CN103078822B - 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 the blind known disturbances removing method of the multichannel transmission systems being applicable to exist co-channel interference.

Background technology

Co-channel interference is the major issue that current mobile communications network faces, and therefore interference cancellation techniques receives the very big concern of industrial quarters and academia in recent years.A kind of co-frequency interference elimination method proposed from the paper " blind known disturbances elimination " (Blind known interference cancellation [EarlyAccess Articles]) of the people such as the Shenzhen University Zhang Shengli that U.S.'s " electronics and the Institution of Electrical Engineers's communications field offprint " (IEEEJournal on Selected Areas in Communications) can retrieve, under the condition of receiving terminal known disturbances symbol (i.e. " known "), directly take the signal transacting of finite complexity can eliminate co-channel interference preferably by receiving terminal, without the need to interference channel state information (i.e. " blind "), thus avoid the expense that this information feed back brings, and prevent the performance loss that channel status measure error causes, therefore, it is possible to obtain superperformance under severe jamming environment.But, blind known disturbances in this paper eliminates (blind known interference cancellation, BKIC) method is single channel transmission system in essence, the method requires to suppress interference to eliminate residual error (although discuss the situation of BKIC for frequency-selective channel in this paper by longer signal transacting length in stable flat channel, but its solution provided is each tap fill order's Channel Processing one by one based on interference channel), and this condition accounts for OFDM (the orthogonal frequency-division multiplexing of dominant position in future mobile communications network, OFDM) may be difficult in system meet.Ofdm system utilizes multiple narrowband subchannels (subcarrier) to communicate simultaneously, with Long Term Evolution (long termevolution, LTE) be example, the subcarrier of 12 15kHz bandwidth is comprised in an one Basic Transmission Unit (Physical Resource Block), the number of symbols of each subcarrier is at normal cyclic prefix (cyclic prefix, CP) 7 are only under configuration, and the channel status of each subcarrier experience may be widely different, in the outdoor environment of city, root mean square delay spread is under the condition of 10 μ s, channel coherence bandwidth is about 20kHz, mean that the channel fading approximate statistical of each subcarrier is independent, therefore existing BKIC method can only process separately the Received signal strength of each subcarrier, be difficult to the process realizing greater depth, residual error composition is eliminated containing stronger interference in causing BKIC to output signal, limit handling property.

Summary of the invention:

The object 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, symbol (after this referred to as " interference symbol ") is sent but under lacking the condition of interference channel information in the complete known co-channel interference of receiving terminal, overcome the blind known disturbances of existing single channel and eliminate (single-channel blind known interference cancellation, SC-BKIC) defect existed when method is used for multichannel transmission systems, more effectively eliminate the co-channel interference composition in multiple channel reception signal.

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 condition that the interference symbol of each subchannel is completely known, first perform weighted difference item by item respectively to each subchannel receiving sequence, wherein receiving sequence difference weights are set to the current interference symbol of this subchannel and next disturbs the business of symbol to eliminate co-channel interference composition completely; Subsequently each subchannel difference sequence is eliminated to the weighted accumulation item by item of useful symbol crosstalk cross term, obtain each road successively and to add up sequence; Finally all cumulative sequences are averaged, first draw the estimated value of the useful symbol of the first subchannel first, then be weighted by add up each symbol of sequence of this estimated value and each road the estimated value that difference obtains all useful symbols respectively; It is characterized in that:

Describedly at transmitting terminal, the combined pretreatment that symbol carries out is sent to each subchannel and be: the first place transmission symbol arranging all subchannels except the first sub-channels except at transmitting terminal, makes it to send symbol with the end of last subchannel equal after being multiplied by respective channel coefficients;

Describedly at receiving terminal to the weighted accumulation item by item that each subchannel difference sequence is carried out be: the difference sequence sum weight arranging every correspondence of each road difference sequence at receiving terminal is: the first place that first place interference symbol and the business of current interference symbol of the corresponding subchannel of this road difference sequence are multiplied by all subchannels before disturbs symbol and end to disturb the business of symbol, this difference sequence sum weight is adopted to carry out weighted accumulation item by item to each subchannel difference sequence, do not included successively and to be added up sequence with each road of symbol crosstalk cross term, wherein except the first via, the add up first term of sequence of each road is obtained by the long-pending summation that last item and the first term of corresponding subchannel difference sequence of sequence be multiplied by corresponding difference sequence sum weight that adds up of last road, adding up in each road, all the other of sequence are every to be obtained with the long-pending summation that the currentitem of corresponding subchannel difference sequence is multiplied by corresponding difference sequence sum weight by the add up last item of sequence of this road,

Describedly at receiving terminal to the estimated value of the first subchannel first symbol and each road weighted difference that sequence carries out that adds up be: after the estimated value drawing the useful symbol of the first subchannel first, the add up cumulative differential of sequence weights of every correspondence of sequence of each road are set and equal the inverse of corresponding above-mentioned difference sequence sum weight, be multiplied by corresponding cumulative differential of sequence weights after the sequence that first subchannel first useful sign estimation value added up with each road respectively every subtracts each other, obtain the estimated value of other each useful symbol in corresponding subchannel receiving sequence.

Owing to this invention takes the mode of the signal of multiple subchannel being carried out to Combined Treatment, namely the combined pretreatment of the first symbol of each subchannel is carried out at transmitting terminal, and combine cumulative and average operation in the difference sequence of receiving terminal to each subchannel, the symbol lengths of disposed of in its entirety is multiplied, avoid the performance bottleneck caused because BKIC treated length is not enough, after effectively inhibit process, residual error composition is eliminated in interference, in good signal to noise situations, compare and independently perform SC-BKIC in each subchannel, or the scheme of SC-BKIC process will be performed after multiple channel reception sequence serial connection, remarkable performance boost can be obtained.The present invention is as general interference elimination method a kind of in the multichannel transmission systems under co-channel interference environment, both can be used for frequency-domain multi-channel transmission, as the multiple subcarriers in coherence time same in ofdm system, also the interference that can be used in time domain multi-channel transmission is eliminated, and is dispersed in the signal transmitted in different coherence time as adopted time domain to interweave.

Accompanying drawing explanation

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

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

Fig. 3 be MC-BKIC method of the present invention for multi-carrier transmission time, transmission data block schematic diagram wherein.

Fig. 4 be MC-BKIC method of the present invention for 2 sub-channels process time, the modulation bit error rate performance comparison diagram under different sub-channel symbol number.

Fig. 5 be MC-BKIC method of the present invention for 2 sub-channels process time, the modulation bit error rate performance figure compared with SC-BKIC method.

Fig. 6 be MC-BKIC method of the present invention for 2 sub-channels process time, residual error power-performance figure is eliminated in the interference compared with SC-BKIC method.

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

When Fig. 8 is the time domain interleaving block Combined Treatment of MC-BKIC method of the present invention for different number, the outage capacity Performance comparision figure under rayleigh fading channel.

Embodiment

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

Described multichannel transmission systems is established to comprise the individual smooth subchannel of K, K=2,3 in the present embodiment ...The useful symbol that receiving terminal receives at kth sub-channels is designated as x _k(t), t=1 ..., N, N are the symbolic number of every sub-channels receiving sequence, and noise symbol is designated as z _kt (), the transmission symbol be disturbed is designated as y _kt (), the interference channel state of its experience is g _k.Generally speaking, useful symbol x _kt transmission symbol s that () is kth sub-channels _kthe state h of (t) and kth sub-channels _kproduct: x _k(t)=h _ks _k(t).Received signal strength 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 portray the OFDM multi-carrier transmission in the coherence time, also can represent and is interweaved by time domain and be dispersed in the single carrier transmission of carrying out multiple coherence time.Conclusion in the paper " blind known disturbances elimination " that can have been retrieved from U.S.'s " electronics and the Institution of Electrical Engineers's communications field offprint ", power and the BKIC treated length of the interference elimination residual error in BKIC output signal are inversely proportional to, therefore, when sub-channel symbol number N numerical value is less, SC-BKIC method can not obtain superperformance.For increase treated length, in the present embodiment put forward MC-BKIC method by 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 gives the figure of the transmitting terminal principles of signal processing in the inventive method.As shown in fig. 1: each circuit-switched data produces the modulation signal s on corresponding each subchannel respectively after flowing through modulation module A ₁(t=1 ..., N), s ₂(t=2 ..., N) ..., s _k(t=2 ..., N), by them respectively stored in kth road modulation symbol Parasites Fauna B _k, k=1 ..., K; Transmitting terminal preliminary treatment produces the first transmission symbol of every sub-channels except the first sub-channels, is set to by the first transmission symbol of kth sub-channels:

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

The s that oblique line square identifies is adopted in Fig. 1 ₂(1), s _k(1) represent the first transmission symbol of each subchannel that preliminary treatment produces, they do not carry new data, but carry out the needs of Combined Treatment at receiving terminal to each subchannel for meeting; The reason that they are so arranged is explained in receiving terminal processing procedure below.The each road signal s obtained after preliminary treatment ₁(t=1 ..., N), s ₂(t=1 ..., N) ..., s _k(t=1 ..., N) be used further to send.

Fig. 2 gives the handling principle figure of the receiving end signal in the inventive method.First, to the first sub-channels receiving sequence r ₁(t=1 ..., N) carry out, by symbol weighted difference, obtaining 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)

Formula (2) represents the operation of first via weighted difference, by the first via receiving symbol shift register C shown in Fig. 2 _1,1and first via receiving sequence weighted difference device D _1,1perform; 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 weight calculator F shown in Fig. 2 ₁according to known disturbances sign register C _iSin 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 weight computing formula (3), first via difference sequence w ₁(t=1 ..., N-1) every there is 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, first via weighted difference operates the interference component eliminated in the first sub-channels, but introduces useful symbol crosstalk simultaneously, therefore following to first via difference sequence w ₁t () carries out first via accumulation operations to eliminate symbol crosstalk cross term x ₁t (), being referred to as cross term is because it appears at adjacent two w of difference sequence simultaneously ₁and w (t-1) ₁in (t).The add up first term of sequence of the first via is:

u ₁(1)＝w ₁(1) (4)

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

u ₁(t)＝u ₁(t-1)+a ₁(t)w ₁(t) (5)

Wherein a ₁(t), t=2 ..., N-1 is the t item of first via difference sequence sum weight, and 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 the weighted accumulation operation of first via difference sequence first term and subsequent item respectively, by the first via weighted summer E shown in Fig. 2 ₁with first via summation sign shift register C _1,2the accumulator module of composition performs, when being calculated to t item, and first via weighted summer E ₁by first via summation sign shift register C _1,2the currentitem w of middle deposited value and first via difference sequence ₁t () is multiplied by corresponding first via difference sequence sum weight a ₁t the long-pending of () is added, obtain the first via and to add up the currentitem u of sequence ₁(t), and stored in first via summation sign shift register C _1,2cover its original value; First via summation sign shift register C _1,2middle deposited initial value is 0.To add up sequence subsequent item calculating formula (5) and first via difference sequence sum weight calculating formula (6) according to add up sequence first term calculating formula (4), the first via of the first via, above-mentioned first via difference sequence weighted accumulation operates the first via obtained and to add up sequence u ₁(t=1 ..., N-1) every there is following form:

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

It to be added up sequential register C stored in the first via _1,3in, the last item u of the sequence that simultaneously first via added up ₁(N-1) stored in the second road summation sign shift register C _2,2as its initial value.

To kth sub-channels, k=2 ..., K, receiving sequence weighted difference operation in kth road is by the kth road receiving symbol shift register C shown in Fig. 2 _{k, 1}and kth road receiving sequence weighted difference device D _{k, 1}perform

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

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

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

According to kth road Received signal strength weighted difference calculating formula (7) and kth road Received signal strength difference weight computing formula (8), obtain kth road difference sequence w _k(t=1 ..., N-1) every there is following form:

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

By kth road difference sequence w _k(t), t=1 ..., N-1 is input to the kth road weighted summer D shown in Fig. 2 _{k, 2}, Shi Qiyuk road summation sign shift register C _{k, 2}in value be weighted summation; As previously mentioned, kth road summation sign shift register C _{k, 2}initial value be add up the last item u of sequence in (k-1) road _k-1(N-1), therefore the add up first term of sequence of kth 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 carried transmitting terminal preliminary treatment formula (1) ensure that the useful symbol of adjacent sub-channel meets x _k(1)=x _k-1(N), symbol crosstalk cross term [x between subchannel _k-1(N)-x _k(1)] be cancelled completely, Zek adds up on road sequence first term u _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, the subsequent item of the sequence that adds up according to following formula calculating kth road:

u _k(t)＝u _k(t-1)+a _k(t)w _k(t) (10)

The wherein t item a of kth road difference sequence sum weight _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 interference symbolic information calculate.The form of easy checking kth road difference sequence sum weight calculating formula (11) also contains weights during t=1 kth road accumulation operations that sequence subsequent item calculating formula (10) provides is added up by the kth road weighted summer E shown in Fig. 2 in add up sequence first term calculating formula (9) and kth road of kth road _kwith kth road summation sign shift register C _{k, 2}the accumulator module of composition completes, when being calculated to t item, and kth road weighted summer E _kby kth road summation sign shift register C _{k, 2}the currentitem w of middle deposited Zhi Yuk road difference sequence _kt () is multiplied by kth road difference sequence sum weight a _kt the long-pending of () is added, obtain kth road and to add up the currentitem u of sequence _k(t), and stored in kth road summation sign shift register C _{k, 2}cover its original value; Kth road summation sign shift register C _{k, 2}initial value be add up the last item u of sequence in (k-1) road _k-1(N-1).To add up sequence subsequent item calculating formula (10) and kth road difference sequence sum weight calculating formula (11) according to add up sequence first term calculating formula (9), kth road of kth road, add up sequence u on the kth road that above-mentioned kth road accumulation operations obtains _k(t=1 ..., N-1) every there is following form:

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

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

It to be added up sequential register C stored in the kth road shown in Fig. 2 _{k, 3}in; For k=2 ..., K-1, the last item u of the sequence that simultaneously added up in kth road _k(N-1) stored in (k+1) road summation sign shift register C _k+1,2as its initial value.Receiving terminal successively the 2nd ..., K sub-channels carries out aforesaid operations.

Finally, the estimation of useful symbol in each subchannel receiving sequence is carried out based on each road sequence that adds up.Xian Jiangge adds up on road sequential register C _{k, 3}in all summation signs input and be averaging module G shown in Fig. 2, calculate the useful symbol x of the first sub-channels first 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, the useful symbol x of the first sub-channels first ₁(1) estimated value (1) following form can be turned to:

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

Wherein e ₁(1) represent that residual error is eliminated in the interference contained in the estimated value of the useful symbol of the first sub-channels first:

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

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

Kth sub-channels, k=1 ..., the follow-up useful symbol x of N _k(t), t=2 ... the estimated value of N t () is by the estimated value of the useful symbol of the first sub-channels first (1) the respective symbol u of the sequence that adds up with each road _k(t-1) weighted difference obtains, and to be added up sequence weighted difference device D by the kth road shown in Fig. 2 _{k, 2}perform:

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

Wherein add up the t item d of differential of sequence weights on kth road _{k, 2}(t), t=2 ..., N is by the cumulative differential of sequence weight calculator F shown in Fig. 2 ₃according to known disturbances sign register C _iSin interference symbolic information calculate:

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

Relatively kth road difference sequence sum weight calculating formula (11) and cumulative differential of sequence weight computing formula (14), add up the t item d of differential of sequence weights on known kth road _{k, 2}t () is actually this road difference sequence sum weight respective items a _kthe inverse of (t).Through calculating, kth sub-channels t useful symbol x _k(t), k=1 ..., N; T=2 ... the estimated value of N t () can turn to following form:

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

Wherein e _kt () represents that residual error is eliminated in the interference contained in the estimated value of kth sub-channels t symbol:

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

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

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

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

Process in the present embodiment, has recovered the useful symbol x of all carrying data from the Received signal strength by co-channel interference infringement ₁(t=1 ..., N), x ₂(t=2 ..., N) ..., x _k(t=2 ..., N).

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

Consider OFDM data block waiting for transmission in the coherence time, as shown in Figure 3, adopt K subcarrier, K=1,2 ..., in each subcarrier k, comprise N number of transmission symbol s _k(t), t=1 ..., N; K=1 ..., K, between transmitting terminal and receiving terminal, the state of channel is h _k.At receiving terminal, the noise of a kth subcarrier is z _kt (), interference symbol is y _kt (), interference channel state is g _k.The Received signal strength of a kth subcarrier is:

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

Carry out processing according to the flow process provided in above-described embodiment 1.Do not carry the symbol of new data in the box indicating OFDM data block of Fig. 3 bend mark, they are determined by the preliminary treatment of transmitting terminal subcarrier.

First situation K=2 subcarrier being performed to MC-BKIC is considered, if the channel status of two subcarriers is h ₁=1, h ₂=-1, respective interference channel state is g ₁=0.5, g ₂=-0.5, send symbol s _k(t) and interference symbol y _kt () is binary phase shift keying (binary phase shift keying, BPSK) modulation symbol if the received noise power on each carrier wave is compare at different sub-carrier number N=7 × m, m=1 in Fig. 4,2,3,4 times, each subcarrier performs the bit error rate performance curve of the scheme gained of SC-BKIC respectively and carry MC-BKIC obtain bit error rate performance curve can find out, when signal to noise ratio is higher, owing to have employed MC-BKIC, treated length is double, restrained effectively interference and eliminate the intensity of residual error, under different sub-carrier numbers, all obtain significant error performance improve, as in signal to noise ratio under, carry that the error rate is reduced to that each subcarrier performs SC-BKIC scheme respectively by MC-BKIC method less than 1/10.

The bit error rate performance of various BKIC scheme when Fig. 5 compares sub-carrier number K=2, single sub-carrier symbol lengths N=14, wherein for adopting the ber curve of MC-BKIC scheme, for each subcarrier performs the ber curve of SC-BKIC scheme respectively, for the bit error rate performance curve by performing SC-BKIC scheme after two subcarrier receiving sequence serial connections.The simulation parameter that Fig. 5 and Fig. 4 uses is all identical except sub-carrier length N.As can be seen from Figure 5, the handling property of two subcarrier serial connection SC-BKIC is obviously the poorest, reason is that the program creates a more serious residual error caused by interference channel state transition in the difference on two subcarrier borders, this error intensity is directly proportional to interference power, and adds up follow-up and be diffused in all output symbols in average operation.On the other side, MC-BKIC then obtains optimal performance in comparatively high s/n ratio region (in as Fig. 5, signal to noise ratio is greater than 12dB), and the scheme that relatively each subcarrier performs SC-BKIC respectively achieves larger performance gain.The interference comparing above-mentioned each scheme in Fig. 6 eliminates residual error performance, wherein curve be respectively MC-BKIC, each subcarrier performs SC-BKIC respectively and after each subcarrier serial connection, the interference of execution SC-BKIC scheme eliminates residual error power curve (respectively with the curve in Fig. 5 corresponding), can find out that MC-BKIC inhibits interference to eliminate residual error most effectively, under 20dB signal to noise ratio, interference eliminates 5 times that residual error power is approximately only noise power, far below the residual error power of two kinds of SC-BKIC schemes.

Note: two subcarrier serial connection SC-BKIC schemes refer to and 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

The difference sequence after serial connection is first obtained by 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

Wherein w ₁(t), w ₂(t), t=1 ..., N-1 is provided by kth road Received signal strength weighted difference calculating formula (7), k=1,2; Complete cumulative, the average operation of SC-BKIC on this basis; Wherein, after serial connection, the middle entry of difference sequence is:

$w^{\′}\left(N\right)=w_{12}=r_1\left(N\right)-\frac{y_1\left(N\right)}{y_2\left(1\right)}{r}_2\left(1\right)$

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

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

Usually, to the situation of any number of subcarrier perform institute put forward MC-BKIC method time, BPSK bit error rate performance as shown in Figure 7, curve in figure k=1,2,3,4 bit error rate performances when be the number of sub carrier wave of Combined Treatment being K.The channel status of each carrier wave is set to: h ₁=1, h ₂=-1, h ₃=1, h ₄=-1, corresponding interference channel state is set to: g ₁=1, g ₂=-1, g ₃=1, g ₄=-1.Here single sub-carrier symbolic number N=7 numerical value is less, and therefore SC-BKIC overall performance is far away from MC-BKIC, and when sub-carrier number K=2, transmitted power are 20dB, the two bit error rate performance differs by more than 10 times.Sub-carrier number K=3 time institute extracting method significantly improves error probability further.The institute MC-BKIC that carries relative SC-BKIC when comparatively low signal-to-noise ratio has and slightly worsens, because the former is accumulated the noise of each subchannel in processing procedure, when transmitted power is lower, it fails to fully demonstrate to the advantage that the interference elimination residual error produced by useful signal effectively suppresses; But this shortcoming not serious for operate in the wireless communication system of middle high s/n ratio in reality more.

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

In actual wireless communication system, a blocks of data is split into the transmission block that multiple time is separated by by the normal method adopting time domain to interweave, i.e. time domain interleaving block, scattering motion complicated in by user mobility or environment causes channel time-varying characteristics stronger, channel coherency time is shorter, fading profiles change is very fast, and time domain interweaves can obtain time diversity.Transmission due to time domain interleaved signal experienced by multiple coherence time, namely have passed through multiple time domain subchannel, carried MC-BKIC method therefore can be adopted to carry out interference and eliminate, and it sends and receive handling process and still can represent with Fig. 1, Fig. 2.

Fig. 8 gives the outage capacity Performance comparision performing MC-BKIC method gained in the time domain interleaving block of different number, curve in figure k=1,2,3,4 is the performance of time domain number of interleaved blocks when being K of process.Here suppose that the symbolic number comprised 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 of MC-BKIC Combined Treatment increases, system break capacity is significantly improved; Although outage capacity is compared with being still faced with the speed upper bound bottleneck brought by the principle of BKIC own below high s/n ratio, but this speed upper bound also increases along with treated length and improves, therefore carried MC-BKIC method can effective improving SNR bottleneck, and obtain diversity gain by the channel merging the independent decline of multiple experience, achieve the spectrum efficiency being significantly better than SC-BKIC.This also shows that the cost that each subchannel head symbol except the first sub-channels that 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 condition that the interference symbol of each subchannel is completely known, first perform weighted difference item by item respectively to each subchannel receiving sequence, wherein receiving sequence difference weights are set to the current interference symbol of this subchannel and next disturbs the business of symbol to eliminate co-channel interference composition completely; Subsequently each subchannel difference sequence is eliminated to the weighted accumulation item by item of useful symbol crosstalk cross term, obtain each road successively and to add up sequence; Finally all cumulative sequences are averaged, first draw the estimated value of the useful symbol of the first subchannel first, then be weighted by add up each symbol of sequence of this estimated value and each road the estimated value that difference obtains all useful symbols respectively; It is characterized in that:

Describedly at transmitting terminal, the combined pretreatment that symbol carries out is sent to each subchannel and be: the first place transmission symbol arranging all subchannels except the first sub-channels except at transmitting terminal, makes it to send symbol with the end of last subchannel equal after being multiplied by respective channel coefficients;

Describedly at receiving terminal to the weighted accumulation item by item that each subchannel difference sequence is carried out be: the difference sequence sum weight arranging every correspondence of each road difference sequence at receiving terminal is: the first place that first place interference symbol and the business of current interference symbol of the corresponding subchannel of this road difference sequence are multiplied by all subchannels before disturbs symbol and end to disturb the business of symbol, this difference sequence sum weight is adopted to carry out weighted accumulation item by item to each subchannel difference sequence, do not included successively and to be added up sequence with each road of symbol crosstalk cross term, wherein except the first via, the add up first term of sequence of each road is obtained by the long-pending summation that last item and the first term of corresponding subchannel difference sequence of sequence be multiplied by corresponding difference sequence sum weight that adds up of last road, adding up in each road, all the other of sequence are every to be obtained with the long-pending summation that the currentitem of corresponding subchannel difference sequence is multiplied by corresponding difference sequence sum weight by the add up last item of sequence of this road,

Describedly at receiving terminal to the estimated value of the useful symbol of the first subchannel first and each road weighted difference that sequence carries out that adds up be: after the estimated value drawing the useful symbol of the first subchannel first, the add up cumulative differential of sequence weights of every correspondence of sequence of each road are set and equal the inverse of corresponding above-mentioned difference sequence sum weight, be multiplied by corresponding cumulative differential of sequence weights after the sequence that first subchannel first useful sign estimation value added up with each road respectively every subtracts each other, obtain the estimated value of other each useful symbol in corresponding subchannel receiving sequence.