of getting of pre-coding matrix is former row, and promptly the best order that obtains channel according to channel sequence information is S, and pre-coding matrix is
Available frequency domain subchannel mapping block 5: send the available frequency domain subchannel of returning by feedback channel and the pre-coding matrix order is selected and the subchannel identification information of subchannel identification information and channel sequence information generating module 20 according to receiving terminal, generate frequency domain subchannel mapping matrix and original equivalent frequency domain symbol is mapped on the available frequency domain subchannel, and forbidding frequency domain subchannel does not transmit information symbol, generates the frequency domain vector of N dimension.This module need be programmed according to the method that the present invention introduces, and is realized by the general digital signal processing chip.In the present embodiment, receiving-transmitting sides realizes appointing that frequency domain subchannel mapping matrix is for satisfying
And the element among the P is (k only
q+ 1, be that 1 other element of these row is 0 stairstepping matrix q+1).
IFFT module (N point) 6: the frequency-region signal that obtains after the mapping of available frequency domain subchannel is transformed to time domain.
Add CP module 7: every frame data that will obtain add Cyclic Prefix.
D/A module 8: with digital signal conversion is analog signal.
Intermediate frequency and rf modulations module 9: signal is modulated to and carries out the intermediate frequency amplification on the intermediate frequency, does rf modulations again, at last modulated signal is launched by antenna.
Channel 10: the frequency domain selectivity mimo channel of transmission signals.
Synchronization module 21: the way by parameter Estimation (for example: blind estimation and based on the estimation of auxiliary data) obtains the various synchrodatas that system needs.Synchronization module is given radio frequency and intermediate frequency demodulation module 11 with the Frequency Synchronization data; Give A/D module 12 with the sampling rate synchrodata; Regularly synchrodata is given CP module 13.At present embodiment, be assumed to be synchronous ideal.
Radio frequency and intermediate frequency demodulation module 11: the frequency spectrum that reception antenna is received signal is moved low frequency from radio frequency or intermediate frequency.Before demodulation, need the frequency deviation that causes with in the Frequency Synchronization data correction signal transmission course.
A/D module 12: analog signal after the demodulation is transformed to digital signal.The A/D conversion need be sampled to analog signal, provides the crystal oscillator of clock signal need follow the crystal oscillator frequency of transmitter D/A module identical, otherwise will cause the sampling rate error.Therefore it is synchronous to carry out sampling rate before the A/D conversion.
Go CP module 13: Cyclic Prefix is removed.At this moment just have the problem of judging which frame data begin from, then going needs to do regularly synchronously before the CP.
FFT module (N point) 14: the time-domain signal that will remove CP transforms to frequency domain.
Channel estimation module 19: with syncsort seemingly, also need to obtain CSI blind Channel Estimation that commonly used generally is and based on the channel estimating of auxiliary data by parameter Estimation.At present embodiment, suppose to estimate accurately.Available frequency domain subchannel and the selection of pre-coding matrix order and subchannel identification information and channel sequence information generating module 20 are utilized the CSI information that estimates, determine the order and the available frequency domain subchannel of pre-coding matrix, and send the subchannel identification information that generates to available frequency domain subchannel mapping block 5 and available frequency domain subchannel inverse mapping module 15, send channel sequence information to precoding module 4 and balance module 16.To estimate to such an extent that CSI gives balance module 16 simultaneously.
Available frequency domain subchannel inverse mapping module 15:, select in the received signal by M according to the subchannel identification information that available frequency domain subchannel and pre-coding matrix order are selected and subchannel identification information and channel sequence information generating module 20 are sent here
SThe equivalent frequency-region signal that individual available frequency domain subchannel carries.This module need be programmed according to the method that the present invention introduces, and is realized by the general digital signal processing chip.
Balance module 16: the channel sequence information that CSI that sends here with channel estimation module 19 and available frequency domain subchannel and pre-coding matrix order are selected and subchannel identification information and channel sequence information generating module 20 are sent here generates balanced matrix and carries out equilibrium.Present embodiment has adopted the balanced and MMSE equilibrium of ZF.
IFFT module (M
sPoint) 17: the equivalent frequency domain symbol after the equilibrium is transformed to equivalent time domain.
Judgement and symbol inverse mapping module 18: rule out the transmission symbol, and its inverse mapping is become bit information.
Available frequency domain subchannel and pre-coding matrix order are selected and subchannel identification information and channel sequence information generating module 20: the estimation CSI that obtains according to channel estimation module 19, the desired errored bit performance of performance loss that the non-ideal factor of taking into account system brings and system, carrying out the order of pre-coding matrix selects and the selection of available frequency domain subchannel, generate subchannel identification information and channel sequence information simultaneously, confession precoding module 4 carries out precoding and balance module 16 carries out equilibrium, and available frequency domain subchannel mapping block 5 and available frequency domain subchannel inverse mapping module 15 are utilized the subchannel identification information to shine upon respectively and selected equivalent frequency domain information symbol in addition.This module need be programmed according to the method that the present invention introduces, and is realized by the general digital signal processing chip.In the present embodiment, the non-ideal factor of supposing the system does not bring performance loss.
This embodiment simulation parameter:
Simulated environment: MATLAB R2007a
Subchannel sum: N=256
CP length: 64
Modulation system: QPSK
Sampling rate: 10M bps
The selected average received signal to noise ratio of emulation scope: SNR=3～14.4 (dB)
Simulated channel environment: adopt 4 * 4SUI-4 channel respectively, but the SUI-4 channel in the present embodiment is not considered Doppler frequency deviation and Antenna Correlation.(can be with reference to D.S.Baum, " Simulating the SUI channel models, " IEEE 802.16 Broad Wireless Access Working Group, 2001, (D.S.Baum, " emulation SUI channel model ", IEEE 802.16 broadband wireless access working groups, 2001))
Do not consider in the emulation that to the influence of system, the error of promptly supposing all synchronization parameters all is 0 to synchronous error (comprising regularly synchronous error of carrier synchronization error, sampling rate synchronous error and frame); The propagation delay time when not considering backward channel passback subchannel identification information and channel sequence information and the influence of transmission error code suppose that promptly propagation delay time and error code all are 0; Do not consider the influence (for example device non-linear etc.) of other non-ideal factors.
Simulation result:
Fig. 2 has provided the comparison of errored bit curve and the errored bit energy of a kind of multi-mode precoding MIMO-ofdm system based on interpolation (64 of wherein equally distributed pilot tones, the code book space that quantizes pre-coding matrix contains 16 pre-coding matrixes) that limits passback and awgn channel of the self-adaptive MIMO-SCFDE system of the low feedback velocity that adopts the inventive method.The SNR that it should be noted that the dotted line abscissa that is labeled as rhombus no longer represents received signal to noise ratio but the balanced back of equivalence signal to noise ratio, and this is to compare for convenience of the BER with awgn channel.As can be seen when using ZF balanced, coincide the substantially errored bit curve of awgn channel of same noise variance of this curve, thereby verified the errored bit performance simple controllable of using the ZF equilibrium. when using MMSE balanced, the self-adaptive MIMO-SCFDE of the low feedback velocity that the present invention proposes is suitable equally, and performance is better than using the ZF equilibrium.A kind of multi-mode precoding MIMO based on interpolation-ofdm system that limits passback adopts 64 equally distributed pilot tones and contains 16 pre-coding matrixes and quantizes the pre-coding matrix code book, and also need the precoding model selection of 2 bits for each carrier wave of system of 4 transmit antennas, therefore the back information amount is 64 * 4+256 * 2=768 bit, when average transmit power that the self-adaptive MIMO-SCFDE when this system has with fixing S=4 is identical and identical bit rate, performance is better than self-adaptive MIMO-SCFDE under low signal-to-noise ratio, but performance is worse than self-adaptive MIMO-SCFDE under the high s/n ratio, and self-adaptive MIMO-SCFDE needs the back information amount of 256+2=258 bit.(can be with reference to N.K.Khaled, B.Mondal, G.Leus, R W.Heath, and F.Petre, " Interpolation-Based Multi-Mode Precoding for MIMO-OFDM system withLimited Feedback, " IEEE Trans.on Wireless Communications, vol.6, no.3, pp.1003-1013, Mar.2007 (N.K.Khaled, B.Mondal, G.Leus, R W.Heath, and F.Petre, " based on the MIMO-OFDM multi-mode precoding of the limited passback of interpolation ", IEEE Trans.on WirelessCommunications, the 6th volume, No. three, the 1003-1013 page or leaf, in March, 2007).
The self-adaptive MIMO-SCFDE system that following table has provided 4 * 4 low feedback velocities is fixedly comparison of the spectrum efficiency during S=4 with it.Wherein this spectrum efficiency is SNR
Req=SNR
PreThe mean value of the spectrum efficiency that fixedly 1000 secondary channel samples obtain under the BER performance of average transmit power and identical system requirements during=10dB.The spectrum efficiency that can find adaptively selected channel sequence is significantly improved, and system complexity does not have much increases.Therefore the pre-coding matrix of the present invention's proposition can simply effectively must resist the scarce order situation of mimo channel.
The self-adaptive MIMO-SCFDE system of 4 * 4 low feedback velocities is fixedly comparison of the spectrum efficiency during S=4 with it
| The fixing self-adaptive MIMO-SCFDE of the low feedback velocity of S=4 | The self adaptation IMO-SCFDE of low feedback velocity | |
| Spectrum efficiency | ??0.3134 | ?0.5153 |
For avoiding confusion, some nouns or the symbol mentioned in this specification are done following explanation:
1, the frequency domain subchannel notion of frequency domain subchannel: MIMO-SCFDE is equal to the notion of the subcarrier among the MIMO-OFDM.
2, equivalent time domain symbol: M
SReach M before the some FFT
SSymbol behind the some IFFT.
3, equivalent frequency domain symbol: M
SReach M behind the some FFT
SSymbol before the some IFFT.
4, time-domain signal: before the N point FFT and the symbol behind the N point IFFT.
5, frequency-region signal: reach the preceding symbol of N point IFFT behind the N point FFT.
6,
The M-P of matrix is contrary.
Claims (4)
1. a method that realizes low feedback velocity of self-adaptive MIMO-SCFDE system is characterized in that, may further comprise the steps:
(1) for N
T* N
RMimo system, N
TThe expression number of transmit antennas, N
RExpression reception antenna number, receiving end is selected available M according to performance loss, the modulation system that is adopted and desired system errored bit performance that the non-ideal factor of channel condition information, system causes from whole N frequency domain subchannel
SThe best order S of individual subchannel and definite channel matrix, have only the available frequency domain subchannel to upload the transmission information symbol, and other frequency domain subchannels do not transmit information symbol for the forbidding subchannel, generate subchannel identification information and channel sequence information then, and this subchannel identification information and channel sequence information sent to via feedback channel make a start;
(2) make a start according to the modulation system that is adopted and subchannel identification information and channel sequence information, form S original equivalent time domain Frame, through M
SPoint FFT becomes equivalent frequency domain symbol with the equivalent time domain sign reversing of initial data frame, and the frequency domain subchannel mapping matrix according to subchannel label information and channel sequence information and receiving-transmitting sides agreement should be mapped to M after the precoding of equivalence frequency domain symbol then
SOn the individual available frequency domain subchannel, generate N
TIndividual N dimension frequency domain vector utilizes N point IFFT to change back to time domain again, and the while was by N after serial to parallel conversion added CP
TIndividual transmitting antenna sends;
(3) receiving end is with N
RAfter the Frame that individual reception antenna receives removes CP, utilize FFT to transform to frequency domain, select M according to subchannel identification information and frequency domain subchannel inverse mapping matrix
SIndividual available frequency domain subchannel is to the signal of last transmission, generates balanced matrix according to channel sequence information and channel condition information then and carries out equilibrium, and conversion rules out transmission information after returning equivalent time domain.
2. the method for realization low feedback velocity of self-adaptive MIMO-SCFDE system according to claim 1 is characterized in that, the detailed implementation procedure in described (1) step is as follows:
After receiving-transmitting sides was set up communication, receiving end channel estimating mode was according to a preconcerted arrangement obtained the channel condition information of current channel, and wherein channel condition information is the channel matrix of all frequency domain subchannels, wherein the channel matrix A on each frequency domain subchannel
k, k=0,1 ..., N-1; The criterion that reaches the selection of available frequency domain subchannel of determining of the best order of channel matrix is, the performance loss that causes when the non-ideal factor that adopts certain modulation system and taking into account system, under the desired errored bit performance of system, transmit information symbol as much as possible, promptly allow the product M of selected available frequency domain number of subchannels under the best order of channel matrix and this order as far as possible
S* S or spectrum efficiency
Maximum; The best order S of channel matrix and available frequency domain subchannel k
q∈ 0,1 ..., the selection of N-1} is as follows:
Satisfying
Down, maximization M
S* S, wherein: M
SBe available subchannels number, M
S∈ 0,1 ..., N}, S ∈ 1,2 ..., N
T, q=0,1 ..., M
S-1, σ
x 2Be the average power of information symbol, σ
w 2Be noise variance, SNR
ReqFor adopting behind certain modulation system and the taking into account system non-ideal factor signal to noise ratio after the pairing equivalent time domain equilibrium of desired system errored bit performance;
Determine the best order S of channel matrix and select M
SBehind the individual available frequency domain subchannel, generate frequency domain subchannel identification information, D={D (k), k=0,1 ..., N-1}, wherein D (k
q)=1 expression k
qIndividual subchannel is an available subchannels, k
q∈ 0,1 ..., N-1}, q=0,1 ..., M
S-1, k subchannel of D (k)=0 expression is unavailable subchannel, k ≠ k
qWhen appointing the column selection of pre-coding matrix before the receiving-transmitting sides communication, also need to generate log2 (N
T) the channel sequence information B of bit, otherwise except the best order information that feeds back to channel, also need the selection of extra feedback information sign S row; Then this subchannel identification information and channel sequence feedback information are postbacked end.
3. the method for realization low feedback velocity of self-adaptive MIMO-SCFDE system according to claim 1 is characterized in that, the detailed implementation procedure in (2) step is as follows in the described step of the present invention:
Make a start and carry out sign map, form S frame M waiting for transmission according to the modulation system that is adopted
SIndividual equivalent time domain symbol
D=1,2 ..., S is through M
SPoint FFT obtains original equivalent frequency domain data frame
The subchannel label information D={D (k) that makes a start and obtain according to feedback, k=0,1 ..., N-1} and channel sequence information B generate frequency domain subchannel mapping matrix P and pre-coding matrix Q, wherein
And the element among the P is (k only
q+ 1, be that other elements of 1 these row is 0 q+1), k
qRepresent k
qIndividual available frequency domain subchannel, k
q∈ 0,1 ..., N-1}, q=0,1 ..., M
S-1, pre-coding matrix Q is the S row of unit matrix, when being chosen at receiving-transmitting sides and appointing before communication of S row, according to channel sequence information, generates Q, and on q equivalent frequency domain subchannel, precoding is with original equivalent frequency domain symbol
Be transformed to
Frequency domain subchannel mapping matrix P incites somebody to action then
Be mapped to M
SIndividual available frequency domain subchannel k
qOn, generate the N dimensional vector, i.e. i transmit antennas frequency domain data frame to be sent
Wherein
Other
I=1,2 ... N
T, to X
N, iBe N point IFFT and obtain i transmit antennas time domain data frame to be sent
I=1,2 ..., N
T, add and carry out the D/A conversion behind the CP and carry out carrier modulation again and send simultaneously by each transmitting antenna.
4. the method for realization low feedback velocity of self-adaptive MIMO-SCFDE system according to claim 1 is characterized in that, the detailed implementation procedure in described (3) step is as follows:
Because the effect of CP, on discrete time-domain, the linear convolution of signal and channel impulse response can convert the product on the discrete frequency domain to, and therefore on k frequency domain subchannel, signal component is
And work as k=k
qThe time,
Otherwise X
N kDo not carry information, k
q∈ 0,1 ..., N-1}, q=0,1 ..., M
S-1, k=0,1 ..., N-1, wherein
Be the original equivalent frequency domain symbol that on q equivalent frequency domain subchannel, transmits,
It is the symbolic vector to be sent on k the frequency domain subchannel;
After receiving terminal removed CP, l root reception antenna received the useful signal part
With the reception noise vector
Being N point FFT obtains frequency domain form and is respectively
With
Then, receiving end generates available frequency domain subchannel inverse mapping matrix P according to the subchannel identification information earlier
T, utilize frequency domain subchannel inverse mapping matrix P
T, select the symbol that on available subchannels, transmits
L=1,2 ..., N
R, promptly only be retained in k
qThe symbol of individual sub-channel
k
q∈ 0,1 ..., N-1}, q=0,1 ..., M
s-1; The A that utilizes estimation to obtain
kWith the pre-coding matrix Q that obtains according to channel sequence information, the symbol of electing is carried out equilibrium, at k
qOn the individual available subchannels, the signal after the equilibrium is
k
q∈ 0,1 ..., N-1}, q=0,1 ..., M
S-1, wherein
Be balanced matrix, when adopting ZF balanced,
When adopting least mean-square error balanced,
Equivalent frequency domain symbol after the equilibrium is carried out M
SObtain estimating the estimation of d data flow behind the some IFFT
Adjudicate, d=1,2 ..., S.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101951308A (en) * | 2010-09-27 | 2011-01-19 | 山东大学 | Self-adaptive transmission method of vehicle speed mobile MIMO-SCFDE system |
| WO2015149312A1 (en) * | 2014-04-02 | 2015-10-08 | 华为技术有限公司 | Beamforming-based communication method and apparatus |
| CN109995495A (en) * | 2013-11-22 | 2019-07-09 | 华为技术有限公司 | A kind of data transmission method and data transmission set |
-
2009
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101951308A (en) * | 2010-09-27 | 2011-01-19 | 山东大学 | Self-adaptive transmission method of vehicle speed mobile MIMO-SCFDE system |
| CN101951308B (en) * | 2010-09-27 | 2012-11-28 | 山东大学 | Self-adaptive transmission method of vehicle speed mobile MIMO-SCFDE system |
| CN109995495A (en) * | 2013-11-22 | 2019-07-09 | 华为技术有限公司 | A kind of data transmission method and data transmission set |
| WO2015149312A1 (en) * | 2014-04-02 | 2015-10-08 | 华为技术有限公司 | Beamforming-based communication method and apparatus |
| CN106031068A (en) * | 2014-04-02 | 2016-10-12 | 华为技术有限公司 | Beamforming-based communication method and apparatus |
| US10069547B2 (en) | 2014-04-02 | 2018-09-04 | Huawei Technologies Co., Ltd. | Beamforming based communications method and apparatus |
| CN106031068B (en) * | 2014-04-02 | 2019-05-28 | 华为技术有限公司 | A kind of communication means and device based on beam forming |
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