CN103763072B - MIMO link self-adaptive transmission method - Google Patents

Abstract

The invention discloses a link self-adaptive transmission method suitable for iteration receiving under limited character input signals. Firstly, under all modulation code schemes, the relation of handling capacity and the frame error rate under the iteration receiving condition is obtained, and the threshold value of handling capacity is calculated according to the requirement of the frame error rate; secondly, the average speed of different codebooks under Gaussian input signals and multiple channel samples is calculated, and then a modulation code scheme is preliminarily selected when the requirement of the frame error rate is met and the handling capacity is maximized; finally, the average mutual information of all precoding codons under limited character input signals and multiple channel samples is calculated, and precoding codons and modulation code schemes meeting the requirement of the frame error rate are selected according to the average mutual information. The link self-adaptive transmission method is suitable for MIMO link self-adaptive control under the iteration receiving condition, calculated amount and transmission delay are lowered, and the method is easy to achieve.

Description

A kind of MIMO link self-adaption transmission method

Technical field

The present invention relates to the link self-adaption transmission method under a kind of limited character input signals, especially relate to multiple antennas Send multiple antennas to receive（MIMO）It is suitable to the link circuit self-adapting of iterative receiver under limited character input signals in wireless communication system Transmission method.

Background technology

For meeting the demand to more high data rate for the future mobile communication system, mimo wireless communication system improves simultaneously Enhance air interface technologies.In actual wireless propagation environment, with user equipment（UE, User Equipment）Shifting Dynamic, UE and base station（BS, Base Station）Between channel may experience different types, thus result in open-loop transmission The decline of systematic function, therefore, in mimo wireless communication system, adopts closed-loop transmission techniques to be adaptive to channel circumstance Change.

Under mimo wireless communication system closed loop transmission pattern and limited character input signals, UE passes through to feed back precoding square The parameters such as battle array, modulation system and code rate realize link circuit self-adapting transmission.Optimum link adaptive transmission method, is characterized in The feedback parameter of UE is completed by Syndicating search：Calculate the optimum pre-coding matrix under each modulation system, equivalent to maximize Channel mutual information is criterion, on the premise of ensureing that system FER is less than pre-determined threshold, selects the modulation system of optimum And its corresponding code rate.In general, under each modulation system and each code rate, iteration is obtained by the method for emulation The mutual information of receiver convergence and FER compares figure, require to obtain mutual information thresholding according to FER.Iterative receiver mutual trust Breath is when not less than mutual information thresholding it is ensured that FER is less than pre-determined threshold.

Iterative receiver be improve wireless communication system receptivity, realize approach channel mutual information transmission have efficacious prescriptions Method.In conjunction with the precoding technique with channel mutual information maximization as criterion, the achievable rate of iterative receiver approaches channel maximum Mutual information.Using this feature, the mutual information under limited character input signals can be used as the achievable rate of iterative receiver.Root According to gained mutual information, can in link circuit self-adapting transmission technology selecting modulation mode and code rate.And optimum link is adaptive The amount of calculation of induction method is very big, and under limited character input signals, the traversal search of pre-coding matrix makes the calculating time increase, It is unfavorable that the delay causing is transmitted to link circuit self-adapting.The present invention provides a kind of efficient chain circuit self-adaptive method, and it compares optimum link The computation complexity of adaptive approach is much lower, and spectrum efficiency approaches the spectrum efficiency of optimum link adaptive approach.

Content of the invention

Goal of the invention：For problems of the prior art and a kind of not enough, limited character input letter of present invention offer Be suitable to the link self-adaption transmission method of iterative receiver under number, the method utilize Gauss input signal under and speed expression formula at the beginning of Step determines modulation system, carries out the search of optimal transmission pre-encoding codeword and the selection of code modulating method on this basis, proposes Method reduce amount of calculation and propagation delay time, and spectrum efficiency approaches the frequency spectrum effect of optimum link adaptive transmission method Rate.

Technical scheme：A kind of MIMO link self-adaption transmission method, comprises the steps：

Step one, under each Modulation and Coding Scheme, by emulation method obtain iterative receiver convergence handling capacity with FER relation, requires to calculate throughput threshold value according to FER；

Step 2, using Gauss input signal it is assumed that calculating average and speed under multiple channel samples for the different code books；

Step 3, while meeting FER requirement with maximize handling capacity for criterion initial option modulating-coding side Case；

Averagely mutual under multiple channel samples using each pre-encoding codeword under step 4, the limited character input signals of calculating Information.

Step 5, select to meet pre-encoding codeword and the Modulation and Coding Scheme of FER requirement according to Average Mutual.

In described link self-adaption transmission method step 3, obtained using under Gauss input signal and speed expression formula Obtain the initial ranges of limited input signal modulated mode.

In described link self-adaption transmission method step 4, after tentatively selecting modulation system, using limited character Mutual information computing formula under input signal calculates each pre-encoding codeword under selected modulation system and multiple channel samples Average Mutual.

In described link self-adaption transmission method step 5, select to make Average Mutual maximized precoding code Word, and using handling capacity and FER relation, select under this pre-encoding codeword, to meet the Modulation and Coding Scheme of FER requirement.

Beneficial effect：Compared with prior art, the link circuit self-adapting under the limited character input signals that the present invention provides passes Transmission method, has advantages below：

1) pre-coding matrix designing can be suitably used for the data transfer between multiple channel samples, have preferable versatility and Practicality.

2) link self-adaption transmission method proposing decreases operand and amount of storage in original system resource, and drops Low propagation delay time is it is easy to realize in practical communication system.

3) link self-adaption transmission method proposing is suitable to receiving terminal and adopts iterative receiver, approaches optimum in handling capacity Link self-adaption transmission method, has efficient efficiency of transmission.

Brief description

Fig. 1 is mimo transmission system block diagram；

Fig. 2 is link circuit self-adapting structured flowchart.

Specific embodiment

With reference to specific embodiment, it is further elucidated with the present invention it should be understood that these embodiments are merely to illustrate the present invention Rather than restriction the scope of the present invention, after having read the present invention, the various equivalences to the present invention for the those skilled in the art The modification of form all falls within the application claims limited range.

Fig. 1 gives mimo transmission system block diagram.Consider that a transmission antenna number is N_T, reception antenna number be N_RLink, Signal input output relation can be expressed as：

y_n=H_nWx_n+z_n, n=1,2 ..., N

Wherein, N represents channel samples number,For n-th reception symbolic vector；Believe for n-th Road matrix samples；x_nFor n-th transmission symbolic vector, there is unit energy, the modulation generating after the modulation of its each element encoding Symbol, takes from modulation symbol collection；Assume total K kind modulation symbol collection, big I is ordered as：M₁＜ M₂＜ ... ＜ M_K；z_nIt is equal Value is zero, variance is σ²Additivity white complex gaussian noise；W is pre-coding matrix, from codebook set Middle generation.

Fig. 2 is the link circuit self-adapting structured flowchart of the present invention.

Step one, under each Modulation and Coding Scheme, by emulation method obtain iterative receiver in the case of handling capacity with FER relation, requires to calculate throughput threshold value according to FER.

In additive white Gaussian noise channel, various modulating-coding sides are obtained by the method that demodulator and decoder are emulated The functional relationship of FER and throughput of system under case

FER=LUT (R, I_MCS)

In formula, R represents throughput of system；I_MCS∈{1,2,...,N_MCS, N_MCSIt is the total number of Modulation and Coding Scheme, letter Number LUT can store in a lookup table.Thus, computation index is I_MCSModulation and Coding Scheme meet link error code word rate and be less than Equal to FER₀The throughput threshold value requiring：

Step 2, for different code books, calculate multiple channel samples under Gauss input signal is assumed system average and Speed.

1. it is directed to code book W_tWith channel samples H_n, calculate the system under Gauss input signal is assumed and speed：

Wherein：For N_T×N_TIdentity matrix.

2. calculate code book W_tFor the average of N number of channel samples and speed：

3. calculate average and speed maximum

Step 3, while meeting FER requirement with maximize handling capacity for criterion initial option modulation system.Tool Body ground, is less than or equal to FER according to FER₀And the criterion selecting modulation mode of maximize handling capacity：

In view of because the selection under Gauss input signal is assumed may bring performance error, tentatively by m^*- 1 and m^*Two kinds Modulation system is as possible modulation system under limited character input signals.

Step 4, in codebook setMiddle determination optimal transmission pre-encoding codeword, and calculate this Average Mutual under multiple channel samples for the pre-encoding codeword.

1. for code book W_t, obtain equivalent channelT=1,2 ..., T.

2. for code book W_tWith two kinds of modulation systems m^*- 1 and m^*, calculate N number of channel sample under limited character input is assumed respectively This Average Mutual：

Whereinx_n,a,mRepresent by M_mUnit adjusts Constellation set x that signal processed is constituted_nIn a-th element.

Step 5, select to meet pre-encoding codeword and the Modulation and Coding Scheme of FER requirement according to Average Mutual.

1. calculate limited character input signals and assume the maximum of lower Average Mutual and optimum code word：

2. it is directed to optimum code word, FER is less than or equal to according to error code word rate₀And the criterion of maximize handling capacity selects modulation to compile Code mode：

Claims (4)

1. a kind of MIMO link self-adaption transmission method is it is characterised in that comprise the steps：

Step one, under each Modulation and Coding Scheme, obtain handling capacity and the by mistake frame of iterative receiver convergence by the method for emulation Rate relation, requires to calculate throughput threshold value according to FER；

Step 2, using Gauss input signal it is assumed that calculating average and speed under multiple channel samples for the different code books；Specifically As follows：

1) it is directed to code book W_tWith channel samples H_n, calculate the system under Gauss input signal is assumed and speed：

$R_{sum}(n,t)={\log }_2\det (I_{N_T}+W_t^H{H}_n^H{H}_n{W}_t)$

Wherein：For N_T×N_TIdentity matrix, N_TFor transmission antenna number；

2) calculate code book W_tFor the average of N number of channel samples and speed：

$R_{sum,avg}\left(t\right)=\frac{1}{N}\underset{n=1}{\overset{N}{\Σ}}{R}_{sum}(n,t)$

3) calculate average and speed maximum

$R_{sum,avg}^{final}=\underset{t\∈\[1,2,\mathrm{...},T\]}{\max }{R}_{sum,avg}\left(t\right)$

Step 3, while meeting FER requirement with maximize handling capacity for criterion initial option Modulation and Coding Scheme；

The average mutual trust under multiple channel samples using each pre-encoding codeword under step 4, the limited character input signals of calculating Breath；

Step 5, select to meet pre-encoding codeword and the Modulation and Coding Scheme of FER requirement according to Average Mutual.

2. MIMO link self-adaption transmission method according to claim 1 is it is characterised in that in described step 3, utilize Under Gauss input signal and speed expression formula obtains the initial ranges of limited input signal modulated mode.

3. MIMO link self-adaption transmission method according to claim 1 is it is characterised in that in described step 4, first After step selectes modulation system, calculate each pre-encoding codeword using the mutual information computing formula under limited character input signals and selecting Modulation system and multiple channel samples under Average Mutual.

4. MIMO link self-adaption transmission method according to claim 1 is it is characterised in that in described step 5, select Make the maximized pre-encoding codeword of Average Mutual, and using handling capacity and FER relation, select full under this pre-encoding codeword The Modulation and Coding Scheme that sufficient FER requires.