CN103078822A - Multi-channel blind known interference cancellation (BKIC) method - Google Patents

Abstract

The invention discloses a multi-channel blind known interference cancellation (BKIC) method, which is characterized by comprising the following steps of: arranging first transmission symbols of all sub-channels except for a first sub-channel at a transmitting end to guarantee that the products of the first transmission symbols and respective channel coefficients are equal to the products of a tail transmission symbol of the previous sub-channel and the respective channel coefficients; sequentially performing each path of term-by-term weighted accumulation at a receiving end according to difference sequence of each sub-channel, wherein the accumulated weight is the product of quotients of specific items of known interference symbols of the current and previous sub-channels, and the first item of each path of accumulated sequence except for the first path is obtained through weighted accumulation of the tail item of the previous path and the first item of the difference sequence of the path of sub-channel; and performing weighted difference through an evaluation value of a first useful symbol of the first sub-channel and each path of accumulated sequence to restore each useful symbol, wherein the difference weight is a reciprocal of the accumulated weight of the corresponding difference sequence. Compared with the conventional BKIC method, the method has the advantages that the entire symbol processing length is doubled, the interference cancellation residual error is suppressed more effectively, and the method can be used for cancelling interference in orthogonal frequency division multiplexing (OFDM) or time domain interlaced transmission.

Description

The blind known disturbances removing method of a kind of multichannel

Technical field

The invention belongs to radio communication and signal processing technology field, be specifically related to be applicable to exist the blind known disturbances removing method of the multichannel transmission systems of co-channel interference.

Background technology

Co-channel interference is the major issue that present mobile communications network faces, so interference cancellation techniques receives the very big concern of industrial quarters and academia in recent years.A kind of co-channel interference removing method that proposes the people's such as the Zhang Shengli of Shenzhen University that can retrieve from U.S.'s " electronics and the Institution of Electrical Engineers's communications field offprint " (IEEEJournal on Selected Areas in Communications) the paper " blind known disturbances elimination " (Blind known interference cancellation [EarlyAccess Articles]), under the condition of receiving terminal known disturbances symbol (i.e. " known "), directly take the signal of finite complexity to process by receiving terminal and can eliminate preferably co-channel interference, need not interference channel state information (i.e. " blind "), thereby the expense of having avoided this information feedback to bring, and prevent from the performance loss that the channel status measure error causes from therefore can under the severe jamming environment, obtaining superperformance.But, blind known disturbances in this paper is eliminated (blind known interference cancellation, BKIC) method is the single channel transmission system design in essence, the method requirement suppresses to disturb the elimination residual error (although the situation of BKIC for frequency-selective channel has been discussed in this paper by long signal treated length in stable flat channel, but each tap that its solution that provides is based on interference channel is fill order's Channel Processing one by one), and this condition accounts in the future mobile communications network in OFDM (orthogonal frequency-division multiplexing, the OFDM) system of dominant position and may be difficult to satisfy.Ofdm system utilizes a plurality of narrowband subchannels (subcarrier) to communicate simultaneously, with Long Term Evolution (long termevolution, LTE) be example, the subcarrier that comprises 12 15kHz bandwidth in the one Basic Transmission Unit (Physical Resource Block), the number of symbols of each subcarrier is at normal cyclic prefix (cyclic prefix, CP) configuration is lower only is 7, and the channel status of each subcarrier experience may be widely different, the root mean square time delay expands under the condition of 10 μ s in the outdoor environment of city, the channel coherence bandwidth is about 20kHz, the channel fading approximate statistical that means each subcarrier is independent, therefore existing BKIC method can only be processed separately the reception signal of each subcarrier, be difficult to realize the processing than big-length, cause containing in the BKIC output signal stronger interference and eliminate the residual error composition, limited handling property.

Summary of the invention:

The objective of the invention is to propose the blind known disturbances of a kind of multichannel and eliminate (multi-channel blind knowninterference cancellation, MC-BKIC) method, send symbol (after this brief note is " interference symbol ") in the complete known co-channel interference of receiving terminal but lack under the condition of interference channel information, overcome the blind known disturbances of existing single channel and eliminate (single-channel blind known interference cancellation, the defective that exists when SC-BKIC) method is used for multichannel transmission systems is eliminated the co-channel interference composition in the multichannel reception signal more effectively.

The blind known disturbances removing method of multichannel of the present invention sends symbol at transmitting terminal to each subchannel and carries out combined pretreatment; At receiving terminal, under the complete known condition of the interference symbol of each subchannel, at first each subchannel receiving sequence is carried out respectively item by item weighted difference, wherein receiving sequence difference weights are set to the merchant of the current interference symbol of this subchannel and next interference symbol to eliminate the co-channel interference composition fully; Subsequently each subchannel difference sequence is eliminated crosstalk the item by item weighted accumulation of cross term of useful symbol, obtain successively the cumulative sequence in each road; At last all cumulative sequences are averaged, draw first the estimated value of the first subchannel the first useful symbol, each symbol by the cumulative sequence of this estimated value and each road is weighted respectively the estimated value that difference obtains all useful symbols again; It is characterized in that:

Describedly at transmitting terminal each subchannel is sent the combined pretreatment that symbol carries out and be: at the first place of transmitting terminal setting all subchannels except first subchannel transmission symbol, make it to equate behind the channel coefficients that multiply by separately with the end transmission symbol of last subchannel;

The described item by item weighted accumulation that each subchannel difference sequence is carried out at receiving terminal is: the difference sequence sum weight that every correspondence of each road difference sequence is set at receiving terminal is: the first place of the corresponding subchannel of this road difference sequence disturbs symbol and the merchant of current interference symbol to multiply by the merchant that symbol and end interference symbol are disturbed in the first place of subchannel before all, adopt this difference sequence sum weight that each subchannel difference sequence is carried out item by item weighted accumulation, do not included successively with the crosstalk cumulative sequence in each road of cross term of symbol, wherein the last item of the first term of the cumulative sequence in each road by the cumulative sequence in last road obtains with the long-pending summation that the first term of corresponding subchannel difference sequence multiply by corresponding difference sequence sum weight except the first via, and every by the cumulative sequence in this road last of all the other of the cumulative sequence in each road multiply by amassing of corresponding difference sequence sum weight with the currentitem of corresponding subchannel difference sequence and sue for peace and obtain;

The described weighted difference that the cumulative sequence of estimated value and each road of the first subchannel the first symbol is carried out at receiving terminal is: after drawing the estimated value of the first subchannel the first useful symbol, the cumulative differential of sequence weights that every correspondence of the cumulative sequence in each road is set equal the inverse of the above-mentioned difference sequence sum weight of correspondence, the first subchannel the first useful sign estimation value be multiply by corresponding cumulative differential of sequence weights afterwards with every the subtracting each other of the cumulative sequence in each road respectively, obtain the estimated value of other each useful symbol in the corresponding subchannel receiving sequence.

Because the present invention has taked the signal of a plurality of subchannels is carried out the mode of Combined Treatment, namely carry out the combined pretreatment of the first symbol of each subchannel at transmitting terminal, and unite cumulative and average operation at receiving terminal to the difference sequence of each subchannel, so that the symbol lengths of disposed of in its entirety is multiplied, avoided owing to the not enough performance bottleneck that causes of BKIC treated length, establishment disturb after processing and eliminate the residual error composition, in the higher situation of signal to noise ratio, compare the independent SC-BKIC of execution in each subchannel, or with carrying out the scheme that SC-BKIC processes after the multichannel receiving sequence serial connection, can obtain remarkable performance boost.The present invention is as a kind of general interference elimination method in the multichannel transmission systems under the co-channel interference environment, both can be used for the frequency domain multi-channel transmission, such as a plurality of subcarriers in same coherence time in the ofdm system, the interference that also can be used in the time domain multi-channel transmission is eliminated, and is dispersed in the signal that transmits in different coherence times as adopting time domain to interweave.

Description of drawings

Fig. 1 is the transmitting terminal principles of signal processing block diagram in the MC-BKIC method of the present invention.

Fig. 2 is the receiving end signal handling principle block diagram in the MC-BKIC method of the present invention.

Fig. 3 is MC-BKIC method of the present invention when being used for multi-carrier transmission, transmission data block schematic diagram wherein.

Fig. 4 is MC-BKIC method of the present invention when being used for 2 sub-channels and processing, the modulation bit error rate performance comparison diagram under different subchannel symbolic numbers.

Fig. 5 is MC-BKIC method of the present invention when being used for 2 sub-channels and processing, the modulation bit error rate performance figure that compares with the SC-BKIC method.

Fig. 6 is MC-BKIC method of the present invention when being used for 2 sub-channels and processing, and residual error power-performance figure is eliminated in the interference of comparing with the SC-BKIC method.

Fig. 7 is MC-BKIC method of the present invention when being used for the subchannel Combined Treatment of different numbers, modulation bit error rate performance comparison diagram.

Fig. 8 is MC-BKIC method of the present invention when being used for the time domain interleaving block Combined Treatment of different numbers, the outage capacity performance comparison diagram under rayleigh fading channel.

Embodiment

Embodiment 1: the blind known disturbances removing method of multichannel flow process.

Establish in the present embodiment and comprise K smooth subchannel in the described multichannel transmission systems, K=2,3 ...Receiving terminal is designated as x at the useful symbol that the k sub-channels receives _k(t), t=1 ..., N, N is the symbolic number of every sub-channels receiving sequence, noise symbol is designated as z _k(t), the transmission symbol that is disturbed is designated as y _k(t), the interference channel state of its experience is g _kGenerally speaking, useful symbol x _k(t) be the transmission symbol s of k sub-channels _k(t) with the state h of k sub-channels _kProduct: x _k(t)=h _ks _k(t).Reception signal on each subchannel is:

$\left\{\begin{array}{c}{r}_1\left(t\right)=x_1\left(t\right)+z_1\left(t\right)+g_1{y}_1\left(t\right)\\ r_2\left(t\right)=x_2\left(t\right)+z_2\left(t\right)+g_2{y}_2\left(t\right)\\ \·\\ \·\\ \·\\ r_K\left(t\right)=x_K\left(t\right)+z_K\left(t\right)+g_K{y}_K\left(t\right)\end{array}\right.,t=\mathrm{1,2},...,N$

This model can be portrayed the OFDM multi-carrier transmission in a coherence time, also can represent to interweave by time domain to be dispersed in the single carrier transmission of carrying out a plurality of coherence times.Conclusion in the paper " blind known disturbances elimination " that can have been retrieved by U.S.'s " electronics and the Institution of Electrical Engineers's communications field offprint " as can be known, power and BKIC treated length that residual error is eliminated in interference in the BKIC output signal are inversely proportional to, therefore the group channel symbol is counted N numerical value hour, and the SC-BKIC method can not obtain superperformance.For increasing treated length, put forward the MC-BKIC method in the present embodiment with the receiving sequence r of Combined Treatment K sub-channels ₁(t=1 ..., N), r ₂(t=1 ..., N) ..., r _K(t=1 ..., N).

Fig. 1 has provided the transmitting terminal principles of signal processing figure in the inventive method.As shown in fig. 1: each circuit-switched data is flowed through and is produced respectively modulation signal s on each corresponding subchannel after the ovennodulation modules A ₁(t=1 ..., N), s ₂(t=2 ..., N) ..., s _K(t=2 ..., N), deposit respectively them in k road modulation symbol register group B _k, k=1 ..., K; The transmitting terminal preliminary treatment produces the first transmission symbol of every sub-channels except first subchannel, and the first transmission symbol of k sub-channels is set to:

$s_k\left(1\right)=\frac{h_{k-1}}{h_k}{s}_{k-1}\left(N\right),k=2,...,K---\left(1\right)$

Adopt the s of oblique line square sign among Fig. 1 ₂(1), s _K(1) the first transmission symbol of each subchannel of expression preliminary treatment generation, they do not carry new data, but are used for satisfying the needs that each subchannel carried out Combined Treatment at receiving terminal; The reason that they are so arranged will be explained in the receiving terminal processing procedure below.Through each the road signal s that obtains after the preliminary treatment ₁(t=1 ..., N), s ₂(t=1 ..., N) ..., s _K(t=1 ..., N) be used further to send.

Fig. 2 has provided the receiving end signal handling principle figure in the inventive method.At first, to first subchannel receiving sequence r ₁(t=1 ..., N) pursue the symbol weighted difference, obtain first via difference sequence w ₁(t=1 ..., N-1):

w ₁(t)＝r ₁(t)-d _1,1(t)r ₁(t+1) (2)

The operation of formula (2) expression first via weighted difference is by the first via receiving symbol shift register C shown in Fig. 2 _1,1And first via receiving sequence weighted difference device D _1,1Carry out; Wherein, the t item d of first via receiving sequence difference weights _1,1(t), t=1 ..., N-1 is by the receiving sequence difference weights calculator F shown in Fig. 2 ₁According to known disturbances sign register C _ISIn the interference symbolic information calculate:

$d_{\mathrm{1,1}}\left(t\right)=\frac{y_1\left(t\right)}{y_1(t+1)}---\left(3\right)$

According to first via weighted difference fraction (2) and receiving sequence difference weights calculating formulas (3), first via difference sequence w ₁(t=1 ..., N-1) every has following form:

$w_1\left(t\right)=x_1\left(t\right)+z_1\left(t\right)-\frac{y_1\left(t\right)}{y_1(t+1)}[x_1(t+1)+z_1(t+1)]$

Can find out that the interference component in first subchannel has been eliminated in the operation of first via weighted difference, crosstalk but introduced simultaneously useful symbol, therefore next to first via difference sequence w ₁(t) carry out the cumulative operation of the first via to eliminate the symbol cross term x that crosstalks ₁(t), being referred to as cross term is to appear at simultaneously adjacent two w of difference sequence because of it ₁(t-1) and w ₁(t) in.The first term of the cumulative sequence of the first via is:

u ₁(1)＝w ₁(1) (4)

Sequence number is t=2 ..., the cumulative sequence subsequent item of the first via of N-1 is calculated by following formula:

u ₁(t)＝u ₁(t-1)+a ₁(t)w ₁(t) (5)

A wherein ₁(t), t=2 ..., N-1 is the t item of first via difference sequence sum weight, it is by difference sequence sum weight calculator F ₂According to known disturbances sign register C _ISIn information calculate:

$a_1\left(t\right)=\frac{y_1\left(1\right)}{y_1\left(t\right)}---\left(6\right)$

Formula (4) and formula (5) represent respectively the weighted accumulation operation of first via difference sequence first term and subsequent item, by the first via weighted summer E shown in Fig. 2 ₁With first via summation sign shift register C _1,2The accumulator module that forms is carried out, when being calculated to the t item, and first via weighted summer E ₁With first via summation sign shift register C _1,2The currentitem w of middle value of depositing and first via difference sequence ₁(t) multiply by corresponding first via difference sequence sum weight a ₁(t) long-pending addition obtains the currentitem u of the cumulative sequence of the first via ₁And deposit first via summation sign shift register C in (t), _1,2Cover its original value; First via summation sign shift register C _1,2The middle initial value of depositing is 0.According to the cumulative sequence first term calculating formula (4) of the first via, the cumulative sequence subsequent item calculating formula (5) of the first via and first via difference sequence sum weight calculating formula (6), the cumulative sequence u of the first via that above-mentioned first via difference sequence weighted accumulation operation obtains ₁(t=1 ..., N-1) every has following form:

$u_1\left(t\right)=x_1\left(1\right)+z_1\left(1\right)-\frac{y_1\left(1\right)}{y_1(t+1)}[x_1(t+1)+z_1(t+1)]$

Deposit it in the first via cumulative sequential register C _1,3In, the last item u of the sequence that simultaneously first via added up ₁(N-1) deposit the second road summation sign shift register C in _2,2As its initial value.

To the k sub-channels, k=2 ..., K, k road receiving sequence weighted difference operates by the k road receiving symbol shift register C shown in Fig. 2 _{K, 1}And k road receiving sequence weighted difference device D _{K, 1}Carry out

w _k(t)＝r _k(t)-d _k,1(t)r _k(t+1) (7)

Wherein, the t item d of k road receiving sequence difference weights _{K, 1}(t), t=1 ..., N-1 is by the receiving sequence difference weights calculator F shown in Fig. 2 ₁According to known disturbances sign register C _ISIn the interference symbolic information calculate:

$d_{k,1}\left(t\right)=\frac{y_k\left(t\right)}{y_k(t+1)}---\left(8\right)$

Receive signal weighting Difference Calculation formula (7) and k road reception signal differential weights calculating formulas (8) according to the k road, obtain k road difference sequence w _k(t=1 ..., N-1) every has following form:

$w_k\left(t\right)=x_k\left(t\right)+z_k\left(t\right)-\frac{y_k\left(t\right)}{y_k(t+1)}[x_k(t+1)+z_k(t+1)]$

With k road difference sequence w _k(t), t=1 ..., N-1 is input to the k road weighted summer D shown in Fig. 2 _{K, 2}, make itself and k road summation sign shift register C _{K, 2}In value be weighted summation; As previously mentioned, k road summation sign shift register C _{K, 2}Initial value be the last item u of the cumulative sequence in (k-1) road _K-1(N-1), therefore the first term of the cumulative sequence in k road is provided by following formula:

$u_k\left(1\right)=u_{k-1}(N-1)+\left(\underset{i=1}{\overset{k-1}{\mathrm{\Π}}}\frac{y_i\left(1\right)}{y_i\left(N\right)}\right)w_k\left(1\right)---\left(9\right)$

Through calculating, it has following form:

$u_k\left(1\right)=x_1\left(1\right)+z_1\left(1\right)-\underset{j=2}{\overset{k-1}{\mathrm{\Σ}}}\left(\underset{i=1}{\overset{j-1}{\mathrm{\Π}}}\frac{y_i\left(1\right)}{y_i\left(N\right)}\right)[z_{j-1}\left(N\right)-z_j\left(1\right)]-\left(\underset{i=1}{\overset{k-1}{\mathrm{\Π}}}\frac{y_i\left(1\right)}{y_i\left(N\right)}\right)\frac{y_k\left(1\right)}{y_k\left(2\right)}[x_k\left(2\right)+z_k\left(2\right)]$

$-\left(\underset{i=1}{\overset{k-1}{\mathrm{\Π}}}\frac{y_i\left(1\right)}{y_i\left(N\right)}\right)[x_{k-1}\left(N\right)-x_k\left(1\right)+z_{k-1}\left(N\right)-z_k\left(1\right)]$

Because the transmitting terminal preliminary treatment formula (1) of carrying has guaranteed that the useful symbol of adjacent sub-channel satisfies x _k(1)=x _K-1(N), the symbol cross term [x that crosstalks between subchannel _K-1(N)-x _k(1)] offset fully, then the cumulative sequence first term u in k road _k(1) form abbreviation is:

$u_k\left(1\right)=x_1\left(1\right)+z_1\left(1\right)-\underset{j=2}{\overset{k}{\mathrm{\Σ}}}\left(\underset{i=1}{\overset{j-1}{\mathrm{\Π}}}\frac{y_i\left(1\right)}{y_i\left(N\right)}\right)[z_{j-1}\left(N\right)-z_j\left(1\right)]-\left(\underset{i=1}{\overset{k-1}{\mathrm{\Π}}}\frac{y_i\left(1\right)}{y_i\left(N\right)}\right)\frac{y_k\left(1\right)}{y_k\left(2\right)}[x_k\left(2\right)+z_k\left(2\right)]$

To sequence number t=2 ..., N-1, calculate the subsequent item of the cumulative sequence in k road according to following formula:

u _k(t)＝u _k(t-1)+a _k(t)w _k(t) (10)

The t item a of k road difference sequence sum weight wherein _k(t), t=2 ..., N-1 is:

$a_k\left(t\right)=\left(\underset{i=1}{\overset{k-1}{\mathrm{\Π}}}\frac{y_i\left(1\right)}{y_i\left(N\right)}\right)\frac{y_k\left(1\right)}{y_k\left(t\right)}---\left(11\right)$

It is by the difference sequence sum weight calculator F shown in Fig. 2 ₂According to known disturbances sign register C _ISIn the interference symbolic information calculate.Weights when easily the form of checking k road difference sequence sum weight calculating formula (11) has also comprised t=1 The cumulative operation in k road that the cumulative sequence subsequent item calculating formula (10) of the cumulative sequence first term calculating formula (9) in k road and k road provides is by the k road weighted summer E shown in Fig. 2 _kWith k road summation sign shift register C _{K, 2}The accumulator module that forms is finished, when being calculated to the t item, and k road weighted summer E _kWith k road summation sign shift register C _{K, 2}The currentitem w of middle value of depositing and k road difference sequence _k(t) multiply by k road difference sequence sum weight a _k(t) long-pending addition obtains the currentitem u of the cumulative sequence in k road _kAnd deposit k road summation sign shift register C in (t), _{K, 2}Cover its original value; K road summation sign shift register C _{K, 2}Initial value be the last item u of the cumulative sequence in (k-1) road _K-1(N-1).According to the cumulative sequence first term calculating formula (9) in k road, the cumulative sequence subsequent item calculating formula (10) in k road and k road difference sequence sum weight calculating formula (11), the cumulative sequence u in k road that the cumulative operation in above-mentioned k road obtains _k(t=1 ..., N-1) every has following form:

$u_k\left(t\right)=x_1\left(1\right)+z_1\left(1\right)-\underset{j=1}{\overset{k}{\mathrm{\Σ}}}\left(\underset{i=1}{\overset{j-1}{\mathrm{\Π}}}\frac{y_i\left(1\right)}{y_i\left(N\right)}\right)[z_{j-1}\left(N\right)-z_j\left(1\right)]$

$-\left(\underset{i=1}{\overset{k-1}{\mathrm{\Π}}}\frac{y_i\left(1\right)}{y_i\left(N\right)}\right)\frac{y_k\left(1\right)}{y_k(t+1)}[x_k(t+1)+z_k(t+1)]$

Deposit it in the k road shown in Fig. 2 cumulative sequential register C _{K, 3}In; For k=2 ..., K-1, the last item u of the sequence that added up in the k road simultaneously _k(N-1) deposit (k+1) road summation sign shift register C in _K+1,2As its initial value.Receiving terminal is successively the 2nd ..., carry out aforesaid operations on the K sub-channels.

At last, carry out the estimation of useful symbol in each subchannel receiving sequence based on the cumulative sequence in each road.First with the cumulative sequential register C in each road _{K, 3}In all summation signs input Fig. 2 shown in be averaging module G, calculate first subchannel the first useful symbol x ₁(1) estimated value:

${\hat{x}}_1\left(1\right)=\frac{1}{K(N-1)}\underset{k=1}{\overset{K}{\mathrm{\Σ}}}\underset{t=1}{\overset{N-1}{\mathrm{\Σ}}}{u}_k\left(t\right)---\left(12\right)$

Through calculating first subchannel the first useful symbol x ₁(1) estimated value (1) can turn to following form:

${\hat{x}}_1\left(1\right)=x_1\left(1\right)+z_1\left(1\right)+e_1\left(1\right)$

E wherein ₁(1) represent that the interference that contains in the estimated value of first subchannel the first useful symbol eliminates residual error:

$e_1\left(1\right)=-\frac{1}{K(N-1)}[\underset{n=2}{\overset{N}{\mathrm{\Σ}}}\frac{y_1\left(1\right)}{y_1\left(n\right)}(x_1\left(n\right)+z_1\left(n\right))+\underset{j=2}{\overset{K}{\mathrm{\Σ}}}\left(\underset{i=1}{\overset{j-1}{\mathrm{\Π}}}\frac{y_i\left(1\right)}{y_i\left(N\right)}\right)\underset{n=2}{\overset{N}{\mathrm{\Σ}}}\frac{y_j\left(1\right)}{y_i\left(n\right)}(x_j\left(n\right)+z_j\left(n\right))]$

$-\underset{j=2}{\overset{K}{\mathrm{\Σ}}}\frac{K-j+1}{K}\left(\underset{i=1}{\overset{j-1}{\mathrm{\Π}}}\frac{y_i\left(1\right)}{y_i\left(N\right)}\right)[z_{j-1}\left(N\right)-z_j\left(1\right)]$

The k sub-channels, k=1 ..., the follow-up useful symbol x of N _k(t), t=2 ... the estimated value of N (t) estimated value by first subchannel the first useful symbol

(1) with the respective symbol u of the cumulative sequence in each road _k(t-1) weighted difference obtains, by the cumulative sequence weighted difference device D in the k road shown in Fig. 2 _{K, 2}Carry out:

${\hat{x}}_k\left(t\right)=d_{k,2}\left(t\right)[{\hat{x}}_1\left(1\right)-u_k(t-1)]---\left(13\right)$

The t item d of the cumulative differential of sequence weights in k road wherein _{K, 2}(t), t=2 ..., N is by the cumulative differential of sequence weights calculator F shown in Fig. 2 ₃According to known disturbances sign register C _ISIn the interference symbolic information calculate:

$d_{k,2}\left(t\right)=\left(\underset{i=1}{\overset{k-1}{\mathrm{\Π}}}\frac{y_i\left(N\right)}{y_i\left(1\right)}\right)\frac{y_k\left(t\right)}{y_k\left(1\right)}---\left(14\right)$

Compare k road difference sequence sum weight calculating formula (11) and cumulative differential of sequence weights calculating formula (14), as can be known the t item d of the cumulative differential of sequence weights in k road _{K, 2}(t) be actually this road difference sequence sum weight respective items a _k(t) inverse.Through calculating k sub-channels t useful symbol x _k(t), k=1 ..., N; T=2 ... the estimated value of N

(t) can turn to following form:

${\hat{x}}_k\left(t\right)=x_k\left(t\right)+z_k\left(t\right)+e_k\left(t\right)$

E wherein _k(t) residual error is eliminated in the interference that contains in the estimated value of t symbol of expression k sub-channels:

$e_k\left(t\right)=-\frac{1}{K(N-1)}\frac{y_k\left(t\right)}{y_k\left(1\right)}\left(\underset{i=1}{\overset{k-1}{\mathrm{\Π}}}\frac{y_i\left(N\right)}{y_i\left(1\right)}\right)[\underset{n=2}{\overset{N}{\mathrm{\Σ}}}\frac{y_1\left(1\right)}{y_1\left(n\right)}(x_1\left(n\right)+z_1\left(n\right))$

$+\underset{j=2}{\overset{K}{\mathrm{\Σ}}}\left(\underset{i=1}{\overset{j-1}{\mathrm{\Π}}}\frac{y_i\left(1\right)}{y_i\left(N\right)}\right)\underset{n=2}{\overset{N}{\mathrm{\Σ}}}\frac{y_j\left(1\right)}{y_j\left(n\right)}(x_j\left(n\right)+z_j\left(n\right))]$

$+\frac{y_k\left(t\right)}{y_k\left(1\right)}\left(\underset{i=1}{\overset{k-1}{\mathrm{\Π}}}\frac{y_i\left(N\right)}{y_i\left(1\right)}\right)\underset{j=2}{\overset{k}{\mathrm{\Σ}}}\frac{j-1}{K}\left(\underset{i=1}{\overset{j-1}{\mathrm{\Π}}}\frac{y_i\left(1\right)}{y_i\left(N\right)}\right)[z_{j-1}\left(N\right)-z_j\left(1\right)]$

$-\frac{y_k\left(t\right)}{y_k\left(1\right)}\left(\underset{i=1}{\overset{k-1}{\mathrm{\Π}}}\frac{y_i\left(N\right)}{y_i\left(1\right)}\right)\underset{j=k+1}{\overset{K}{\mathrm{\Σ}}}\frac{K-j+1}{K}\left(\underset{i=1}{\overset{j-1}{\mathrm{\Π}}}\frac{y_i\left(1\right)}{y_i\left(N\right)}\right)[z_{j-1}\left(N\right)-z_j\left(1\right)]$

Through the processing in the present embodiment, from the reception signal that is subjected to the co-channel interference infringement, recovered the useful symbol x of all carrying data ₁(t=1 ..., N), x ₂(t=2 ..., N) ..., x _K(t=2 ..., N).

Embodiment 2:MC-BKIC is used for eliminating the co-channel interference of OFDM transmission.

Consider OFDM data block waiting for transmission in the coherence time, as shown in Figure 3, adopt K subcarrier, K=1,2 ..., comprise N in each subcarrier k and send symbol s _k(t), t=1 ..., N; K=1 ..., K, the state of channel is h between transmitting terminal and the receiving terminal _kAt receiving terminal, the noise of k subcarrier is z _k(t), disturbing symbol is y _k(t), the interference channel state is g _kThe reception signal of k subcarrier is:

r _k(t)＝h _ks _k(t)+z _k(t)+g _ky _k(t)，k＝1,2,…,K，t＝1,2,…,N

Process according to the flow process that provides in above-described embodiment 1 and to get final product.Do not carry the symbol of new data in the box indicating OFDM data block of Fig. 3 bend sign, they are determined by the preliminary treatment of transmitting terminal subcarrier.

At first consider K=2 subcarrier carried out the situation of MC-BKIC, the channel status of establishing two subcarriers is h ₁=1, h ₂=-1, interference channel state separately is g ₁=0.5, g ₂=-0.5, send symbol s _k(t) and disturb symbol y _k(t) be binary phase shift keying (binary phase shift keying, BPSK) modulation symbol

If the received noise power on each carrier wave is

Compared among Fig. 4 in different sub-carrier and counted N=7 * m, m=1,2,3,4 times, each subcarrier is carried out respectively the bit error rate performance curve of the scheme gained of SC-BKIC

And the bit error rate performance curve of the institute's MC-BKIC that carries acquisition

Can find out, when signal to noise ratio is higher, owing to adopted MC-BKIC that treated length is double, effectively suppress to disturb the intensity of eliminating residual error, under different sub-carrier numbers, all obtain significant error performance and improved, as in signal to noise ratio

Lower, the MC-BKIC method of carrying is reduced to each subcarrier with the error rate and carries out respectively below 1/10 of SC-BKIC scheme.

The bit error rate performance of various BKIC schemes when Fig. 5 has compared sub-carrier number K=2, single sub-carrier symbol lengths N=14, wherein Be the ber curve of employing MC-BKIC scheme,

For each subcarrier is carried out respectively the ber curve of SC-BKIC scheme,

For carrying out the bit error rate performance curve of SC-BKIC scheme after two subcarrier receiving sequence serial connections.Fig. 5 is all identical except the sub-carrier length N with the simulation parameter that Fig. 4 uses.As can be seen from Figure 5, the handling property of two subcarriers serial connection SC-BKIC is obviously the poorest, reason is that the difference of this scheme on two subcarrier borders produced a more serious residual error that is caused by the interference channel state transition, this error intensity is directly proportional with interference power, and is diffused in all output symbols in follow-up cumulative and average operation.On the other side, MC-BKIC is then obtaining optimal performance than high s/n ratio zone (signal to noise ratio is greater than 12dB in such as Fig. 5), and each subcarrier scheme of carrying out respectively SC-BKIC has obtained larger performance gain relatively.Compare the interference of above-mentioned each scheme among Fig. 6 and eliminated residual error performance, wherein curve

Be respectively MC-BKIC, each subcarrier carry out respectively the interference of carrying out the SC-BKIC scheme after SC-BKIC and each subcarrier serial connection eliminate the residual error power curve (respectively with Fig. 5 in curve Corresponding), can find out that MC-BKIC has suppressed to disturb most effectively to eliminate residual error that disturbing and eliminating residual error power approximately only is 5 times of noise power, far below the residual error power of two kinds of SC-BKIC schemes under the 20dB signal to noise ratio.

Annotate: two subcarriers serial connection SC-BKIC scheme refers to the two-way receiving sequence is concatenated into a sequence

r'(t＝1,...,2N)＝[r ₁(1),...,r ₁(N),r ₂(1),...,r ₂(N)] ^T

Obtain first difference sequence after the serial connection by the SC-BKIC method:

w'(t＝1,...,2N-1)＝[w ₁(1),...,w ₁(N-1),w ₁₂,w ₂(1),...,w ₂(N-1)] ^T

W wherein ₁(t), w ₂(t), t=1 ..., N-1 receives signal weighting Difference Calculation formula (7) by the k road and provides k=1,2; Finish on this basis cumulative, the average operation of SC-BKIC; Wherein, the middle entry of difference sequence is after the serial connection:

$w^{\&prime;}\left(N\right)={\mathrm{<figure-callout\; id="12"\; label="w"\; filenames="HDA00002727321300022.png,HDA00002727321300031.png"\; state="\{\{state\}\}">w</figure-callout>}}_{12}=r_1\left(N\right)-\frac{y_1\left(N\right)}{y_2\left(1\right)}{r}_2\left(1\right)$

$=x_1\left(N\right)+z_1\left(N\right)-\frac{y_1\left(N\right)}{y_2\left(1\right)}[x_2\left(1\right)+z_2\left(1\right)]+(g_1-g_2)y_1\left(N\right)$

It is the last item r by first subcarrier receiving sequence ₁(N) with the first term r of second subcarrier receiving sequence ₂(1) weighted difference obtains, and wherein has the error term (g that causes because of the transition of different sub carrier interference channel state ₁-g ₂) y ₁(N), and this error term can not be eliminated in follow-up SC-BKIC operation, therefore damaged systematic function.Because the power of this error term is directly proportional with interference power, the infringement that it causes is particularly remarkable in strong interference environment.

Usually, the situation of any a plurality of subcarriers is carried out institute when putting forward the MC-BKIC method, the BPSK bit error rate performance as shown in Figure 7, curve among the figure

K=1,2,3,4 bit error rate performances when being K for the number of sub carrier wave of Combined Treatment.The channel status of each carrier wave is made as: h ₁=1, h ₂=-1, h ₃=1, h ₄=-1, corresponding interference channel state is made as: g ₁=1, g ₂=-1, g ₃=1, g ₄=-1.Here single sub-carrier symbolic number N=7 numerical value is less, so the SC-BKIC overall performance is far away from MC-BKIC, is that the two bit error rate performance differs above 10 times in the situation of 20dB in sub-carrier number K=2, transmitted power.Sub-carrier number K=3 time institute extracting method has further significantly improved error probability.The MC-BKIC that carries of institute relative SC-BKIC than low signal-to-noise ratio the time has slightly deterioration, because of the former added up in the processing procedure noise of each subchannel, its advantage that the residual error establishment is eliminated in interference that is produced by useful signal fails to demonstrate fully when transmitted power is low; But this shortcoming also not serious for the wireless communication system that operates in middle high s/n ratio in the reality more.

Embodiment 3:MC-BKIC is used for eliminating the co-channel interference of time domain interleaved signal.

The normal method that adopts time domain to interweave splits into a blocks of data transmission block of being separated by on a plurality of times in the actual wireless communication system, it is the time domain interleaving block, scattering thing motion complicated in by user mobility or environment causes in the stronger situation of channel time-varying characteristics, channel is shorter coherence time, the decline situation changes very fast, and time domain interweaves and can obtain time diversity.Because a plurality of coherence times have been experienced in the transmission of time domain interleaved signal, have namely passed through a plurality of time domain subchannels, therefore can adopt the MC-BKIC method of carrying to disturb elimination, its transmission and reception ﹠ disposal flow process still available Fig. 1, Fig. 2 represent.

Fig. 8 provided in the time domain interleaving block of different numbers carry out MC-BKIC method gained the outage capacity Performance Ratio, curve among the figure

K=1, the performance when 2,3, the 4 time domain number of interleaved blocks for processing are K.Here suppose that the symbolic number that comprises in the coherence time is N=10, independent identically distributed rayleigh fading channel is experienced in the transmission of each time domain interleaving block, and the average of channel gain is 1.As can be seen from Figure 8, along with the time domain number of interleaved blocks increase of MC-BKIC Combined Treatment, the system break capacity is significantly improved; Although outage capacity still is being faced with the speed upper bound bottleneck that is brought by the principle of BKIC own below high s/n ratio, but this speed upper bound also increases and improves along with treated length, therefore the MC-BKIC method of carrying can effectively be improved performance bottleneck, and obtain diversity gain by the channels that merge the independent decline of a plurality of experience, obtained the spectrum efficiency that significantly is better than SC-BKIC.The cost that this each subchannel head symbol except first subchannel that shows that yet the transmitting terminal preliminary treatment is paid does not carry data is worth.

Claims (1)

1. the blind known disturbances removing method of multichannel sends symbol at transmitting terminal to each subchannel and carries out combined pretreatment; At receiving terminal, under the complete known condition of the interference symbol of each subchannel, at first each subchannel receiving sequence is carried out respectively item by item weighted difference, wherein receiving sequence difference weights are set to the merchant of the current interference symbol of this subchannel and next interference symbol to eliminate the co-channel interference composition fully; Subsequently each subchannel difference sequence is eliminated crosstalk the item by item weighted accumulation of cross term of useful symbol, obtain successively the cumulative sequence in each road; At last all cumulative sequences are averaged, draw first the estimated value of the first subchannel the first useful symbol, each symbol by the cumulative sequence of this estimated value and each road is weighted respectively the estimated value that difference obtains all useful symbols again; It is characterized in that:

Describedly at transmitting terminal each subchannel is sent the combined pretreatment that symbol carries out and be: at the first place of transmitting terminal setting all subchannels except first subchannel transmission symbol, make it to equate behind the channel coefficients that multiply by separately with the end transmission symbol of last subchannel;

The described item by item weighted accumulation that each subchannel difference sequence is carried out at receiving terminal is: the difference sequence sum weight that every correspondence of each road difference sequence is set at receiving terminal is: the first place of the corresponding subchannel of this road difference sequence disturbs symbol and the merchant of current interference symbol to multiply by the merchant that symbol and end interference symbol are disturbed in the first place of subchannel before all, adopt this difference sequence sum weight that each subchannel difference sequence is carried out item by item weighted accumulation, do not included successively with the crosstalk cumulative sequence in each road of cross term of symbol, wherein the last item of the first term of the cumulative sequence in each road by the cumulative sequence in last road obtains with the long-pending summation that the first term of corresponding subchannel difference sequence multiply by corresponding difference sequence sum weight except the first via, and every by the cumulative sequence in this road last of all the other of the cumulative sequence in each road multiply by amassing of corresponding difference sequence sum weight with the currentitem of corresponding subchannel difference sequence and sue for peace and obtain;

The described weighted difference that the cumulative sequence of estimated value and each road of the first subchannel the first symbol is carried out at receiving terminal is: after drawing the estimated value of the first subchannel the first useful symbol, the cumulative differential of sequence weights that every correspondence of the cumulative sequence in each road is set equal the inverse of the above-mentioned difference sequence sum weight of correspondence, the first subchannel the first useful sign estimation value be multiply by corresponding cumulative differential of sequence weights afterwards with every the subtracting each other of the cumulative sequence in each road respectively, obtain the estimated value of other each useful symbol in the corresponding subchannel receiving sequence.

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