WO2013075298A1 - Method and device for cancelling cell search interference - Google Patents

Method and device for cancelling cell search interference Download PDF

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Publication number
WO2013075298A1
WO2013075298A1 PCT/CN2011/082717 CN2011082717W WO2013075298A1 WO 2013075298 A1 WO2013075298 A1 WO 2013075298A1 CN 2011082717 W CN2011082717 W CN 2011082717W WO 2013075298 A1 WO2013075298 A1 WO 2013075298A1
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sss
interference cancellation
cell
interference
value
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PCT/CN2011/082717
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French (fr)
Chinese (zh)
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易立强
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中兴通讯股份有限公司
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Priority to PCT/CN2011/082717 priority Critical patent/WO2013075298A1/en
Publication of WO2013075298A1 publication Critical patent/WO2013075298A1/en

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    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04WWIRELESS COMMUNICATION NETWORKS
    • H04W48/00Access restriction; Network selection; Access point selection
    • H04W48/16Discovering, processing access restriction or access information

Abstract

Disclosed are a method and device for cancelling cell search interference. The method includes: when performing cell search, performing channel estimation interference cancellation based on a determined joint channel estimation value and an interference signal channel estimation value; after the channel estimation interference cancellation is completed, performing relevant value interference cancellation based on a relevant value, an interference signal relevant value and an interference factor of an SSS local code before interference cancellation. The present invention can solve the problem in the prior art that cell detection is affected by the interference of cells with relatively strong signals, thus improving the performance of weak cell search.

Description

 Method and device for cell search interference cancellation

 The present invention relates to the field of wireless communications, and more particularly to a method and apparatus for cell search interference cancellation. Background technique

 In a wireless communication system, a user equipment (UE) performs cell search immediately after being turned on, idle, and in an active state, and acquires more detailed information of a cell and a neighboring cell, so as to further monitor paging or initiate on the network. The call establishes a physical layer process such as a connection. For the cell search process of the third generation mobile communication Long Term Evolution (LTE) system based on Orthogonal Frequency Division Multiplexing (OFDM) technology, the UE not only needs time and frequency synchronization with the serving cell, It is also necessary to detect the cell identity and cell/system (cell or system) specific information of the physical layer of the serving cell and the like. In addition to the initial cell search, the UE also periodically searches for neighboring cells to prepare for cell reselection and handover.

In the face of complex multi-cell environments, cell search will be affected by interference. In the LTE, the cell search secondary synchronization signal (SSS, Second Synchronization signal) detection is usually used for coherent detection in order to obtain a better detection effect. In coherent detection, a primary synchronization signal (PSS, Primary Synchronization signal) is needed for channel estimation. Although the PSS sequence 歹1 J is three groups, there are still peripheral two-layer co-frequency neighbors d, and the same code group (ie, intra-group ID) is used for synchronization of Time Division Duplexing LTE (TDD-LTE). The system, especially for microcells, results in a small transmission delay that causes the estimation of the channel estimation by the PSS to largely include the interfering cell channel estimate, thereby degrading the detection performance of the detected cell.

In the 3GPP protocol, the SSS sequence adopts the M-sequence scrambling method, and its cross-correlation property is significantly worse than that of the M-sequence. The ratio of the maximum correlation interference peak of the cross-correlation to the true correlation peak is reached. 0.4839, In a multi-cell environment, cell detection with weak signal strength will be affected by the interference peak of the same signal strength cell with larger signal strength, especially in the same intra-group ID case.

 It can be seen that the traditional LTE cell search detection method has little consideration for the above interference, which will affect the detection performance of the cell search in a complex environment. Summary of the invention

 In view of this, the main object of the present invention is to provide a method and apparatus for cell search interference cancellation, which solves the problem that the cell detection is affected by the strong cell interference of the signal in the prior art, thereby improving the performance of the weak cell search.

 In order to achieve the above object, the technical solution of the present invention is achieved as follows:

 A method for cell search interference cancellation, comprising: performing channel estimation interference cancellation based on the determined joint channel estimation value and the interference cell channel estimation value when performing cell search; after the channel estimation interference cancellation is completed, determining the pre-interference cancellation SSS The correlation value of the local code, the interference signal correlation value, and the interference factor are used to eliminate the correlation value interference.

 The time domain PSS of the obtained target cell is subjected to FFT transformation and channel estimation to obtain the joint channel estimation value; and the acquired time domain SSS of the interference cell is subjected to FFT transformation and channel estimation to obtain the interference. Cell channel estimate.

 And performing channel estimation interference cancellation, specifically: performing cancellation processing on the joint channel estimation value and the interference cell channel estimation value to obtain channel estimation values after interference cancellation, and completing channel estimation interference cancellation.

 After the channel estimation interference cancellation is completed, and the correlation value interference cancellation is performed, the method further includes: performing FFT transformation on the acquired time domain SSS of the target cell to obtain a frequency domain SSS of the target cell; using the channel estimation value pair after the interference cancellation The frequency domain SSS of the target cell performs channel compensation to obtain the compensated SSS frequency domain value of the target cell; the SSS frequency domain value of the compensated target cell and the acquired multiple field SSS symbol frequency domain compensation value Perform coherent accumulation.

Determining a correlation value of the SSS local code before the interference cancellation, specifically: based on the coherent The added result is related to the SSS local code required for the acquired SSS detection, and the correlation value of the sss local code before the interference cancellation is obtained: ς The s (^ is sss

Figure imgf000004_0001

The k-th sub-carrier value of the required i-th SSS local code is detected, and the R() is the result of the coherent accumulation, and the number of valid sub-carriers.

Determining the interference signal correlation value, specifically: determining, according to the result of the coherent accumulation, the acquired SSS local code of the interfering cell, and the timing information of the target cell and the interfering cell, the correlation value of the interference signal is:

Figure imgf000004_0002
The kth subcarrier value of the SSS local code of the interfering cell, the / is the interfering cell ID group number, the R() is the result of the coherent accumulation, and the number of valid subcarriers, The N is the number of samples of the time domain symbol, and 6 is the number of timing deviation samples determined according to the timing information of the target cell and the interfering cell, and |i|<N/16; j represents a complex number.

 Determining the interference factor, specifically: the SSS local code required for the acquired SSS correlation process, the acquired SSS local code of the interfering cell, and the timing information of the target cell and the interfering cell,

 L-i *

Determining the interference factor is: Α =∑{^(^)} 'S person k .e w ;

 k=0

 The 5 (k) is the kth subcarrier value of the i-th SSS local code required for the SSS detection, the k-th sub-carrier value of the SSS local code of the interfering cell, and the valid sub-carrier The number is N, the number of samples of the time domain symbol, and 6 is the number of timing deviation samples determined according to the timing information of the target cell and the interfering cell, and |i|<N/16; j represents a complex number.

The method further includes: determining the i value corresponding to the interference strength in the SSS local code cross correlation, specifically: m 0 = m { / = 1, 2, 3, 4, 5, 6

^ ^The same value, Bay 1 J where or;

m, = ± / Q < i < min{ Q + 7,30} m, the same as the value, or;

< m 0 < m ]

Figure imgf000005_0001

Mm, / = 1,2,3 ,4,5,6 m n >0 m, the same as the value of n , then either;

m n =mi - I / = 7 l<mi <9 ^ The same value, Bay 1 J

Figure imgf000005_0002

Corresponding i value is determined according to ( Q , m x ); wherein / is the interfering cell ID group number, and ( , m ) is a parameter indication corresponding to the interfering cell ID group number.

 The correlation value interference cancellation is specifically: after multiplying the interference signal correlation value by the interference factor, and subtracting the correlation value of the SSS local code before the interference cancellation, and obtaining the sss local code after the interference cancellation The correlation values are: . =ς. -λ, Cj.

 After the correlation value interference cancellation is completed, the method further includes: performing energy calculation on the correlation value of the SSS local code after the interference cancellation, and obtaining correlation value energy; performing peak threshold calculation according to the correlation value energy, and based on The calculated peak threshold completes the peak search for the correlation value energy.

 A device for cell search interference cancellation, comprising:

 The interference cancellation module is configured to perform channel estimation interference cancellation according to the determined joint channel estimation value and the interference cell channel estimation value, and is further configured to: after the channel estimation interference cancellation is completed, determine a correlation value of the pre-SSS local code based on the determined interference cancellation, The interference signal correlation value and the interference factor are used to perform correlation value interference cancellation.

The interference cancellation module is further configured to: after obtaining the time domain PSS of the acquired target cell, performing FFT transformation and performing channel estimation to obtain a joint channel estimation value; and further, performing FFT transformation on the acquired time domain SSS of the interference cell, and And performing channel estimation to obtain an interference cell channel estimation value; and performing cancellation processing on the joint channel estimation value and the interference cell channel estimation value to obtain an interference cancellation channel estimation value. The device further includes: an SSS detection module, configured to: perform FFT transformation on the acquired time domain SSS of the target cell to obtain a frequency domain SSS of the target cell; and further use the channel estimation value after the interference cancellation determined by the interference cancellation module Performing channel compensation on the frequency domain SSS of the target cell to obtain the SSS frequency domain value of the compensated target cell; and using the compensated target cell SSS frequency domain value and the plurality of field SSS symbol frequency domain compensation values Perform coherent accumulation.

 The interference cancellation module is further configured to perform correlation processing on the SSS local code required for the SSS detection based on the result of the coherent accumulation of the SSS detection module, and obtain a correlation value of the SSS local code before the interference cancellation:

Figure imgf000006_0001

 The 5 (k) is the kth subcarrier value of the i-th SSS local code required for SSS detection, and the R(A) is the result of the coherent accumulation, and the number of valid subcarriers. The interference cancellation module is further configured to: based on the result of the coherent accumulation determined by the SSS detection module, the acquired SSS local code of the interfering cell, and the acquired timing of the target cell and the interfering cell

1 z_1 — kd information, determining that the interference signal correlation value is: C, =丄{5* )}* . R( )€ ;

 L k=Q

The k-th subcarrier value of the SSS local code of the interfering cell, the R( ) is the result of the coherent accumulation, the number of valid subcarriers, and the N is the number of samples of the time domain symbol, 6 is a timing deviation sample number determined according to timing information of the target cell and the interference cell, and

Figure imgf000006_0002

The interference cancellation module is further configured to determine, according to the acquired SSS local code, the acquired SSS local code of the interfering cell, and the acquired timing information of the target cell and the interfering cell, to determine that the interference factor is: S^k)} ' S person k . ew ; wherein 5 ( ) is the k-th sub-carrier value of the i-th SSS local code required for SSS correlation processing, and the first is the SSS local code of the interfering cell k subcarrier values, the number of valid subcarriers, the N is the number of samples of the time domain symbol, and 6 is based on the target cell and the number of The number of timing offset samples determined by the timing information of the scrambling cell, and |i | < N/16.

 The interference cancellation module is further configured to multiply the interference signal correlation value and the interference factor, and is further configured to subtract the correlation result of the multiplication and the correlation value of the SSS local code before the interference cancellation to obtain The correlation value of the sss local code after interference cancellation is: ζ. = ς. - λ, . Cj .

 The device further includes: a PSS detection module and a parameter measurement module; wherein:

 The PSS detection module is configured to acquire target cell information, and provide timing information of a target cell in a time domain PSS and a target cell to the interference cancellation module, and provide a time domain SSS of the target cell to the SSS detection module;

 The parameter measurement module is configured to acquire the interference cell information, and provide the time domain SSS of the interference cell and the timing information of the interference cell to the interference cancellation module.

 The SSS detection module is further configured to generate an SSS local code required for the SSS detection, and is further configured to generate an SSS local code of the interfering cell according to the interference cell information provided by the interference cancellation module, and is further configured to detect the SSS The required SSS local code and the SSS local code of the interfering cell are provided to the interference cancellation module.

 The SSS detection module is further configured to: perform energy calculation on a correlation value of the SSS local code obtained by the interference cancellation module, and obtain a correlation value energy; perform peak threshold calculation according to the correlation value energy, and The calculated peak threshold completes the peak search for the correlation value energy.

 The method and device for cell search interference cancellation according to the present invention perform channel estimation interference cancellation based on the determined joint channel estimation value and the interference cell channel estimation value when performing cell search, thus solving the small transmission delay and making the PSS channel The estimated estimated value largely includes the problem of interfering cell channel estimation values, and improves the detection performance of the detected cell (ie, the target cell);

At the same time, the application also considers the influence of SSS sequence (local code) cross-correlation on cell search, and adopts the means of correlation value interference elimination: After channel estimation interference cancellation is completed, based on the determined dry The correlation value of the SSS local code, the interference signal correlation value and the interference factor are eliminated before the interference is eliminated, and the correlation value interference cancellation is performed. DRAWINGS

 1 is a schematic flowchart of a method for cell search interference cancellation according to the present invention;

 2 is a schematic structural diagram of a cell search interference cancellation process according to the present invention;

 Figure 3 is a block diagram of channel estimation processing;

 Figure 4 is a schematic diagram of (^ j related interference term;

 FIG. 5 is a schematic diagram of a method for determining a SINR of a cell;

 FIG. 6 is a structural diagram of an apparatus for area search interference cancellation according to the present invention. Detailed ways

 The basic idea of the scheme for cell search interference cancellation provided by the present invention is: performing interference cancellation on cell search based on information of a target cell of a cell search and information of an interfering cell that generates interference to a target cell, including: channel estimation interference cancellation and correlation The value interference is eliminated to solve the problem that the cell detection is affected by the strong cell interference of the signal in the prior art, thereby improving the performance of the weak cell search.

 It should be noted that, in comparison with the prior art, the interfering cell involved in the solution of the present invention is an interfering cell with strong signal strength, and may be a serving cell or a co-frequency neighboring cell with strong signal.

 As shown in FIG. 1, the method for cell search interference cancellation includes:

 Step 101: Perform channel estimation interference cancellation based on the determined joint channel estimation value and the interference cell channel estimation value when performing cell search.

 Step 102: After the channel estimation interference cancellation is completed, the correlation value interference cancellation is performed based on the correlation value of the SSS local code before the interference cancellation, the interference signal correlation value, and the interference factor.

The channel estimation interference cancellation and correlation value interference cancellation will be described in detail below with reference to FIG. The process of channel estimation interference cancellation is as follows:

 Step 1: After the time domain PSS of the target cell is subjected to FFT transformation and channel estimation, the PSS frequency domain value of the target cell, that is, the joint channel estimation value is obtained;

 Step 2: The time domain SSS of the interfering cell is subjected to FFT transform and then channel estimation to obtain an SSS frequency domain value of the interfering cell, that is, an interference cell channel estimation value;

 Step 3: Decoupling the joint channel estimation value and the interference cell channel estimation value to obtain the channel estimation value after the interference cancellation, and the channel estimation interference cancellation is completed.

 As shown in FIG. 3, the channel estimation value may be a result of the cancellation of the joint channel estimation value and the interference cell channel estimation value, or may be the result of the denoising process after the two are cancelled. Denoising can be done using a DFT-based approach.

 The joint channel estimation value and the interference cell channel estimation value may be obtained by using a least squares (LS) method. Let ^ ( ) denote the joint channel estimation value of the kth subcarrier, denote the interfering cell channel estimation value of the kth subcarrier, 6 denote the number of the target cell and the interfering cell timing deviation sample, and may be based on the timing information of the target cell and the interfering cell Timing information is determined, then interference

 .2 , , The channel estimate of the kth subcarrier after cancellation is: ^( t) = ^( t) - ^( t).

 After the channel estimation interference cancellation is completed, the time domain SSS of the target cell is subjected to FFT transformation to obtain the frequency domain SSS of the target cell, and then the channel estimation value after the interference cancellation is used to perform channel compensation on the frequency domain SSS of the target cell, and the compensated target is obtained. The SSS frequency domain value of the cell; coherently accumulating the compensated SSS frequency domain value of the target cell and the plurality of field SSS symbol frequency domain compensation values, and then performing correlation value interference cancellation, the process is as follows:

 Step 1: Correlate the result based on the coherent accumulation with the SSS local code required for the SSS related processing, and obtain the correlation value of the SSS local code before the interference cancellation;

 Step 2: Calculate the interference signal correlation value based on the result of the coherent accumulation, the SSS local code of the interfering cell, and the timing information of the target cell and the interfering cell;

Step 3: SSS local code required for SSS related processing, SSS local of interfering cell The code and the timing information of the target cell and the interfering cell are calculated to obtain an interference factor; Step 4, multiplying the interference signal correlation value and the interference factor;

 Step 5: Subtract the correlation value of the SSS local code before the interference cancellation obtained in step 1 and the multiplication result in step 4 to obtain the correlation value of the SSS local code after the interference cancellation, and the correlation value interference cancellation is completed.

Specifically, the correlation value after interference cancellation can be obtained by the following formula: =∑{aux-k)-e N ;

 k=

Cj = T ∑{SAk)} - R{k) -e N ; );

Figure imgf000010_0001

ς = - i ■ c 1 .

 Wherein, the kth subcarrier value indicating the i-th SSS local code (required for SSS detection), the k-th subcarrier value indicating the SSS local code of the interfering cell, / is the interfering cell ID group number, and 4 is the i-th group The interference factor of the SSS local code (required for SSS detection); j indicates the complex number.

 R( ) represents the result of coherent accumulation of the SSS frequency domain value of the compensated target cell and the frequency compensation of the plurality of field SSS symbols, and is the interference signal correlation value;

 ς为干 ·ί尤 Eliminate the correlation value of the previous i-group sss local code (required for sss detection);

C. For the >1⁄2 elimination, the relevant values of the i-th SSS local code (required for SSS detection);

N represents the number of samples of the time domain symbol, indicating the number of valid subcarriers, and 6 is the number of timing offset samples of the target cell and the interfering cell. Generally, the interference cancellation limit |i | < N/16 ; 6 can be based on the timing of the target cell The information and the timing information of the interfering cell are determined.

Using the above calculation method, each group of SSS required for the SSS detection by the interfering cell needs to be used. The local code performs interference cancellation, and the calculation amount is relatively large. Preferably, only the interference strength in the SSS local code cross-correlation can be selected for interference cancellation, that is, the i value corresponding to the interference strength in the SSS local code cross-correlation can be further determined.

 In particular, the present invention provides a method of determining an ID group number interference strength in the case where the IDs in the interfering cell group are the same. The interference term can be divided into a timing in-phase interference term and a timing out-of-phase interference term, as shown in FIG. 4, where X represents the parameter indication ( , ) coordinate position corresponding to the interference cell ID group number, and the coordinate position in the dotted line frame represents the interference. The timing in-phase interference term caused by the cell ID group number, and the coordinate position in the solid line frame indicates the timing out-of-phase interference term caused by the interfering cell ID group number.

The method for determining the interference strength caused by the interference cell ID group number is as follows, where the parameter corresponding to the interference cell ID group number is indicated as

Figure imgf000011_0001
); where / is the interfering cell ID group number. Determine the timing and coherence 4 special items: If the value is the same as ^, then

m 0 + 7,30} If ^ is the same as the value, then

Figure imgf000011_0002

Mi ± / max{m 1 - 7, 0} < m 0 < m l Determine the timing out-of-phase interference term: If ^ is the same as the value, then

 0.

If. Same as the value, then

Figure imgf000011_0003

m, m! + 1 1 = 7 m( < 2 . Finally, according to the protocol, if the corresponding i value can be determined according to ( m 0 , m x ), the interference in the SSS local code cross correlation corresponding to the i value can be used. The strong term performs correlation value interference cancellation.

After the correlation value interference cancellation is completed, the energy value of the correlation value after the interference cancellation is obtained to obtain the correlation value energy; then, the peak threshold is calculated according to the correlation value energy, and the peak value is searched for the correlation value energy based on the peak threshold, and the SSS is further obtained. Detection results, such as cell frame timing, Cell ID, etc.

 In addition, it is important to accurately determine the interference cell in the interference cancellation, which directly affects the performance of the interference cancellation. Specifically, the following two methods can be used:

 1. Determine whether the cell satisfies the condition of the interfering cell according to the cell measurement information, such as RSRP and RSRQ;

 2. Determine whether the cell satisfies the interference cell condition by estimating the SINR of the cell and the measured RSRP value.

Assuming that the first subcarrier signal of the _/.th reference signal symbol of the received time slot of the subframe is R and the corresponding scrambling code is ς, the SINR calculation block diagram of the cell is as shown in FIG. 5, and the calculation method is as follows:

Figure imgf000012_0001

N t =— {c ; jk R ; jk ) - {c ; +ljk R ; +ljk ί - S;

^ jk 1

SINR = -

N t where N is the number of reference signals in the measurement bandwidth slot.

 The discriminating steps of the interfering cell are as follows:

 S1: Acquire parameter measurement values in the cell list: RSRP and SINR (or RSRQ);

S2: Determine whether the RSRP value of the cell is greater than a threshold and whether the measured value of the cell SINR (or RSRQ) is less than a threshold, and the cell that meets the two conditions enters the interference cell list, otherwise it is a non-interfering cell. The number of interfering cells can be limited to M, and the size of M is determined by the interference cancellation capability. When the number of interfering cells reaches M and there are new interfering cells, the RSRP of the interfering cell is compared. If the RSRP of the new interfering cell is larger than the RSRP of one or more interfering cells in the interfering cell list, the new one is used. The interfering cell replaces the interfering cell with the smallest RSRP in the interfering cell list. If the interfering cell does not exist, the cell in the interfering cell list is deleted. S3: Refresh the interference cell measurement value and re-enter S2.

 S4: When the number of interfering cells in the interfering cell list is not empty, the cell search interference cancellation operation is performed.

 In combination with the foregoing cancellation method, the present invention provides a device for cell search interference cancellation. As shown in FIG. 6, the method includes: an interference cancellation module, configured to perform channel estimation interference according to the determined joint channel estimation value and the interference cell channel estimation value. The method is further configured to: after the channel estimation interference cancellation is completed, perform correlation value interference cancellation based on the correlation value of the SSS local code before the interference cancellation, the interference signal correlation value, and the interference factor.

 When performing channel estimation interference cancellation:

 1. The interference cancellation module obtains the joint channel estimation value by performing FFT transformation and then performing channel estimation on the acquired time domain PSS of the target cell;

 2. The interference cancellation module obtains the estimated channel estimation value of the interfering cell by performing FFT transformation and then performing channel estimation on the acquired time domain SSS of the interfering cell;

 3. The interference cancellation module demodulates the joint channel estimation value and the interference cell channel estimation value to obtain the interference estimation channel estimation value, and completes the channel estimation interference cancellation.

 The apparatus further includes an SSS detection module, configured to: after the interference cancellation module completes the channel estimation interference cancellation, perform the correlation value interference cancellation, and obtain the frequency domain SSS of the target cell by performing FFT transformation on the acquired time domain SSS; The channel estimation value after the interference cancellation module determined by the interference cancellation module performs channel compensation on the frequency domain SSS of the target cell, and obtains the SSS frequency domain value of the compensated target cell; and the SSS frequency domain value of the compensated target cell and multiple The half frame SSS symbol frequency domain compensation value is coherently accumulated.

 When performing correlation value interference cancellation:

 1. The interference cancellation module performs correlation processing on the SSS local code required by the SSS detection module based on the coherent accumulation result determined by the SSS detection module, and obtains the correlation value of the SSS local code before the interference cancellation: ς = ^{5 R( ) ;

k=0 2. The interference cancellation module determines the interference signal correlation value based on the result of the coherent accumulation determined by the SSS detection module, the acquired SSS local code of the interfering cell, and the acquired timing information of the target cell and the interfering cell: c, =丄R( ) e ;

3. The interference cancellation module determines the interference factor based on the SSS local code required for the acquired SSS detection, the acquired SSS local code of the interfering cell, and the acquired timing information of the target cell and the interfering cell: =∑{ ( )} - S ^ - e N ;

 k=0

 Where (k) is the kth subcarrier value of the i-th SSS local code required for SSS detection, the kth subcarrier value of the SSS local code of the interfering cell, and R() is the result of coherent accumulation, and is valid. The number of subcarriers, N is the number of samples of the time domain symbol, and 6 is the number of timing offset samples determined according to the timing information of the target cell and the interfering cell, and |i | < N/16.

 4. The interference cancellation module multiplies the interference signal correlation value and the interference factor;

 5. The interference cancellation module subtracts the correlation value of the SSS local code before the interference cancellation and the multiplied result, and obtains the correlation value of the sss local code after the interference cancellation: ζ. = ς - . c, .

 After the correlation value interference is eliminated, the SSS detection module is further configured to perform energy calculation on the correlation value of the SSS local code after the interference cancellation module obtains the interference, and obtain the correlation value energy; calculate the peak threshold according to the correlation value energy, and calculate based on the correlation value The resulting peak threshold completes the peak search for the correlation value energy.

 It should be noted that the interference cancellation module needs to be started simultaneously with the SSS detection module, and receives part of the bandwidth signal occupied by the synchronization signal output by the synchronization signal filter, and performs corresponding processing.

 In addition, the device further includes a PSS detection module and a parameter measurement module;

a PSS detection module, configured to acquire target cell information, and provide time domain PSS of the target cell and timing information of the target cell to the interference cancellation module; and provide a time domain SSS of the target cell to the SSS detection module; a module, configured to acquire interference cell information, and The time domain SSS of the interfering cell and the timing information of the interfering cell are provided to the interference cancellation module.

 Specifically, as shown in FIG. 6, the signal transmitted by the base station is received by the antenna and converted into a baseband signal by the down converter; then, the synchronization signal filter and the reference signal filter respectively process the baseband signal: Synchronous signal filter , used to process the baseband signal output by the down converter to obtain a part of the bandwidth signal occupied by the synchronization signal; the reference signal filter is used to process the baseband signal output by the down converter to obtain an interference cell (such as a serving cell) Part of the bandwidth signal occupied by the reference signal.

 The PSS detection module processes part of the bandwidth signal occupied by the synchronization signal output by the synchronization signal filter, and acquires target cell information, such as timing information, PSS symbol timing position, and intra-group ID information; and further, according to the PSS symbol of the target cell. The timing location may acquire the time domain PSS of the target cell and the SSS symbol timing location of the target cell; the time domain SSS of the target cell may be acquired according to the SSS symbol timing location of the target cell.

 The parameter measurement module performs calculation of cell measurement information (such as RSRP and RSRQ) according to a part of the bandwidth signal occupied by the reference signal of the interference cell output by the reference signal filter, and determines the interference cell information according to the SINR and the calculated cell measurement information ( Including the interfering cell timing information, and the interfering cell ID); further, determining the interfering cell SSS symbol timing position according to the timing information of the interfering cell, so that the time domain SSS of the interfering cell can be acquired.

 The SSS detection module is further configured to generate an SSS local code required for the SSS detection, and is further configured to generate an SSS local code of the interfering cell according to the interference cell information provided by the interference cancellation module (the interference cancellation module provides the interference cell information provided by the parameter measurement module) For SSS detection module reference, generate the SSS local code of the corresponding interfering cell); also used to provide the SSS local code required for SSS detection and the SSS local code of the interfering cell to the interference cancellation module (for correlation value interference cancellation).

 The above is only the preferred embodiment of the present invention and is not intended to limit the scope of the present invention.

Claims

Claim
 A cell search interference cancellation method, the method comprising: performing channel estimation interference cancellation based on the determined joint channel estimation value and the interference cell channel estimation value when performing cell search;
 After the channel estimation interference cancellation is completed, the correlation value interference cancellation is performed based on the correlation value of the SSS local code before the interference cancellation, the interference signal correlation value, and the interference factor.
 The cell search interference cancellation method according to claim 1, wherein the acquired time domain PSS of the target cell is subjected to FFT transform and then channel estimation is performed to obtain the joint channel estimation value;
 The time domain SSS of the acquired interfering cell is subjected to FFT transform and channel estimation is performed to obtain the interference cell channel estimation value.
 The cell search interference cancellation method according to claim 2, wherein the performing channel estimation interference cancellation is specifically:
 Decomposing the joint channel estimation value and the interfering cell channel estimation value to obtain an interference canceled channel estimation value, and completing channel estimation interference cancellation.
 The method for cell-based interference cancellation according to claim 3, wherein after the channel estimation interference cancellation is completed and the correlation value interference cancellation is performed, the method further includes:
 Observing the frequency domain SSS of the target cell by performing FFT transformation on the acquired time domain SSS of the target cell; performing channel compensation on the frequency domain SSS of the target cell by using the channel estimation value after the interference cancellation, to obtain the compensated target cell SSS frequency domain value;
 The SSS frequency domain value of the compensated target cell and the acquired plurality of field SSS symbol frequency domain compensation values are coherently accumulated.
The cell search interference cancellation method according to claim 4, wherein determining the correlation value of the SSS local code before the interference cancellation is specifically: based on the result of the coherent accumulation and the acquired SSS detection required Correlated processing is performed on the SSS local code to obtain the interference cancellation The relevant value of the SSS local code is: ς· =^{Ξ^)}* -R(k);
 k=0
 The 5 (k) is the kth subcarrier value of the i-th SSS local code required for SSS detection, and the R() is the result of the coherent accumulation, and the number of valid subcarriers.
The cell search interference cancellation method according to claim 4, wherein the determining the interference signal correlation value is specifically: based on the result of the coherent accumulation, the acquired SSS local code of the interfering cell, and the target cell and Interfering with the timing information of the cell, determining that the interference signal correlation value is:
Figure imgf000017_0001
 The kth subcarrier value of the SSS local code of the interfering cell, the / is the interfering cell ID group number, the R() is the result of the coherent accumulation, and the number of valid subcarriers is N is the number of samples of the time domain symbol, and 6 is the number of timing deviation samples determined according to the timing information of the target cell and the interfering cell, and |i |<N/16; j denotes a complex number.
The cell search interference cancellation method according to claim 4, wherein the determining the interference factor is specifically: an SSS local code required for the acquired SSS correlation process, an acquired SSS local code of the interfering cell, and The timing information of the target cell and the interfering cell determines that the interference factor is: =∑{aux-j(k)-e N ; wherein the 5 (k) is the i-th SSS local code required for SSS detection The kth subcarrier value, the kth subcarrier value of the SSS local code of the interfering cell, the number of valid subcarriers, the N is the number of samples of the time domain symbol, and 6 is according to the target cell and interference The number of timing deviation samples determined by the timing information of the cell, and |i | <N/16; j represents a complex number.
8. A method for cell search interference cancellation according to claim 5 or 7, characterized in that The method further includes: determining the i value corresponding to the interference strength item in the SSS local code cross correlation, specifically: ^ ^ value is the same, B 1 J or;
Q + 7,30} m, the same value, then
Figure imgf000018_0001
or;
m Q J ±l max{m 1 — 7,0} < . < m ] m,
m, the same as the value of n , or;
m 0 m 0
^ The same value, Bay 1 J
m,
Figure imgf000018_0002
1 = 1 m'<2 Determine the corresponding i value according to ( m 0 , m 1 );
 Where / is the interfering cell ID group number, and ( i, ) is the parameter indication corresponding to the interfering cell ID group number.
 The cell search interference cancellation method according to claim 5, 6 or 7, wherein the correlation value interference cancellation is specifically: multiplying the interference signal correlation value by the interference factor, and then The correlation value of the SSS local code before the interference cancellation is subtracted, and the correlation value of the SSS local code after the interference cancellation is obtained: ζ. = C. Cj.
The method for the cell search interference cancellation according to claim 9, wherein after the completion of the correlation value interference cancellation, the method further comprises:
 Performing energy calculation on the correlation value of the SSS local code after the interference cancellation, obtaining correlation value energy; performing peak threshold calculation according to the correlation value energy, and performing peak search on the correlation value energy based on the calculated peak threshold .
 11. A device for cell search interference cancellation, comprising:
An interference cancellation module, configured to perform channel estimation interference cancellation according to the determined joint channel estimation value and the interference cell channel estimation value; and further, after the channel estimation interference cancellation is completed, based on The correlation value of the SSS local code before the interference is eliminated, the interference signal correlation value and the interference factor are eliminated, and the correlation value interference cancellation is performed.
 12. The apparatus for cell-based interference cancellation according to claim 11, wherein the interference cancellation module is further configured to perform FFT transformation on the acquired time domain PSS of the target cell, and then perform channel estimation to obtain joint channel estimation. The value is also used to perform FFT transformation on the acquired time domain SSS of the interfering cell, and then perform channel estimation to obtain an interference cell channel estimation value; and is further used for decoupling the joint channel estimation value and the interference cell channel estimation value. The channel estimation value after interference cancellation is obtained.
 The apparatus for performing cell search interference cancellation according to claim 12, further comprising: an SSS detecting module, configured to perform FFT transform on the acquired time domain SSS of the target cell to obtain a frequency domain SSS of the target cell; And performing channel compensation on the frequency domain SSS of the target cell by using the channel estimation value after the interference cancellation determined by the interference cancellation module, to obtain a SSS frequency domain value of the compensated target cell; and using the compensated The SSS frequency domain value of the target cell and the plurality of field SSS symbol frequency domain compensation values are coherently accumulated.
 The apparatus for performing cell search interference cancellation according to claim 13, wherein the interference cancellation module is further configured to perform, according to a result of coherent accumulation of the SSS detection module and an SSS local code required for the acquired SSS detection. Correlation processing, the correlation value of the SSS local code before the interference cancellation is obtained: ς = ;
Figure imgf000019_0001
 The 5 (k) is the kth subcarrier value of the i-th SSS local code required for SSS detection, and the R() is the result of the coherent accumulation, and the number of valid subcarriers.
The apparatus for performing cell search interference cancellation according to claim 13, wherein the interference cancellation module is further configured to: based on a result of the coherent accumulation determined by the SSS detection module, the acquired SSS local code of the interfering cell Obtaining timing information of the target cell and the interfering cell, determining that the interference signal correlation value is: 1
Cj = T ∑{SAk)} - R{k) -e N ; the kth subcarrier value of the SSS local code of the interfering cell, the R() being the result of the coherent accumulation, the being valid Number of subcarriers, where N is the number of samples of the time domain symbol, and 6 is the number of timing offset samples determined according to the timing information of the target cell and the interfering cell, and
Figure imgf000020_0001
The apparatus for performing cell search interference cancellation according to claim 13, wherein the interference cancellation module is further configured to: detect, according to the acquired SSS, a required SSS local code, an acquired SSS local code of the interfering cell, and acquire The timing information of the target cell and the interfering cell determines that the interference factor is: =∑{aux-S k) - e N ; wherein the 5 (k) is the i-th SSS local code required for SSS related processing The kth subcarrier value, the kth subcarrier value of the SSS local code of the interfering cell, the number of valid subcarriers, the N is the number of samples of the time domain symbol, and 6 is according to the target cell and The number of timing offset samples determined by the timing information of the interfering cell, and |i | < N/16.
 17. Apparatus for cell search interference cancellation according to claim 14, 15 or 16, characterized in that
 The interference cancellation module is further configured to multiply the interference signal correlation value and the interference factor, and is further configured to subtract the correlation result of the multiplication and the correlation value of the SSS local code before the interference cancellation to obtain The correlation value of the sss local code after interference cancellation is: ζ. = ς. - λ, . Cj.
 18. The apparatus for cell search interference cancellation according to claim 14, 15 or 16, wherein the apparatus further comprises: a PSS detection module and a parameter measurement module; wherein:
The PSS detection module is configured to acquire target cell information, and provide time domain PSS of the target cell and timing information of the target cell to the interference cancellation module; a time domain SSS of the cell is provided to the SSS detection module;
 The parameter measurement module is configured to acquire the interference cell information, and provide the time domain SSS of the interference cell and the timing information of the interference cell to the interference cancellation module.
 The apparatus for detecting interference cancellation of a cell according to claim 18, wherein the SSS detection module is further configured to generate an SSS local code required for SSS detection, and is further configured to perform interference according to the interference cancellation module. The cell information is used to generate an SSS local code of the interfering cell, and is further configured to provide the SSS local code required by the SSS detection and the SSS local code of the interfering cell to the interference cancellation module.
 The apparatus for performing cell search interference cancellation according to claim 17, wherein the SSS detecting module is further configured to perform energy calculation on a correlation value of the SSS local code after the interference cancellation obtained by the interference cancellation module, Obtaining a correlation value energy; performing a peak threshold calculation according to the correlation value energy, and performing a peak search on the correlation value energy based on the calculated peak threshold.
PCT/CN2011/082717 2011-11-23 2011-11-23 Method and device for cancelling cell search interference WO2013075298A1 (en)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1343406A (en) * 1999-03-17 2002-04-03 艾利森公司 Synchronization and cell search method and apparatus for wireless communications
CN101969657A (en) * 2010-10-26 2011-02-09 东南大学 Same-frequency cell detection method of FDD-LTE system
CN102223696A (en) * 2011-06-17 2011-10-19 电子科技大学 Cell searching method in LTE (long term evolution) system

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1343406A (en) * 1999-03-17 2002-04-03 艾利森公司 Synchronization and cell search method and apparatus for wireless communications
CN101969657A (en) * 2010-10-26 2011-02-09 东南大学 Same-frequency cell detection method of FDD-LTE system
CN102223696A (en) * 2011-06-17 2011-10-19 电子科技大学 Cell searching method in LTE (long term evolution) system

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