CN1949682A

CN1949682A - Method and apparatus for cancellation eliminating common-frequency cell signal interference based on serial interference

Info

Publication number: CN1949682A
Application number: CNA2006101179137A
Authority: CN
Inventors: 单鸣
Original assignee: Kaiming Information Science & Technology Co Ltd
Current assignee: SHANGHAI XUANPU INDUSTRIAL Co Ltd
Priority date: 2006-11-03
Filing date: 2006-11-03
Publication date: 2007-04-18
Anticipated expiration: 2026-11-03
Also published as: CN1949682B

Abstract

The invention provides a serial interference offset-based same-frequency cell signal interference eliminating method and device, for each cell, superposing the reconstructed signal of the cell in the previous-stage interference eliminating course and the residual signal obtained after removing all cell interfering signals in the current-stage interference eliminating course, and restoring the received signal of the cell; then reconstructing cell interfering signal by the demodulation symbol generated, based on combined detection; removing the reconstructed signal of the cell in the current-stage interference eliminating course from the input signal and obtaining the residual signal; according to serial progression, repeating executing the above steps. And the invention can eliminate the influence of same-frequncy cell signals and improve the signal receving performance of the cell on the mal-condition that the powers of the adjacent same-frequency cells are higher than that of the cell.

Description

Method and device for eliminating signal interference of co-frequency cell based on serial interference cancellation

Technical Field

The invention relates to a method and a device for serially eliminating co-channel interference for a Time Division synchronous code Division Multiple Access (TD-SCDMA) mobile communication system, in particular to a method and a device for serially eliminating the influence of co-channel interference signals on useful signals to the maximum extent and improving the receiving performance of a receiver.

Background

In a direct spread spectrum code division multiple access (DS-CDMA) system, because of the code division multiple access technology, there is a possibility that different cells use the same-frequency networking objectively, which means that a certain base station (NodeB) may be interfered by signals of mobile stations (UE) in neighboring cells of the same frequency, or a certain mobile station may be interfered by signals of base stations of multiple same-frequency cells. Due to the different propagation delays of different signals and the existence of scrambling codes, the spreading code sets adopted by the respective signals are not completely orthogonal, and this Interference caused by non-zero cross-correlation coefficient is often called Multiple Access Interference (MAI). In CDMA systems, Matched filters (MF for short) or Multi-user detectors (MUD for short) are usually used to recover data before spreading and scrambling. The traditional Rake receiver can not effectively restrain multiple access interference, and multi-user detection can better eliminate the influence caused by MAI.

The multi-user detection method mainly comprises two methods: linear multi-user detection and non-linear multi-user detection. Since linear multi-user detection (joint detection receiver) needs to complete the operation of system matrix inversion, when the Spreading Factor (SF) adopted by the CDMA system is large, the scrambling code length is long, or the number of interfering users is too large, the dimension of the system matrix will increase, and the operation amount of matrix inversion will become unacceptable. In this case, the nonlinear multi-user detection method (interference cancellation) can achieve better reception performance with lower implementation complexity. The non-linear multi-user detection method is mainly divided into two types: parallel Interference Cancellation (PIC) and Successive Interference Cancellation (SIC). In contrast, the PIC has the advantages of short processing delay, no need of power sequencing of each cell, and the like; and SIC consumes less resources, and has better stability and performance when the signal power difference of each cell is larger.

Fig. 1 is a schematic diagram of a frame structure of a TD-SCDMA system. The structure is given in accordance with the low chip rate time division duplex (LCR-TDD) mode (1.28Mcps) in the 3G partnership project (3GPP) specification TS 25.221(Release 4), or the chinese wireless communication standard (CWTS) specification TSM05.02(Release 3). The chip rate of TD-SCDMA system is 1.28Mcps, and each Radio Frame (Radio Frame)10₀、10₁Is 5ms, i.e., 6400 chips (for a 3GPP LCR-TDD system, each radio frame is 10ms in length and can be divided into two subframes (subframes) of 5ms in length, where each Subframe contains 6400 chips). Wherein, each radio frame 10 in TD-SCDMA system (or sub-frame in LCR system)₀、10₁Can be divided into 7 time slots (TS 0-TS 6)11₀-11₆And two pilot slots: a downlink pilot time slot (DwPTS)12 and an uplink pilot time slot (UpPTS)14, and a Guard interval (Guard) 13. Further, TS0 time slot 11₀Is used to carry the system broadcast channel and possibly other downlink traffic channels; and TS 1-TS 6 time slot 11₁-11₆It is used to carry the uplink and downlink traffic channels. An uplink pilot time slot (UpPTS)14 and a downlink pilot time slot (DwPTS)12 are used to establish initial uplink and downlink synchronization, respectively. TS 0-TS 6 time slot 11₀-11₆Each of 0.675ms or 864 chips in length, including two 352 chip DATA segments DATA1(17) and DATA2(19), and a middle 14 chip4-chip (chip) training sequence — Midamble (Midamble) sequence 18. The Midamble sequence has significance in TD-SCDMA, and modules including cell identification, channel estimation and synchronization (including frequency synchronization) and the like are all used. DwPTS slot 12 contains a guard interval 20 of 32 chips and a downlink synchronization code (SYNC-DL) codeword 15 of 64 chips, which is used for cell identification and initial synchronization establishment; the UpPTS timeslot, in turn, contains an uplink synchronization code (SYNC-UL) codeword 16 of length 128 chips, which is used by the ue to perform the relevant uplink access procedure.

DATA carried by two parts of DATA segments DATA1(17) and DATA2(19) of a TD-SCDMA downlink time slot are spread and wound by using spreading codes and scrambling codes. Under the condition of co-channel interference, because the lengths of Spreading codes (Spreading codes) and scrambling codes (scrambling codes) adopted by the TD-SCDMA system are both relatively short (both are only 16 chips), the cross-correlation characteristics between the Spreading codes and the scrambling codes of different cells are not ideal, and the influence of interference signals of adjacent cells cannot be effectively inhibited by a traditional Rake receiver or a single-cell joint detection device (JD for short), which causes the degradation of the receiving performance of the TD-SCDMA system. In order to obtain higher system capacity for the TD-SCDMA system, it is necessary to improve its receiving performance under co-channel interference. The invention introduces a method for counteracting serial interference, and effectively improves the receiving performance of the TD-SCDMA system under the same frequency interference condition.

Disclosure of Invention

The invention aims to provide a method and a device for eliminating signal interference of a common-frequency cell based on serial interference cancellation, which can eliminate the influence of the signal of the common-frequency cell to a great extent and improve the receiving performance of the signal of the cell under the severe condition that the power of a common-frequency adjacent cell is higher than that of the cell with lower implementation complexity.

The invention provides a method for eliminating signal interference of a common-frequency cell based on serial interference cancellation, which is characterized in that the cell and each common-frequency adjacent cell respectively and independently adopt a method for reconstructing signals of each cell based on demodulation symbols generated by joint detection to serially eliminate the interference, and the method comprises the following steps:

step 1, for each cell, namely the current cell and M same-frequency adjacent cells, a cell received signal recovery unit eliminates the reconstructed signal of the cell in the s-1 level interference elimination process

And residual signals after removing interference signals of all previous cells in the s-th-stage interference elimination process

Superposing and recovering the received signals of each cell

{\hat{e}}_{j}^{s} = {\hat{r}}_{j - 1}^{s} + {\hat{x}}_{j}^{s - 1}

Wherein S is 1, 2, Λ, S, and S represents the number of serial interference cancellation stages set by the system;

j＝1，2，Λ，M，M+1；

step 2, according to the sampling input of the current received data I/Q way

Or the s-1 th signal after interference cancellation, a Channel Estimation and interference reconstruction unit (Channel Estimation and interference Gen)The operation Unit, referred to as CEIGU for short) adopts a method of reconstructing signals of each cell based on demodulation symbols generated by Joint Detection (JD), and sequentially and serially completes reconstruction of received signals of each cell to obtain reconstructed signals of each cell at the s-th level:

wherein, S ═ 1, 2, Λ, S, j ═ 1, 2, Λ, M +1, and Z are the lengths of the sampling sequences;

the step 2 specifically comprises:

step 2.1, separating effective paths;

step 2.2, generating channel impulse response;

step 2.3, generating demodulation symbols based on joint detection, comprising:

step 2.4, reconstructing cell signals;

step 3, for each cell, the cell reconstruction signal removing unit sequentially eliminates the reconstruction signal of the cell in the s-th level interference elimination process

From input signalsThe s-th residual signal after the interference of the cell is removed is obtained

{\hat{r}}_{j}^{s} = {\hat{e}}_{j}^{s} - {\hat{x}}_{j}^{s};

Wherein, S ═ 1, 2, Λ, S, j ═ 1, 2, Λ, M + 1;

and 4, repeatedly executing the steps 1-3 according to SIC series preset by the system until SIC operation of all stages is completed.

In step 1, when s is equal to 1, that is, the first-stage interference cancellation is performed, the reconstructed signal of the cell in the previous-stage interference cancellation process is 0.

In step 1, when j is equal to 1, that is, interference cancellation is performed in the first cell, and a residual signal obtained by removing interference signals of all previous cells in the current stage of interference cancellation process is 0.

The method for reconstructing a cell signal using a demodulation symbol generated based on joint detection in step 2 specifically includes:

step 2.1, separating effective paths;

step 2.1.1, for each cell, the last 128 chips of the Midamble sequence (Midamble code) part of the input signal are data-mapped

Respectively matching Basic Midamble sequence (Basic Midamble) BM ═ m with the base Midamble sequence (m) of the cell by a matched filter₁，m₂，Λ，m₁₂₈) Performing bit-by-bit cyclic exclusive-or operation, and calculating the power (Delay Profile, DP) of each bit-by-bit exclusive-or result on each path:

step 2.1.2, detecting the effective path through the effective path detector:

comparing the DP on each Path (Path) with a certain threshold Th; selecting a path corresponding to the DP greater than or equal to the threshold Th as an effective path, otherwise, selecting an invalid path; the L effective paths detected by the final effective path detector are: p_eff＝(p₁，p₂，Λ，p_L)；

Step 2.2, generating Channel Impulse response (Channel Impulse):

step 2.2.1, calculating Channel Estimation (ChE) on each path through a matched filter and a Channel estimator:

the basic midamble sequence according to the current cell is BM ═ (m)₁，m₂，Λ，m₁₂₈) And the data of the last 128 chips of the midamble sequence portion in the received input signal is

The channel estimate ChE on each path is calculated as:

step 2.2.2, generating channel impulse response H ═ H (H) by the channel impulse responder according to the effective path obtained in step 2.1.2 and the channel estimation obtained in step 2.2.1₁，h₂，Λ，h_T) The length T represents the maximum delay supported by the system, the value at the position of the effective path of the channel impulse response is the channel estimation value on the path, and the value at the position of the non-effective path is zero, that is:

<math> <mrow> <msub> <mi>h</mi> <mi>i</mi> </msub> <mo>=</mo> <mfenced open='{' close=''> <mtable> <mtr> <mtd> <msub> <mi>ChE</mi> <mi>i</mi> </msub> </mtd> <mtd> <msub> <mi>DP</mi> <mi>i</mi> </msub> <mo>&GreaterEqual;</mo> <mi>Th</mi> </mtd> </mtr> <mtr> <mtd> <mn>0</mn> </mtd> <mtd> <msub> <mi>DP</mi> <mi>i</mi> </msub> <mo><</mo> <mi>Th</mi> </mtd> </mtr> </mtable> </mfenced> <mo>;</mo> </mrow> </math>

step 2.3, generating demodulation symbols based on joint detection:

step 2.3.1, descrambling and despreading the data part in the input signal by the matched filter:

according to the position P of the active path, the scrambling code ScC of the current cell and the activated spreading code ChC ═ C₁，C₂，Λ，C_N)，

Where N denotes the number of active code channels and SF denotes the spreading factor, and a matched filter is used to match the data portion of the input signalDescrambling and despreading operations are carried out, and symbols obtained after descrambling and despreading are as follows:

wherein,

indicating the symbol corresponding to the nth active code channel,the symbol on the l effective path of the nth active code channel is represented, and K represents the number of the symbols;

step 2.3.2, maximum ratio merger carries out maximum ratio merger to the symbol obtained after descrambling and despreading to obtain a demodulated symbol:

according to the channel impulse response, namely the channel estimation on the effective path, the maximal ratio combiner carries out the maximal ratio combining operation on the descrambled and despread symbols on different paths to obtain the demodulated symbol on each active code channel:

wherein,

indicating a demodulation symbol corresponding to the nth active code channel;

step 2.3.3, joint detection:

step 2.3.3.1, the System matrix generator performs convolution with the channel impulse response according to the scrambling code adopted by the current cell, the dot product result of the activated spreading code and the channel impulse response to generate a System matrix (System ResponseMatrix):

according to the scrambling code ScC of the current cell generated by the scrambling code and spreading code generator, the activated spreading code ChC ═ C₁，C₂，Λ，C_N)，

Wherein N represents the number of active code channels, SF represents the spreading factor, and the system matrix a is calculated by the system matrix generator from the channel impulse response H obtained in step 1.2.2:

bⁿ＝H*(ScC.*C_n)；

B＝[b¹，b²，Λ，b^N]^T；

wherein, the [ alpha ], [ beta ]]^TRepresenting matrix transposition, wherein the number of B matrixes in the A matrix is equal to the number of symbols needing joint detection;

step 2.3.3.2, the joint detector performs joint detection operation by adopting Zero-Forcing Block Linear Equalizer algorithm (ZF-BLE for short) or Minimum Mean Square Error Block Linear Equalizer algorithm (MMSE-BLE for short), so as to obtain a demodulation symbol;

by adopting the zero forcing linear block equalizer algorithm, the obtained demodulation symbols are as follows:

wherein, A represents a system matrix,

represents the input I/Q path signal,

indicating the demodulated symbols resulting from the joint detection.

The minimum mean square error linear block equalizer algorithm is adopted, and the obtained demodulation symbols are as follows:

wherein, A represents a system matrix,representing the input I/Q-path signal, σ²Which represents the variance of the noise, is,indicating the demodulated symbols resulting from the joint detection.

Step 2.3.4, the symbol decision device makes symbol decision to the demodulation symbol generated by the joint detector, and the estimated value of the obtained sending symbol is:

whereinAnd the judgment result of the demodulation symbol corresponding to the nth active code channel is shown.

In step 2.3.4, the symbol decision includes hard decision and soft decision:

the hard decision is operated by a demodulation symbol hard decision device, and the result after the hard decision is obtained is as follows:

<math> <mrow> <msubsup> <mi>d</mi> <mi>k</mi> <mi>n</mi> </msubsup> <mo>=</mo> <mi>sign</mi> <mrow> <mo>(</mo> <msubsup> <mi>y</mi> <mi>k</mi> <mi>n</mi> </msubsup> <mo>)</mo> </mrow> <mo>=</mo> <mfenced open='{' close=''> <mtable> <mtr> <mtd> <mn>1</mn> </mtd> <mtd> <msubsup> <mi>y</mi> <mi>k</mi> <mi>n</mi> </msubsup> <mo>&GreaterEqual;</mo> <mn>0</mn> </mtd> </mtr> <mtr> <mtd> <mo>-</mo> <mn>1</mn> </mtd> <mtd> <msubsup> <mi>y</mi> <mi>k</mi> <mi>n</mi> </msubsup> <mo><</mo> <mn>0</mn> </mtd> </mtr> </mtable> </mfenced> <mo>;</mo> </mrow> </math>

the soft decision is operated by a demodulation symbol soft decision device, and the result after the soft decision is obtained is as follows:

where m represents the mean value of the received signal amplitude, σ²Representing the noise variance of the received signal and tanh representing the hyperbolic tangent function.

Step 2.4, reconstructing cell signals:

step 2.4.1, the modulation spreader performs modulation spread spectrum operation on the result of the symbol decision to obtain a chip sequence on the active code channel:

according to the scrambling code ScC adopted by the current cell and the spreading code ChC ═ on the active code channel (C)₁，C₂，Λ，C_N)，

Modulating and spreading the result of the symbol decision by a modulation spreader to obtain a chip-level transmission signal estimation value on each active code channel:

wherein

A transmitted signal estimate representing the chip level on the nth active code channel;

step 2.4.2, the received signals on the plurality of active code channels are correspondingly reconstructed by a plurality of convolvers:

the convolver completes the convolution operation on the chip sequence on each active code channel obtained in step 2.4.1 and the channel impulse response obtained in step 2.2 to obtain a reconstructed signal on each active code channel:

<math> <mrow> <msup> <mover> <mi>w</mi> <mo>^</mo> </mover> <mi>n</mi> </msup> <mo>=</mo> <mi>H</mi> <mo>&CircleTimes;</mo> <msup> <mover> <mi>v</mi> <mo>^</mo> </mover> <mi>n</mi> </msup> <mo>;</mo> </mrow> </math>

wherein,

representing the reconstructed signal on the nth code channel;

step 2.4.3, the activation code channel signal superimposer superimposes the reconstruction signal on each activation code channel to complete the combination of the activation code channels, thereby completing the reconstruction of the cell signal and obtaining the reconstruction signal of the cell

Step 2.4.4, reconstruction signal weighting: reconstructing the signal of the cell

Multiplication by a particular weighting factor p^sPerformance loss due to incorrect symbol decisions is reduced:

in the method, when each co-frequency adjacent cell is subjected to signal reconstruction, the required basic cell information of the current co-frequency adjacent cell, including a basic midamble sequence, a scrambling code, an activated spreading code and the like, is known by a system or is obtained by detection.

Corresponding to the method, the invention also provides a device for eliminating the signal interference of the same-frequency cell based on Serial Interference Cancellation (SIC), which comprises a cell receiving signal recovery unit, a JD-based CEIGU and a cell reconstruction signal removing unit which are connected in sequence;

the cell received signal recovery unit is used for sequentially eliminating the reconstructed signal of the cell in the s-1 level interference elimination process for the current cell and M same-frequency adjacent cells

Superposing and sequentially recovering the received signals of all cells

{\hat{e}}_{j}^{s} = {\hat{r}}_{j - 1}^{s} + {\hat{x}}_{j}^{s - 1}

Wherein S is 1, 2, Λ, S, and S represents the number of serial interference cancellation stages set by the system; j ═ 1, 2, Λ, M + 1.

When s is equal to 1, that is, the apparatus performs first-stage interference cancellation, the reconstructed signal of the cell in the previous-stage interference cancellation process is 0.

When j is 1, that is, the apparatus performs interference cancellation in the first cell, the residual signal after removing the interference signals of all the previous cells in the current stage of interference cancellation process is 0.

The JD-based CEIGU is used for inputting the sampling of the I/Q path of the currently received data

Or the signal after the interference elimination of the s-1 level adopts a processing method for reconstructing the cell signal by using the demodulation symbol generated based on JD to sequentially and serially complete the reconstruction of the receiving signal of each cell, so as to obtain the reconstruction signal of each cell of the s level:

where S ═ 1, 2, Λ, S, j ═ 1, 2, Λ, M +1, and Z are the lengths of the sampling sequences.

The JD-based CEIGU comprises an effective path separation device, a channel impulse response device, a demodulation symbol generation device based on joint detection and a cell signal reconstruction device which are connected through circuits;

the cell reconstruction signal removing unit is used for sequentially removing the reconstruction signal of each cell in the s-th level interference elimination process

From input signals

The s-th residual signal after the interference of the cell is removed is obtained

{\hat{r}}_{j}^{s} = {\hat{e}}_{j}^{s} - {\hat{x}}_{j}^{s};

Where, S ═ 1, 2, Λ, S, j ═ 1, 2, Λ, M + 1.

The effective path separation device comprises a first matched filter and an effective path detector which are connected in sequence;

the input of the first matched filter receives the last 128 chip data BM ═ m (m) of the midamble sequence in the input signal₁，m₂，Λ，m₁₂₈) Basic midamble sequence with current cell

Carrying out bit-by-bit cyclic XOR operation, and calculating the power of each bit-by-bit XOR result:

the effective path detector compares the DP value on each path output by the first matched filter with a specific threshold Th; selecting a path corresponding to the DP greater than or equal to the threshold Th as an effective path, otherwise, selecting an invalid path; the L effective paths detected by the final effective path detector are: p_eff＝(p₁，p₂，Λ，p_L)。

The channel impulse response device comprises a second matched filter, a channel estimator and a channel impulse response device which are connected in sequence;

the input of the second matched filter receives the last 128 chip data BM ═ m (m) of the midamble sequence in the input signal₁，m₂，Λ，m₁₂₈) Combining the basic midamble sequence of the current cell

The channel estimation ChE on each path is calculated by the channel estimator as:

the input end of the channel impulse responder is also connected with the output end of the effective path detector; the channel impulse response device generates the channel impulse response H ═ (H) according to the effective path and the channel estimation₁，h₂，Λ，h_T)：

Wherein, the length T of the channel impulse response represents the maximum time delay supported by the system.

The demodulation symbol generating device based on the joint detection comprises a third matched filter, a maximum ratio combiner, a joint detection device and a symbol decision device which are connected in sequence;

the input of the third matched filter receives the data part of the input signal and is connected with the effective path detector, and the third matched filter is based on the position P of the effective path, the scrambling code ScC of the current cell and the activated spreading code ChC ═ C (C)₁，C₂，Λ，C_N)，

Wherein N denotes the number of active code channels, SF tableIndicating spreading factor, for data portions of the input signal

Descrambling and despreading operations are carried out, and symbols obtained after descrambling and despreading are as follows:

wherein,

indicating the symbol corresponding to the nth active code channel,

the symbol on the l effective path of the nth active code channel is represented, and K represents the number of the symbols;

the input end of the maximal ratio combiner is also connected with a channel impulse responder, and the maximal ratio combiner carries out maximal ratio combining operation on the descrambled and despread symbols on different paths output by the third matched filter according to the channel impulse response, namely the channel estimation on an effective path, so as to obtain the demodulated symbol on each active code channel:

wherein,

indicating a demodulation symbol corresponding to the nth active code channel;

the joint detection device comprises a scrambling code, a spread spectrum code generator, a system matrix generator and a joint detector which are connected in sequence;

the scrambling code, the scrambling code ScC of the current cell generated by the spreading code generator, and the activated spreading code ChC ═ C₁，C₂，Λ，C_N)，

Wherein N represents the number of the active code channels, and SF represents the spreading factor;

the input end of the system matrix generator is also connected with the output end of the channel impulse responder, and the system matrix A is obtained by calculation according to the scrambling code ScC of the current cell generated by the scrambling code generator, the activated spreading code ChC and the channel impulse response H generated by the channel impulse responder:

bⁿ＝H*(ScC.*C_n)；

B＝[b¹，b²，Λ，b^N]^T；

the input end of the joint detector is respectively connected with the system matrix generator and the maximum ratio combiner; adopting zero forcing linear block equalizer algorithm or minimum mean square error linear block equalizer algorithm to carry out joint detection operation to obtain demodulation symbol

The joint detector adopts a zero forcing linear block equalizer algorithm, and the detected demodulated symbols are as follows:

wherein, A represents a system matrix,

represents the input I/Q path signal,indicating the demodulated symbols resulting from the joint detection.

The joint detector adopts a minimum mean square error linear block equalizer algorithm, and the detected demodulation symbols are as follows:

wherein, A represents a system matrix,

representing the input I/Q-path signal, σ²Representation of noiseThe variance of the sound is such that,

indicating the demodulated symbols resulting from the joint detection.

The symbol decision device carries out symbol decision on the demodulation symbol output by the maximal ratio combiner to obtain an estimation value of a sending symbol:

wherein

And the judgment result of the demodulation symbol corresponding to the nth active code channel is shown.

The symbol decision device is a demodulation symbol hard decision device, and the hard decision result obtained by adopting the demodulation symbol hard decision device is as follows:

the symbol decision device is a demodulation symbol soft decision device, and the soft decision result obtained by adopting the demodulation symbol soft decision device is as follows:

The cell signal reconstruction device comprises a modulation frequency spreader, N convolvers and an active code channel signal superimposer which are connected in sequence;

the modulation frequency spreader is based on the scrambling code ScC adopted by the current cell and the spreading code ChC ═ C (C) on the active code channel₁，C₂，Λ，C_N)，

Decision on symbol decision device outputAnd modulating and spreading to obtain the estimated value of the transmitted signal at the chip level on each active code channel:

wherein

the input ends of the N convolvers are also connected with a channel impulse corresponder, and the convolving operation is completed on the chip sequence on each active code channel output by the modulation frequency spreader and the channel impulse response generated by the channel impulse corresponder to obtain a reconstructed signal on each active code channel:

wherein,representing the reconstructed signal on the nth code channel; the activation code channel signal superimposer superimposes the reconstruction signal on each activation code channel to complete the combination of the activation code channels, thereby completing the reconstruction of the cell signal and obtaining the reconstruction signal of the cell

Furthermore, the cell signal reconstruction device also comprises a weighting multiplier, the input end of the weighting multiplier is connected with the output end of the active code channel signal superimposer, and the weighting multiplier is used for reconstructing the cell reconstruction signal output by the active code channel signal superimposerMultiplication by a particular weighting factor p^sPerformance loss due to incorrect symbol decisions is reduced:

the device calculates residual signals of all cells after interference elimination according to SIC series S preset by the system and the last SIC stage

And for each SIC stage, repeatedly executing the operation of eliminating the signal interference of the cells with the same frequency until the SIC operation of all stages is completed.

The method and the device for eliminating the signal interference of the common-frequency cell based on the serial interference cancellation can eliminate the influence of the signal of the common-frequency cell to a great extent with lower implementation complexity, particularly under the severe condition that the power of the common-frequency adjacent cell is higher than that of the cell, and improve the receiving performance of the signal of the cell.

Drawings

FIG. 1 is a frame structure diagram of TD-SCDMA system according to the 3GPP specification in the background art;

FIG. 2 is a schematic structural diagram of eliminating co-channel interference by a serial interference cancellation method according to the present invention;

fig. 3 is a schematic structural diagram of a CEIGU based on joint detection demodulation results provided in the present invention.

Detailed Description

The invention is described in detail below with reference to fig. 2 to 3 by way of preferred embodiments.

Taking serial interference cancellation of a time slot of TD-SCDMA as an example, assume that the received signal of the time slot is

Wherein r is₁～r₃₅₂A received signal, r, representing a DATA segment DATA1₁₁₃ ^BM，r₁₁₄ ^BM，Λ，r₁₂₈ ^BM，r₁ ^BM，Λr₁₂₈ ^BMRepresenting the received midamble sequence signal, r₃₅₃～r₇₀₄Representing the received signal of the DATA segment DATA 2.

As shown in fig. 3, a schematic structural diagram of a CEIGU based on joint detection demodulation results provided by the present invention includes the following specific operation steps:

step 1, effective path separation:

step 1.1, aiming at each cell, the data of the last 128 chips of the midamble sequence part in the input signal passes through a matched filter 4101, and the data and the basic midamble sequence of the cell are respectively subjected to bit-by-bit cyclic exclusive OR operation to calculate DP;

let BM ═ m be the basic midamble sequence of the current cell₁，m₂，Λ，m₁₂₈) The data of the last 128 chips of the midamble sequence portion in the received input signal is

The calculation formula of DP on each path is:

step 1.2, the active path is detected by the active path detector 490 connected to the matched filter 410_ 2:

comparing the DP on each path with a particular threshold Th; selecting a path corresponding to the DP greater than or equal to the threshold Th as an effective path, otherwise, selecting an invalid path; the final effective path detector detects L piecesThe effective path is as follows: p_eff＝(p₁，p₂，Λ，p_L)；

Step 2, generating channel impulse response:

step 2.1, computing ChE on each path through the matched filter 410_2 and the channel estimator 480 which are connected in sequence:

The channel estimate ChE on each path is then:

step 2.2, generating channel impulse response by the channel impulse responder 470:

the channel impulse responder 470 is connected to the outputs of the effective path detector 490 and the channel estimator 480, respectively, and generates a channel impulse response H ═ (H ═ H) according to the effective path and the channel estimation output, respectively₁，h₂，Λ，h_T) Length of the tableShowing the maximum time delay supported by the system, the value at the position of the effective path of the channel impulse response is the channel estimation value at the path, and the value at the position of the non-effective path is zero, that is:

step 3, generating a demodulation symbol based on the matched filter;

step 3.1, the matched filter 410_3 descrambles and despreads the data part in the input signal:

the input of the matched filter 410_3 is further connected to an effective path detector 490, which outputs the position P of the effective path, the scrambling code ScC of the current cell and the activated spreading code ChC ═ C (C)₁，C₂，Λ，C_N)，

Where N represents the number of active code channels, SF represents the spreading factor, and matched filter 410_3 pairs the data portions of the input signal

wherein,

indicating the symbol corresponding to the nth active code channel,

step 3.2, maximum ratio combiner 420 performs maximum ratio combining on the descrambled and despread symbols to obtain demodulated symbols:

the input end of the maximal ratio combiner 420 is connected to the matched filter 410_3 and the channel impulse responder 470, respectively, and according to the channel impulse response, i.e. the channel estimation on the effective path, the maximal ratio combiner 420 performs the maximal ratio combining operation on the descrambled and despread symbols on different paths to obtain the demodulated symbol on each active code channel:

wherein,

indicating a demodulation symbol corresponding to the nth active code channel;

step 3.3, joint detection:

step 3.3.1, the system matrix generator 590 performs convolution with the channel impulse response according to the scrambling code adopted by the current cell, the dot product result of the activated spreading code, and generates a system matrix:

the input end of the system matrix generator 590 is connected to the scrambling code/spreading code generator 580 and the channel impulse responder 470, respectively, and the activated spreading code ChC ═ C (C) is determined according to the scrambling code ScC of the current cell generated by the scrambling code/spreading code generator 580₁，C₂，Λ，C_N)，

Wherein N represents the number of active code channels, SF represents the spreading factor, and the channel impulse response H generated by the channel impulse response generator 470, and the system matrix a is calculated as:

bⁿ＝H*(ScC.*C_n)；

B＝[b¹，b²，Λ，b^N]^T；

step 3.3.2, the joint detector 530 adopts a zero-forcing linear block equalizer algorithm or a minimum mean square error linear block equalizer algorithm to carry out joint detection operation to obtain a demodulation symbol;

the input terminals of the joint detector 530 are respectively connected to the system matrix generator 590 and the maximal ratio combiner 420;

the joint detector 530 uses the zero-forcing linear block equalizer algorithm to obtain demodulated symbols as follows:

wherein, A represents a system matrix,represents the input I/Q path signal,

indicating the demodulated symbols resulting from the joint detection.

The joint detector 530 uses the minimum mean square error linear block equalizer algorithm to obtain the demodulated symbols as follows:

wherein, A represents a system matrix,

representing the input I/Q-path signal, σ²Which represents the variance of the noise, is,representation of joint inspectionThe resulting demodulated symbols are measured.

Step 3.4, symbol decision device 430 performs symbol decision on the demodulated symbol generated by joint detector 530, and obtains the estimated value of the transmitted symbol as:

wherein

In step 3.4, the symbol decision includes a hard decision and a soft decision, and the symbol decision device 430 may be a demodulation symbol hard decision device or a demodulation symbol soft decision device;

Step 4, reconstructing cell signals:

step 4.1, the modulation spreader 440 performs modulation spreading operation on the result of symbol decision to obtain the chip sequence on the active code channel:

the input end of the modulation spreader 440 is connected to a symbol decider 430, which is configured to determine (C) the spreading code ChC on the active code channel according to the scrambling code ScC adopted by the current cell₁，C₂，Λ，C_N)，

The decision result output by the symbol decision device 430 is modulated and spread to obtain the chip-level transmit signal estimation value on each active code channel:

wherein

step 4.2, the N convolvers 460 correspondingly complete the reconstruction of the received signals on the plurality of active code channels:

the input end of the N convolvers 460 is connected to the modulation spreader 440 and the channel impulse responder 470, respectively, and performs convolution operation on the output chip sequence and the channel impulse response on each active code channel to obtain a reconstructed signal on each active code channel:

wherein,

representing the reconstructed signal on the nth code channel;

step 4.3, the activation code channel signal superimposer 450 connected with the N convolvers 460 superimposes the reconstruction signal on each activation code channel to complete the combination of the activation code channels, thereby completing the reconstruction of the cell signal and obtaining the reconstruction signal of the cell

Step 4.4, the weighting multiplier connected with the output end of the activated code channel signal adder 450 weights the cell reconstruction signal: reconstructing the signal of the cell

as shown in fig. 2, a schematic structural diagram of eliminating co-channel interference by using a serial interference cancellation method, the core idea of which is to serially reconstruct signals of each co-channel cell and complete interference signal elimination based on the serial reconstruction, the specific steps are as follows:

setting M same-frequency adjacent cells for the current cell; the current received data I/Q way sampling input is

Wherein, N is the length of the sampling sequence; the number of series interference cancellation stages set by the system is S;

step 1, for each cell, the cell received signal recovery unit 320 eliminates the reconstructed signal of the cell in the s-1 th level interference elimination process

Superposing and recovering the received signal of the cell

{\hat{e}}_{j}^{s} = {\hat{r}}_{j - 1}^{s} + {\hat{x}}_{j}^{s - 1};

Wherein, S ═ 1, 2, Λ, S, j ═ 1, 2, Λ, M + 1;

in step 1, each cell multiplexes the cell received signal recovery unit 320;

in step 1, if first-stage interference cancellation is performed, that is, if s is 1, then the reconstructed signal of the cell in the previous-stage interference cancellation process is 0; if the cell is the first cell to perform interference cancellation, that is, j is 1, the residual signal after removing the interference signals of all the previous cells in the current-stage interference cancellation process is 0;

step 2, reconstructing the cell signal according to the demodulation symbol generated based on JD as shown in fig. 3, where the JD-based CEIGU 500 is based on the received signal of each cell of the s-th level obtained in step 1Correspondingly and serially completing reconstruction of the received signals of all the cells to obtain a reconstructed signal of each cell at the s-th level:

wherein, S ═ 1, 2, Λ, S, j ═ 1, 2, Λ, M + 1;

in the step 2, each cell reuses the CEIGU to complete interference signal reconstruction;

step 3, for each cell, the cell reconstruction signal removing unit 330 removes the reconstruction signal of the cell from the input signal in the interference elimination process of the current stage, so as to obtain a residual signal after the interference of the cell is removed; namely, the cell reconstruction signal removing unit 330 removes the reconstruction signal of the cell in the s-th interference elimination process

{\hat{r}}_{j}^{s} = {\hat{e}}_{j}^{s} - {\hat{x}}_{j}^{s};

Wherein, S ═ 1, 2, Λ, S, j ═ 1, 2, Λ, M + 1;

in step 3, each cell multiplexes the cell reconstruction signal removing unit 330.

And 4, repeatedly executing the steps 1-3 according to the SIC series S preset by the system until SIC operation of all stages is completed.

It is obvious and understood by those skilled in the art that the preferred embodiments of the present invention are only for illustrating the present invention and not for limiting the present invention, and the technical features of the embodiments of the present invention can be arbitrarily combined without departing from the idea of the present invention. The method and the device for eliminating the signal interference of the co-channel cells based on the serial interference cancellation disclosed by the invention can be modified in many ways, and the invention can also have other embodiments besides the preferred modes specifically given above. Therefore, any method or improvement that can be made by the idea of the present invention is included in the scope of the claims of the present invention. The scope of the invention is defined by the appended claims.

Claims

1. A method for cancelling and eliminating signal interference of a common-frequency cell based on serial interference is characterized in that a method for reconstructing signals of each cell by a demodulation symbol generated based on joint detection is independently adopted by a cell and each common-frequency neighbor cell respectively, and the method for cancelling and eliminating the interference in serial comprises the following steps:

step 1, for each cell, namely the current cell and M same-frequency adjacent cells, a cell received signal recovery unit (320) eliminates the reconstructed signal of the cell in the s-1 level interference elimination process

Superposition and recovery of the receive signal E of each cell_j ^s：

{\hat{e}}_{j}^{s} = {\hat{r}}_{j - 1}^{s} + {\hat{x}}_{j}^{s - 1};

Wherein S is 1, 2, Λ, S, and S represents the number of serial interference cancellation stages set by the system; j ═ 1, 2, Λ, M + 1;

step 2, according to the sampling input of the current received data I/Q way

Or the signal after the s-1 level interference elimination, the channel estimation and interference reconstruction unit (500) adopts a method for reconstructing signals of all cells based on demodulation symbols generated by joint detection, and sequentially and serially completes reconstruction of received signals of all cells to obtain a reconstructed signal of each cell of the s level:

the step 2 specifically comprises:

step 2.1, separating effective paths;

step 2.2, generating channel impulse response;

step 2.3, generating a demodulation symbol based on joint detection;

step 2.4, reconstructing cell signals;

step 3, for each cell, the cell reconstruction signal removing unit (330) sequentially eliminates the reconstruction signal of the cell in the s-th level interference elimination processFrom input signal E_j ^sThe s-th residual signal after the interference of the cell is removed is obtained

{\hat{r}}_{j}^{s} = {\hat{e}}_{j}^{s} - {\hat{x}}_{j}^{s};

Wherein, S ═ 1, 2, Λ, S, j ═ 1, 2, Λ, M + 1;

and 4, repeatedly executing the steps 1-3 according to the serial interference cancellation series preset by the system until the serial interference cancellation operation of all the stages is completed.

2. The method according to claim 1, wherein in step 1, when s is 1, the first stage interference cancellation is performed, and the reconstructed signal of the cell in the previous stage interference cancellation process is 0.

3. The method according to claim 1, wherein in step 1, when j is 1, that is, the interference cancellation of the first cell is performed, and the residual signal after removing the interference signals of all the previous cells in the current-stage interference cancellation process is 0.

4. The method for eliminating co-channel cell signal interference based on successive interference cancellation according to claim 1, wherein in the method for reconstructing cell signal by using demodulation symbols generated based on joint detection in step 2, the step 2.1 comprises the following sub-steps:

step 2.1.1, for each cell, the last 128 chips of the midamble sequence part in the input signal are used for data

The basic midamble sequences BM of the cells are matched to (m) by a matched filter (410_1)₁，m₂，Λ，m₁₂₈) Performing bit-by-bit cyclic exclusive-or operation, and calculating to obtain the power DP of each bit-by-bit exclusive-or result on each path:

step 2.1.2, detecting the effective path by an effective path detector (490):

comparing the DP on each path with a certain threshold Th; selecting a path corresponding to the DP which is greater than or equal to the threshold Th as an effective path, otherwise, selecting the path as an invalid path; the L valid paths detected by the final valid path detector (490) are: p_eff＝(p₁，p₂，Λ，p_L)。

5. The method for eliminating co-channel cell signal interference based on successive interference cancellation according to claim 1, wherein in the method for reconstructing cell signal by using demodulation symbols generated based on joint detection in step 2, the step 2.2 comprises the following sub-steps:

step 2.2.1, calculating the channel estimate ChE on each path through the matched filter (410_2) and the channel estimator (480):

The channel estimate ChE on each path is calculated as:

step 2.2.2, generating channel impulse response H ═ (H) by channel impulse responder (470) according to the effective path obtained in step 2.1.2 and the channel estimation obtained in step 2.2.1₁，h₂，Λ，h_T) The length T represents the maximum delay supported by the system, the value at the position of the effective path of the channel impulse response is the channel estimation value on the path, and the value at the position of the non-effective path is zero, that is:

<math> <mrow> <msub> <mi>h</mi> <mi>i</mi> </msub> <mo>=</mo> <mfenced open='{' close=''> <mtable> <mtr> <mtd> <msub> <mi>ChE</mi> <mi>i</mi> </msub> </mtd> <mtd> <msub> <mi>DP</mi> <mi>i</mi> </msub> <mo>&GreaterEqual;</mo> <mi>Th</mi> </mtd> </mtr> <mtr> <mtd> <mn>0</mn> </mtd> <mtd> <msub> <mi>DP</mi> <mi>i</mi> </msub> <mo><</mo> <mi>Th</mi> </mtd> </mtr> </mtable> </mfenced> <mo>.</mo> </mrow> </math>

6. the method according to claim 1, wherein in the method for reconstructing cell signals by using demodulation symbols generated based on joint detection in step 2, the step 2.3 specifically includes:

step 2.3.1, descrambling and despreading the data part in the input signal by the matched filter (410_ 3):

Where N represents the number of active code channels and SF represents the spreading factor, a matched filter (410_3) is used to match the data portion of the input signal

wherein,

indicating the symbol corresponding to the nth active code channel,

step 2.3.2, maximum ratio merger (420) carries out maximum ratio merger on the symbols obtained after descrambling and despreading to obtain demodulated symbols:

according to the channel impulse response, namely the channel estimation on the effective path, the maximal ratio combiner (420) carries out the maximal ratio combining operation on the descrambled and despread symbols on different paths to obtain the demodulation symbols on each active code channel:

wherein,

indicating a demodulation symbol corresponding to the nth active code channel;

step 2.3.3, joint detection;

step 2.3.4, symbol decision is carried out on the demodulation symbol by a symbol decision device (430) to obtain an estimation value of the sending symbol:

wherein,and the judgment result of the demodulation symbol corresponding to the nth active code channel is shown.

7. The method for eliminating co-channel cell signal interference based on successive interference cancellation according to claim 6, wherein the step 2.3.3 includes the following sub-steps:

step 2.3.3.1, the system matrix generator (590) convolutes with the channel impulse response according to the point multiplication result of the scrambling code and the activated spreading code adopted by the current cell, and generates a system matrix:

the activated spreading code ChC is (C) according to the current cell scrambling code ScC generated by the scrambling code and spreading code generator (580)₁，C₂，Λ，C_N)，

Wherein N represents the number of active code channels, SF represents the spreading factor, and the system matrix a is calculated by the system matrix generator (590) from the channel impulse response H obtained in step 1.2.2:

bⁿ＝H*(ScC.*C_n)；

B＝[b¹，b²，Λ，b^N]^T；

step 2.3.3.2, the joint detector (530) performs joint detection operation using zero-forcing linear block equalizer algorithm or minimum mean square error linear block equalizer algorithm to obtain demodulated symbols

8. The method of claim 7, wherein in step 2.3.3.2, the demodulated symbols obtained by the zero forcing linear block equalizer algorithm are used

Comprises the following steps:

wherein, A represents a system matrix,

9. The method of claim 7, wherein in step 2.3.3.2, the demodulation symbol obtained by the MMSE linear block equalizer algorithm is used

Comprises the following steps:

10. The method according to claim 6, wherein in step 2.3.4, the symbol decision is a hard decision, and the demodulation symbol hard decision device performs symbol decision on the demodulation symbol, and the obtained hard decision result is:

<math> <mrow> <msubsup> <mi>d</mi> <mi>k</mi> <mi>n</mi> </msubsup> <mo>=</mo> <mi>sign</mi> <mrow> <mo>(</mo> <msubsup> <mi>y</mi> <mi>k</mi> <mi>n</mi> </msubsup> <mo>)</mo> </mrow> <mo>=</mo> <mfenced open='{' close=''> <mtable> <mtr> <mtd> <mn>1</mn> </mtd> <mtd> <msubsup> <mi>y</mi> <mi>k</mi> <mi>n</mi> </msubsup> <mo>&GreaterEqual;</mo> <mn>0</mn> </mtd> </mtr> <mtr> <mtd> <mo>-</mo> <mn>1</mn> </mtd> <mtd> <msubsup> <mi>y</mi> <mi>k</mi> <mi>n</mi> </msubsup> <mo><</mo> <mn>0</mn> </mtd> </mtr> </mtable> </mfenced> <mo>.</mo> </mrow> </math>

11. the method according to claim 6, wherein in step 2.3.4, the symbol decision is a soft decision, and the demodulation symbol soft decision device performs symbol decision on the demodulation symbol, and the obtained soft decision result is:

where m represents the mean value of the received signal amplitude, σ²Representing the noise side of the received signalThe difference, tanh, represents the hyperbolic tangent function.

12. The method for eliminating co-channel cell signal interference based on successive interference cancellation according to claim 6, wherein in the method for reconstructing cell signal by using demodulation symbols generated based on joint detection in step 2, the step 2.4 comprises the following sub-steps:

step 2.4.1, the modulation spreader (440) performs modulation spread spectrum operation on the result of the symbol decision to obtain a chip sequence on the active code channel:

The result of the symbol decision is modulated and spread by a modulation spreader (440) to obtain a chip-level transmit signal estimate on each active code channel:

whereinA transmitted signal estimate representing the chip level on the nth active code channel;

step 2.4.2, a plurality of convolvers (460) correspondingly complete the reconstruction of the received signals on a plurality of active code channels:

and (3) a convolver (460) performs convolution operation on the chip sequence on each active code channel obtained in the step 2.4.1 and the channel impulse response obtained in the step 2.2 to obtain a reconstructed signal on each active code channel:

wherein,

representing the reconstructed signal on the nth code channel;

step 2.4.3, the activation code channel signal superimposer (450) superimposes the reconstruction signal on each activation code channel to complete the combination of the activation code channels, thereby completing the reconstruction of the cell signal and obtaining the reconstruction signal of the cell

13. The method for eliminating co-channel cell signal interference based on successive interference cancellation according to claim 12, wherein said step 2.4 further comprises a step 2.4.4 of reconstructing a signal for the cellMultiplication by a particular weighting factor p^sAnd performing weighting operation:

14. a device for eliminating signal interference of a common-frequency cell based on serial interference cancellation is characterized by comprising a cell received signal recovery unit (320), a channel estimation and interference reconstruction unit (500) based on joint detection and a cell reconstruction signal removal unit (330) which are connected in sequence;

the cell received signal recovery unit (320) is used for sequentially eliminating the reconstructed signal of the cell in the s-1 level interference elimination process for the current cell and M co-frequency adjacent cells

And residual signals after removing interference signals of all previous cells in the s-th-stage interference elimination processSuperposition and sequential recovery of the receive signal E of each cell_j ^s：

{\hat{e}}_{j}^{s} = {\hat{r}}_{j - 1}^{s} + {\hat{x}}_{j}^{s - 1}

the channel estimation and interference reconstruction unit (500) based on joint detection inputs the sampling of the current received data I/Q path

Or the signal after the interference elimination of the s-1 level adopts a processing method for reconstructing the cell signal based on the demodulation symbol generated by the joint detection to sequentially and serially complete the reconstruction of the receiving signal of each cell, and the reconstructed signal of each cell of the s level is obtained:

the channel estimation and interference reconstruction unit (500) based on joint detection comprises an effective path separation device, a channel impulse response device, a demodulation symbol generation device based on joint detection and a cell signal reconstruction device which are connected through circuits;

the cell reconstruction signal removing unit (330) removes the reconstruction signal of the cell in the s-th level interference elimination process for each cell in turn

From input signal E_j ^sThe s-th residual signal after the interference of the cell is removed is obtained

{\hat{r}}_{j}^{s} = {\hat{e}}_{j}^{s} - {\hat{x}}_{j}^{s};

Where, S ═ 1, 2, Λ, S, j ═ 1, 2, Λ, M + 1.

15. The apparatus for canceling co-channel cell signal interference based on successive interference cancellation according to claim 14, wherein when s is 1, that is, the apparatus performs the first-stage interference cancellation, and the reconstructed signal of the cell in the previous-stage interference cancellation process is 0.

16. The apparatus according to claim 14, wherein when j is 1, the apparatus performs interference cancellation in the first cell, and the residual signal after removing the interference signals in all the previous cells in the current stage of interference cancellation process is 0.

17. The apparatus for canceling co-channel cell signal interference based on successive interference cancellation according to claim 14, wherein said effective path separating means comprises a first matched filter (410_1) and an effective path detector (490) connected in series;

the input of the first matched filter (410_1) receives the last 128 chips of the midamble sequence in the input signal (m ═ m)₁，m₂，Λ，m₁₂₈) Basic midamble sequence with current cell

Carrying out bit-by-bit cyclic XOR operation, and calculating the power DP of each bit-by-bit XOR result:

the active path detector (490) compares the DP value on each path output by the first matched filter (410_1) with a particular threshold Th; selecting a path corresponding to the DP which is greater than or equal to the threshold Th as an effective path, otherwise, selecting the path as an invalid path; the L valid paths detected by the final valid path detector (490) are: p_eff＝0(p₁，p₂，Λ，p_L)。

18. The apparatus for canceling co-channel cell signal interference based on serial interference cancellation according to claim 14, wherein the channel impulse response means comprises a second matched filter (410_2), a channel estimator (480) and a channel impulse response device (470) connected in sequence;

the second matched filter (410_2) has an input receiving the last 128 chip data BM ═ m of the midamble sequence in the input signal₁，m₂，Λ，m₁₂₈) Combining the basic midamble sequence of the current cell

The channel estimator (480) calculates the channel estimation ChE on each path as:

the input end of the channel impulse responder (470) is also connected with the output end of the effective path detector (490); the channel impulse responder (470) generates a channel impulse response H ═ H (H) according to the effective path and the channel estimation₁，h₂，Λ，h_T)：

19. The apparatus for canceling co-channel cell signal interference based on successive interference cancellation according to claim 14, wherein the demodulation symbol generation means based on joint detection comprises a third matched filter (410_3), a maximum ratio combiner (420), a joint detection means and a symbol decision device (430) connected in sequence.

20. The apparatus for canceling co-channel cell signal interference based on successive interference cancellation according to claim 19, wherein the input terminal of the third matched filter (410_3) receives the data portion of the input signal and is connected to the effective path detector (490);

the third matched filterThe filter (410_3) is based on the position P of the active path, the scrambling code ScC of the current cell and the activated spreading code ChC ═ C₁，C₂，Λ，C_N)，

Wherein N represents the number of active code channels and SF represents the spreading factor for the data portion of the input signalDescrambling and despreading operations are carried out, and symbols obtained after descrambling and despreading are as follows:

wherein,indicating the symbol corresponding to the nth active code channel,

the symbol on the l effective path of the nth active code channel is shown, and K represents the number of the symbols.

21. The apparatus for canceling co-channel cell signal interference based on serial interference cancellation according to claim 19, wherein the input terminal of the maximal ratio combiner (420) is further connected to a channel impulse responder (470), which performs maximal ratio combining operation on the descrambled and despread symbols on different paths output by the third matched filter (410_3) according to a channel impulse response, i.e. a channel estimation on an effective path, to obtain a demodulated symbol on each active code channel:

wherein,indicating the demodulation symbol corresponding to the nth active code channel.

22. The apparatus for eliminating co-channel cell signal interference based on successive interference cancellation according to claim 19, wherein the joint detection apparatus comprises a scrambling code, a spreading code generator (580), a system matrix generator (590) and a joint detector (530) connected in sequence.

23. The apparatus for canceling co-channel cell signal interference based on successive interference cancellation according to claim 22, wherein the scrambling code, the scrambling code ScC of the current cell generated by the spreading code generator (580), and the activated spreading code ChC ═ C (C)₁，C₂，Λ，C_N)，

Where N denotes the number of active code channels and SF denotes the spreading factor.

24. The apparatus for canceling co-channel cell signal interference based on serial interference cancellation according to claim 22, wherein the input terminal of the system matrix generator (590) is further connected to the output terminal of the channel impulse responder (470), and the system matrix a is calculated according to the scrambling code ScC of the current cell generated by the scrambling code and spreading code generator (580), the activated spreading code ChC, and the channel impulse response H generated by the channel impulse responder (470):

bⁿ＝H*(ScC.*C_n)；

B＝[b¹，b²，Λ，b^N]^T；

wherein, the [ alpha ], [ beta ]]^TAnd (3) representing matrix transposition, wherein the number of B matrixes in the A matrix is equal to the number of symbols needing joint detection.

25. The apparatus for canceling co-channel cell signal interference based on successive interference cancellation according to claim 22, wherein the inputs of the joint detector (530) are respectively connected to the system matrix generator (590) and the maximal ratio combiner (420); adopting zero forcing linear block equalizer algorithm or minimum mean square error linear block equalizer algorithm to carry out joint detection operation to obtain demodulation symbol

26. The apparatus for canceling co-channel cell signal interference based on successive interference cancellation according to claim 25, wherein the joint detector (530) employs a zero-forcing linear block equalizer algorithm, and detects the demodulated symbols as:

wherein, A represents a system matrix,

represents the input I/Q path signal,

indicating the demodulated symbols resulting from the joint detection.

27. The apparatus for canceling co-channel cell signal interference based on successive interference cancellation according to claim 25, wherein the joint detector (530) employs a minimum mean square error linear block equalizer algorithm, and detects the demodulated symbols as:

wherein, A represents a system matrix,representing the input I/Q-path signal, σ²Which represents the variance of the noise, is,

indicating the demodulated symbols resulting from the joint detection.

28. The apparatus for canceling co-channel cell signal interference based on successive interference cancellation according to claim 19, wherein the symbol decider (430) performs symbol decision on the demodulated symbol outputted from the maximal ratio combiner (420) to obtain the estimated value of the transmitted symbol:

wherein

29. The apparatus for canceling co-channel cell signal interference based on successive interference cancellation according to claim 28, wherein the symbol decider (430) is a demodulation symbol hard decider, and the hard decision result obtained by using the demodulation symbol hard decider is:

30. the apparatus for canceling co-channel cell signal interference based on successive interference cancellation according to claim 28, wherein the symbol decision device (430) is a demodulated symbol soft decision device, and the soft decision result obtained by using the demodulated symbol soft decision device is:

31. The apparatus for eliminating co-channel signal interference based on successive interference cancellation according to claim 14, wherein the cell signal reconstructing apparatus comprises a modulation spreader (440), a plurality of convolvers (460) and an active code channel signal superimposer (450) connected in sequence.

32. The apparatus for canceling co-channel cell signal interference based on successive interference cancellation according to claim 31, wherein the modulation spreader (440) activates the spreading code ChC ═ C (C) on the code channel according to the scrambling code ScC adopted by the current cell₁，C₂，Λ，C_N)，

And modulating and spreading the decision result output by the symbol decision device (430) to obtain a chip-level transmission signal estimation value on each active code channel:

wherein

Representing the chip-level transmit signal estimate on the nth active code channel.

33. The apparatus for canceling co-channel cell signal interference based on successive interference cancellation according to claim 31, wherein the number of said convolvers (460) is N, corresponding to N active code channels; the input ends of the N convolvers (460) are respectively connected with a channel impulse corresponding device (470);

the N convolvers (460) perform convolution operation on the chip sequence on each active code channel output by the modulation spreader (440) and the channel impulse response generated by the channel impulse response generator (470), so as to obtain a reconstructed signal on each active code channel:

wherein,representing the reconstructed signal on the nth code channel.

34. The apparatus for canceling and eliminating co-channel cell signal interference based on successive interference cancellation according to claim 31, wherein the active code channel signal superimposer (450) superimposes the reconstructed signal on each active code channel to complete the combination of the active code channels and the reconstruction of the cell signal, thereby obtaining the reconstructed signal of the cell

35. The apparatus for canceling co-channel cell signal interference based on successive interference cancellation according to claim 31, wherein the cell signal reconstructing apparatus further comprises a weight multiplier whose input terminal is connected to the output terminal of the active code channel signal superimposer (450);

the weight multiplier is used for reconstructing a cell reconstruction signal output by an active code channel signal adder (450)

Multiplication by a particular weighting factor p^s：

36. The apparatus according to claim 14, wherein the apparatus cancels the co-channel cell signal interference based on the serial interference cancellation order S set by the system and the residual signal after the interference is removed from each cell calculated by the previous serial interference cancellation order

And repeating the operation of eliminating the signal interference of the cells with the same frequency for each serial interference cancellation stage until the serial interference cancellation operation of all stages is completed.