CN102227098B - A frequency-domain bearing point selection method for multi-mode MIMO-SCFDE adaptive transmission system - Google Patents

Abstract

The present invention provides a multimode MIMO-SCFDE adaptive transmission system frequency domain bearing point selection method, comprising the following steps: (1) initializing all frequency domain bearing points are available, and calculating the noise amplification of all frequency domain bearing points at this time (2) Eliminate the frequency domain bearing point with the largest noise amplification factor, and update the noise amplification factor of all bearing points in the subchannel where the frequency domain bearing point is located; (3) Determine whether the signal-to-noise ratio after full balance is not less than the system requirement If the signal-to-noise ratio corresponding to the bit error rate is not satisfied, jump back to step (2). If it is satisfied, generate frequency-domain bearing point identification information according to the distribution of the remaining available frequency-domain bearing points at this time. The multi-mode MIMO-SCFDE self-adaptive transmission system frequency domain bearing point selection method proposed by the present invention can make the system spectrum resources more fully utilized and effectively improve the spectrum utilization rate of the system.

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 broadband wireless communication technique field.

Background technology

New generation broadband wireless communication system need to provide the radio multimedium business such as wireless Internet access, wireless video and mobile computing at a high speed for user, and this all has higher requirement to the transmission rate of information and transmission quality.The decline being caused by signal transmission multipath transmisstion is the principal element that affects 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 is all the piecemeal transmission technology based on 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 broadband wireless communications, so OFDM and SCFDE become the mainstream technology of current 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 subject to extensive concern with its conventional single-antenna spectrum efficiency that technology is beyond one's reach in recent years.The key technology that the combination MIMO-OFDM of MIMO and the piecemeal transmission technology based on CP and MIMO-SCFDE become future wireless.

Mimo system is used 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 different antennae, obtains high channel capacity, thereby improves the availability of frequency spectrum and reliability.OFDM based on piecemeal transmission, can, effectively to anti-multipath fading, because subcarrier spectrum main lobe is overlapping, have higher spectrum efficiency; CP can well absorb inter-frame-interference; And can take simple frequency-domain equilibrium method to eliminate the channel disturbance of introducing due to time delay expansion; The baseband modulation process of OFDM can complete with invert fast fourier transformation (hereinafter to be referred as IFFT:Inverse Fast Fourier Transform), and base band demodulating process can be with fast fourier transform (hereinafter to be referred as FFT:Fast Fourier Transform)) complete.SCFDE is the piecemeal transmission technology that is similar to OFDM, although equally can be effectively to anti-multipath fading and the height power ratio (PAPR, Peak-to-average Power Ratio) that do not have OFDM to make a start, concerned degree is far away from OFDM.

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

While utilizing the adaptive technique of channel condition information (hereinafter to be referred as CSI:Channel State Information) effectively to resist, frequently, empty selectivity, thereby more reliably more effectively communicate.Precoding is the adaptive technique extensively adopting in current wideband MIMO system, it can be according to the situation of the channel matrix of Narrow-Band MIMO Channel, the bit number of this Narrow-Band MIMO Channel transmission of the precoding adaptively modifying by transmitting terminal, can greatly improve the efficiency of each scarce order or the transmission of ill-condition Narrow-Band MIMO Channel, thereby improve the efficiency of whole wideband MIMO system.

Chinese patent literature CN101969417A discloses a kind of MIMO-SCFDE system self-adaption multi-mode transmission method of low passback, and the method complexity is low, 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, reception antenna number is N _r, and N _t≤ N _r, its signal indication and signal processing are as follows:

Receiving-transmitting sides is set up after communication, and receiving terminal utilizes channel estimating or channel prediction arithmetic to obtain current channel condition information, supposes

be k frequency domain subchannel gains of channel between i root transmitting antenna and l root reception antenna, i=1 wherein, 2 ..., N _t, l=1,2 ..., N _r, k=0,1 ..., N-1; A ^kthe channel matrix that represents k frequency domain subchannel, wherein the capable i column element of l is

that is:

Then according to channel capacity, choose available frequency domain bearing point (noting: on each frequency domain subchannel, the one deck that transmitting antenna is corresponding, is called a frequency domain bearing point), and generate frequency domain bearing point beacon information D={D _q, q=0,1 ..., N * N _t-1}, wherein D _q=0 or 1, D _q=1 this frequency domain bearing point of expression can be used, D _q=0 represents this frequency domain bearing point forbidding.

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

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

(2), by the comparison of tabling look-up, selecting order to add 1 rear channel capacity increases maximum subchannel f, its order is added to 1, i.e. R _f=R _f+ 1, judge now whether system satisfies condition

if met, repeat this step, until jump to next step while not satisfying condition;

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

(4) by each subchannel order information R, generate frequency domain channel beacon information D={D (k), k=0,1 ..., N-1}, wherein D (k)={ D (k _s), s=0,1 ... N _t-1}, the value of D (k) is by the order R of k sub-channels _kdetermine the front R of D (k) _kindividual value is 1, below be 0.

Transmitting terminal, according to frequency domain bearing point beacon information, calculates the sum M of available bearing point, according to the modulation system that will adopt, M bit information is carried out to 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 meet average be 0, variance is

to x _mdo M point FFT conversion and obtain corresponding M dimension frequency domain data frame then according to frequency domain channel beacon information D by X _mbe mapped as a row N * N _tdimension frequency domain data frame

be about to X _mm frequency domain data symbol be inserted into successively corresponding D _k=1 position, D _k=0 position zero padding.Then by serial to parallel conversion, by the N * N obtaining _tdimension frequency domain data frame

top n data symbol as first row, N+1 to 2 * N data symbol

as secondary series, by that analogy, will

be transformed into N _trow N dimension frequency domain data frame

i=1,2 ..., N _t.Again every column data frame is done to N point IFFT conversion, change to time domain and be

i=1,2 ..., N _t, add after CP respectively by N _troot transmitting antenna sends simultaneously.

Receiving terminal is received after signal, first goes CP to process, and the signal that now l root reception antenna receives can be expressed as vector $r_{N,l}=y_{N,l}+w_{N,l}={(y_{N,l}^0,y_{N,l}^1,\·\·\·,y_{N,l}^{N-1})}^T+{(w_{N,l}^0,W_{N,l}^1,\·\·\·,w_{N,l}^{N-1})}^T,$ L=1,2 ... N _r, wherein $y_{N,l}={(y_{N,l}^0,y_{N,l}^1,\·\·\·,y_{N,l}^{N-1})}^T$ Represent to receive the useful signal part of signal, $w_{N,l}={(w_{N,l}^0,w_{N,l}^1,\·\·\·,w_{N,l}^{N-1})}^T$ Represent to receive the noise section of signal, suppose that noise is 0 for meeting average, variance is

additive white Gaussian noise; Then the signal above-mentioned l root reception antenna being received is done N point FFT conversion, and the frequency domain form that obtains useful signal is

l=1,2 ... N _r, the frequency domain form of noise is

l=1,2 ... N _r.Next carry out frequency domain equalization, according to selected frequency-domain equilibrium method, utilize channel condition information to generate the balanced matrix G of k frequency domain subchannel ^k, as balanced in adopted ZF,

get matrix A ^kq ^kmoore-Penrose (M-P) contrary be balanced matrix; By the N obtaining after equilibrium _trow N dimension frequency domain symbol vectors is by serial to parallel conversion, the end to end row N * N that becomes _tdimension frequency domain symbol vectors

then according to frequency domain channel beacon information D, select D _qm frequency domain symbol corresponding to=1 position forms a new M dimension frequency domain symbol vectors X _n+ V _n; The M dimension frequency domain symbol vectors obtaining is done to M point IFFT to be become time domain again and obtains x _mand noise $v_M=\mathrm{IFF}{T}_M\left(V_M\right)={(v_M^0,v_M^1,\·\·\·,v_M^{M-1})}^T,$ Then to x _m+ v _mcarry out symbol judgement.

By to system performance analysis, can obtain the equilibrium of system before signal to noise ratio be:

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

After system equalization, signal to noise ratio can be expressed as:

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

After the equilibrium of system, signal to noise ratio is judgement signal to noise ratio, and therefore, the size of balanced rear signal to noise ratio, can the direct error performance that affects system.When carrying out the choosing of frequency domain carrier frequency point, can by control balanced after the noise error performance of control system recently.

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

Summary of the invention

The problem that the frequency spectrum resource existing while choosing carrier frequency point for prior art due 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 system frequency domain bearing point choosing method of the present invention, comprises the following steps:

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

(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 signal to noise ratio is not less than the signal to noise ratio corresponding to bit error rate of system requirements after full equilibrium, if do not met, rebound step (2), if met, according to the distribution of now remaining available frequency domain bearing point, generates frequency domain bearing point beacon information.

The concrete methods of realizing of described step (1) is as follows:

First generate a capable N of N _tmatrix P=(the P of row ¹, P ²..., P ⁿ) ^t, wherein k is capable

each element of initialization matrix P is 1, represents that all carrier frequency points are available; Now the pre-coding matrix of k frequency domain subchannel is expressed as $Q^k=\mathrm{diag}\left(P^k\right)=\mathrm{diag}(p_1^k,p_2^k,\&CenterDot;\&CenterDot;\&CenterDot;,p_{N_T}^k);$ Then calculate matrix

a wherein ^kthe channel matrix that represents k frequency domain subchannel, gets matrix

n _tindividual diagonal element obtains the N of k frequency domain subchannel _tthe noise amplification coefficient of individual frequency domain bearing point

order

calculate the noise amplification coefficient of all frequency domain bearing points, form the capable N of N _tthe matrix Ζ=(Z of row ¹, Z ²..., Z ⁿ) ^t, corresponding one by one with the element of matrix P.

The concrete methods of realizing of described step (2) is as follows:

Inquiry matrix Ζ=(Z ¹, Z ²..., Z ⁿ) ^tthe element Ζ of middle maximum _maxposition, and in order matrix P, correspondence position element value becomes 0, supposes Ζ _maxcapable at l, the pre-coding matrix Q of l frequency domain subchannel now ^lalso change, by formula

upgrade, then recalculate k frequency domain subchannel

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

The concrete methods of realizing of described step (3) is as follows:

Judge whether to meet balanced rear signal to noise ratio snr _postbe not less than the signal to noise ratio snr corresponding to bit error rate of system requirements _req, whether meet

1 number in M representing matrix P wherein,

represent signal power,

represent noise power,

represent noise amplification coefficient sum, if do not meet rebound step (2); If met, this process finishes, and the matrix P now obtaining is the capable N of N _tthe matrix that row are comprised of 0 or 1 element, wherein, element value is that its corresponding frequency domain bearing point of 1 expression can be used, 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 and form N * N with previous column _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.

Accompanying drawing explanation

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.

In figure: 1, information source module, 2, sign map module, 3, FFT module (M point), 4, signal spectrum conversion, 5, serial/parallel module, 6, IFFT module (N point), 7, add Cyclic Prefix (CP) module, 8, D/A module, 9, intermediate frequency and rf modulations module, 10, mimo channel, 11, radio frequency and intermediate frequency demodulation module, 12, A/D module, 13, go CP module, 14, FFT module (N point), 15, balance module, 16 parallel/serial modules, 17, 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 base band simulation result, does not consider the impact of synchronous error, and does not consider channel estimation errors, and 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: data based the adopted modulation system that information source is produced is mapped in 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: according to feedback channel, send the channel beacon information of returning, the M point frequency-region signal of module 3 outputs is mapped on M available frequency domain bearing point, and the zero setting of forbidding frequency domain bearing point, or fill non-information data, just obtain a frame N * N _tdimension frequency domain vector.The method programming that this module need to be introduced according to the present invention, is realized by general digital signal processing chip.

Serial/parallel module 5: N * N that module 4 is obtained _tdimension 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 again time domain.

Add CP module 7: the every frame data that obtain are added to Cyclic Prefix.

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

Intermediate frequency and rf modulations module 9: signal is modulated to and on intermediate frequency, carries out intermediate frequency amplification, then does rf modulations, finally by modulated signal by antenna transmission.

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

Radio frequency and intermediate frequency demodulation module 11: the frequency spectrum that reception antenna is received to signal is moved low frequency from radio frequency or intermediate frequency.Before demodulation, need the frequency deviation causing with in Frequency Synchronization data correction signal transmitting procedure.

A/D module 12: analog signal after demodulation is transformed to digital signal.A/D conversion need to be sampled to analog signal, provides the crystal oscillator of clock signal need to follow the crystal oscillator frequency of transmitter D/A module identical, otherwise will cause sampling rate error.Therefore before A/D conversion, to carry out sampling rate synchronous.

Go CP module 13: Cyclic Prefix is removed.At this moment the problem with regard to existing judgement one frame data from which to start, goes CP to need to do before Timing Synchronization.

N point FFT module 14: the time-domain signal that removes CP is transformed to frequency domain.

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

Parallel/serial module 16: will cross the N obtaining after 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 carrying on M available frequency domain bearing point according to channel beacon information.The method programming that this module need to be introduced according to the present invention, is realized by general digital signal processing chip.

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

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

Synchronization module 20: for example, way by parameter Estimation (: blind estimation and the estimation based on auxiliary data) obtains the various synchrodatas that system needs.Synchronization module is given radio frequency and intermediate frequency demodulation module 11 by Frequency Synchronization data; By sampling rate synchrodata, give A/D module 12; By Timing Synchronization data, give CP module 13.At the present embodiment, be assumed to be synchronous ideal.

Channel estimation module 21: with syncsort seemingly, also need to obtain CSI by parameter Estimation, conventional is generally blind Channel Estimation and the channel estimating based on auxiliary data.At the present embodiment, suppose to estimate accurately.

Frequency domain bearing point beacon information module 22: the CSI obtaining according to channel estimation module 21, chooses available frequency domain bearing point according to the method for selecting, and generates 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 * 4SUI-4 channel model in 802.16 standards, but 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; " IEEE802.16Broad Wireless Access Working Group, 2001, (D.S.Baum, < < emulation SUI channel model > >, IEEE802.16 broadband wireless access working group, 2001))

In emulation, do not consider the impact of synchronous error (comprising carrier synchronization error, sampling rate synchronous error and frame Timing Synchronization error) on system, the error of supposing all synchronization parameters is all 0; Do not consider the propagation delay time of backward channel return path identification information and the impact of transmission error code, suppose that propagation delay time and error code are all 0; Do not consider the impact (such as device non-linear etc.) of other non-ideal factors.

Simulation requirements is guaranteeing under the prerequisite of identical error performance, the method for using the present invention to propose is chosen to frequency domain bearing point and contrast with the availability of frequency spectrum and the back information amount of using channel capacity criterion to choose frequency domain bearing point.

Simulation result:

Fig. 2 has provided BER Performance Ratio that MIMO-SCFDE self adaptation multimode transmission system used two kinds of frequency domain bearing point choosing methods, gives that to have the BER curve of the Gaussian channel of signal to noise ratio before identical equilibrium for referencial use simultaneously.As shown in Figure 2, two kinds of method BER performances are all simply controlled, with there is 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:

In table, data are the in the situation that of fixed transmission power, get 1000 secondary channel samples and carry out the selection of frequency domain bearing point, the available frequency domain obtaining carrying is counted, the availability of frequency spectrum and back information amount mean value.Observe table 1, can find, relative usage channel capacity criterion is chosen frequency domain bearing point, the method of using the present invention to propose is chosen frequency domain bearing point, in back information amount, increase relatively to some extent, but system is chosen the available frequency domain bearing point showed increased for communication, effectively raise the availability of frequency spectrum of system.

Claims (3)

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

(1) all frequency domain bearing points of initialization are all available, and calculate the now noise amplification coefficient of all frequency domain bearing points; On each frequency domain subchannel, the one deck that transmitting antenna is corresponding, is called a frequency domain bearing point;

(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 to meet balanced rear signal to noise ratio and be not less than the signal to noise ratio corresponding to bit error rate of system requirements, if do not met, rebound step (2), if met, according to the distribution of now remaining available frequency domain bearing point, generates frequency domain bearing point beacon information;

The concrete methods of realizing of described step (1) is as follows:

First generate a capable N of N _tthe matrix of row $P={(P^1,P^2,\&CenterDot;\&CenterDot;\&CenterDot;,P^N)}^T,$ Wherein k is capable $P^k=(p_1^k,p_2^k,\&CenterDot;\&CenterDot;\&CenterDot;,p_{N_T}^k),$ Each element of initialization matrix P is 1, represents that all carrier frequency points are available; Now the pre-coding matrix of k frequency domain subchannel is expressed as $Q^k=\mathrm{diag}\left(P^k\right)=\mathrm{diag}(p_1^k,p_2^k,\&CenterDot;\&CenterDot;\&CenterDot;,p_{N_T}^k);$ Then calculate matrix

value, A wherein ^kthe channel matrix that represents k frequency domain subchannel, gets matrix

n _tindividual diagonal element obtains the N of k frequency domain subchannel _tthe noise amplification coefficient of individual frequency domain bearing point

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..., Z ⁿ) ^t, corresponding one by one with the element of matrix P; Wherein: N _tfor number of transmit antennas, N is reception antenna number, () ⁺the Moore-Penrose of representing matrix () is contrary.

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

Inquiry matrix Ζ=(Z ¹, Z ²..., Z ⁿ) ^tthe element Ζ of middle maximum _maxposition, and in order matrix P, correspondence position element value becomes 0, supposes Ζ _maxcapable at l, the pre-coding matrix Q of l frequency domain subchannel now ^lalso change, by formula

upgrade, then recalculate k frequency domain subchannel

value, and get the noise amplification coefficient value that diagonal element upgrades each frequency domain bearing point of this subchannel, wherein () ⁺the Moore-Penrose of representing matrix () is contrary.

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

Judge whether to meet balanced rear signal to noise ratio snr _postbe not less than the signal to noise ratio snr corresponding to bit error rate of system requirements _req, whether meet

1 number in M representing matrix P wherein,

represent signal power,

represent noise power, represent noise amplification coefficient sum, if do not meet rebound step (2); If met, this process finishes, and the matrix P now obtaining is the capable N of N _tthe matrix that row are comprised of 0 or 1 element, wherein, element value is that its corresponding frequency domain bearing point of 1 expression can be used, 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 and form N * N with previous column _tthe matrix of row 1 row, is frequency domain bearing point beacon information D; G wherein ^kthe balanced matrix that represents k frequency domain subchannel.

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