CN102227098A - Selection method of bearing point of frequency domain of multi-mode MIMO-SCFDE adaptive transmission system - Google Patents

Abstract

The invention provides a selection method of a bearing point of a frequency domain of a multi-mode multiple-input multiple-output and signal carrier with frequency domain equalization (MIMO-SCFDE) adaptive transmission system. The method comprises the following steps: (1), initializing all bearing points of a frequency domain, wherein the all bearing points are available; and calculating noise amplification coefficients of the all bearing points of the frequency domain; (2), rejecting a bearing point of the frequency domain, wherein the bearing point has a largest noise amplification coefficient; and updating noise amplification coefficients of all bearing points of a sub channel, wherein the bearing point of the frequency domain is located at the sub channel; (3), determining whether that a signal to noise ratio after equalization is not less than a signal to noise ratio that corresponds to a bit error rate and is required by a system is satisfied; if not, going back to (2); if so, generating indication information of the bearing point of the frequency domain according to distribution of remaining available bearing points of the frequency domain at present. According to the selection method of the bearing point of the frequency domain of the multi-mode MIMO-SCFDE adaptive transmission system provided in the invention, the frequency spectrum resources of the system can be utilized fully and a utilization rate of frequency spectrum of the system can be effectively improved.

Description

A kind of multimode MIMO-SCFDE Adaptive Transmission system frequency domain bearing point choosing method

Technical field

The present invention relates to a kind of many antennas broadband wireless communications transmission method, belong to the broadband wireless communication technique field.

Background technology

The new generation broadband wireless communication system need provide radio multimedium business such as wireless Internet access, wireless video and mobile computing at a high speed for the user, and this all has higher requirement to transmission of Information speed and transmission quality.By the decline that the transmission signals multipath transmisstion causes, be the principal element that influences system of broadband wireless communication transmission rate and transmission quality.

OFDM (hereinafter to be referred as OFDM:Orthogonal Frequency Division Multiplexing) technology and single carrier frequency domain equalization (hereinafter to be referred as SCFDE:Single Carrier with Frequency Domain Equalization) technology all is based on the piecemeal transmission technology of Cyclic Prefix (hereinafter to be referred as CP:Cyclic Prefix), be the simple and highly effective technology that tackles the frequency selective fading that multipath transmisstion causes in the broadband wireless communications, so OFDM and SCFDE become the mainstream technology of present broadband wireless communications.Spectrum efficiency is the research emphasis of wireless communication technology always, and multiple-input and multiple-output (hereinafter to be referred as MIMO:Multiple-input Multiple-output) is subjected to extensive concern with its conventional single-antenna spectrum efficiency that technology is beyond one's reach in recent years.MIMO and become the key technology of future wireless in conjunction with MIMO-OFDM and MIMO-SCFDE based on the piecemeal transmission technology of CP.

Mimo system uses many antennas to receive and send messages at transmitting terminal and receiving terminal, utilizes in the wireless propagation environment with rich multipath 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; CP 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; The baseband modulation process of OFDM can be finished with invert fast fourier transformation (hereinafter to be referred as IFFT:Inverse Fast Fourier Transform), and the base band demodulating process can be with fast fourier transform (hereinafter to be referred as FFT:Fast Fourier Transform)) finish.SCFDE is the piecemeal transmission technology that is similar to OFDM, though the high peak-to-average power ratio (PAPR, Peak-to-average Power Ratio) that can effectively resist multipath fading equally and not have OFDM to make a start is subjected to degree of concern far away from OFDM.

The subject matter that MIMO broadband wireless communications (mainly being MIMO-OFDM and MIMO-SCFDE) faces is: the time, frequently, the channel fading that causes of empty selectivity.This decline shows as scarce order of local channel matrix or the ill-condition that receiving terminal removes a series of arrowbands mimo channel that obtains behind the CP, and this scarce order or ill-condition cause very big influence to the detection of MIMO signal, is the principal element of restriction wideband MIMO systematic function.

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.Precoding is the adaptive technique that extensively adopts in the present wideband MIMO system, it can be according to the situation of the channel matrix of arrowband mimo channel, the bit number of this arrowband mimo channel transmission of the precoding adaptively modifying by transmitting terminal, can greatly improve the efficient of each scarce order or ill-condition arrowband mimo channel transmission, thereby improve the efficient of whole wideband MIMO system.

Chinese patent literature CN101969417A discloses a kind of MIMO-SCFDE system self-adaption multimode transmission method of low passback, and this method complexity is low, the back information amount is little, and has the higher availability of frequency spectrum.Fig. 1 has provided the block diagram of MIMO-SCFDE system self-adaption multimode transmission system, and wherein number of transmit antennas is N _T, the reception antenna number is N _R, and N _T≤ N _R, its signal indication and signal processing are as follows:

After receiving-transmitting sides was set up communication, receiving terminal utilized channel estimating or channel prediction arithmetic to obtain current state information of channel, supposes

Be k frequency domain subchannel gains of channel between i root transmitting antenna and l root reception antenna, i=1 wherein, 2, L, N _T, l=1,2, L, N _R, k=0,1, L, N-1; A ^kThe channel matrix of representing k frequency domain subchannel, wherein the capable i column element of l is

That is:

$A^k=\left(\begin{array}{ccc}{\mathrm{<figure-callout\; id="1"\; label="H"\; filenames="HDA0000069801190000021.png"\; state="\{\{state\}\}">H</figure-callout>}}_{\mathrm{1,1}}^{\mathrm{<figure-callout\; id="1"\; label="k\; H"\; filenames="HDA0000069801190000021.png"\; state="\{\{state\}\}">k</figure-callout>}}& H_{}^{}{}_{\mathrm{1,2}}^{\mathrm{<figure-callout\; id="1"\; label="k\; L\; H"\; filenames="HDA0000069801190000021.png"\; state="\{\{state\}\}">k</figure-callout>}}& L& H_{}^{}{}_{1,N_{\mathrm{<figure-callout\; id="2"\; label="T\; k\; H"\; filenames="HDA0000069801190000021.png"\; state="\{\{state\}\}">T</figure-callout>}}}^k& \\ H_{}^{}{}_{\mathrm{2,1}}^{\mathrm{<figure-callout\; id="2"\; label="k\; H"\; filenames="HDA0000069801190000021.png"\; state="\{\{state\}\}">k</figure-callout>}}& H_{}^{}{}_{\mathrm{2,2}}^{\mathrm{<figure-callout\; id="2"\; label="k\; L\; H"\; filenames="HDA0000069801190000021.png"\; state="\{\{state\}\}">k</figure-callout>}}& L& H_{}^{}{}_{2,N_T}^k\\ M& M& O& M\\ H_{N_R,1}^k& H_{N_R,2}^k& L& H_{N_R,N_T}^k\end{array}\right)$

Choose available frequency domain bearing point (annotate: on each frequency domain subchannel, one deck of a transmitting antenna correspondence is called a frequency domain bearing point) according to channel capacity then, and generate frequency domain bearing point beacon information D={D _q, q=0,1, L, N * N _T-1}, wherein D _q=0 or 1, D _q=1 this frequency domain bearing point of expression can be used D _qThis frequency domain bearing point forbidding of=0 expression.

Wherein, the concrete steps of choosing the available frequency domain bearing point according to the channel capacity criterion are:

(1) order of each frequency domain subchannel of initialization all is 0, i.e. R ₀=R ₁=L=R _N-1=0, by shannon capacity formula C=Blog ₂(1+SNR), the order that calculates each subchannel be respectively 1,2, L, N _TChannel capacity, exist in the table;

(2) by the comparison of tabling look-up, selecting order to add 1 back channel capacity increases maximum subchannel f, its order is added 1, i.e. R _f=R _f+ 1, judge this moment, whether system satisfied condition If satisfy, repeat this step, when not satisfying condition, jump to next step;

(3) last order is added the subchannel order that causes system no longer to satisfy condition after 1 and deduct 1 again, the order information R={R of record each frequency domain subchannel at this moment _k, k=0,1, L, N-1}.

(4) generate frequency domain channel beacon information D={D (k), k=0,1L, N-1}, wherein D (k)={ D (k by each subchannel order information R _s), s=0,1, L N _T-1}, the value of D (k) is by the order R of k subchannel _kDecision, the preceding R of D (k) _kIndividual value is 1, the back be 0.

Transmitting terminal calculates the sum M of available bearing point according to frequency domain bearing point beacon information, according to the modulation system that will adopt, M bit information is carried out sign map, forms a row M and ties up original time domain data frame

Suppose between each symbol element it is independent identically distributed here, and to satisfy average be 0, variance is

To x _MDo M point FFT conversion and obtain corresponding M dimension frequency domain data frame $X_M={\mathrm{FFT}}_M\left(x_M\right)={(X_M^0,{\mathrm{<figure-callout\; id="1"\; label="X\; M"\; filenames="HDA0000069801190000021.png"\; state="\{\{state\}\}">X</figure-callout>}}_M^{},L,X_M^{M-1})}^T,$ Then according to frequency domain channel beacon information D with X _MBe mapped as a row N * N _TDimension frequency domain data frame ${\stackrel{\&OverBar;}{X}}_{N\&times;N_T}={({\stackrel{\&OverBar;}{X}}_{N\&times;N_T}^0,{\stackrel{\&OverBar;}{X}}_{N\&times;{\mathrm{<figure-callout\; id="1"\; label="N\; T"\; filenames="HDA0000069801190000021.png"\; state="\{\{state\}\}">N</figure-callout>}}_T}^1,L,{\stackrel{\&OverBar;}{X}}_{N\&times;N_T}^{N\&times;N_T-1})}^T,$ Be about to X _MM frequency domain data symbol be inserted into corresponding D successively _k=1 position, D _k=0 position zero padding.Then by serial to parallel conversion, with the N * N that obtains _TDimension frequency domain data frame

The top n data symbol

L,

As first row, N+1 to 2 * N data symbol

L,

As secondary series, by that analogy, will

Be transformed into N _TRow N dimension frequency domain data frame ${\stackrel{\&OverBar;}{X}}_{N,i}={({\stackrel{\&OverBar;}{X}}_{N,i}^0,{\stackrel{\&OverBar;}{X}}_{N,i}^1,L,{\stackrel{\&OverBar;}{X}}_{N,i}^{N-1})}^T,$ i＝1，2，L，N _T。Again every row Frame is done N point IFFT conversion, change to time domain and be $x_{N,i}={\mathrm{IFFT}}_N\left(X_{N,i}\right)={(x_{N,i}^0,x_{N,i}^1,L,x_{N,i}^{N-1})}^T,$ I=1,2, L, N _T, add behind the CP respectively by N _TThe root transmitting antenna sends simultaneously.

After receiving terminal is received signal, at first go CP to handle, the signal that this moment, l root reception antenna received can be expressed as vector $r_{N,l}=y_{N,l}+w_{N,l}={(y_{N,l}^0,y_{N,\mathrm{<figure-callout\; id="1"\; label="l"\; filenames="HDA0000069801190000021.png"\; state="\{\{state\}\}">l</figure-callout>}}^1,L,y_{N,l}^{N-1})}^T+{(w_{N,l}^0,w_{N,\mathrm{<figure-callout\; id="1"\; label="l"\; filenames="HDA0000069801190000021.png"\; state="\{\{state\}\}">l</figure-callout>}}^1,L,w_{N,l}^{N-1})}^T,$ L=1,2, L N _R, wherein $y_{N,l}={(y_{N,l}^0,y_{N.\mathrm{<figure-callout\; id="1"\; label="l"\; filenames="HDA0000069801190000021.png"\; state="\{\{state\}\}">l</figure-callout>}}^1,L,y_{N,l}^{N-1})}^T$ The useful signal part of expression received signal, $w_{N,l}={(w_{N,l}^0,w_{N,\mathrm{<figure-callout\; id="1"\; label="l"\; filenames="HDA0000069801190000021.png"\; state="\{\{state\}\}">l</figure-callout>}}^1,L,w_{N,l}^{N-1})}^T$ The noise section of expression received signal supposes that noise is 0 for satisfying average, and variance is

Additive white Gaussian noise; The signal that above-mentioned l root reception antenna is received is done N point FFT conversion then, and the frequency domain form that obtains useful signal is $Y_{N,l}={\mathrm{FFT}}_N\left(y_{N,l}\right)={(Y_{N,l}^0,Y_{N,\mathrm{<figure-callout\; id="1"\; label="l"\; filenames="HDA0000069801190000021.png"\; state="\{\{state\}\}">l</figure-callout>}}^1,L,Y_{N,l}^{N-1})}^T,$ L=1,2, L N _R, the frequency domain form of noise is $W_{N,l}={\mathrm{FFT}}_N\left(w_{N,l}\right)={(W_{N,l}^0,W_{N,\mathrm{<figure-callout\; id="1"\; label="l"\; filenames="HDA0000069801190000021.png"\; state="\{\{state\}\}">l</figure-callout>}}^1,L,W_{N,l}^{N-1})}^T,$ l＝1，2，L?N _R。Next carry out frequency domain equalization,, utilize channel condition information to generate the balanced matrix G of k frequency domain subchannel according to selected frequency-domain equilibrium method ^k, as adopting the ZF equilibrium, then

Promptly get matrix A ^kQ ^kMoore-Penrose (M-P) contrary be balanced matrix; With the N that obtains after the equilibrium _TRow N dimension frequency domain symbol vectors is passed through serial to parallel conversion, the end to end row N * N that becomes _TThe dimension frequency domain symbol vectors Select D according to frequency domain channel beacon information D then _qThe M of=1 position correspondence frequency domain symbol formed a new M dimension frequency domain symbol vectors X _N+ V _NThe M that obtains dimension frequency domain symbol vectors is M point IFFT to be become time domain again and obtains x _MAnd noise $v_M={\mathrm{IFFT}}_M\left(V_M\right)={(v_M^0,v_{\mathrm{<figure-callout\; id="1"\; label="M"\; filenames="HDA0000069801190000021.png"\; state="\{\{state\}\}">M</figure-callout>}}^1,L,v_M^{M-1})}^T,$ Then to x _M+ v _MCarry out symbol judgement.

By to system performance analysis, can obtain system balanced before signal to noise ratio be:

${\mathrm{SNR}}_{\mathrm{pre}}=\frac{\underset{k=0}{\overset{N-1}{\mathrm{\&Sigma;}}}{\mathrm{Pow}}_{Y_N^k}}{\underset{k=0}{\overset{N-1}{\mathrm{\&Sigma;}}}{\mathrm{Pow}}_{W_N^k}}=\frac{\underset{k=0}{\overset{N-1}{\mathrm{\&Sigma;}}}{\mathrm{\&sigma;}}_{\mathrm{<figure-callout\; id="2"\; label="x"\; filenames="HDA0000069801190000021.png"\; state="\{\{state\}\}">x</figure-callout>}}^2\&CenterDot;\mathrm{tr}\left[\left(A^k{Q}^k\right){\left(A^k{Q}^k\right)}^H\right]}{\underset{k=0}{\overset{N-1}{\mathrm{\&Sigma;}}}{N}_R{\mathrm{\&sigma;}}_{\mathrm{<figure-callout\; id="2"\; label="w"\; filenames="HDA0000069801190000021.png"\; state="\{\{state\}\}">w</figure-callout>}}^2}=\frac{{\mathrm{\&sigma;}}_x^2\underset{k=0}{\overset{N-1}{\mathrm{\&Sigma;}}}\mathrm{tr}\left[\left(A^k{Q}^k\right){\left(A^k{Q}^k\right)}^H\right]}{{\mathrm{NN}}_R{\mathrm{\&sigma;}}_w^2}$

Signal to noise ratio can be expressed as behind the system equalization:

${\mathrm{SNR}}_{\mathrm{post}}=\frac{{\mathrm{M\&sigma;}}_{\mathrm{<figure-callout\; id="2"\; label="x"\; filenames="HDA0000069801190000021.png"\; state="\{\{state\}\}">x</figure-callout>}}^2}{\underset{k=0}{\overset{N-1}{\mathrm{\&Sigma;}}}{\mathrm{Pow}}_{V_N^k}}=\frac{{\mathrm{M\&sigma;}}_{\mathrm{<figure-callout\; id="2"\; label="x"\; filenames="HDA0000069801190000021.png"\; state="\{\{state\}\}">x</figure-callout>}}^2}{{\mathrm{\&sigma;}}_w^2\underset{k=1}{\overset{N}{\mathrm{\&Sigma;}}}\mathrm{tr}\left[G^k{\left(G^k\right)}^H\right]}$

The balanced back signal to noise ratio of system is the judgement signal to noise ratio, and therefore, the size of balanced back signal to noise ratio can the direct error performance that influences system.When carrying out the choosing of frequency domain carrier frequency point, can be by the balanced back of the control noise error performance of control system recently.

The MIMO-SCFDE system self-adaption multimode transmission method of above-mentioned low passback is owing to use the channel capacity criterion to choose the carrier frequency point, and frequency spectrum resource is not fully utilized.

Summary of the invention

The problem that the frequency spectrum resource that exists when choosing carrier frequency point at prior art owing to use channel capacity criterion is not fully used the invention provides a kind of multimode MIMO-SCFDE Adaptive Transmission system frequency domain bearing point choosing method that can make full use of frequency spectrum resource.

Multimode MIMO-SCFDE Adaptive Transmission of the present invention system frequency domain bearing point choosing method may further comprise the steps:

(1) all frequency domain bearing points of initialization are all available, and calculate the noise amplification coefficient of all frequency domain bearing points this moment;

(2) the frequency domain bearing point of cancelling noise amplification coefficient maximum, and upgrade the noise amplification coefficient of all bearing points of this frequency domain bearing point place subchannel;

(3) judge whether that full balanced back signal to noise ratio is not less than the signal to noise ratio of the bit error rate correspondence of system requirements, if do not satisfy, rebound step (2) if satisfy, according to the distribution of remaining available frequency domain bearing point this moment, generates frequency domain bearing point beacon information.

The specific implementation method of described step (1) is as follows:

At first generate a capable N of N _TMatrix P=(the P of row ¹, P ², L, P ^N) ^T, wherein k is capable

Each element of initialization matrix P is 1, represents that all carrier frequency points are available; Then the pre-coding matrix of k frequency domain subchannel is expressed as at this moment $Q^k=\mathrm{diag}\left(P^k\right)=\mathrm{diag}(p_1^k,p_2^k,L,p_{N_T}^k);$ Calculate matrix then

Value, A wherein ^kThe channel matrix of representing k frequency domain subchannel is got matrix

N _TIndividual diagonal element obtains the N of k frequency domain subchannel _TThe noise amplification coefficient of individual frequency domain bearing point

L,

Order

Calculate the noise amplification coefficient of all frequency domain bearing points, form the capable N of N _TMatrix Z=(the Z of row ¹, Z ², L, Z ^N) ^T, corresponding one by one with the element of matrix P.

The specific implementation method of described step (2) is as follows:

Inquiry matrix Z=(Z ¹, Z ², L, Z ^N) ^TMiddle maximum element Z _MaxThe position, and the correspondence position element value becomes 0 among the order matrix P, supposes Z _MaxCapable at l, then this moment l frequency domain subchannel pre-coding matrix Q ^lAlso change, by formula $Q^l=\mathrm{diag}\left(P^l\right)=\mathrm{diag}(p_1^l,p_2^l,L,p_{N_T}^l)$ Upgrade, recomputate k frequency domain subchannel then

Value, and get the noise amplification coefficient value that diagonal element upgrades each frequency domain bearing point of this subchannel.

The specific implementation method of described step (3) is as follows:

Judge whether to satisfy balanced back signal to noise ratio snr _PostBe not less than the signal to noise ratio snr of the bit error rate correspondence of system requirements _Req, promptly whether satisfy

1 number among the M representing matrix P wherein,

The expression signal power,

The expression noise power, Expression noise amplification coefficient sum is not if satisfy rebound step (2); If satisfy, this process finishes, and the matrix P that obtain this moment is the capable N of N _TThe matrix that row are made up of 0 or 1 element, wherein, element value is that 1 its corresponding frequency domain bearing point of expression can be used, and element value is its corresponding frequency domain bearing point forbidding of 0 expression, and each row of matrix P value are joined end to end with previous column forms N * N _TThe matrix of row 1 row is frequency domain bearing point beacon information D.

The multimode MIMO-SCFDE Adaptive Transmission system frequency domain bearing point choosing method that the present invention proposes can make system spectral resources be utilized more fully, effectively raises the availability of frequency spectrum of system.

Description of drawings

Fig. 1 is the block diagram of MIMO-SCFDE system self-adaption multimode transmission system.

Fig. 2 is the MIMO-SCFDE self adaptation multimode transmission system errored bit curve chart that adopts the multimode MIMO-SCFDE Adaptive Transmission system frequency domain bearing point choosing method of the present invention's proposition.

Among the figure: 1, information source module, 2, the sign map module, 3, FFT module (M point), 4, the signal spectrum conversion, 5, serial/parallel module, 6, IFFT module (N point), 7, add Cyclic Prefix (CP) module, 8, the D/A module, 9, intermediate frequency and rf modulations module, 10, mimo channel, 11, radio frequency and intermediate frequency demodulation module, 12, the A/D module, 13, go the CP module, 14, FFT module (N point), 15, balance module, 16 parallel/serial modules, 17, the signal spectrum inverse transform block, 18, IFFT module (M point), 19, judgement and symbol inverse mapping module, 20, synchronization module, 21, channel estimation module, 22, frequency domain bearing point beacon information module, 23, feedback channel.

Embodiment

What embodiment provided is the base band simulation result, does not consider the influence of synchronous error, and does not consider channel estimation errors, and promptly channel estimating is desirable.

Each module effect of Fig. 1 is as follows:

Information source module 1: the data that generation will be transmitted.

Sign map module 2: the data based modulation system that adopts that information source is produced is mapped on the planisphere corresponding points.

M point FFT module 3: the individual mapping signal of every frame M is transformed to frequency domain, obtain the M point frequency-region signal of signal.

Signal spectrum conversion module 4: send the channel beacon information of returning according to feedback channel, the M point frequency-region signal of module 3 outputs is mapped on M the available frequency domain bearing point, and forbids the zero setting of frequency domain bearing point, or fill non-information data, just obtain a frame N * N _TThe dimension frequency domain vector.This module need be programmed according to the method that the present invention introduces, and is realized by the general digital signal processing chip.

Serial/parallel module 5: N * N that module 4 is obtained _TThe dimension frequency domain vector is transformed into N _TIndividual N dimension frequency domain vector.

N point IFFT module 6: will obtain frequency-region signal and transform to time domain again.

Add CP module 7: every frame data that will obtain add Cyclic Prefix.

D/A module 8: digital signal conversion is become 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.

Mimo channel 10: the frequency domain selectivity mimo channel of transmission signals.

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.

N point FFT module 14: the time-domain signal that will remove CP transforms to frequency domain.

Balance module 15: each subchannel order information that CSI that sends according to channel estimation module 21 and module 22 are sent generates balanced matrix and carries out equilibrium.Balanced way can be selected one of three kinds of balanced ways: zero forcing equalization, least mean-square error equilibrium, hybrid mode equilibrium.

Parallel/serial module 16: will cross the N that obtains behind the balance module 15 _TIndividual N dimensional vector is transformed to N * N _TDimensional vector.

Signal spectrum inverse transform block 17: select the equivalent frequency-region signal that carries on M the available frequency domain bearing point according to the channel beacon information.This module need be programmed according to the method that the present invention introduces, and is realized by the general digital signal processing chip.

M point IFFT module 18: the equivalent frequency domain symbol after the equilibrium is transformed to equivalent time domain.

Judgement and symbol inverse mapping module 19:, finish the judgement of time-domain signal according to the modulation system that system adopted.

Synchronization module 20: 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.

Channel estimation module 21: 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.

Frequency domain bearing point beacon information module 22: the CSI according to channel estimation module 21 obtains, choose the available frequency domain bearing point according to the method for selecting for use, and generate frequency domain bearing point beacon information.

Backward channel 23: frequency domain bearing point beacon information is returned to transmitting terminal.

This embodiment simulation parameter:

Simulated environment: MATLAB R2010a

Subchannel sum: N=1024

CP length: 256

Modulation system: QPSK

Sampling rate: 20M

The selected average received signal to noise ratio of emulation scope: SNR=2～14 (dB)

Simulated channel environment: adopt 4 * 4 SUI-4 channel models in 802.16 standards, 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); Do not consider the propagation delay time of backward channel return path identification 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 requirements is under the prerequisite that guarantees identical error performance, and the availability of frequency spectrum and back information amount that the method for using the present invention to propose is chosen the frequency domain bearing point and used the channel capacity criterion to choose the frequency domain bearing point compare.

Simulation result:

Fig. 2 has provided MIMO-SCFDE self adaptation multimode transmission system and has used the BER performance of two kinds of frequency domain bearing point choosing methods to compare, and the BER curve that gives the Gaussian channel with the preceding signal to noise ratio of identical equilibrium simultaneously is for referencial use.As shown in Figure 2, two kinds of method BER performances are simple controllable all, with have identical equilibrium before the BER curve of Gaussian channel of signal to noise ratio paste very near.

Following table has provided MIMO-SCFDE self adaptation multimode transmission system and has used the availability of frequency spectrum of two kinds of frequency domain bearing point choosing methods and the comparison of back information amount:

Data are under the situation of fixed transmission power in the table, get 1000 secondary channel samples and carry out the frequency domain bearing point and select, the available frequency domain carrying that obtains is counted, the availability of frequency spectrum and back information amount mean value.Observe table 1, can find, use the channel capacity criterion to choose the frequency domain bearing point relatively, the method of using the present invention to propose is chosen the frequency domain bearing point, increase relatively to some extent in the back information amount, but system chooses the available frequency domain bearing point showed increased that is used for message transmission, effectively raises the availability of frequency spectrum of system.

Claims (4)

1. a multimode MIMO-SCFDE Adaptive Transmission system frequency domain bearing point choosing method is characterized in that, may further comprise the steps:

(1) all frequency domain bearing points of initialization are all available, and calculate the noise amplification coefficient of all frequency domain bearing points this moment;

(2) the frequency domain bearing point of cancelling noise amplification coefficient maximum, and upgrade the noise amplification coefficient of all bearing points of this frequency domain bearing point place subchannel;

(3) judge whether that full balanced back signal to noise ratio is not less than the signal to noise ratio of the bit error rate correspondence of system requirements, if do not satisfy, rebound step (2) if satisfy, according to the distribution of remaining available frequency domain bearing point this moment, generates frequency domain bearing point beacon information.

2. multimode MIMO-SCFDE Adaptive Transmission according to claim 1 system frequency domain bearing point choosing method is characterized in that the specific implementation method of described step (1) is as follows:

At first generate a capable N of N _TMatrix P=(the P of row ¹, P ², L, P ^N) ^T, wherein k is capable

Each element of initialization matrix P is 1, represents that all carrier frequency points are available; Then the pre-coding matrix of k frequency domain subchannel is expressed as at this moment $Q^k=\mathrm{diag}\left(P^k\right)=\mathrm{diag}(p_1^k,p_2^k,L,p_{N_T}^k);$ Calculate matrix then Value, A wherein ^kThe channel matrix of representing k frequency domain subchannel is got matrix

N _TIndividual diagonal element obtains the N of k frequency domain subchannel _TThe noise amplification coefficient of individual frequency domain bearing point

L,

Order

Calculate the noise amplification coefficient of all frequency domain bearing points, form the capable N of N _TMatrix Z=(the Z of row ¹, Z ², L, Z ^N) ^T, corresponding one by one with the element of matrix P.

3. multimode MIMO-SCFDE Adaptive Transmission according to claim 1 system frequency domain bearing point choosing method is characterized in that the specific implementation method of described step (2) is as follows:

Inquiry matrix Z=(Z ¹, Z ², L, Z ^N) ^TMiddle maximum element Z _MaxThe position, and the correspondence position element value becomes 0 among the order matrix P, supposes Z _MaxCapable at l, then this moment l frequency domain subchannel pre-coding matrix Q ^lAlso change, by formula $Q^l=\mathrm{diag}\left(P^l\right)=\mathrm{diag}(p_1^l,p_2^l,{L,p}_{N_T}^l)$ Upgrade, recomputate k frequency domain subchannel then

Value, and get the noise amplification coefficient value that diagonal element upgrades each frequency domain bearing point of this subchannel.

4. multimode MIMO-SCFDE Adaptive Transmission according to claim 1 system frequency domain bearing point choosing method is characterized in that the specific implementation method of described step (3) is as follows:

Judge whether to satisfy balanced back signal to noise ratio snr _PostBe not less than the signal to noise ratio snr of the bit error rate correspondence of system requirements _Req, promptly whether satisfy 1 number among the M representing matrix P wherein,

The expression signal power,

The expression noise power, Expression noise amplification coefficient sum is not if satisfy rebound step (2); If satisfy, this process finishes, and the matrix P that obtain this moment is the capable N of N _TThe matrix that row are made up of 0 or 1 element, wherein, element value is that 1 its corresponding frequency domain bearing point of expression can be used, and element value is its corresponding frequency domain bearing point forbidding of 0 expression, and each row of matrix P value are joined end to end with previous column forms N * N _TThe matrix of row 1 row is frequency domain bearing point beacon information D.

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