CN102571668B - Phase compensation method and system in LTE (long term evolution) system - Google Patents

Abstract

The invention discloses a phase compensation method and a phase compensation system in a LTE (long term evolution) system, wherein the method comprises the following steps: acquiring an OFDM (orthogonal frequency division multiplexing) symbol which comprises a CP (cyclic prefix) and is subjected to analog-to-digital conversion according to a timing point; intercepting a sampling point with a length equal to a preset lead L in the CP, and carrying out phase compensation on data in a FFT (fast fourier transform) window so as to obtain compensation data; carrying out FFT conversion on the compensation data so as to obtain corresponding frequency domain data, and then sending the frequency domain data to a data buffer area; and acquiring reference signals in the frequency domain data stored in the data buffer area, and according to the reference signals, estimating errors of time domain timing, and updating the timing point. According to the method and the system, through intercepting the sampling point with the length equal to the preset lead L in the CP, and acquiring the compensation data subjected to the processing above and carrying out the FFT conversion on the compensation data, the influence of phase rotation on the performance of a subsequent channel-estimated linear interpolation in the prior art is overcome, thereby improving the performance of the whole system.

Description

Phase compensating method and system in a kind of LTE system

Technical field

The present invention relates to communication technical field, in particular, relate to phase compensating method and system in a kind of LTE (Long Term Evolution system, Long Term Evolution) system.

Background technology

Current for the development of the communication technology, from the 3G epoch, start to carry out transition to the 4G epoch, and LTE (Long Term Evolution system, Long Term Evolution) system is thought 4G wireless communication system widely.Wherein, the physical layer of LTE adopts OFDM (Orthogonal Frequency Division Multiplexing, OFDM) technology.As shown in Figure 1, be two OFDM symbols continuous in time, OFDM symbol n and OFDM symbol n+1.Wherein, this structure that meets the time domain OFDM symbol of LTE definition comprises: CP (Cyclic Prefix) part and data (data) part.

In the prior art ideally, as regularly accurate, channel is AWGN (Additive White Gaussion Noise, additive white Gaussian noise), the data division that enters FFT (Fast Fourier Transformation, fast Fourier transform) unit is the data in FFT window 1.

As shown in Figure 2, digital base band processor structure for a LTE terminal receiver in prior art, mainly comprise: AD (analog-to-digital conversion) sampling unit 201, timing adjustment unit 202, this timing adjustment unit 202 obtains the complete OFDM symbol comprise CP according to timing point T; Go to CP unit 203, in the ideal case, as regularly accurately, channel is under AWGN, directly by the data cutout entering in FFT window 1, out gives FFT unit; 204 pairs of the FFT unit data that receive are carried out FFT conversion, obtain frequency domain data, and it is medium pending that this frequency domain data is put into data buffer zone 205.

But under fading channel, ideal position regularly (so-called ideal position is exactly timing position accurately) is the position of centre of gravity of multipath channel, the namely mean place of the multipath of each different capacity and time delay.The power time delay figure of two typical multipath channels as shown in Figure 3 a and Figure 3 b shows.Wherein, the most powerful path that Fig. 3 a represents is the first footpath; Fig. 3 b represents that most powerful path is a certain middle footpath.In above-mentioned two situations, desirable timing point T be all positioned at the first footpath after.If start data to send into FFT unit from timing point T position, the data in the FFT window 1 that is about to indicate in Fig. 1 are sent to FFT unit.Because timing point is now not the position in the first footpath, so the afterbody of FFT window 1 interior data has been subject to the interference of next OFDM symbol header data, caused ISI (intersymbol interference).For fear of above-mentioned interference, the position of generally FFT being windowed is in the prior art to prerequisite, and the data that in fact FFT unit receives are that the lead L in Fig. 1 is obtained by empirical value as shown in Figure 1 by the data in the FFT window 2 forming after lead L.Adopt said method can effectively reduce the ISI in ofdm system.

Structure from CP, now the data of FFT window 2 are cyclic shifts of the data in FFT window 1, can there is phase rotating in the frequency domain data therefore obtaining after FFT, and the index value of this phase rotating and subcarrier is relevant, and the angle of the larger rotation of index value is just larger.Owing to recovering the stage in data, need to use channel estimating, the channel of usually supposing close several subcarriers in the middle of channel estimating is linear change, so can use linear interpolation to recover the channel on data subcarrier.But the phase rotating causing in advance due to the position of FFT window can destroy the prerequisite of above-mentioned execution linear interpolation, the precision of linear interpolation is reduced greatly, thereby cause the decline of whole system performance.

Summary of the invention

In view of this, the invention provides phase compensating method and system in a kind of LTE system, to overcome in prior art because the phase rotating of FFT window position after in advance reduced the precision of linear interpolation, thereby cause the problem of whole system hydraulic performance decline.

For achieving the above object, the invention provides following technical scheme:

A phase compensating method in Long Term Evolution LTE system, comprising:

According to timing point, obtain the orthogonal frequency division multiplex OFDM symbol that comprises cyclic prefix CP through analog-to-digital;

The sampled point that in intercepting CP, length is default lead L, carries out phase compensation to the data in fast Fourier transform FFT window, is compensated data;

Described offset data is carried out to FFT conversion, obtain the frequency domain data of corresponding described offset data and be sent to data buffer zone;

Obtain and be stored in the reference signal in frequency domain data in described data buffer zone, according to described reference signal, estimate time domain error regularly, upgrade described timing point.

Preferably, the data in fast Fourier transform FFT window are compensated, the detailed process that is compensated data comprises:

Intercepting CP tail length is the first sampled point of default lead L and the data in FFT window 1;

Utilize described the first sampled point to cover the data that the interior tail length of described FFT window 1 is L, determine that the data in the FFT window 1 after afterbody is capped are offset data.

Preferably, the data in fast Fourier transform FFT window are compensated, the detailed process that is compensated data comprises:

Intercepting CP tail length is the second sampled point of default lead L and the data in FFT window 2, and described the second sampled point is the head of the data in described FFT window 2;

Described the second sampled point is cyclicly shift to described FFT window 2 afterbodys, determine by the second sampled point of head compensate to the data in the FFT window 2 of afterbody be offset data.

Preferably, it is characterized in that, according to described reference signal, estimate time domain error regularly, the detailed process of upgrading described timing point comprises:

In a descending sub frame, the channel response of the reference signal of the neighbouring same antenna port getting is carried out related calculation, and sue for peace, obtain the first correlation of each reference signal that is positioned at same antenna port;

Described the first correlation to same antenna port is sued for peace again, obtains the second correlation;

Described in conversion calculations, the value of the second correlation arc tangent, obtains timing offset;

Timing offset described in smothing filtering, obtains the new timing offset after level and smooth;

According to described new timing offset, adjust described timing point, obtain the timing point after renewal.

Preferably, the preset procedures of described default lead L specifically comprises:

Obtain the position of main synchronizing symbol PSS place OFDM symbol, determine the data acquisition sampling point that length is Len above, and determine that described PSS place OFDM symbol and described data acquisition sampling point form first path search data segment, the length of described first path search data segment is: L _seq+ Len;

Wherein, the original position of described first path search data segment is T-Len, and T is timing point; L _seqlength for described PSS place OFDM symbol;

Data described in low-pass filter beyond the shared bandwidth of PSS, output sequence length is L _seqthe sequence Sr of+Len (n), n=0,1,2 ..., L _seq+ Len-1;

Export local PSS sequence Sl (n), n=0,1,2 ..., L _seq-1, described local PSS sequence length is L _seq;

Utilize described local PSS sequence and described first path search data segment to carry out first path search, determine default lead L.

Preferably, the process that generates described local PSS sequence comprises:

Under LTE system protocol, according to No. ID generation frequency domain PSS sequence of current service cell, described frequency domain PSS sequence comprises 62 data points, and length is 62;

In the centre position of described frequency domain PSS sequence, insert one 0 as direct current subcarrier, the frequency domain PSS sequence that formation length is 63;

Zero padding is carried out in the both sides of the frequency domain PSS sequence that is 63 to length, generates the length Fourier transform FFT corresponding with the current bandwidth identical new frequency domain PSS sequence of counting;

Described in fast Fourier transform IFFT, new frequency domain PSS sequence is to time domain;

Add CP being converted in the PSS sequence of time domain, generate local PSS sequence.

The process of preferably, carrying out described first path search comprises:

Utilize described local PSS sequence Sl (n) to do slip related operation in described first path search data segment, obtain sequence of correlation values $\mathrm{corr}\_\mathrm{result}\left(n\right)=\underset{i=0}{\overset{L_{\mathrm{seq}}-1}{\mathrm{\Σ}}}\mathrm{Sr}(n+i)*\mathrm{conj}\left(\mathrm{Sl}\left(i\right)\right),$ N=0,1,2 ..., Len-1, wherein, coj () is for asking conjugate operation, and n is the original position of this search window, and i is sampling point index value, and the length j of search window (is L _seq, the length of slip is that search length is Len;

Ask described sequence of correlation values mould square, obtain correlation peak sequence peak seq (n), this peak_seq (n)=|| corr_result (n) || ², n=0,1,2 ..., Len-1, wherein, n is the original position of this search window;

In described correlation peak sequence, search for the peak value that first surpasses default thresholding, be designated as i _fP;

Obtain described i _fPand the distance L between timing point _c, to described L _cdo smoothing processing, using the level and smooth result getting as default lead L.

Preferably, described LTE system is supported mobile terminal single antenna receiving mode.

Preferably, described LTE system is supported mobile terminal multi-antenna receiving mode;

According to the sky line options control signal that gets, a reception antenna under described many antenna receptions pattern is processed, and the processing mode of each the root reception antenna under described many antenna receptions pattern during with described single antenna receiving mode is identical;

Wherein, the acquisition process of described antenna selection signals comprises:

Receive the yield value that reception antenna automatic gain control and compensation is used described in each road, and select the index value of the reception antenna of corresponding minimum gain value, it is configured as sky line options control signal.

A Phase Compensation System in Long Term Evolution LTE system, at least comprises the phase compensation device of one group of corresponding mobile terminal reception antenna, and described phase compensation device comprises:

Analog-to-digital conversion sampling unit, for carrying out to received signal analog-to-digital conversion;

Timing adjustment unit, for obtaining the orthogonal frequency division multiplex OFDM symbol that comprises cyclic prefix CP through analog-to-digital according to timing point;

Phase compensation unit, for intercepting CP length for the sampled point of default lead L, carries out phase compensation to the data in fast Fourier transform FFT window, is compensated data;

FFT converter unit, for described offset data is carried out to FFT conversion, obtains the frequency domain data of corresponding described offset data and is sent to data buffer zone;

Data buffer unit, for frequency domain data described in buffer memory;

Timing estimation unit, for obtaining the reference signal that is stored in frequency domain data in described data buffer zone, estimates time domain error regularly according to described reference signal, upgrades described timing point, and the described timing point after upgrading is sent to timing adjustment unit.

Preferably, described phase compensation unit comprises:

The first phase compensation unit, for intercepting CP tail length for the first sampled point of default lead L and the data in FFT window 1, utilize described the first sampled point to cover the data that the interior tail length of described FFT window 1 is L, determine that the data in the FFT window 1 after afterbody is capped are offset data;

Or, the second phase compensation unit, for intercepting CP tail length for the second sampled point of default lead L and the data in FFT window 2, described the second sampled point is the head of the data in described FFT window 2, described the second sampled point is cyclicly shift to described FFT window 2 afterbodys, determine by the second sampled point of head compensate to the data in the FFT window 2 of afterbody be offset data.

Preferably, also comprise: low-pass filter unit, PSS sequence generating unit and first footpath estimation unit;

Described timing adjustment unit, also for the position according to main synchronizing symbol PSS place OFDM symbol, determine the data acquisition sampling point that length is Len above, and determine that described PSS place OFDM symbol and described data acquisition sampling point form first path search data segment, the length of described first path search data segment is: L _seq+ Len; Wherein, the original position of described first path search data segment is T-Len, and T is timing point; L _seqlength for described PSS place OFDM symbol;

Low-pass filter unit, for the data beyond the shared bandwidth of PSS described in low-pass filter, output sequence length is L _seqthe sequence Sr of+Len (n), n=0,1,2 ..., L _seq+ Len-1;

PSS sequence generating unit, for exporting local PSS sequence Sl (n), n=0,1,2 ..., L _seq-1, described local PSS sequence length is L _seq;

First footpath estimation unit, for utilizing described local PSS sequence and described first path search data segment to carry out first path search, determines default lead L.

Preferably, described first footpath estimation unit comprises:

Slip correlation unit, for utilizing described local PSS sequence Sl (n) to do slip related operation in described first path search data segment, obtains sequence of correlation values corr_result (n), n=0, and 1,2 ..., Len-1;

Ask the squared unit of mould, for ask described sequence of correlation values mould square, obtain correlation peak sequence peak_seq (n);

Search unit, the peak value that surpasses default thresholding for search for first in described correlation peak sequence, is designated as i _fP;

Smooth unit, for obtaining described i _fPand the distance L between timing point _c, to described L _cdo smoothing processing, using the level and smooth result getting as default lead L.

Preferably, when mobile terminal exists multipath reception antenna, comprising: the described phase compensation device that number is identical with described reception antenna number;

Described low-pass filter unit has multiple signals input;

Antenna selected cell, for receiving the yield value that reception antenna automatic gain control and compensation is used described in each road, and select automatic gain to control the index value of the reception antenna that minimum yield value is corresponding, using it as sky line options control signal, configure to described low-pass filter unit and described timing estimation unit.

Known via above-mentioned technical scheme, compared with prior art, the invention discloses phase compensating method and system in a kind of LTE system.By the complete OFDM symbol that comprises CP obtaining through timing adjustment is carried out to phase compensation, mainly by the sampled point that in intercepting CP, length is default lead L, data in FFT window are carried out to phase compensation, and obtain the offset data after above-mentioned processing, this offset data is carried out to FFT conversion to overcome the impact of phase rotating of the prior art on the performance of channel estimating linear interpolation afterwards, thereby improve the performance of whole system.

Accompanying drawing explanation

In order to be illustrated more clearly in the embodiment of the present invention or technical scheme of the prior art, to the accompanying drawing of required use in embodiment or description of the Prior Art be briefly described below, apparently, accompanying drawing in the following describes is only embodiments of the invention, for those of ordinary skills, do not paying under the prerequisite of creative work, other accompanying drawing can also be provided according to the accompanying drawing providing.

Fig. 1 is the structural representation of the frequency-domain OFDM symbol based on LTE agreement;

Fig. 2 is the digital base band processor structural representation of LTE terminal receiver in prior art;

Fig. 3 a～Fig. 3 b is the power time delay figure of radio communication multipath channel;

Fig. 4 is the flow chart of the phase compensating method in the disclosed a kind of LTE system of the embodiment of the present invention one;

Fig. 5 a～Fig. 5 b is the design sketch of the embodiment of the present invention two disclosed phase compensations;

Fig. 6 is the open frequency domain frame structure schematic diagram based on LTE agreement of the embodiment of the present invention two;

Fig. 7 is the flow chart of the disclosed renewal timing point of the embodiment of the present invention two;

Fig. 8 is the disclosed a kind of flow chart of estimating lead L of the embodiment of the present invention three;

Fig. 9 is the structural representation of the disclosed first path search data segment of the embodiment of the present invention three;

Figure 10 is the flow chart of the local PSS sequence of the disclosed generation of the embodiment of the present invention three;

Figure 11 is the flow chart of the embodiment of the present invention three disclosed first path search;

Figure 12 is the phase compensation device structural representation in the disclosed a kind of LTE system of the embodiment of the present invention;

Figure 13 is the phase compensation device structural representation in the disclosed another kind of LTE system of the embodiment of the present invention;

Figure 14 is the phase compensation device structural representation under the disclosed multi-antenna mode of the embodiment of the present invention.

Embodiment

For quote and know for the purpose of, the explanation of the technical term hereinafter using, write a Chinese character in simplified form or abridge and be summarized as follows:

LTE:Long Term Evolution system, long evolving system;

AGC:Automatic Gain Control, automatic gain is controlled;

FFT:Fast Fourier Transformation, fast Fourier transform;

AD: analog-to-digital conversion;

CP: Cyclic Prefix;

RS:reference signal, reference signal;

OFDM:Orthogonal Frequency Division Multiplexing, OFDM;

PSS:Primary Synchronization Signal, main synchronizing symbol.

Below in conjunction with the accompanying drawing in the embodiment of the present invention, the technical scheme in the embodiment of the present invention is clearly and completely described, obviously, described embodiment is only the present invention's part embodiment, rather than whole embodiment.Embodiment based in the present invention, those of ordinary skills, not making the every other embodiment obtaining under creative work prerequisite, belong to the scope of protection of the invention.

For what mention in above-mentioned background technology, carrying out the data recovery stage, need to utilize channel estimating, and the channel of current several subcarriers that general hypothesis is close when carrying out channel estimating is linear change, therefore can utilize linear interpolation to recover the channel on data subcarrier, but, because the structure of CP is known, after intersymbol interference in utilizing prior art reduction ofdm system, now the data of FFT window 2 are cyclic shifts of the data in FFT window 1, can there is phase rotating in the frequency domain data therefore obtaining after FFT, the phase rotating causing in advance due to the position of FFT window can destroy the prerequisite of above-mentioned execution linear interpolation, the precision of linear interpolation is reduced greatly, thereby cause the decline of whole system performance.

Therefore, the invention provides phase compensating method and system in a kind of LTE system, by the complete OFDM symbol that comprises CP obtaining through timing adjustment is carried out to phase compensation, mainly by the sampled point that in intercepting CP, length is default lead L, data in FFT window are carried out to phase compensation, and obtain the offset data after above-mentioned processing, this offset data is carried out to FFT conversion to overcome the impact of phase rotating of the prior art on the performance of channel estimating linear interpolation afterwards.Detailed process is elaborated by following examples.

Embodiment mono-

Refer to accompanying drawing 4, the flow chart for the phase compensating method in the disclosed a kind of LTE system of the embodiment of the present invention, mainly comprises the following steps:

Step S101, obtains the OFDM symbol through the analog-to-digital CP of comprising according to timing point T.

When execution step S101, first carry out to received signal analog-to-digital conversion, obtain the numerical chracter that carries OFDM symbol, and then obtain according to timing point T the OFDM symbol that comprises CP in numerical chracter, so that carry out following phase compensation.

Step S102, the sampled point that in intercepting CP, length is default lead L, carries out phase compensation to the data in FFT window, is compensated data.

Execution step S102 carries out phase compensation, the OFDM symbol that comprises CP above-mentioned steps S101 being obtained carries out phase compensation, and the mode compensating is the sampled point that in intercepting CP, length is default lead L the data in FFT window are carried out to phase compensation, and obtain corresponding offset data.

Step S103, carries out FFT conversion to described offset data, obtains the frequency domain data of corresponding described offset data and is sent to data buffer zone.

Step S104, obtains and is stored in the RS in frequency domain data in described data buffer zone, according to described RS, estimates time domain error regularly, upgrades described timing point T.

By above-mentioned, obtain the OFDM symbol that comprises CP, and intercept length in CP for the sampled point of default lead L, the data in FFT window are carried out to phase compensation, and obtain the offset data after above-mentioned processing, this offset data is carried out to FFT conversion.By said process, can reduce on the basis of intrasystem intersymbol interference, the phase rotating that the position of FFT window is caused in advance carries out phase compensation, can avoid its impact on the performance of channel estimating linear interpolation afterwards, thereby improve the performance of whole system.

Embodiment bis-

On the basis of the invention described above the disclosed embodiments, as shown in Fig. 5 a and Fig. 5 b, in the process of phase compensation that performs step S102, specifically there are following two kinds of way of example:

One, as shown in Figure 5 a, the sampled point that length is default lead L in intercepting CP, carries out phase compensation to the data in FFT window and is compensated data mainly for the data in FFT window 1.

First, the data in intercepting FFT window 1, and CP tail length is the first sampled point of default lead L.

Secondly, the first sampled point that is L by the length of intercepting takes out, and utilizes this first sampled point to cover the data that the interior tail length of described FFT window 1 is L.

Finally, determine that the data in the FFT window 1 after afterbody is capped are offset data, utilize this offset data.

Its two, as shown in Figure 5 b, the sampled point that length is default lead L in intercepting CP, carries out phase compensation to the data in FFT window and is compensated data mainly for the data in FFT window 2.

First, the data in intercepting FFT window 2, and CP tail length is the second sampled point of default lead L, and this second sampled point is the head of the data in described FFT window 2.

Secondly, described the second sampled point is cyclicly shift to described FFT window 2 afterbodys, with the data-linkage of these FFT window 2 afterbodys.

Finally, determine by the second sampled point of head compensate to the data in the FFT window 2 of afterbody be offset data.

OFDM symbol based on comprising CP, when carrying out the phase compensation of above-mentioned first kind of way, FFT window 1 accounts for the whole Data part of OFDM symbol, the first sampled point that is L from the CP part intercepted length of OFDM symbol, carried out data-moving to the afterbody of FFT window 1, covered the data of the isometric L of afterbody.Complete the phase compensation to data in FFT window.

When carrying out the phase compensation of the second way, FFT window 2 accounts for OFDM symbolic component CP and part Data, wherein, the length of shared CP part is L, the CP that intercepts this length and be L is the second sampled point, the head part that this second sampled point is FFT window 2, moves to the afterbody of FFT window 2 and the data of afterbody and is connected, and completes the compensation to FFT window 2 interior data.

By above-mentioned two kinds of modes, can realize the phase rotating that the position of FFT window is caused in advance and carry out phase compensation, can avoid its impact on the performance of channel estimating linear interpolation afterwards, thereby improve the performance of whole system.

On the basis of the invention described above the disclosed embodiments, at execution step S104, obtain and be stored in the RS in frequency domain data in described data buffer zone, according to described RS, estimate time domain error regularly, upgrade in the process of described timing point T, the frequency domain frame structure of the LTE agreement based on as shown in Figure 6 upgrades described timing point T, and detailed process as shown in Figure 7, mainly comprises the following steps:

Step S701, in a descending sub frame, carries out related calculation to the channel response of the RS of the neighbouring same antenna port getting, and summation, obtains the first correlation of each reference signal that is positioned at same antenna port.

Based on accompanying drawing 6, to the n row on descending sub frame m, n=1,2,3,4, as shown in Figure 6, the channel response of the RS of neighbouring same antenna port carries out related calculation, and utilizes formula (1) summation, obtains the first correlation.

${\mathrm{sum}\_\mathrm{corr}}_n=\underset{i=0}{\overset{N-2}{\mathrm{\Σ}}}{h}_i*\mathrm{conj}\left(h_{i+1}\right)---\left(1\right)$

Wherein, sum_corr _nfor the n row RS correlation on subframe m and, N is the number of RS in these row, h _iit is the channel response of i RS.

Step S702, sues for peace again to described first correlation of same antenna port, obtains the second correlation.

Based on accompanying drawing 6, by 4 correlations of the same antenna port on descending sub frame m and, i.e. the Output rusults of step S701, recycling formula (2) summation, obtains the second correlation.

${\mathrm{sum}\_\mathrm{corr}}_m=\underset{n=1}{\overset{4}{\mathrm{\Σ}}}{\mathrm{sum}\_\mathrm{corr}}_n---\left(2\right)$

Wherein, sum_corr _mfor the correlation of subframe m output and, according to function, need can be again cumulative by the correlation of different antennae port output simultaneously.

Step S703, the value of the second correlation arc tangent, obtains timing offset described in conversion calculations.Based on formula (3) to negate tangent be converted into timing offset of the correlation of exporting in step S702.

${\mathrm{time}\_\mathrm{err}}_m=\frac{N_{\mathrm{fft}}\×\∠{\mathrm{sum}\_\mathrm{corr}}_m}{2\mathrm{\π}\×6}---\left(3\right)$

Wherein, time_err _mbe the timing offset of m subframe output, sum_corr _mfor the correlation of subframe m output and, N _fftfor FFT counts, N _fftrelevant with system bandwidth, if 1.4M is 128 points, 3M is 256 points, and 5M is 512 points, and 10M is 1024 points, and 15M is 1536 points, and 20M is 2048 points.

Step S704, timing offset described in smothing filtering, obtains the new timing offset after level and smooth.

Execution step S704, obtains the new timing offset after level and smooth based on formula (4).

time_err _out＝time_err _out×(1-α)+time_err _m×α (4)

Wherein, α is smoothing factor, and 0≤α≤1, can set according to actual performance; Time_err _outtiming offset for output after level and smooth; Time_err _mit is the timing offset of m subframe output.

Step S705, adjusts described timing point T according to described new timing offset, obtains the timing point T after renewal ₀.

New timing offset time_err based on execution step S704 output _outadjust timing point T, adjustment process as shown in formula (5),

T ₀＝T+time_err _out (5)

Wherein, T ₀for the timing point after upgrading, T is the timing point before adjusting.

Sampled point by length is default lead L in disclosed two kinds of intercepting CP in the present embodiment, carries out phase compensation to the data in FFT window, and obtains the offset data after above-mentioned processing, and this offset data is carried out to FFT conversion.By said process, can reduce on the basis of intrasystem intersymbol interference, the phase rotating that the position of FFT window is caused in advance carries out phase compensation, can avoid its impact on the performance of channel estimating linear interpolation afterwards, thereby improve the performance of whole system.

In addition, the frequency domain data that conversion obtains through FFT is transferred in buffering area and is further processed, utilize the RS in data buffer zone to estimate time domain error regularly, thereby determine new timing point, so that when step S101 once obtains the OFDM symbol that comprises CP on carrying out, carry out the phase compensation of a new round according to new timing point.

Embodiment tri-

Above-mentioned disclosed embodiment relates to the sampled point that in intercepting CP, length is default lead L.In general, default lead L obtains based on engineering experience, its physical significance is: carry out the timing point T of timing estimation to the distance in fading channel the first footpath, this distance can count to measure with sampled point, and the accuracy of this distance estimations also can affect the performance of whole system simultaneously.For the length accuracy of the intercepting CP that guarantees to carry out in the present invention to relate in the process of phase compensation, the accuracy of default lead L, guarantees that the performance of whole system is unaffected.Therefore, the present embodiment, on the basis of the invention described above the disclosed embodiments, discloses a kind of mode of estimating lead L, that is to say the method for default lead L.Specifically refer to accompanying drawing 8, mainly comprise the following steps:

Step S801, the data acquisition sampling point that is Len according to length before the location positioning of PSS place OFDM symbol, determines that PSS place OFDM symbol and data acquisition sampling point form first path search data segment, the length of this head path search data segment is: L _seq+ Len;

Wherein, the original position of this head path search data segment is T-Len, and T is timing point; L _seqfor the length of described PSS place OFDM symbol, i.e. a complete OFDM symbol that comprises CP; While being correlated with when sliding, the search window length of sliding relevant is L _seq, the length of slip is that search length is Len.As shown in Figure 9.

In disclosed embodiment of this invention, according to engineering experience determine search length Len preferably option be the length that equals CP.

Step S802, low-pass filter falls the data beyond the shared bandwidth of PSS, and output sequence length is L _seqthe sequence Sr of+Len (n), n=0,1,2 ..., L _seq+ Len-1.

Step S803, exports local PSS sequence Sl (n), n=0, and 1,2 ..., L _seq-1, described local PSS sequence length is L _seq.

Step S804, utilizes described local PSS sequence and described first path search data segment to carry out first path search, determines default lead L.

For the detailed process that generates described local PSS sequence in above-mentioned execution step S803 as shown in figure 10, comprise the following steps:

Step S1001, under LTE system protocol, No. ID generation frequency domain PSS sequence according to current service cell, comprises 62 data points in this frequency domain PSS sequence altogether, length is 62.

It should be noted that, the process that this frequency domain PSS sequence generates can be carried out in real time, can be also to call the frequency domain PSS sequence generating and storing in advance.

Step S1002, inserts one 0 as direct current subcarrier in the centre position of described frequency domain PSS sequence, the frequency domain PSS sequence that formation length is 63.

Zero padding is carried out in the both sides of the frequency domain PSS sequence that step S1003 is 63 to length, generates the length FFT corresponding with the current bandwidth identical new frequency domain PSS sequence of counting.

For the zero padding in step S1003, describe, when current bandwidth is 1.4 million, it is 128 that corresponding FFT counts, and it is 128 that zero padding to its length is carried out in the both sides of the frequency domain PSS sequence that is now 63 in length; Equally, current bandwidth is 3,000,000 o'clock, and it is 256 that corresponding FFT counts, and it is 256 that zero padding to its length is carried out in the both sides of the frequency domain PSS sequence that is now 63 in length; Current bandwidth is 5,000,000 o'clock, and it is 512 that corresponding FFT counts, and it is 512 that zero padding to its length is carried out in the both sides of the frequency domain PSS sequence that is now 63 in length; Current bandwidth is 10,000,000 o'clock, and it is 1024 that corresponding FFT counts, and it is 1024 that zero padding to its length is carried out in the both sides of the frequency domain PSS sequence that is now 63 in length; Current bandwidth is 15,000,000 o'clock, and it is 1536 that corresponding FFT counts, and it is 1536 that zero padding to its length is carried out in the both sides of the frequency domain PSS sequence that is now 63 in length; Current bandwidth is 20,000,000 o'clock, and it is 2084 that corresponding FFT counts, and it is 2084 that zero padding to its length is carried out in the both sides of the frequency domain PSS sequence that is now 63 in length; The like, in this embodiment of the present invention, give an example no longer one by one.

Step S1004, carries out IFFT to this new frequency domain PSS sequence and converts it in time domain.

Step S1005, adds CP being converted in the PSS sequence of time domain, generates local PSS sequence.

For the detailed process of the first path search carrying out in above-mentioned execution step S804 as shown in figure 11, comprise the following steps:

Step S1101, utilizes described local PSS sequence Sl (n) to do slip related operation in described first path search data segment, obtains sequence of correlation values corr_result (n).Specifically with formula (6), be expressed as:

$\mathrm{corr}\_\mathrm{result}\left(n\right)=\underset{i=0}{\overset{L_{\mathrm{seq}}-1}{\mathrm{\Σ}}}\mathrm{Sr}(n+i)*\mathrm{conj}\left(\mathrm{Sl}\left(i\right)\right),n=\mathrm{0,1,2},...,\mathrm{Len}-1---\left(6\right)$

Wherein, conj () is for asking conjugate operation, and n is the original position of this search window, and i is sampling point index value, and the length of search window is L _seq, the length of slip is that search length is Len; Sl () is local PSS sequence; Sr () is the sequence of exporting after the data beyond the shared bandwidth of above-mentioned low-pass filter PSS.

Step S1102, to the sequence of correlation values getting in step S1101 ask mould square, obtain correlation peak sequence peak_seq (n).Specifically with formula (7), be expressed as:

peak_seq(n)＝||corr_result(n)|| ²，n＝0，1，2，...，Len-1 (7)

Wherein, n is the original position of this search window; Corr_result (n) is sequence of correlation values.

Step S1103 searches for the peak value that first surpasses default thresholding in described correlation peak sequence, is designated as iFp.

In the process of execution step S1103, search makes an i of peak_seq (i) >=threshould, wherein, i=0,1,2 ..., Len-1, threshould is predetermined threshold value.First i satisfying condition searching for out is above designated as to i _fP.

Step S1104, obtains described i _fPand the distance L between timing point T _c, to described L _cdo smoothing processing, using the level and smooth result getting as default lead L.

Specifically execution step S1104 process in to L _cthe formula for process (8) that carries out smoothing processing is expressed as:

L＝L×(1-β)+L _c×β (8)

Wherein, β is smoothing factor, and 0≤β≤1, and this β value can be set according to actual performance.

After determining default lead L by said process, can directly apply in other embodiment disclosed by the invention.

Embodiment tetra-

On the basis of the method in the disclosed embodiment mono-of the invention described above, embodiment bis-and embodiment tri-, when only there is a reception antenna in UE, directly adopt disclosed mode in above-described embodiment one, embodiment bis-or embodiment tri-, single antenna receives the mode of signal.Due to, LTE system is supported the configuration of many reception antennas of UE, therefore, when UE has many (more than two or two) reception antennas, now, for the every reception antenna of UE, adopt separately the receive mode of embodiment mono-, embodiment bis-or embodiment tri-, carry out accordingly phase compensation.The mode of concrete compensation can, referring to the mode in above-described embodiment one, embodiment bis-or embodiment tri-, repeat no more here.

Embodiment five

In the invention described above embodiment tetra-, disclosed LTE system is supported the configuration of many reception antennas of UE, in the situation that UE has many (more than two or two) reception antennas, directly adopt the scheme of real-time example four, the every reception antenna of one a pair of UE adopts separately the receive mode of embodiment mono-, embodiment bis-or embodiment tri-, carries out accordingly phase compensation.Adopt the mode of embodiment tetra-can make the baseband portion of UE have larger amount of calculation.Therefore, for avoiding consuming more power consumption.The present invention selects antenna to control in disclosed embodiment five.Detailed process is:

According to the sky line options control signal that gets, an antenna under described multi-antenna transmission pattern to be processed, the processing mode of each the root antenna under described multi-antenna transmission pattern during with described single antenna transmissions pattern is identical.

Concrete, the acquisition process of this antenna selection signals comprises: receive the yield value that reception antenna automatic gain control and compensation is used described in each road, and select the index value of the reception antenna of corresponding minimum gain value, it is configured as sky line options control signal.

By above-mentioned, only the data of the antenna of selecting are carried out to the calculating in the disclosed embodiment of the invention described above, can greatly reduce amount of calculation, thereby further reduce the power consumption of system, improve the performance of whole system.

In the disclosed embodiment of the invention described above, describe the phase compensating method in a kind of LTE system in detail, for method of the present invention, can adopt the system of various ways to realize, therefore the invention also discloses the Phase Compensation System in a kind of LTE system, provide specific embodiment below and be elaborated.

Method based on the disclosed phase compensation of the invention described above embodiment, the situation of only having a reception antenna for UE, the invention discloses a kind of phase compensation device that at least comprises one group of corresponding mobile terminal reception antenna, as shown in figure 12, described phase compensation device comprises:

AD sampling unit 401, for carrying out to received signal analog-to-digital conversion.

Timing adjustment unit 402, for obtaining the orthogonal frequency division multiplex OFDM symbol that comprises cyclic prefix CP through analog-to-digital according to timing point.

Phase compensation unit 403, for intercepting CP length for the sampled point of default lead L, carries out phase compensation to the data in fast Fourier transform FFT window, is compensated data.

It should be noted that, at this phase compensation unit 403, comprise:

The first phase compensation unit 4031, for intercepting CP tail length for the first sampled point of default lead L and the data in FFT window 1, utilize described the first sampled point to cover the data that the interior tail length of described FFT window 1 is L, determine that the data in the FFT window 1 after afterbody is capped are offset data.

Or, the second phase compensation unit 4032, for intercepting CP tail length for the second sampled point of default lead L and the data in FFT window 2, described the second sampled point is the head of the data in described FFT window 2, described the second sampled point is cyclicly shift to described FFT window 2 afterbodys, determine by the second sampled point of head compensate to the data in the FFT window 2 of afterbody be offset data.

Can select to adopt above-mentioned two kinds of modes to carry out phase compensation, that is to say that phase compensation unit 403 can be equivalent to the first phase compensation unit 4031, also can be equivalent to the second phase compensation unit 4032, also can comprise the first phase compensation unit 4031 and the second phase compensation unit 4032 simultaneously, in carrying out the process of phase compensation, select to carry out one of them.

FFT unit 404, for described offset data is carried out to FFT conversion, obtains the frequency domain data of corresponding described offset data and is sent to data buffer zone.

Data buffer unit 405, for frequency domain data described in buffer memory.

Timing estimation unit 406, for obtaining the reference signal that is stored in frequency domain data in described data buffer zone, estimates time domain error regularly according to described reference signal, upgrades described timing point, and the described timing point after upgrading is sent to timing adjustment unit.

When above-mentioned unit excute phase compensation, detailed process can, with reference to the embodiment of the present invention one and the disclosed particular content of embodiment bis-, no longer repeat here.

On the basis of the default lead L of the disclosed execution of the invention described above, in the system of corresponding method disclosed by the invention, be provided with equally the unit that correspondence is obtained default lead L.Refer to shown in accompanying drawing 13, specifically comprise:

AD sampling unit 701, timing adjustment unit 702, phase compensation unit 703, FFT unit 704, data buffer unit 705, timing estimation unit 706, PSS sequence generating unit 707, low-pass filter unit 708 and first footpath estimation unit 709.

Above-mentioned AD sampling unit 701, timing adjustment unit 702, phase compensation unit 703, FFT unit 704, data buffer unit 705 and timing estimation unit 706 no longer repeat here with in Figure 12, disclosed unit is identical, can cross-references.

Wherein, this timing adjustment unit 702, the data acquisition sampling point that is also Len for length before the location positioning according to PSS place OFDM symbol, determines that described PSS place OFDM symbol and described data acquisition sampling point form first path search data segment, and exports the OFDM symbol of this PSS.The length of this head path search data segment is: L _seq+ Len; Wherein, the original position of described first path search data segment is T-Len, and T is timing point; L _seqlength for described PSS place OFDM symbol.

Low-pass filter unit 708, for the OFDM symbol of the PSS of timing adjustment unit 702 outputs is carried out to low-pass filter, filters the shared bandwidth of this PSS data in addition, and output sequence length is L _seqthe sequence Sr of+Len (n), n=0,1,2 ..., L _seq+ Len-1.

PSS sequence generating unit 707, for exporting local PSS sequence Sl (n), wherein, and n=0,1,2 ..., L _seq-1, described local PSS sequence length is L _seq.

First footpath estimation unit 709, for utilizing local PSS sequence and the described first path search data segment of above-mentioned low-pass filter unit 708 and 707 outputs of PSS sequence generating unit to carry out first path search, determines default lead L.

Method based on the disclosed phase compensation of the invention described above embodiment, for UE, there is the situation of many (more than two or two) reception antennas, the invention also discloses a kind of phase compensation device that comprises many group corresponding UE reception antennas, comprise the phase compensation device that number is identical with described reception antenna number, as shown in figure 14, in primary path, mainly comprise parallel many groups phase compensation device, wherein one group of phase compensation device comprises: AD sampling unit 1001, timing adjustment unit 1002, phase compensation unit 1003, FFT unit 1004, data buffer unit 1005 and timing estimation unit 1006.For whole Phase Compensation System, there is a timing estimation unit 1006, PSS sequence generating unit 1007, low-pass filter unit 1008, first footpath estimation unit 1009 and an antenna selected cell 1010.

Wherein, timing estimation unit 1006, low-pass filter unit 1008 and antenna selected cell 1010 can both be supported multiple signals input.

Wherein, antenna selected cell 1010, for receiving gain (gain) value of reception antenna AGC compensation use described in each road, and the gain (gain) that selects AGC minimum is worth the index value of corresponding reception antenna, using it as sky line options control signal, configure to described low-pass filter unit 1008 and described timing estimation unit 1006.

By above-mentioned antenna selected cell 1010, select the antenna that signal quality is good, select the reception antenna corresponding to gain of AGC minimum to illustrate that now the signal quality of this road antenna is best, its corresponding index value is sent to timing estimation unit 1006 and low-pass filter unit 1008, select Jiang Gai road signal as the calculating of inputting and participate in this unit, can greatly reduce amount of calculation, thereby further reduce the power consumption of system, improve the performance of whole system.

In sum:

The disclosed method of the above embodiment of the present invention and corresponding system thereof, by obtaining the OFDM symbol that comprises CP, and intercept length in CP for the sampled point of default lead L, data in FFT window are carried out to phase compensation, and obtain the offset data after above-mentioned processing, this offset data is carried out to FFT conversion.By said process, can reduce on the basis of intrasystem intersymbol interference, the phase rotating that the position of FFT window is caused in advance carries out phase compensation, can avoid its impact on the performance of channel estimating linear interpolation afterwards, thereby improve the performance of whole system.

In addition,, when the configuration for many antennas, the processing of only data of the antenna of selecting being correlated with, has greatly reduced amount of calculation, thereby has further reduced the power consumption of system, has improved the performance of whole system.

In this specification, each embodiment adopts the mode of going forward one by one to describe, and each embodiment stresses is the difference with other embodiment, between each embodiment identical similar part mutually referring to.For the disclosed device of embodiment, because it corresponds to the method disclosed in Example, so description is fairly simple, relevant part partly illustrates referring to method.

The software module that the method for describing in conjunction with embodiment disclosed herein or the step of algorithm can directly use hardware, processor to carry out, or the combination of the two is implemented.Software module can be placed in the storage medium of any other form known in random asccess memory (RAM), internal memory, read-only memory (ROM), electrically programmable ROM, electrically erasable ROM, register, hard disk, moveable magnetic disc, CD-ROM or technical field.

Above-mentioned explanation to the disclosed embodiments, makes professional and technical personnel in the field can realize or use the present invention.To the multiple modification of these embodiment, will be apparent for those skilled in the art, General Principle as defined herein can, in the situation that not departing from the spirit or scope of the present invention, realize in other embodiments.Therefore, the present invention will can not be restricted to these embodiment shown in this article, but will meet the widest scope consistent with principle disclosed herein and features of novelty.

Claims (13)

1. the phase compensating method in Long Term Evolution LTE system, is characterized in that, comprising:

According to timing point, obtain the orthogonal frequency division multiplex OFDM symbol that comprises cyclic prefix CP through analog-to-digital;

The sampled point that in intercepting CP, length is default lead L, carries out phase compensation to the data in fast Fourier transform FFT window, is compensated data;

Described offset data is carried out to FFT conversion, obtain the frequency domain data of corresponding described offset data and be sent to data buffer zone;

Obtain and be stored in the reference signal in frequency domain data in described data buffer zone, according to described reference signal, estimate time domain error regularly, upgrade described timing point;

Wherein, the described reference signal of described foundation is estimated time domain error regularly, and the detailed process of upgrading described timing point comprises:

In a descending sub frame, the channel response of the reference signal of the neighbouring same antenna port getting is carried out related calculation, and sue for peace, obtain the first correlation of each reference signal that is positioned at same antenna port;

Described the first correlation to same antenna port is sued for peace again, obtains the second correlation;

Described in conversion calculations, the value of the second correlation arc tangent, obtains timing offset;

Timing offset described in smothing filtering, obtains the new timing offset after level and smooth;

According to described new timing offset, adjust described timing point, obtain the timing point after renewal.

2. method according to claim 1, is characterized in that, the data in fast Fourier transform FFT window are compensated, and the detailed process that is compensated data comprises:

Intercepting CP tail length is the first sampled point of default lead L and the data in FFT window 1;

Utilize described the first sampled point to cover the data that the interior tail length of described FFT window 1 is L, determine that the data in the FFT window 1 after afterbody is capped are offset data.

3. method according to claim 1, is characterized in that, the data in fast Fourier transform FFT window are compensated, and the detailed process that is compensated data comprises:

Intercepting CP tail length is the second sampled point of default lead L and the data in FFT window 2, and described the second sampled point is the head of the data in described FFT window 2;

Described the second sampled point is cyclicly shift to described FFT window 2 afterbodys, determine by the second sampled point of head compensate to the data in the FFT window 2 of afterbody be offset data.

4. according to the method described in any one claim in claim 1～3, it is characterized in that, the preset procedures of described default lead L specifically comprises:

Obtain the position of main synchronizing symbol PSS place OFDM symbol, determine the data acquisition sampling point that length is Len above, and determine that described PSS place OFDM symbol and described data acquisition sampling point form first path search data segment, the length of described first path search data segment is: L _seq+ Len;

Wherein, the original position of described first path search data segment is T-Len, and T is timing point; L _seqlength for described PSS place OFDM symbol;

Data described in low-pass filter beyond the shared bandwidth of PSS, output sequence length is L _seqthe sequence Sr of+Len (n), n=0,1,2 ..., L _seq+ Len-1;

Export local PSS sequence Sl (n), n=0,1,2 ..., L _seq-1, described local PSS sequence length is L _seq;

Utilize described local PSS sequence and described first path search data segment to carry out first path search, determine default lead L.

5. method according to claim 4, is characterized in that, the process that generates described local PSS sequence comprises:

Under LTE system protocol, according to No. ID generation frequency domain PSS sequence of current service cell, described frequency domain PSS sequence comprises 62 data points, and length is 62;

In the centre position of described frequency domain PSS sequence, insert one 0 as direct current subcarrier, the frequency domain PSS sequence that formation length is 63;

Zero padding is carried out in the both sides of the frequency domain PSS sequence that is 63 to length, generates the length Fourier transform FFT corresponding with the current bandwidth identical new frequency domain PSS sequence of counting;

Described in fast Fourier transform IFFT, new frequency domain PSS sequence is to time domain;

Add CP being converted in the PSS sequence of time domain, generate local PSS sequence.

6. method according to claim 4, is characterized in that, the process of carrying out described first path search comprises:

Utilize described local PSS sequence Sl (n) to do slip related operation in described first path search data segment, obtain sequence of correlation values $\mathrm{corr}\_\mathrm{result}\left(n\right)=\underset{i=0}{\overset{L_{\mathrm{seq}}-1}{\mathrm{\Σ}}}\mathrm{Sr}(n+i)*\mathrm{conj}\left(\mathrm{Sl}\left(i\right)\right),$ N=0,1,2 ..., Len-1, wherein, conj () is for asking conjugate operation, and n is the original position of this search window, and i is sampling point index value, and the length of search window is L _seq, the length of slip is that search length is Len;

Ask described sequence of correlation values mould square, obtain correlation peak sequence peak_seq (n), this peak_seq (n)=|| corr_result (n) || ², n=0,1,2 ..., Len-1, wherein, n is the original position of this search window;

In described correlation peak sequence, search for the peak value that first surpasses default thresholding, be designated as i _fP;

Obtain described i _fPand the distance L between timing point _c, to described L _cdo smoothing processing, using the level and smooth result getting as default lead L.

7. method according to claim 1, is characterized in that, described LTE system is supported mobile terminal single antenna receiving mode.

8. method according to claim 7, is characterized in that, described LTE system is supported mobile terminal multi-antenna receiving mode;

According to the sky line options control signal that gets, a reception antenna under described many antenna receptions pattern is processed, and the processing mode of each the root reception antenna under described many antenna receptions pattern during with described single antenna receiving mode is identical;

Wherein, the acquisition process of described antenna selection signals comprises:

Receive the yield value that reception antenna automatic gain control and compensation is used described in each road, and select the index value of the reception antenna of corresponding minimum gain value, it is configured as sky line options control signal.

9. the Phase Compensation System in Long Term Evolution LTE system, is characterized in that, at least comprises the phase compensation device of one group of corresponding mobile terminal reception antenna, and described phase compensation device comprises:

Analog-to-digital conversion sampling unit, for carrying out to received signal analog-to-digital conversion;

Timing adjustment unit, for obtaining the orthogonal frequency division multiplex OFDM symbol that comprises cyclic prefix CP through analog-to-digital according to timing point;

Phase compensation unit, for intercepting CP length for the sampled point of default lead L, carries out phase compensation to the data in fast Fourier transform FFT window, is compensated data;

FFT converter unit, for described offset data is carried out to FFT conversion, obtains the frequency domain data of corresponding described offset data and is sent to data buffer zone;

Data buffer unit, for frequency domain data described in buffer memory;

Timing estimation unit, for obtaining the reference signal that is stored in frequency domain data in described data buffer zone, estimates time domain error regularly according to described reference signal, upgrades described timing point, and the described timing point after upgrading is sent to timing adjustment unit; Wherein, the described reference signal of described foundation is estimated time domain error regularly, and the detailed process of upgrading described timing point comprises:

In a descending sub frame, the channel response of the reference signal of the neighbouring same antenna port getting is carried out related calculation, and sue for peace, obtain the first correlation of each reference signal that is positioned at same antenna port;

Described the first correlation to same antenna port is sued for peace again, obtains the second correlation;

Described in conversion calculations, the value of the second correlation arc tangent, obtains timing offset;

Timing offset described in smothing filtering, obtains the new timing offset after level and smooth;

According to described new timing offset, adjust described timing point, obtain the timing point after renewal.

10. system according to claim 9, is characterized in that, described phase compensation unit comprises:

The first phase compensation unit, for intercepting CP tail length for the first sampled point of default lead L and the data in FFT window 1, utilize described the first sampled point to cover the data that the interior tail length of described FFT window 1 is L, determine that the data in the FFT window 1 after afterbody is capped are offset data;

Or, the second phase compensation unit, for intercepting CP tail length for the second sampled point of default lead L and the data in FFT window 2, described the second sampled point is the head of the data in described FFT window 2, described the second sampled point is cyclicly shift to described FFT window 2 afterbodys, determine by the second sampled point of head compensate to the data in the FFT window 2 of afterbody be offset data.

11. according to the system described in claim 9 or 10, it is characterized in that, also comprises: low-pass filter unit, PSS sequence generating unit and first footpath estimation unit;

Described timing adjustment unit, also for the position according to main synchronizing symbol PSS place OFDM symbol, determine the data acquisition sampling point that length is Len above, and determine that described PSS place OFDM symbol and described data acquisition sampling point form first path search data segment, the length of described first path search data segment is: L _seq+ Len; Wherein, the original position of described first path search data segment is T-Len, and T is timing point; L _seqlength for described PSS place OFDM symbol;

Low-pass filter unit, for the data beyond the shared bandwidth of PSS described in low-pass filter, output sequence length is L _seqthe sequence Sr of+Len (n), n=0,1,2 ..., L _seq+ Len-1;

PSS sequence generating unit, for exporting local PSS sequence Sl (n), n=0,1,2 ..., L _seq-1, described local PSS sequence length is L _seq;

First footpath estimation unit, for utilizing described local PSS sequence and described first path search data segment to carry out first path search, determines default lead L.

12. according to the system described in claim 11, it is characterized in that, described first footpath estimation unit comprises:

Slip correlation unit, for utilizing described local PSS sequence Sl (n) to do slip related operation in described first path search data segment, obtains sequence of correlation values corr_result (n), n=0, and 1,2 ..., Len-1;

Ask the squared unit of mould, for ask described sequence of correlation values mould square, obtain correlation peak sequence peak_seq (n);

Search unit, the peak value that surpasses default thresholding for search for first in described correlation peak sequence, is designated as i _fP;

Smooth unit, for obtaining described i _fPand the distance L between timing point _c, to described L _cdo smoothing processing, using the level and smooth result getting as default lead L.

13. according to the system described in claim 11, it is characterized in that, when mobile terminal exists multipath reception antenna, comprising: the described phase compensation device that number is identical with described reception antenna number;

Described low-pass filter unit has multiple signals input;

Antenna selected cell, for receiving the yield value that reception antenna automatic gain control and compensation is used described in each road, and select automatic gain to control the index value of the reception antenna that minimum yield value is corresponding, using it as sky line options control signal, configure to described low-pass filter unit and described timing estimation unit.