CN106603189B - Cell searching interference elimination method in a kind of LTE system - Google Patents

Cell searching interference elimination method in a kind of LTE system Download PDF

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Publication number
CN106603189B
CN106603189B CN201611078252.1A CN201611078252A CN106603189B CN 106603189 B CN106603189 B CN 106603189B CN 201611078252 A CN201611078252 A CN 201611078252A CN 106603189 B CN106603189 B CN 106603189B
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pss
sss
signal
correlation
correlation peak
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CN201611078252.1A
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CN106603189A (en
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张红飞
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广州慧睿思通信息科技有限公司
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    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04JMULTIPLEX COMMUNICATION
    • H04J11/00Orthogonal multiplex systems, e.g. using WALSH codes
    • H04J11/0069Cell search, i.e. determining cell identity [cell-ID]
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04JMULTIPLEX COMMUNICATION
    • H04J11/00Orthogonal multiplex systems, e.g. using WALSH codes
    • H04J11/0069Cell search, i.e. determining cell identity [cell-ID]
    • H04J11/0073Acquisition of primary synchronisation channel, e.g. detection of cell-ID within cell-ID group
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04WWIRELESS COMMUNICATION NETWORKS
    • H04W56/00Synchronisation arrangements

Abstract

The invention discloses cell searching interference elimination methods in a kind of LTE system, three groups of local PSS sequences first carry out related operation with reception signal respectively, obtain three groups of PSS correlations, it is searched in PSS correlation by the first thresholding by the former PSS correlation peak of relationship ranking from big to small for every group of PSS correlation, saves mark in these PSS correlation peak locations and cell ID group;Since maximum PSS correlation peak location, for each PSS correlation peak location, SSS coherent detection is carried out to signal is received, SSS correlation peak successively detected according to descending order by the second thresholding, after each coherent detection, SSS signal reconstruction at maximum SSS correlation peak is come out, is cut with being received in signal from corresponding position, realizes that SSS interference is eliminated.The present invention can simultaneously scan for relatively strong and weaker cell, improve UE down-going synchronous performance and handover switching performance, improve user experience.

Description

Cell searching interference elimination method in a kind of LTE system

Technical field

The present invention relates to LTE (Long Term Evolution, long term evolution project) systems technology fields, in particular to Cell searching interference elimination method in a kind of LTE system.

Background technique

LTE is known as 3.9G by popular, and the data download capabilities with 100Mbps are considered the master from 3G to 4G evolution Flow Technique.It improves and enhances the aerial access technology of 3G, using OFDM and MIMO as the unique of its wireless network evolution Standard.If UE (equipment) in LTE system will be communicated by LTE cellular network, need to carry out cell searching to detect To the physical-layer cell identifier of cell.Due to each cell and a pair of of primary synchronization signal (PSS) and auxiliary synchronous signal (SSS) phase It is mutually corresponding, therefore during cell searching, UE can be detected the physical-layer cell identifier of cell (i.e. by detecting PSS and SSS Cell ID).Detection physical-layer cell identifier is related to obtaining cell ID group mark from by the SSS sequence of base station broadcastAnd cell ID group mark has been obtained from by the PSS sequence of base station broadcastCell ID group Interior markFrom PSS Sequence Detection to cell ID group in markLater from SSS sequence Detect cell ID group markDetecting cell ID group markWith mark in cell ID groupLater, can make WithRelationship determine physical-layer cell identifier, wherein NIDIt is physical-layer cell identifier, That is cell ID, because there are 168 unique Cell ID groups to identify in each groupWith mark in three unique Cell ID groupsSo there is 504 unique physical layer identifications in total in LTE cellular network.

In complete cell search process, it usually needs successively determine multiple candidate cells, be first detected Cell is usually the strongest cell of signal, if the signal in this group of mean people area is not eliminated, will generate shadow to the detection of subsequent cell It rings, for this purpose, in actual application, often taking measures to carry out interference elimination after determining a cell every time, then again Carry out the detection of next cell.

The PSS that Reconstruction Method eliminates the cell being searched is generallyd use in the prior art, to realize cell searching mistake Interference in journey is eliminated;Since there are identical networkings for LTE network, there can be the co-channel interference between neighboring community.Due to Only there are three PSS for whole network, therefore adjacent two cell may use the same PSS, then use the two of the same PSS When the downlink synchronous signal of cell reaches UE simultaneously substantially, the PSS for using Reconstruction Method carrying out that elimination is interfered to will lead to two cells is same When be eliminated, so as to cause that can only search relatively stronger cell, and relatively weak cell cannot be searched, therefore PSS detection-phase carries out interfering the cell for eliminating and will lead to and searching under certain scenes incomplete using Reconstruction Method.For relatively Weak cell carries out PSS interference using Reconstruction Method and eliminates and can cause PSS cannot be by greatest extent because channel estimation value is inaccurate Elimination, while can also introduce biggish interference, cause weaker cell that cannot be detected.

Since SSS has 504, neighboring community can not use same cell ID (mark), therefore neighboring community is used SSS be different, along with the scrambling code that adjacent two cell using the same PSS is used when generating SSS is identical, therefore phase Interference between adjacent two cells can become by force, eliminate to be not enough to eliminate to greatest extent using the progress SSS interference of zero setting method merely and work as Interference under preceding scene between two cells.

Summary of the invention

The purpose of the present invention is to overcome the shortcomings of the existing technology with it is insufficient, it is dry to provide cell searching in a kind of LTE system The method for disturbing elimination, this method is directed to be reached simultaneously using the downlink synchronous signal of the homogeneous frequency adjacent area of the same PSS signal The case where UE, both may search for the relatively stronger cell of signal, and also may search for the relatively weak cell of signal, overcome small The infull technical problem of area searching, can be improved the performance of UE down-going synchronous and the performance of handover, to improve user's body It tests.

The purpose of the invention is achieved by the following technical solution: cell searching interference elimination method in a kind of LTE system, Steps are as follows:

S1, reception signal is obtained;

S2, three groups of local PSS sequences are gone into time domain from frequency domain respectively, are then carried out respectively with reception signal in step S1 Three groups of PSS correlations are obtained after related operation;

S3, be directed to each group of PSS correlation, by the first thresholding by PSS correlation by relationship ranking from big to small It searches out to come in former PSS correlation peaks, be arrived until searching for less than the PSS correlation peak or current search for crossing the first thresholding PSS correlation peak reaches certain number X, then terminates to search for, and saves each PSS relevant peaks searched above by the first thresholding It is worth mark in position and cell ID group;

S4, for each PSS correlation peak location got in each group of PSS correlation in step S3, from maximum PSS correlation peak location starts, with the sequence of PSS correlation peak from big to small, for each PSS correlation peak location, into The following operation of row:

S41, first according to current PSS correlation peak location, carry out SSS coherent detection to signal is received, obtain SSS correlation Value, then searched for the SSS correlation peak of the second thresholding, and therefrom get a maximum SSS phase by the second thresholding Close peak value;Enter step S42;

S42, SSS interference are eliminated: the corresponding SSS signal reconstruction of maximum SSS correlation peak being come out, then will be reconstructed The SSS signal come is cut from the reception signal of corresponding position, obtains the signal after interference is eliminated;Subsequently into step S43;

S43, according to current PSS correlation peak location, the reception signal after eliminating for step S42 interference carries out SSS again Coherent detection obtains SSS correlation, and the SSS correlation peak of the second thresholding was then searched for by the second thresholding, is judged whether there is Cross the SSS correlation peak of the second thresholding;

If so, selecting a maximum SSS correlation peak from the SSS correlation peak for crossing the second thresholding;Then sentence Whether the number for the maximum SSS correlation peak that open close the second thresholding of mistake has been chosen in total reaches certain number Y, if it is not, S42 is then entered step, if so, entering step S44;

If it is not, then entering step S44;

Under S44, current PSS correlation peak location, SSS interference, which is eliminated, to be completed, for next PSS correlation peak location, Back to step S41.

Preferably, three groups of local PSS sequences from frequency domain go to time domain respectively specific step is as follows in the step S2:

S21, the interior mark of cell ID group according to PSS sequenceValue 0,1 and 2, get three groups of local frequency domains PSS sequence, wherein the length of local frequency domain PSS sequence is 62;

S22, every group of local frequency domain PSS sequence is both mapped on each 31 subcarriers in direct current subcarrier front and back;

S23, for the every group of signal got in step S22,33 are supplemented before local frequency domain PSS sequence subcarrier Zero, 32 zero are supplemented later, are removed 128 point, inverse fast Fourier transforms of progress after frequency processing, are finally obtained three groups of local time domains PSS sequence.

Preferably, each group PSS correlation is got by following steps in the step S2:

S24, starting point P0 is got in receiving signal, 256 sampled points is then taken since starting point P0, then to it The FFT transform for doing at 256 points obtains the first frequency-region signal;Wherein receiving the first starting point P0 got in signal is reception First sampled point of signal.

S25,128 sampled points are taken from one group of local time domain PSS sequence, zero padding to 256 sampled points is simultaneously 256 points of FFT Transformation, obtains the second frequency-region signal;

S26, the first frequency-region signal and the second frequency-region signal conjugate multiplication are obtained into third signal, then by third signal into The IFFT that 256 points of row obtains time-domain signal;

Preceding 128 sampled point of S27, the time-domain signal for taking step S26 to get, as one group of local time domain PSS sequence with It receives signal and slides the correlation after 128 related operations;

S28, judge whether carry out related calculation to obtain correlation at reception signal ending, if so, this group of related operation knot Beam;If it is not, returning to step S24 after starting point P0 is then added 128 sampled points.

Preferably, each group of PSS correlation is directed in step S3, by the first thresholding by PSS correlation according to from big It is come out to small relationship ranking in former PSS correlation peaks with sequential search from big to small, detailed process is as follows:

S31, it is directed to each group of PSS correlation, sets the first thresholding first;

S32, the PSS correlation peak that the first thresholding was searched for by the first thresholding, judged whether there is the PSS of the first thresholding Correlation peak;

If so, selecting a maximum PSS correlation peak from the PSS correlation peak for crossing the first thresholding, then sentence Whether the number of the disconnected current maximum PSS correlation peak chosen in total by the first thresholding reaches certain number X, if It is then to enter step S34;If it is not, then entering step S33;

If it is not, then entering step S34;

S33, by each several positions of the maximum PSS correlation peak location got in step S32 and its adjacent front and back The correlation zero setting set;It is then return to step S32;

S34, the search by the first thresholding for PSS correlation peak terminate.

Further, it is 5 that the threshold value of first thresholding, which is 9000, X value,.

Preferably, the process of SSS coherent detection is carried out such as according to current PSS correlation peak location in step S41 and S43 Under:

S411, using current PSS correlation peak location as PSS timing position, in conjunction with the various relative positions of PSS and SSS Relationship determines each timing position of SSS;

S412,128 point SSS time-domain signals are taken respectively in each timing position of SSS, then by 128 point SSS time-domain signals 128 FFT transform are carried out, 128 sampled point frequency-region signals are obtained;

The corresponding data of label 65 in S413,128 sampled point frequency domain sequences are direct current subcarrier, before direct current subcarrier 31 frequency domain sequences are respectively extracted afterwards, and the frequency domain sequence of 62 points of composition is SSS frequency-region signal;

S414, the generating mode according to SSS are gradually descrambled and are carried out related calculation using the correlation of m-sequence, obtain SSS Correlation peak, and therefrom get SSS maximum correlation peaks;

S415, according to SSS maximum correlation peaks, carry out duplex mode, CP type, cell ID group and identify and front and back field Judgement, is so far obtained with cell ID and frame timing.

Further, the relative positional relationship of PSS and SSS includes four kinds, wherein TDD (time division duplex) and Normal Under CP (general cyclic prefix) relative positional relationship, the relative position PSS and SSS is 412 sampled points;TDD and Extended CP Under (extended cyclic prefix) relative positional relationship, the relative position PSS and SSS is 480 sampled points;FDD (frequency division duplex) and Under Normal CP relative positional relationship, the relative position PSS and SSS is 137 sampled points;FDD and Extended CP is with respect to position It sets under relationship, is 160 under PSS and SSS relative positional relationship.

Further, the corresponding SSS signal reconstruction of SSS maximum correlation peaks is come out in the step S42 specific Process is as follows:

S421, according in step S415 determine cell ID and frame timing, generate SSS frequency-region signal;

S422, the corresponding SSS signal of SSS maximum correlation peaks is extracted from reception signal;

S423, minimum is carried out for the SSS signal obtained in the SSS frequency-region signal and step S422 generated in step S421 Two multiply channel estimation, and carry out time domain noise reduction processing to channel estimation value sequence;

S444, the time domain noise reduction for getting step S423 treated channel estimation value sequence are multiplied by step S421 SSS frequency-region signal, obtained sequence are the SSS frequency-region signal for reconstructing and;

S445, the step S444 SSS frequency-region signal reconstructed is gone in time domain, and adds prefix, that is, reconstructed Whole SSS time-domain signal.

Preferably, the threshold value of the second thresholding is 200 in the step S4;Y is 2.

Preferably, the reception signal obtained in the step S1 be filtering and it is down-sampled treated receive signal.

The present invention has the following advantages and effects with respect to the prior art:

(1) the method for the present invention uses three groups of local PSS sequences to carry out related operation with reception signal respectively first, to obtain Get three groups of PSS correlations, for each group of PSS correlation, and by the first thresholding search for PSS correlation in by from greatly to Small relationship ranking saves mark in these PSS correlation peak locations and cell ID group in former PSS correlation peaks;It connects Get off for these PSS correlation peak locations saved, since the position of maximum PSS correlation peak, for each PSS Correlation peak location carries out SSS coherent detection to signal is received in position corresponding with PSS correlation peak location, passes through the The search of two thresholdings successively detected SSS correlation peak according to sequence from big to small, and every time after SSS coherent detection, SSS signal reconstruction at SSS correlation peak is come out, reception signal of the next SSS signal from corresponding position then will be reconstructed In cut, realize SSS interference eliminate.It can be seen that for small using the homogeneous frequency adjacent of the same PSS signal in LTE system The case where downlink synchronous signal in area reaches UE simultaneously, by the method for the invention in cell searching, both may search for same frequency The strong cell of signal in neighboring community also may search for the cell that signal is weak into homogeneous frequency adjacent area, therefore the method for the present invention Ensure the complete of cell searching, effectively preventing eliminating using Reconstruction Method progress PSS interference in the prior art causes to search Rope to the relatively stronger cell of signal, and the relatively weak cell of signal cannot be searched to the phenomenon that.It greatly improves under UE The performance of row synchronous performance and handover, to improve user experience.And use Reconstruction Method by SSS in the method for the present invention It is eliminated, can be eliminated to greatest extent under current scene using the interference between adjacent two cell of the same PSS.

(2) the method for the present invention by the first thresholding by PSS correlation by relationship ranking from big to small in former PSS When correlation peak searches out next, wherein these PSS correlation peaks are successively searched with sequence from big to small, are being searched for every time When, a maximum PSS correlation peak in the PSS correlation peak of thresholding was chosen, and get the PSS correlation peak position It sets, the correlation of each several positions of the PSS correlation peak location and its adjacent front and back is then subjected to zero setting;Due to searching for every time When, current maximum PSS correlation peak is set to zero, therefore when searching for next time, the PSS correlation peak searched will be second to this Maximum PSS correlation peak, therefore the present invention effectively eliminates PSS strong correlation peak to the weak relevant peaks of PSS by way of zero setting Interference, achieve the purpose that interference is eliminated, the interference of PSS can be eliminated to greatest extent, determine potential effective relevant peaks It is worth mark in position and cell ID group, effectively reduces the complexity that PSS interference is eliminated, improves the efficiency that PSS interference is eliminated. And the present invention is in zeroing process, before and after current maximum PSS correlation peak the correlation of adjacent each several positions also by It is set to zero, therefore the method for the present invention can avoid current maximum PSS correlation peak front-rear position correlation to next time simultaneously The interference that PSS correlation peak generates when searching for, eliminates interference of the PSS strong correlation peak to the weak relevant peaks of PSS to greatest extent.This Inventive method effectively prevents in the prior art for relatively weak cell, and carrying out that PSS interference eliminates using Reconstruction Method can be because It is inaccurate for channel estimation value, cause PSS that cannot be eliminated to greatest extent, while can also introduce biggish interference, causes weaker Cell the technical issues of cannot being detected.

(3) signal is received in the method for the present invention to be first filtered and drop before carrying out related operation with local PSS sequence Sampling processing, wherein the performance of cell searching is improved, by down-sampled by filtering out the signal other than PSS and SSS bandwidth The calculation amount of related operation is reduced, cell searching efficiency is improved.

Detailed description of the invention

Fig. 1 is the method for the present invention flow chart.

Specific embodiment

Present invention will now be described in further detail with reference to the embodiments and the accompanying drawings, but embodiments of the present invention are unlimited In this.

Embodiment

Present embodiment discloses cell searching interference elimination methods in a kind of LTE system, as shown in Figure 1, steps are as follows:

S1, reception signal is obtained;The reception signal obtained in the present embodiment be filtering and it is down-sampled treated receive letter Number, wherein being 30.72MHz, pass band width 472.5KHz, resistance to the sample rate for receiving the filter that signal is filtered Band initial frequency is 547.5KHz, attenuation outside a channel 20dB, passband fluctuation 0.1dB;It is used when down-sampled processing in step S1 Be 16 times.

S2, three groups of local PSS sequences are gone into time domain from frequency domain respectively, are then carried out respectively with reception signal in step S1 Three groups of PSS correlations are obtained after related operation.

Three groups of local PSS sequences from frequency domain go to time domain respectively specific step is as follows in this step S2:

S21, the interior mark of cell ID group according to PSS sequenceValue 0,1 and 2, get three groups of local frequency domains PSS sequence, wherein the length of local frequency domain PSS sequence is 62;

S22, every group of local frequency domain PSS sequence is both mapped on each 31 subcarriers in direct current subcarrier front and back;

S23, for the every group of signal got in step S22,33 are supplemented before local frequency domain PSS sequence subcarrier Zero, 32 zero are supplemented later, are removed progress 128 point IFFT transformation (fast Fourier inverse transformation) after frequency processing, are finally obtained three The local time domain PSS sequence of group.

Each group PSS correlation is got by following steps in this step:

S24, starting point P0 is got in receiving signal, 256 sampled points is then taken since starting point P0, then to it The FFT transform (Fast Fourier Transform) for doing at 256 points, obtains the first frequency-region signal S1;Wherein receive the got in signal One starting point P0 is the first sampled point for receiving signal.

S25,128 sampled points are taken from one group of local time domain PSS sequence, zero padding to 256 sampled points is simultaneously 256 points of FFT Transformation, obtains the second frequency-region signal S2;

S26, the first frequency-region signal S1 and the second frequency-region signal S2 conjugate multiplication are obtained into third signal S3, then by third The IFFT that signal S3 carries out at 256 points obtains time-domain signal S4;

S27, preceding 128 sampled point for taking time-domain signal S4, as one group of local time domain PSS sequence and reception signal sliding Correlation after 128 related operations;

S28, judge whether carry out related calculation to obtain correlation at reception signal ending, if so, this group of related operation knot Beam;If it is not, returning to step S24 after starting point P0 is then added 128 sampled points.

S3, be directed to each group of PSS correlation, by the first thresholding by PSS correlation by relationship ranking from big to small It searches out to come in former PSS correlation peaks, be arrived until searching for less than the PSS correlation peak or current search for crossing the first thresholding PSS correlation peak reaches certain number X, then terminates to search for, and saves each PSS relevant peaks searched above by the first thresholding It is worth mark in position and cell ID group;It is 5 that the threshold value of the first thresholding, which is 9000, X value, in the present embodiment.

In step S3 be directed to each group of PSS correlation, by the first thresholding by PSS correlation according to pass from big to small It is that ranking is come out in former PSS correlation peaks with sequential search from big to small, detailed process is as follows:

S31, it is directed to each group of PSS correlation, sets the first thresholding first;

S32, the PSS correlation peak that the first thresholding was searched for by the first thresholding, judged whether there is the PSS of the first thresholding Correlation peak;

If so, selecting a maximum PSS correlation peak from the PSS correlation peak for crossing the first thresholding, then sentence Whether the number of the disconnected current maximum PSS correlation peak chosen in total by the first thresholding reaches certain number X, if It is then to enter step S34;If it is not, then entering step S33;

If it is not, then entering step S34;

S33, by each several positions of the maximum PSS correlation peak location got in step S32 and its adjacent front and back The correlation zero setting set;It is then return to step S32;It will wherein be got most in step S32 in this step in the present embodiment The correlation zero setting of each position of a big PSS correlation peak location and its adjacent front and back;

S34, the search by the first thresholding for PSS correlation peak terminate.

Through the above steps can by PSS correlation according to relationship ranking from big to small in former PSS relevant peaks Value is come out with sequential search from big to small, to get corresponding PSS correlation peak location.

S4, for each PSS correlation peak location got in each group of PSS correlation in step S3, from maximum PSS correlation peak location starts, and for each PSS correlation peak location, proceeds as follows:

S41, first according to current PSS correlation peak location, carry out SSS coherent detection to signal is received, obtain SSS correlation Value, then searched for the SSS correlation peak of the second thresholding, and therefrom get a maximum SSS phase by the second thresholding Close peak value;Enter step S42;The threshold value of the second thresholding is 200 in the present embodiment.

S42, SSS interference are eliminated: the corresponding SSS signal reconstruction of maximum SSS correlation peak being come out, then will be reconstructed The SSS signal come is cut from the reception signal of corresponding position, obtains the signal after interference is eliminated;Subsequently into step S43;

S43, according to current PSS correlation peak location, the reception signal after eliminating for step S42 interference carries out SSS again Coherent detection obtains SSS correlation, and the SSS correlation peak of the second thresholding was then searched for by the second thresholding, is judged whether there is Cross the SSS correlation peak of the second thresholding;

If so, selecting a maximum SSS correlation peak from the SSS correlation peak for crossing the second thresholding;Then sentence Whether the number for the maximum SSS correlation peak that open close the second thresholding of mistake has been chosen in total reaches certain number Y, if it is not, S42 is then entered step, if so, entering step S44;

If it is not, then entering step S44;

Under S44, current PSS correlation peak location, SSS interference, which is eliminated, to be completed, for next PSS correlation peak location, Back to step S41.

In the present embodiment, according to current PSS correlation peak location in step S41 and S43, the mistake of SSS coherent detection is carried out Journey is as follows:

S411, using current PSS correlation peak location as PSS timing position, in conjunction with the various relative positions of PSS and SSS Relationship determines each timing position of SSS;Wherein the relative positional relationship of PSS and SSS includes four kinds, wherein TDD (the time-division Duplex) and Normal CP (general cyclic prefix) relative positional relationship under, the relative position PSS and SSS be 412 sampled points; Under TDD and Extended CP (extended cyclic prefix) relative positional relationship, the relative position PSS and SSS is 480 sampled points; Under FDD (frequency division duplex) and Normal CP relative positional relationship, the relative position PSS and SSS is 137 sampled points;FDD and It is 160 under PSS and SSS relative positional relationship under Extended CP relative positional relationship.

S412,128 point SSS time-domain signals are taken respectively in each timing position of SSS, then by 128 point SSS time-domain signals 128 FFT transform are carried out, 128 frequency-region signals are obtained;

The corresponding data of label 65 in S413,128 sampled point frequency domain sequences are direct current subcarrier, before direct current subcarrier 31 frequency domain sequences are respectively extracted afterwards, and the frequency domain sequence of 62 points of composition is SSS frequency-region signal;

S414, the generating mode according to SSS are gradually descrambled and are carried out related calculation using the correlation of m-sequence, obtain SSS Correlation peak, and therefrom get SSS maximum correlation peaks;

S415, according to SSS maximum correlation peaks, carry out duplex mode, CP type, cell ID group and identify and front and back field Judgement, is so far obtained with cell ID and frame timing.

The detailed process for coming out the corresponding SSS signal reconstruction of SSS maximum correlation peaks in the present embodiment step S42 is such as Under:

S421, according in step S415 determine cell ID and frame timing, generate SSS frequency-region signal;

S422, the corresponding SSS signal of SSS maximum correlation peaks is extracted from reception signal;

S423, minimum is carried out for the SSS signal obtained in the SSS frequency-region signal and step S422 generated in step S421 Two multiply channel estimation, and carry out time domain noise reduction processing to channel estimation value sequence;

S444, the time domain noise reduction for getting step S423 treated channel estimation value sequence are multiplied by step S421 SSS frequency-region signal, obtained sequence are the SSS frequency-region signal for reconstructing and;

S445, the step S444 SSS frequency-region signal reconstructed is gone in time domain, and adds prefix, that is, reconstructed Whole SSS time-domain signal.

The present embodiment above method carries out related operation with reception signal respectively by three groups of local PSS sequences, to obtain Three groups of PSS correlations are got, for each group of PSS correlation, are obtained in PSS correlation by relationship ranking from big to small preceding Several PSS correlation peaks gets maximum several PSS correlation peaks in PSS correlation peak;Then from maximum PSS phase The position for closing peak value starts, and for each PSS correlation peak location, carries out one or many SSS coherent detections, so as to It, can be relatively strong by signal when downlink synchronous signal in the homogeneous frequency adjacent area using the same PSS signal reaches UE simultaneously Cell and the relatively weak cell of signal search, effectively prevent in the prior art using Reconstruction Method carry out PSS interference disappear Except leading to can only to search the relatively stronger cell of signal, and the relatively weak cell of signal cannot be searched to the phenomenon that.Greatly The performance of big raising UE down-going synchronous and the performance of handover, to improve user experience.And it is adopted in the method for the present invention SSS is eliminated with reconstruct side, can be eliminated to greatest extent under current scene using between adjacent two cell of the same PSS Interference.

In the present embodiment by repeat after above-mentioned steps S32 and S33 can by PSS correlation according to from big to small Relationship ranking come out in former PSS correlation peaks with sequence from big to small is searched.In each search, selection is moved into one's husband's household upon marriage A maximum PSS correlation peak in the PSS correlation peak of limit, and the PSS correlation peak location is got, then should The correlation of each several positions of PSS correlation peak location and its adjacent front and back carries out zero setting;It is current maximum when due to searching for every time PSS correlation peak be set to zero, therefore when searching for next time, the PSS correlation peak searched will be second to this maximum PSS phase Close peak value.

Therefore the present invention effectively eliminates interference of the PSS strong correlation peak to the weak relevant peaks of PSS by way of zero setting, reaches The purpose eliminated is interfered, the interference of PSS can be eliminated to greatest extent, determines potential effectively correlation peak location and cell Mark in ID group effectively reduces the complexity that PSS interference is eliminated, and improves the efficiency that PSS interference is eliminated.And the present invention exists In zeroing process, the correlation of adjacent each several positions is also set to zero, therefore this before and after current maximum PSS correlation peak Inventive method can avoid current maximum PSS correlation peak front-rear position correlation from searching PSS correlation peak next time simultaneously The interference generated when rope eliminates interference of the PSS strong correlation peak to the weak relevant peaks of PSS to greatest extent.The method of the present invention is effective It avoids in the prior art for relatively weak cell, carries out the PSS interference meeting of elimination because of channel estimation value using Reconstruction Method It is inaccurate, cause PSS that cannot be eliminated to greatest extent, while can also introduce biggish interference, causes weaker cell cannot be by The technical issues of detecting.

The above embodiment is a preferred embodiment of the present invention, but embodiments of the present invention are not by above-described embodiment Limitation, other any changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principles of the present invention, It should be equivalent substitute mode, be included within the scope of the present invention.

Claims (10)

1. cell searching interference elimination method in a kind of LTE system, which is characterized in that steps are as follows:
S1, reception signal is obtained;
S2, three groups of local PSS sequences are gone into time domain from frequency domain respectively, it is then related to signal progress is received in step S1 respectively Three groups of PSS correlations are obtained after operation;
S3, be directed to each group of PSS correlation, by the first thresholding by PSS correlation by relationship ranking from big to small preceding Several PSS correlation peaks, which searches out, to be come, until searching for less than the PSS correlation peak or current search for crossing the first thresholding to PSS phase It closes peak value and reaches certain number X, then terminate to search for, save each PSS correlation peak position searched above by the first thresholding Set and cell ID group in mark;
S4, for each PSS correlation peak location got in each group of PSS correlation in step S3, from maximum PSS phase It closes peak position to start, be carried out as follows with the sequence of PSS correlation peak from big to small for each PSS correlation peak location Operation:
S41, first according to current PSS correlation peak location, carry out SSS coherent detection to signal is received, obtain SSS correlation, Then the SSS correlation peak of the second thresholding was searched for by the second thresholding, and therefrom got a maximum SSS relevant peaks Value;Enter step S42;
S42, SSS interference eliminate: the corresponding SSS signal reconstruction of maximum SSS correlation peak is come out, then by reconstruct come SSS signal is cut from the reception signal of corresponding position, obtains the signal after interference is eliminated;Subsequently into step S43;
S43, according to current PSS correlation peak location, the reception signal after eliminating for step S42 interference carries out SSS correlation again Detection, obtains SSS correlation, the SSS correlation peak of the second thresholding was then searched for by the second thresholding, judges whether there is the The SSS correlation peak of two thresholdings;
If so, selecting a maximum SSS correlation peak from the SSS correlation peak for crossing the second thresholding;Then judgement is logical Whether the number for crossing the maximum SSS correlation peak that the second thresholding has been chosen in total reaches certain number Y, if it is not, then into Enter step S42, if so, entering step S44;
If it is not, then entering step S44;
Under S44, current PSS correlation peak location, SSS interference, which is eliminated, to be completed, and for next PSS correlation peak location, is returned To step S41.
2. cell searching interference elimination method in LTE system according to claim 1, which is characterized in that the step Three groups of local PSS sequences from frequency domain go to time domain respectively specific step is as follows in S2:
S21, the interior mark of cell ID group according to PSS sequenceValue 0,1 and 2, get three groups of local frequency domain PSS sequences Column, wherein the length of local frequency domain PSS sequence is 62;
S22, every group of local frequency domain PSS sequence is both mapped on each 31 subcarriers in direct current subcarrier front and back;
S23, for the every group of signal got in step S22,33 zero are supplemented before local frequency domain PSS sequence subcarrier, 32 zero are supplemented later, are removed 128 point, inverse fast Fourier transforms of progress after frequency processing, are finally obtained three groups of local time domain PSS Sequence.
3. cell searching interference elimination method in LTE system according to claim 1, which is characterized in that the step Each group PSS correlation is got by following steps in S2:
S24, starting point P0 is got in receiving signal, 256 sampled points is then taken since starting point P0, then it is done 256 points of FFT transform obtains the first frequency-region signal;The first starting point P0 got in signal is wherein received to believe to receive Number the first sampled point;
S25,128 sampled points are taken from one group of local time domain PSS sequence, zero padding to 256 sampled points simultaneously does 256 points of FFT transform, Obtain the second frequency-region signal;
S26, the first frequency-region signal and the second frequency-region signal conjugate multiplication are obtained into third signal, then carries out third signal 256 points of IFFT obtains time-domain signal;
Preceding 128 sampled point of S27, the time-domain signal for taking step S26 to get, as one group of local time domain PSS sequence and reception Signal slides the correlation after 128 related operations;
S28, judge whether carry out related calculation to obtain correlation at reception signal ending, if so, this group of related operation terminates;If It is no, then step S24 is returned to after starting point P0 being added 128 sampled points.
4. cell searching interference elimination method in LTE system according to claim 1, which is characterized in that in step S3 For each group of PSS correlation, by the first thresholding by PSS correlation according to relationship ranking from big to small former PSS correlation peak is come out with sequential search from big to small, and detailed process is as follows:
S31, it is directed to each group of PSS correlation, sets the first thresholding first;
S32, the PSS correlation peak that the first thresholding was searched for by the first thresholding, the PSS for judging whether there is the first thresholding are related Peak value;
If so, selecting a maximum PSS correlation peak from the PSS correlation peak for crossing the first thresholding, then judgement is worked as Whether the preceding number for passing through the maximum PSS correlation peak that the first thresholding has been chosen in total reaches certain number X, if so, Then enter step S34;If it is not, then entering step S33;
If it is not, then entering step S34;
S33, by each several positions of the maximum PSS correlation peak location got in step S32 and its adjacent front and back Correlation zero setting;It is then return to step S32;
S34, the search by the first thresholding for PSS correlation peak terminate.
5. cell searching interference elimination method in LTE system according to claim 4, which is characterized in that described first The threshold value of thresholding is that 9000, X value is 5.
6. cell searching interference elimination method in LTE system according to claim 1, which is characterized in that step S41 and According to current PSS correlation peak location in S43, the process for carrying out SSS coherent detection is as follows:
S411, using current PSS correlation peak location as PSS timing position, in conjunction with the various relative positional relationships of PSS and SSS, Determine each timing position of SSS;
S412,128 point SSS time-domain signals are taken respectively in each timing position of SSS, then carry out 128 point SSS time-domain signals 128 FFT transform obtain 128 sampled point frequency-region signals;
The corresponding data of label 65 in S413,128 sampled point frequency domain sequences are direct current subcarrier, each before and after direct current subcarrier 31 frequency domain sequences are extracted, the frequency domain sequence of 62 points of composition is SSS frequency-region signal;
S414, the generating mode according to SSS are gradually descrambled and are carried out related calculation using the correlation of m-sequence, and SSS correlation is obtained Peak value, and therefrom get SSS maximum correlation peaks;
S415, according to SSS maximum correlation peaks, carry out that duplex mode, CP type, cell ID group identify and front and back field is sentenced Certainly, cell ID and frame timing are so far obtained with.
7. cell searching interference elimination method in LTE system according to claim 6, which is characterized in that PSS and SSS Relative positional relationship include four kinds, wherein time division duplex (TDD) and general cyclic prefix (Normal CP) relative positional relationship Under, the relative position PSS and SSS is 412 sampled points;TDD and extended cyclic prefix (Extended CP) relative positional relationship Under, the relative position PSS and SSS is 480 sampled points;Under frequency division duplex (FDD) and Normal CP relative positional relationship, PSS and The relative position SSS is 137 sampled points;Under FDD and Extended CP relative positional relationship, PSS and SSS relative positional relationship It is down 160.
8. cell searching interference elimination method in LTE system according to claim 6, which is characterized in that the step By the corresponding SSS signal reconstruction of SSS maximum correlation peaks, detailed process is as follows out in S42:
S421, according in step S415 determine cell ID and frame timing, generate SSS frequency-region signal;
S422, the corresponding SSS signal of SSS maximum correlation peaks is extracted from reception signal;
S423, least square is carried out for the SSS signal obtained in the SSS frequency-region signal and step S422 generated in step S421 Channel estimation, and time domain noise reduction processing is carried out to channel estimation value sequence;
S444, the time domain noise reduction for getting step S423 treated channel estimation value sequence are multiplied by the SSS in step S421 Frequency-region signal, obtained sequence are the SSS frequency-region signal for reconstructing and;
S445, the step S444 SSS frequency-region signal reconstructed is gone in time domain, and adds prefix, that is, reconstructed complete SSS time-domain signal.
9. cell searching interference elimination method in LTE system according to claim 1, which is characterized in that the step The threshold value of the second thresholding is 200 in S4;Y is 2.
10. cell searching interference elimination method in LTE system according to claim 1, which is characterized in that the step The reception signal obtained in S1 be filtering and it is down-sampled treated receive signal.
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