CN102271015B - A kind of blind search method of LTE system terminal frequency point and device - Google Patents
A kind of blind search method of LTE system terminal frequency point and device Download PDFInfo
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Abstract
The invention provides the blind search method of a kind of LTE system terminal frequency point and device, belong to moving communicating field, described method takes three-wave mixing method, the precise controlling that step-length reduces gradually reduces search band limits gradually, position repeatability and frequency continuity are guaranteed to move closer to real system frequency, utilize local master sync signal to do coherent detection while finding correct frequency, also obtain true local master sync signal and sync bit; The invention also discloses that a kind of LTE system terminal frequency point is blind searches device; Compared with prior art, the present invention effectively can resist the impact of noise and multipath, and in candidate's frequency, find the probability of correct frequency to promote more than 30%, frequency is blind searches time shorten more than 35%, greatly improves the blind performance of searching of frequency.
Description
Technical field
The invention belongs to moving communicating field, particularly the blind search method of a kind of TDD (time division duplex) LTE system terminal frequency point and device.
Background technology
Demand to data service is day by day increased in order to meet people, third generation partner program (The3rdgenerationPartnershipProject, 3GPP) start 3GPP " Long Term Evolution project ", be called for short 3GPPLTE (LongTermEvolution) project, this project is intended to the 3G system by continuous evolution, there is provided more powerful data service support, for user provides better service.According to the TDDLTE system frame structure of definition in 3GPP standard TS36.211 (R8), as shown in Figure 1, radio frames length is 10ms, corresponding 307200Ts.Each radio frames again Further Division is the field of two 5ms, and each field comprises 5 1ms subframes.If the system up-downgoing transfer point cycle is 5ms; second subframe then in each field is special subframe, and order comprises descending pilot frequency time slot (referred to as DwPTS), main protection interval (referred to as GP), uplink pilot time slot (referred to as UpPTS).Described DwPTS, GP, UpPTS are respectively used to cell ID and initial synchronisation is set up, provide up-downgoing to protect interval and uplink synchronous.If the system up-downgoing transfer point cycle is 10ms, then special subframe exists only in the first field in radio frames.In each field, 5 subframes, except special subframe, also comprise conventional subframe, comprise again two 0.5ms time slots in each conventional subframe.Each subframe label i=0 ~ 9 in radio frames, the administrative slot index of each conventional subframe is respectively 2i, 2i+1.Subframe 0,5, DwPTS all the time for downlink transfer, and after special subframe conventional subframe immediately and UpPTS all the time for uplink.
The information such as sequence generation, resource mapping of 3GPP standard TS36.211 (R8) to LTE system primary and secondary synchronizing signal has carried out clear stipulaties.The synchronous frequency domain sequence of primary and secondary by relevant with cell ID (master sync signal sequence generate only with cell set in identify relevant, subsynchronous burst generates to be determined jointly by identifying in cell ID group and cell set) known manner generate, and map to each 31 sub-carrier positions in direct current carrier both sides, after symmetrical increase reserved protection subcarrier, OFDM time-domain symbol is generated through OFDM modulation, master sync signal is arranged in the 3rd OFDM symbol of Subframe#1 and Subframe#6 first time slot, there is position repeatability within the 5ms cycle, may be used for that frequency is blind to be searched and initial cell search, subsynchronous signal is arranged in last OFDM symbol of subframe #0 and subframe #5 second time slot.According to TS36.211, in LTE TDD system, physical-layer cell identifier has 504, and consider the control identifying complexity, described 504 cell IDs are divided into 168 physical-layer cell identifier groups, each group comprises mark in 3 groups, and described grouping can use following formula directviewing description:
Wherein,
respective cell identified group, span 0 ~ 167;
mark in corresponding group, span 0 ~ 2; The cell ID group class that each community is corresponding unique.
Frequency domain master sync signal is Zadoff-Chu sequence, is generated by following formula:
Wherein, u is determined by following table 1:
Table 1
with the corresponding relation of u
From upper table 1, mark in the group of master sync signal essence respective cell.
Subcarrier mapping aspect, master's synchronous frequency domain sequence order of 62 maps on each 31 subcarriers in DC both sides, and available following formula is intuitively shown out:
a
k，l＝d(n)，n＝0，...，61
Wherein, d (n) is master sync signal frequency domain sequence, a
k, lcorresponding Resource Unit, the OFDM symbol subscript at 1 corresponding master sync signal place.
n＝-5，-4，...，-1，62，63，...66
By above formula, the OFDM symbol subcarrier upper limit that master sync signal is corresponding is 72, and the relation table in conjunction with transmission bandwidth and the subcarrier upper limit is known, and master sync signal uses system lowest-bandwidth to send.
Blind the searching of full frequency band frequency point refers to that UE (communication terminal) is when starting shooting or lose the network coverage, terminal when do not have serving base station cell prior information or search prestore community failure, attempt the activity receiving in band limits search effective Serving cell working frequency points of carrying out at it.The concentrated reflection of its result meets effective working frequency points region of resident condition, is that UE successfully can access the key with persistent district.
3GPP gives the frequency spectrum planning proposal of LTE system, the available spectrum resources of TDDLTE system is defined from 15M-100MHz in standard TS36.101 (R8), viewing system configures and determines, and points out that possible bandwidth of operation set is [1.4,3 simultaneously, 5,10,15,20] MHz, channel grid is 100KHz, and namely real work frequency is the integral multiple of 100KHz.Assuming that system available spectrum resources is 100MHz to the maximum, if so carry out a frequency search at interval of 100KHz, 100MHz/100KHz=1000, namely 1001 frequency search are needed, if frequency search needs radio frames (10ms) each time, so at least need 10s, the frequency blind time of searching is oversize, cause access Cell time oversize, have impact on the overall performance of UE significantly.Application number be 200810187530.6 Chinese patent provide a kind of evolution system full frequency band frequency point scanning method and device, it takes two-step method to carry out, and frequency is blind searches, the first step is the received signal strength indicator (ReceivedSignalStrengthIndicator utilizing a subframe or radio frame signal, being called for short RSSI) quick position is to the maximum frequency point ranges of one section of possibility, reduce the blind scope of searching of frequency, second step is in this section of frequency point ranges selected, utilize the position of the interval scan strategic orientation master sync signal of low complex degree, and using the peak value of the synchronous related power of the master of two fields as frequency measured value, carried out the data fitting of full frequency band measured value simultaneously, final comprehensive master sync signal positional information obtains the list of rational candidate's frequency with the peak value of main synchronous related power, for UE fast resident providing provide powerful support for.But, when the method exists following problems and shortcomings: the skew 1) effectively cannot resisting the synchronous correlated power peak of master that frequency selective fading is brought, the peak value of the synchronous related power of master of current frequency blind search algorithm Main Basis two fields, and frequency selective fading can cause the distortion of master sync signal frequency spectrum, cause in frequency hunting zone, the peak value of main synchronous correlation power value, not in the position of correct frequency, creates skew within the specific limits.Again because adopt interval scan strategy, cause correct frequency to be positioned at candidate's frequency list tail end, or not in the list of candidate's frequency, add the time of access community, finally cause UE overall performance and decline; 2) shared by master sync signal, bandwidth is only 1.4MHz, take into account that frequency is blind searches performance and low complex degree requirement, adopt lower grid interval scan, step-length is 200KHz, so under the prerequisite completing the first step (scanning band is 20MHz), at least need 20M/200K=100 radio frames, i.e. 1s, consider to resist white Gaussian noise, improve performance, each scanning frequency may need multiple radio frames to add up, and which increases the frequency blind time of searching, and asks when elongating community access.
Summary of the invention
Technical problem solved by the invention be to propose a kind of reduce blindly search the time, improve blindly search accuracy rate, the blind search method of frequency that multipath fading environments can be resisted and device.
For overcoming the above problems, the invention provides the blind search method of a kind of LTE system terminal frequency point, comprising:
The first step: terminal is receiving a radio frames long data at interval of on the frequency of step-length A1, calculates it and receives information strength instruction RSSI, find out the frequency F1 that RSSI is maximum, select the frequency of its left and right X1 centered by this frequency, generated frequency range L ocal1;
Second step: in selection frequency point ranges Local1, a radio frames long data is being received at interval of on the frequency of step-length A2, these data are divided into two isometric fields, calculate the performance number of two field long data slip correlations, obtain the power maximum of correlation and the position in this radio frames thereof, all frequencies are selected possibility frequency F2, and the synchronous rough position P2 of the validity master of correspondence, centered by frequency F2, select the frequency range Local2 of its left and right X2;
3rd step: in selection frequency point ranges Local2, receiving a radio frames long data at interval of on the frequency of step-length 100KHz, therefrom get length 128TS data, with local master sync signal
calculate the performance number of slip correlation, detect maximum power value, retain
and the position corresponding to maximum power value is recorded as main synchronous rough position; After searching for all frequencies, obtain the maximum performance number of all frequencies, search for the maximum of the maximum performance number of all frequencies, by frequency corresponding to it and about it two frequencies be added into the list of candidate's frequency, obtain the list of candidate's frequency;
Wherein, A1 value is that 2-5MHz, A2 get scope [200,500] KHz, X1=N1 × A1, N1=1,2,3 or 4, X2=N2 × A2, N2=1,2,3 or 4.
Preferably, described in the first step when system available spectrum resources is 100MHz, interval steps A1 value 5MHz; When system available spectrum resources is 15MHz, interval steps A1 value 2MHz.
Preferably, after second step calculates the performance number of two field long correlation values, before obtaining the power peak of correlation, the above radio frames of two frames is carried out to result of calculation and adds up.
Preferably, second step selects possibility frequency F2 on all frequencies, and the synchronous rough position P2 of the validity master of correspondence, comprises further:
A) scan all frequencies, obtain frequency correlation peak array p_freq and frequency master sync signal position array pos_freq;
B) screen in pos_freq the main sync bit possessing position repeatability, namely filter out the main sync bit that at least count1 position difference is no more than 1;
C) possess the successional main sync bit of frequency in screening pos_freq, from above main sync bit, namely filter out at least count2 frequency sequence number continuous print frequency sequence number further, these points are effective frequency;
D) frequency range Effective judgement, if effectively frequency quantity is less than count3, then blindly searches unsuccessfully, returns to the first step of the present invention; Otherwise enter step e;
E) correlation peak that invalid frequency in frequency correlation peak array p_freq (removing the frequency sequence number after effective frequency) is corresponding is set to 0, and the maximum detected in correlation peak array p_freq, frequency corresponding to maximum is possible frequency F2, and its position is the corresponding synchronous rough position P2 of validity master;
Wherein, count1 span 1-3, count2 value 1-3, count3 span 2-4.
Preferably, in step e) also comprise before, the step of effective frequency singular value point correction:
When effective frequency sequence number left and right two frequency bins is all effective, middle frequency is also set to effectively, and main sync bit corresponding for middle frequency is set to the main sync bit of previous frequency, obtain the revised effective frequency of singular value point, invalid frequency in frequency master sync signal position array pos_freq (removing the frequency sequence number after effective frequency) respective value is set to 0, obtains the revised main sync bit of singular value point.
Preferably, in step e) before, low-pass filtering is implemented to p_freq;
Preferably, may frequency F2 and have more than two by the frequency range Local2 that it is determined described in second step.
Preferably, in the maximum of the maximum performance number of all frequencies of search described in 3rd step, after two frequencies are added into the list of candidate's frequency by frequency corresponding to it with about it, comprise the step utilizing plots peak search strategy to search for other candidate's frequency further, comprising:
Region of search peak value in p_freq_precise, namely current frequency maximum is greater than its last frequency maximum and a frequency maximum thereafter, will meet the frequency of this condition stored in area_peak;
If comprise the maximum frequency in p_freq_precise in area_peak, then it is removed from area_peak, otherwise do not do any operation;
By the descending order of performance number, in search area_peak, these these frequencies and left and right two frequency thereof are added into candidate's frequency list freq_candidate_precise by two or more frequencies of corresponding p_freq_precise respectively.
For overcoming the above problems, the present invention also provides that a kind of LTE system terminal frequency point is blind searches device, comprising:
Frequency control unit: determine to search for frequency range, to determine that step-length determines to receive the frequency of data;
Wireless frame data receiving element: receive radio frames long data on the frequency determined;
RSSI computing unit: calculate the information strength instruction RSSI that it receives wireless frame data;
Correlator: slip correlation computations is done to two segment datas, and calculate the performance number of correlation;
Effective value screening unit: the correlation peak array p_freq of each frequency and frequency master sync signal position array pos_freq is judged, filtering out effectively may frequency F2 and the synchronous rough position P2 of validity master; It comprises further:
Position repeatability judging unit: possess the main sync bit of position repeatability in screening pos_freq, namely filters out the main sync bit that at least count1 position difference is no more than 1;
Frequency continuity judging unit: possess the successional main sync bit of frequency in screening pos_freq, namely filter out at least count2 frequency sequence number continuous print frequency sequence number further from above main sync bit, these points are effective frequency;
Frequency range Effective judgement unit: judge whether effective frequency sequence number quantity is less than count3
Wherein, count1 span 1-3;
Comparing unit: the maximum finding wireless frame data RSSI value on each frequency, determines the frequency F1 of this maximum, selects the frequency of its left and right X1 centered by this frequency, generated frequency range L oca11, be transferred to frequency control unit; Or find the maximum of performance number and the position in radio frames of this maximum of two segment data slip correlations on each frequency, all frequencies are selected possibility frequency F2, and the synchronous rough position P2 of the validity master of correspondence, centered by frequency F2, select the frequency range Local2 of its left and right X2, be transferred to frequency control unit; Or find the maximum of the performance number of 128TS data slip correlation on each frequency, by frequency corresponding to it and about it two frequencies be added into the list of candidate's frequency, pass to candidate's frequency list cell;
Candidate's frequency list cell: preserve the list of candidate's frequency;
Further, comprise accumulator, after calculating the performance number of two segment data correlations, before obtaining the power peak of correlation, the above radio frames of two frames is carried out to result of calculation and adds up;
Further, effective value screening unit also comprises, singular value point amending unit, when effective frequency sequence number left and right two frequency bins is all effective, middle frequency is also set to effectively, and main sync bit corresponding for middle frequency is set to the main sync bit of previous frequency, obtain the revised effective frequency of singular value point, invalid frequency in frequency master sync signal position array pos_freq (removing the frequency sequence number after effective frequency) respective value is set to 0, obtains the revised main sync bit of singular value point;
Further, effective value screening unit also comprises, and low-pass filter unit, implements low-pass filtering to p_freq.
The present invention takes three-wave mixing method, the precise controlling that step-length reduces gradually reduces search band limits gradually, position repeatability and frequency continuity are guaranteed to move closer to real system frequency, utilize local master sync signal to do coherent detection while finding correct frequency, also obtain true local master sync signal and sync bit; Compared with prior art, the present invention effectively can resist the impact of noise and multipath, and in candidate's frequency, find the probability of correct frequency to promote more than 30%, frequency is blind searches time shorten more than 35%, greatly improves the blind performance of searching of frequency.
Accompanying drawing explanation
Fig. 1 is TDDLTE system frame structure;
Fig. 2 is the blind search method flow chart of LTE system terminal frequency point of the present invention;
To be that LTE system terminal frequency point of the present invention is blind search device preferred embodiment structure chart to Fig. 3;
Fig. 4 is effective value of the present invention screening unit preferred embodiment structure chart
Fig. 5 is another preferred embodiment structure chart of effective value of the present invention screening unit
To be that LTE system terminal frequency point of the present invention is blind search another preferred embodiment structure chart of device to Fig. 6;
Embodiment
Clearly understand to make object of the present invention, technical scheme and advantage, below in conjunction with drawings and Examples, be described in further detail the blind search method of LTE system terminal frequency point and device, known implementation no longer describes in detail, to avoid there is unnecessary obscuring with content of the present invention.
The invention provides the blind search method of a kind of LTE system terminal frequency point, comprising:
The first step: terminal is receiving a radio frames at interval of on the frequency of step-length A1, calculates received signal strength indicator RSSI, finds out the frequency F1 that RSSI is maximum, select its left and right X1 centered by frequency, determine second step band scan range L ocal1;
In system available spectrum resources Uf, at interval of a larger step-length A1, receive a radio frames, and calculate its received signal strength indicator RSSI:
RSSI(k)＝abs(real(data
k))
2+abs(imag(data
k))
2
Wherein, data is a radio frames, and k represents the frequency sequence number of scanning, k=1,2 ..., Uf/A1+1;
Select the frequency that RSSI is maximum, centered by this frequency, the frequency range of delimiting each X1 in left and right is second step band scan range L ocal1, is expressed as [F1-X1, F1+X1], X1=N1 × A1, N1=1,2,3 or 4;
The present embodiment system available spectrum resources is 100MHz, step-length A1 be 2.5MHz, N1 is 2, and determining that second step frequency range describes scope is 10MHz;
Second step: in selection frequency point ranges Local1, receiving a radio frames long data at interval of on the frequency of step-length A2, calculating the performance number of two field long data correlations, obtaining the power peak of correlation and the position in this radio frames thereof, all frequencies are selected possibility frequency F2, mark its position P2, centered by frequency F2, select the frequency range Local2 of its left and right X2, be expressed as [F2-X2, F2+X2], X2=N2 × A2, N2=1,2,3 or 4, comprise further:
In the 10MHz band limits that previous step is determined, with step-length A2 for step-length carries out frequency point scanning, frequency receives a radio frames, and be divided into two fields, utilize the master sync signal of LTE system two fields to have position repeatability, with sliding step SL, slip is carried out to the signal of two fields and is correlated with, calculate the performance number of correlation, the power peak obtaining correlation is master sync signal correlation peak, and the position of peak value is master sync signal position;
Wherein, A2 value [200,500] KHz, sliding step SL value [16,64] TS; The present embodiment A2 is 400KHz, and sliding step SL is 32Ts, Ts=1/30.72MHz;
Preferably, after calculating the performance number of correlation, before obtaining the power peak of correlation, multiple radio frames is carried out on result of calculation and adds up and can resist the impact of noise and multipath further; The present embodiment radio frames that adds up is 4;
All frequencies are selected possibility frequency F2, and the synchronous rough position P2 of the validity master of correspondence, comprise further:
A) scan all frequencies, obtain frequency correlation peak array p_freq and frequency master sync signal position array pos_freq;
B) screen in pos_freq the main sync bit possessing position repeatability, namely filter out the main sync bit that at least count1 position difference is no more than 1;
C) possess the successional main sync bit of frequency in screening pos_freq, from above main sync bit, namely filter out at least count2 frequency sequence number continuous print frequency sequence number further, these points are effective frequency;
Wherein, count1 span 1-3, count2 value 1-3, the present embodiment count1 value 2, count2 value 2;
Illustrate below: suppose there are 9 frequency sequence numbers, the main sync bit that each frequency is corresponding is as shown in the table;
| Frequency sequence number | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |
| Main sync bit | 30 | 57 | 69 | 56 | 70 | 70 | 70 | 152 | 70 |
In this example, the position of the 3rd, 5,6,7,9 some correspondence is 69 or 70, then the 3rd, 5,6,7,9 point just possesses position repeatability; Then in these points selected, remove discontinuous 3rd, 9 point of frequency sequence number, select continuous print point, i.e. the 5th, 6,7 points in frequency, possess frequency continuity.
Preferably, can carry out frequency continuous modification further to the main sync bit in pos_freq, the point being about to simultaneously meet position repeatability and 2 the frequency sequence numbers in frequency successional some interval is set to effective frequency;
Because of the impact by external environment, have some frequencies in frequency may with meet position repeatability and frequency 2, successional some interval frequency simultaneously, thus lead to errors, these are put in fact also should meet repeatability and continuity, therefore, these points are set to effective frequency; Sequence number as previous example is the frequency of 3,9; Be set to effective frequency, therefore effectively frequency sequence number is: 3,5,6,7,9.
D) frequency range Effective judgement
If effectively frequency quantity is less than count3, then blindly search unsuccessfully, return to the first step of the present invention; Otherwise enter step e; Count3 span 2-4, the present embodiment is 3;
E) correlation peak that invalid frequency in frequency correlation peak array p_freq (removing the frequency sequence number after effective frequency) is corresponding is set to 0, and the maximum detected in correlation peak array p_freq, frequency corresponding to maximum is possible the synchronous rough position P2 of validity master of frequency F2 and correspondence thereof
Preferably, in step e) also comprise before, the step of effective frequency singular value point correction:
When effective frequency sequence number left and right two frequency bins is all effective, middle frequency is also set to effectively, and main sync bit corresponding for middle frequency is set to the main sync bit of previous frequency, obtain the revised effective frequency of singular value point, invalid frequency in frequency master sync signal position array pos_freq (removing the frequency sequence number after effective frequency) respective value is set to 0, obtains the revised main sync bit of singular value point;
As example above, because sequence number is 3 and 5 all effective, then frequency sequence number 4 is singular value point, is modified to effective frequency, in like manner, frequency sequence number 8 is modified to effective frequency, and therefore, the revised effective frequency of singular value point is 3,4,5,6,7,8,9; The revised main sync bit of singular value point be expressed as into:
| Frequency sequence number | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |
| Main sync bit | 0 | 0 | 69 | 69 | 70 | 70 | 70 | 70 | 70 |
Preferably, in step e) before, implement low-pass filtering to p_freq, concrete steps are:
1) FFT conversion is carried out to p_freq, obtain its frequency spectrum;
2) low pass filter is set, carries out low-pass filtering, obtain result
First defining ideal low-pass filter frequency responds the Nx that counts: arrange low pass filter parameter:
H＝[ones(1，Nx)zeros(1，2
n-2×Nx)ones(1，Nx)]
Wherein, ones (1, Nx) represents that length is the row vector of Nx, zeros (1,2
n-2 × Nx) represent that length is 2
nthe row vector of-2 × Nx; Why filter will define 2
npoint is because FFT easy to use realizes; Low pass filter bandwidth is set to Nx because obtained by the Sa Functional Analysis obtained after carrying out FFT conversion to the correlation peak array do not connect through channel and noise; FFT conversion is known technology, no longer detailed at this.
Then carry out low-pass filtering, obtain result
p_filter＝real(ifft(p_freq·＊H))
Wherein, real represents and gets real part computing, intercepts 1st ~ 2 of p_filter
n-2 × Nx point;
3rd step: in selection frequency point ranges Local2, a radio frames long data is being received at interval of on the frequency of step-length 100KHz, therefrom get X3 length 128TS data with step-length 1-2TS, 3 the local master sync signals being 128TS with length calculate the performance number of slip correlation, from the performance number of three slip correlations, detect maximum power value; Obtain X3 maximum power value; Then from X3 maximum power value, again detect maximum, and retain
with main synchronous rough position; Search for the maximum in the maximum performance number array p_freq_precise of all frequencies, by frequency corresponding to it and about it two frequencies be added in candidate's frequency list freq_candidate_precise;
Wherein, the starting position of getting X3 length 128TS data is P2, P2-32 or P2-64;
Further, in the maximum of maximum performance number of all frequencies of search, by frequency corresponding to it with after two frequencies are added into the list of candidate's frequency about it, comprise further and utilize plots peak search strategy to search for other candidate's frequency, comprising:
Region of search peak value in p_freq_precise, namely current frequency maximum is greater than its last frequency maximum and a frequency maximum thereafter, will meet the frequency of this condition stored in area_peak;
If comprise the maximum frequency in p_freq_precise in area_peak, then it is removed from area_peak, otherwise do not do any operation;
By the descending order of performance number, in search area_peak, these these frequencies and left and right two frequency thereof are added into candidate's frequency list freq_candidate_precise by two or more frequencies of corresponding p_freq_precise respectively.
Further, the master of all frequencies in the list of candidate's frequency and correspondence thereof is synchronously correlated with performance number reporting to high-rise.
The present invention also provides that a kind of LTE system terminal frequency point is blind searches device, comprising:
Frequency control unit: determine to search for frequency range, to determine that step-length determines to receive the frequency of data;
Wireless frame data receiving element: receive radio frames long data on the frequency determined;
RSSI computing unit: the reception information strength instruction RSSI calculating wireless frame data;
Correlator: slip correlation computations is done to two segment datas, and calculate the performance number of correlation;
Effective value screening unit: the correlation peak array p_freq of each frequency and frequency master sync signal position array pos_freq is judged, filtering out effectively may frequency F2 and the synchronous rough position P2 of validity master; It comprises further:
Position repeatability judging unit: possess the main sync bit of position repeatability in screening pos_freq, namely filters out the main sync bit that at least count1 position difference is no more than 1;
Frequency continuity judging unit: possess the successional main sync bit of frequency in screening pos_freq, namely filter out at least count2 frequency sequence number continuous print frequency sequence number further from above main sync bit, these points are effective frequency;
Frequency range Effective judgement unit: judge whether effective frequency sequence number quantity is less than count3
Wherein, count1 span 1-3;
Comparing unit: the maximum finding wireless frame data RSSI value on each frequency, determines the frequency F1 of this maximum, selects the frequency of its left and right X1 centered by this frequency, generated frequency range L ocal1, be transferred to frequency control unit; Or find the maximum of performance number and the position in radio frames of this maximum of two segment data slip correlations on each frequency, all frequencies are selected possibility frequency F2, and the synchronous rough position P2 of the validity master of correspondence, centered by frequency F2, select the frequency range Local2 of its left and right X2, be transferred to frequency control unit; Or find the maximum of the performance number of 128TS data slip correlation on each frequency, by frequency corresponding to it and about it two frequencies be added into the list of candidate's frequency, pass to candidate's frequency list cell;
Candidate's frequency list cell: preserve the list of candidate's frequency;
Further, comprise accumulator, after calculating the performance number of two segment data correlations, before obtaining the power peak of correlation, the above radio frames of two frames is carried out to result of calculation and adds up;
Further, effective value screening unit also comprises, singular value point amending unit, when effective frequency sequence number left and right two frequency bins is all effective, middle frequency is also set to effectively, and main sync bit corresponding for middle frequency is set to the main sync bit of previous frequency, obtain the revised effective frequency of singular value point, invalid frequency in frequency master sync signal position array pos_freq (removing the frequency sequence number after effective frequency) respective value is set to 0, obtains the revised main sync bit of singular value point;
Further, effective value screening unit also comprises, low-pass filter unit, and implement low-pass filtering to p_freq, it comprises further:
FFT arithmetic unit: carry out FFT conversion to p_freq, obtains its frequency spectrum;
Low pass filter, arranges low pass filter parameter, carries out low-pass filtering, obtains result
First defining ideal low-pass filter frequency responds the Nx that counts: arrange low pass filter parameter:
H＝[ones(1，Nx)zeros(1，2
n-2×Nx)ones(1，Nx)]
Wherein, ones (1, Nx) represents that length is the row vector of Nx, zeros (1,2
n-2 × Nx) represent that length is 2
nthe row vector of-2 × Nx; Why filter will define 2
npoint is because FFT easy to use realizes; Low pass filter bandwidth is set to Nx because obtained by the Sa Functional Analysis obtained after carrying out FFT conversion to the correlation peak array do not connect through channel and noise; FFT conversion is known technology, no longer detailed at this.
Then carry out low-pass filtering, obtain result
p_filter＝real(ifft(p_freq·＊H))
Wherein, real represents and gets real part computing, intercepts 1st ~ 2 of p_filter
n-2 × Nx point;
The present invention has carried out further detailed description for execution mode or embodiment to the object, technical solutions and advantages of the present invention; be understood that; above lifted execution mode or embodiment are only the preferred embodiment of the present invention; not in order to limit the present invention; all any amendments made for the present invention within the spirit and principles in the present invention, equivalent replacement, improvement etc., all should be included within protection scope of the present invention.
Claims (11)
1. the blind search method of LTE system terminal frequency point, is characterized in that, comprising:
The first step: terminal is receiving a radio frames long data at interval of on the frequency of step-length A1, calculates it and receives information strength instruction RSSI, find out the frequency F1 that RSSI is maximum, select the frequency of its left and right X1 centered by this frequency, generated frequency range L ocal1;
Second step: in selection frequency point ranges Local1, a radio frames long data is being received at interval of on the frequency of step-length A2, these data are divided into two isometric fields, calculate the performance number of two field long data slip correlations, obtain the power maximum of correlation and the position in this radio frames thereof, all frequencies are selected possibility frequency F2, and the synchronous rough position P2 of the validity master of correspondence, centered by frequency F2, select the frequency range Local2 of its left and right X2;
3rd step: in selection frequency point ranges Local2, receiving a radio frames long data at interval of on the frequency of step-length 100KHz, therefrom get length 128TS data, with local master sync signal
calculate the performance number of slip correlation, detect maximum power value, retain
and the position corresponding to maximum power value is recorded as main synchronous rough position; After searching for all frequencies, obtain the maximum performance number of all frequencies, search for the maximum of the maximum performance number of all frequencies, by frequency corresponding to it and about it two frequencies be added into the list of candidate's frequency, obtain the list of candidate's frequency;
Wherein, A1 value is that 2-5MHz, A2 get scope [200,500] KHz, X1=N1 × A1, N1=1,2,3 or 4, X2=N2 × A2, N2=1,2,3 or 4;
Described second step selects possibility frequency F2 on all frequencies, and the synchronous rough position P2 of the validity master of correspondence, comprises further:
A) scan all frequencies, obtain frequency correlation peak array p_freq and frequency master sync signal position array pos_freq;
B) screen in pos_freq the main sync bit possessing position repeatability, namely filter out the main sync bit that at least count1 position difference is no more than 1;
C) possess the successional main sync bit of frequency in screening pos_freq, from above main sync bit, namely filter out at least count2 frequency sequence number continuous print frequency sequence number further, these points are effective frequency;
D) frequency range Effective judgement, if effectively frequency quantity is less than count3, then blindly searches unsuccessfully, returns to the first step of the present invention; Otherwise enter step e;
E) correlation peak corresponding for invalid frequency in frequency correlation peak array p_freq is set to 0, and the maximum detected in correlation peak array p_freq, frequency corresponding to maximum is possible frequency F2, and its position is the corresponding synchronous rough position P2 of validity master;
Wherein, count1 span 1-3, count2 value 1-3, count3 span 2-4.
2. the blind search method of terminal frequency point as claimed in claim 1, is characterized in that, in the first step when system available spectrum resources is 100MHz, and interval steps A1 value 5MHz; When system available spectrum resources is 15MHz, interval steps A1 value 2MHz.
3. the blind search method of terminal frequency point as claimed in claim 1, is characterized in that, after second step calculates the performance number of two field long correlation values, before obtaining the power peak of correlation, carries out the above radio frames of two frames add up to result of calculation.
4. the blind search method of terminal frequency point as claimed in claim 1, is characterized in that, in step e) before also comprise, the step of effective frequency singular value point correction:
When effective frequency sequence number left and right two frequency bins is all effective, middle frequency is also set to effectively, and main sync bit corresponding for middle frequency is set to the main sync bit of previous frequency, obtain the revised effective frequency of singular value point, frequency respective value invalid in frequency master sync signal position array pos_freq is set to 0, obtains the revised main sync bit of singular value point.
5. the blind search method of terminal frequency point as claimed in claim 1, is characterized in that, in step e) before, low-pass filtering is implemented to p_freq.
6. the blind search method of terminal frequency point as claimed in claim 1, is characterized in that, may frequency F2 and have more than two by the frequency range Local2 that it is determined described in second step.
7. the blind search method of terminal frequency point as claimed in claim 1, it is characterized in that, in the maximum of the maximum performance number of all frequencies of search described in 3rd step, after by frequency corresponding to it with about it, two frequencies are added into the list of candidate's frequency, comprise the step utilizing plots peak search strategy to search for other candidate's frequency further, comprising:
Region of search peak value in the maximum performance number p_freq_precise of all frequencies, namely current frequency maximum is greater than its last frequency maximum and a frequency maximum thereafter, will meet the frequency of this condition stored in area_peak;
If comprise the maximum frequency in p_freq_precise in area_peak, then it is removed from area_peak, otherwise do not do any operation;
By the descending order of performance number, in search area_peak, these these frequencies and left and right two frequency thereof are added into candidate's frequency list freq_candidate_precise by two or more frequencies of corresponding p_freq_precise respectively.
8. LTE system terminal frequency point is blind searches a device, it is characterized in that, comprising:
Frequency control unit: determine to search for frequency range, determine with step-length A2 the frequency receiving data;
Wireless frame data receiving element: receive radio frames long data on the frequency determined;
RSSI computing unit: calculate the information strength instruction RSSI that it receives wireless frame data;
Correlator: slip correlation computations is done to two fields that radio frames is divided into, and calculates the performance number of correlation;
Effective value screening unit: the correlation peak array p_freq of each frequency and frequency master sync signal position array pos_freq is judged, filtering out effectively may frequency F2 and the synchronous rough position P2 of validity master, and it comprises further:
Position repeatability judging unit: possess the main sync bit of position repeatability in screening pos_freq, namely filters out the main sync bit that at least count1 position difference is no more than 1;
Frequency continuity judging unit: possess the successional main sync bit of frequency in screening pos_freq, namely filter out at least count2 frequency sequence number continuous print frequency sequence number further from above main sync bit, these points are effective frequency;
Frequency range Effective judgement unit: if effectively frequency quantity is less than count3, then blindly search unsuccessfully, wherein count3 span 2-4;
Comparing unit: the maximum finding wireless frame data RSSI value on each frequency, determines the frequency F1 of this maximum, selects the frequency of its left and right X1 centered by this frequency, generated frequency range L ocal1, be transferred to frequency control unit; Find the maximum of performance number and the position in radio frames of this maximum of two segment data slip correlations on each frequency, all frequencies are selected possibility frequency F2, and the synchronous rough position P2 of the validity master of correspondence, centered by frequency F2, select the frequency range Local2 of its left and right X2, be transferred to frequency control unit; Find the maximum of the performance number of 128TS data slip correlation on each frequency, by frequency corresponding to it and about it two frequencies be added into the list of candidate's frequency, pass to candidate's frequency list cell;
Candidate's frequency list cell: preserve the list of candidate's frequency.
9. terminal frequency point is blind as claimed in claim 8 searches device, it is characterized in that, also comprises:
Accumulator, after calculating the performance number of two segment data correlations, before obtaining the power peak of correlation, carries out the above radio frames of two frames to result of calculation and adds up.
10. terminal frequency point is blind as claimed in claim 8 searches device, it is characterized in that, effective value screening unit also comprises:
Singular value point amending unit, when effective frequency sequence number left and right two frequency bins is all effective, middle frequency is also set to effectively, and main sync bit corresponding for middle frequency is set to the main sync bit of previous frequency, obtain the revised effective frequency of singular value point, frequency respective value invalid in frequency master sync signal position array pos_freq is set to 0, obtains the revised main sync bit of singular value point.
11. terminal frequency point is blind as claimed in claim 8 search device, it is characterized in that, effective value screening unit also comprises:
Low-pass filter unit, implements low-pass filtering to correlation peak array p_freq.
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| CN103428819A (en) * | 2012-05-24 | 2013-12-04 | 富士通株式会社 | Carrier frequency point searching method and device |
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| CN103259755B (en) * | 2013-04-08 | 2016-02-10 | 东南大学 | A kind of universe covers the main synchronizing sequence method for designing of multi-beam satellite LTE |
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| CN103957556B (en) * | 2014-04-17 | 2017-04-05 | 京信通信系统（广州）有限公司 | LTE signal detecting methods and system |
| CN105704783B (en) * | 2014-11-24 | 2019-06-14 | 中国移动通信集团公司 | A kind of sweep interval is determining and terminal frequency sweeping method, device and terminal |
| CN106341865A (en) * | 2015-07-10 | 2017-01-18 | 深圳市中兴微电子技术有限公司 | Accurate sweep frequency method, device and terminal |
| CN106470462B (en) * | 2015-08-17 | 2019-11-15 | 深圳市中兴微电子技术有限公司 | A kind of frequency sweeping method, device and terminal |
| CN107509236A (en) * | 2016-06-14 | 2017-12-22 | 展讯通信（上海）有限公司 | A kind of manual method for searching network, device and mobile terminal |
| CN108811044B (en) * | 2017-04-28 | 2021-01-26 | 深圳市中兴微电子技术有限公司 | Frequency scanning method and device for small-bandwidth communication system |
| CN109525524B (en) * | 2018-06-28 | 2020-07-17 | 大唐联仪科技有限公司 | Signal synchronization method and device |
| CN112235219B (en) * | 2020-10-14 | 2023-02-10 | 紫光展锐(重庆)科技有限公司 | Timing synchronization detection method and device |
| CN116963298A (en) * | 2022-04-15 | 2023-10-27 | 华为技术有限公司 | Communication method and device |
| CN115866716B (en) * | 2023-02-13 | 2023-05-23 | 北京智联安科技有限公司 | Frequency sweeping method, device and medium |
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| CN101436900B (en) * | 2008-12-25 | 2013-01-02 | 重庆重邮信科通信技术有限公司 | Method and apparatus for scanning whole frequency band frequency point of advance system |
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