CN105847212A - Detection method and device of downlink primary synchronization signals in LTE system - Google Patents
Detection method and device of downlink primary synchronization signals in LTE system Download PDFInfo
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2647—Arrangements specific to the receiver only
- H04L27/2655—Synchronisation arrangements
- H04L27/2657—Carrier synchronisation
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/69—Spread spectrum techniques
- H04B1/707—Spread spectrum techniques using direct sequence modulation
- H04B1/7073—Synchronisation aspects
- H04B1/7087—Carrier synchronisation aspects
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/0014—Carrier regulation
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/0014—Carrier regulation
- H04L2027/0024—Carrier regulation at the receiver end
- H04L2027/0026—Correction of carrier offset
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Abstract
The invention discloses a detection method and device of downlink primary synchronization signals in an LTE system. The method includes the following steps that: a frequency deviation value is pre-added to a receiving sequence X (n), so that a sequence Y (n) can be formed through combination; the sequence Y (n) is processed by a low-pass filter, so that a sequence Z (n) can be formed; x-times extraction is performed on the sequence Z (n), m sets of data sequences of which the length is y can be generated; z sets of sequences are selected from the m sets of data sequences, and sliding correlation is performed on the z sets of sequences and one set of local sequence; a maximum value is found out in all operation results of the sliding correlation, the maximum value is compared with a preset threshold value; if the maximum value is larger than the preset threshold value, the maximum value is a correlation peak value, and a time counter is zeroed; if the maximum value is smaller than or equal to the preset threshold value, and the counting of the time counter achieves a full frame cycle, the frequency deviation value is updated, and the correlation peak value is searched again; and the primary synchronization signals are positioned according to the correlation peak value. With the detection method and device of the invention adopted, when large frequency deviation occurs on a system, frequency deviation correction is automatically carried out, and detection of the PSS (primary synchronization signals) can be ensured.
Description
Technical field
The present invention relates to wireless communication technology field, specifically, believe particularly to main synchronization descending in a kind of LTE system
Number detection method and device.
Background technology
LTE (Long Term Evolution, Long Term Evolution) is the new of main flow in the world after 3G (Third Generation) Moblie
Generation mobile communication standard, has transfer rate high, availability of frequency spectrum high.When user terminal (UE) is linked into LTE net
During network, first have to through cell searching, obtain Time And Frequency and synchronize, identify sign and the Cell Broadcast CB etc. of community simultaneously
A little information.
In order to realize cell searching, LTE system descending defines two synchronizing sequences, the most main synchronizing sequence (PSS) and
Secondary synchronization sequences (SSS).TDD-LTE, PSS are positioned in the 3rd OFDM symbol of subframe 1 and subframe 6；SSS is positioned at subframe
0 and subframe 5 last OFDM symbol on.For FDD-LTE, PSS is positioned at last of time slot 0 and time slot 10
In OFDM symbol, SSS is positioned in the penultimate OFDM symbol of time slot 0 and time slot 10.Therefore in LTE system, PSS sequence
Arranging every 5ms to occur once, i.e. in a complete 10ms frame, a cycle will appear from twice PSS sequence.
PSS and SSS is respectively positioned on 72 subcarriers at center, and 62 wherein middle carrier waves have data, the 5 of both sides
Individual subcarrier is protection sideband, equal zero filling.
Community in physical layer is divided into 168 cell identification groups, has 3 different cell identification number in each group, altogether
504 different cell identification number.Wherein, during cell identification group 0-167 lies in SSS sequence;Cell identification 0-2 lies in
In PSS sequence.
A kind of algorithm of traditional searching PSS sequence be by receiving sequence by low-pass filtering and down-sampled after, with
Zadoff-Chu sequence generates three groups of this locality sequences match and is correlated with, and is positioned the position of PSS by detection correlation peak.
Above-mentioned algorithm can be suitable for when receiving sequence does not exist frequency deviation or frequency deviation is less.If system clock instability causes
When bigger skew occurs in carrier frequency, peak value may be can't detect by traditional method or peak value is inconspicuous, thus have impact on main same
The detection performance of step signal.
For in prior art when carrier frequency occur bigger skew time, the detection of descending master sync signal in LTE system
The problem of poor performance, the most not yet proposes effective solution.
Summary of the invention
Present invention is primarily targeted at detection method and the device that descending master sync signal in a kind of LTE system is provided,
To solve in prior art when bigger skew occurs in carrier frequency, the detection poor performance of descending master sync signal in LTE system
Problem.
According to one aspect of the present invention, it is provided that the detection method of descending master sync signal, the party in a kind of LTE system
Method includes: for one frequency deviation value of receiving sequence X (n) pre-add, synthesizing one group of sequence Y (n), wherein, n is the length of data sequence,
Sequence X (n) is downlink data in LTE system；By sequence Y (n) after low pass filter processes, obtain sequence Z (n)；To sequence
Row Z (n) carry out x times and extract, and produce m group length and are the data sequence of y, and wherein, x, y and m are the positive integer more than 1；Choosing
Select the z group sequence in m group data sequence, do slip to l group this locality sequence respectively relevant, wherein, a length of y, z of local sequence
For the positive integer more than 1 and less than or equal to m, l is the positive integer more than 1；The relevant all operation results that slide are found out
Maximum, and maximum is compared with predetermined threshold value；If maximum is more than predetermined threshold value, then maximum is relevant peaks
Value, and time counter is reset；If maximum is less than or equal to predetermined threshold value, and time counter has counted a full frame week
Phase, then update frequency deviation value, re-start the search of correlation peak；And position master sync signal according to correlation peak.
Further, for one frequency deviation value of receiving sequence X (n) pre-add, the step synthesizing one group of sequence Y (n) specifically includes:
Frequency deviation value being inputted a DDS module, does frequency offset correction for sequence X (n), wherein, DDS module is for adjusting sequence X (n)
Phase, to obtain sequence Y (n).
Further, frequency deviation value is included in a look-up table, and look-up table size and step value enter according to the needs of system
Row sum-equal matrix, frequency deviation value value condition in a lookup table is determined according to the size of correlation peak by state machine.
Further, low pass filter is used for retaining the valid data of 0.96M bandwidth in the middle of sequence Y (n).
Further, x=4, m=4, y=64, z=4, l=3.
Further, the step finding out maximum in the relevant all operation results that slide specifically includes: phase of sliding
The all operation results closed are normalized；And the result obtained after normalized determines maximum, wherein,
Normalized uses below equation to calculate:
Wherein,The result obtained after representing normalized,For one group in m group data sequence,For l
In the local sequence of group one group, u represents cell identification number, wherein, and u=25,29,34.
Further, following steps are used to generate three groups of this locality sequences:
Calculate according to below equation:
Wherein, u is the subscript of the root sequence of Zadoff-Chu, u=25,29,34, and different according to u value, generate three group 62 respectively
The local sequence of point, is designated as d0 (n), rear 31 d1 (n) being designated as, by sequence [0, d1 (n), 0, d0 (n)] through IFFT by first 31
After conversion, obtain the correlated series in three groups of time domains and be three groups of this locality sequences.
According to another aspect of the present invention, it is provided that the detection device of descending master sync signal in a kind of LTE system, should
Device includes: frequency offset processing module, for for one frequency deviation value of receiving sequence X (n) pre-add, synthesizes one group of sequence Y (n), wherein,
N is the length of data sequence, and sequence X (n) is downlink data in LTE system；Low pass filter, for passing through by sequence Y (n)
Row low-pass filtering is to obtain sequence Z (n)；Slip correlation module, extracts for sequence Z (n) is carried out x times, produces m group length equal
For the data sequence of y, wherein, x, y and m are the positive integer more than 1, and select the z group sequence in m group data sequence, respectively
It is relevant that sequence local to l group does slip, and wherein, a length of y, z of local sequence is the positive integer more than 1 and less than or equal to m,
L is the positive integer more than 1；Peak value searching module, for finding out maximum in the relevant all operation results that slide, and will be
Big value compares with predetermined threshold value, and wherein, if maximum is more than predetermined threshold value, then maximum is correlation peak, and will
Time counter resets, if maximum is less than or equal to predetermined threshold value, and time counter has been counted a full frame period, more
New frequency deviation value, re-starts the search of correlation peak；And master sync signal locating module, for main according to correlation peak location
Synchronizing signal.
Further, frequency offset processing module specifically performs following steps: frequency deviation value is inputted a DDS module, for sequence X
N () does frequency offset correction, wherein, DDS module is for carrying out phase modulation to sequence X (n), to obtain sequence Y (n).
Further, described frequency deviation value is included in a look-up table, and described look-up table size and step value are according to system
Needs be adjusted, described frequency deviation value value condition in described look-up table is by big according to described correlation peak of state machine
Little determine.
Further, low pass filter is used for retaining the valid data of 0.96M bandwidth in the middle of sequence Y (n).
Further, x=4, m=4, y=64, z=4, l=3.
Further, peak value searching module finds out the step of maximum in performing all operation results after slip is correlated with
Time, specifically perform following steps: relevant all operation results are normalized by sliding；And after normalized
Determining maximum in the result obtained, wherein, described normalized uses below equation to calculate:
Wherein,The result obtained after representing normalized,For one group in m group data sequence,For l
In the local sequence of group one group, u represents cell identification number, wherein, and u=25,29,34.
Further, described device also includes local sequence generating module, is used for using following steps to generate three groups of this locality
Sequence:
Calculate according to below equation:
Wherein, u is the subscript of the root sequence of Zadoff-Chu, u=25,29,34, and different according to u value, generate three group 62 respectively
The local sequence of point；First 31 are designated as d0 (n), rear 31 d1 (n) being designated as；By sequence [0, d1 (n), 0, d0 (n)] through IFFT
After conversion, obtain the correlated series in three groups of time domains and be three groups of this locality sequences.
By the present invention, in receiving LTE system after downlink data sequence X (n), to one the frequency deviation value synthesis of its pre-add
One group of sequence Y (n), then carries out low-pass filtering treatment and carries out x times and extract sequence Y (n), produces m group length and is the number of y
According to sequence, subsequently select the z group sequence in m group data sequence, do slip to l group this locality sequence respectively relevant, in slip phase
The all operation results closed find out maximum, and maximum is compared with predetermined threshold value, carry out searching of correlation peak
Rope, if maximum is more than predetermined threshold value, then maximum is correlation peak, and is reset by time counter, if maximum is less than
Or equal to predetermined threshold value, and time counter has counted a full frame period, then update frequency deviation value, re-start correlation peak
Search, until searching correlation peak, positions master sync signal finally according to correlation peak, thus, in system, big frequency occurs
Time partially, can automatically carry out frequency offset correction within the specific limits, it is ensured that the detection of PSS signal.
Described above is only the general introduction of technical solution of the present invention, in order to better understand the technological means of the present invention, and can
It is practiced according to the content of description, and in order to allow above and other objects of the present invention, the feature and advantage can be brighter
Aobvious understandable, below especially exemplified by the detailed description of the invention of the present invention.
Accompanying drawing explanation
By reading the detailed description of hereafter preferred implementation, various other advantage and benefit common for this area
Technical staff will be clear from understanding.Accompanying drawing is only used for illustrating the purpose of preferred implementation, and is not considered as the present invention
Restriction.And in whole accompanying drawing, it is denoted by the same reference numerals identical parts.In the accompanying drawings:
Fig. 1 is the flow chart of the detection method of descending master sync signal in LTE system according to a first embodiment of the present invention；
Fig. 2 is the flow chart of the detection method of descending master sync signal in LTE system according to a second embodiment of the present invention；
Fig. 3 is peak value searching in the detection method of descending master sync signal in LTE system according to a second embodiment of the present invention
Flow chart；
Fig. 4 to Fig. 7 is the peak value figure produced after receiving sequence cross-correlation according to a second embodiment of the present invention；
Fig. 8 is the block diagram of the detection device of descending master sync signal in LTE system according to a third embodiment of the present invention.
Detailed description of the invention
The present invention will be further described with detailed description of the invention below in conjunction with the accompanying drawings.It is pointed out that and do not conflicting
In the case of, the embodiment in the application and the feature in embodiment can be mutually combined.
Embodiment one
Fig. 1 is the flow chart of the detection method of descending master sync signal in LTE system according to a first embodiment of the present invention, such as figure
Shown in 1, the method includes that steps S102 is to step S116.
Step S102: for one frequency deviation value of receiving sequence X (n) pre-add, synthesize one group of sequence Y (n).
Wherein, sequence X (n) is descending I/Q data in the one group of LTE system received, and n is the length of data sequence, is connecing
After receiving sequence X (n), by this step, add a default frequency deviation value for it, sequence X (n) is mixed down sequence Y(n).
Specifically, frequency deviation value M is inputted a DDS(Direct Digital Synthesizer) module, do frequency deviation school for X (n)
Just.Wherein, DDS module is the function of simulation DDS chip, it is achieved to receiving sequence X (n) phase modulation, thus obtain one group of new sequence
Row Y (n), it has low cost, resolution height, the features such as output frequency is many, switch speed is fast.
Wherein, the value of M is included in a look-up table as shown in table 1 below, and this look-up table size and step value can roots
It is adjusted according to the needs of system.M value value condition in a lookup table is to be come certainly according to the size of peak value by a state machine
Fixed.
In this embodiment, can be learnt by experiment, when not carrying out frequency offset correction, frequency deviation obtains between [-2k ,+2k]
To correlation peak or obvious, the super peak value that goes beyond the scope is the most inconspicuous.Stepping is the biggest, and the time of frequency offset correction is the shortest,
Preferably, the value within stepping is located at 4.It is highly preferred that the scope of look-up table [-8K ,+7k], stepping is 1, represents 1K.
Step S104: by sequence Y (n) after low pass filter processes, obtain sequence Z (n).
62 carrier waves middle due to PSS have data, in order to avoid the interference of other signals, in this is force,
By the I/Q data of 20M through a low pass filter, filter the data of other frequency bands, only retain the effective of middle 0.96M bandwidth
Data, which enhance the accuracy of synchronization signal detection.The Y (n) after frequency offset correction letter after 0.96M low pass filter
Number sequence is Z (n).
Step S106: sequence Z (n) is carried out x times and extracts, produces m group length and is the data sequence of y.
Wherein, x, y and m are the positive integer more than 1.
Preferably, use 30.72M clock, gather an OFDM (Orthogonal Frequency Division
Multiplexing, i.e. OFDM) a length of 2048 points of symbol.In this embodiment, sample rate is reduced to
3.84M, the length gathering an OFDM symbol needs 256 points.And the local sequence generated is 64 points, it is therefore preferred that by Z (n)
Sequence carries out 4 times of extractions, produces the data sequence r1 of 4 groups 64, r2, r3, r4.
Step S108: select the z group sequence in m group data sequence, do slip to l group this locality sequence respectively relevant.
Wherein, a length of y, z of local sequence is the positive integer more than 1 and less than or equal to m, and l is the most whole more than 1
Number.
Owing to local clock crystal oscillator is unstable, there is the frequency of little scope in each cycle in the I/Q data causing receiving terminal to collect
Rate offsets, if only extracting one group to do cross-correlation with local sequence, peak value fluctuation ratio is relatively big, and some cycle detections are less than peak value.For
Avoid the generation of this situation, preferably 4 groups of separation sequences are all preserved, do slip phase with three groups of this locality sequences respectively
Close.So simultaneously participate in relevant sequence one of sliding and have 4*3=12 group.
Step S110: find out maximum in the relevant all operation results that slide, and by maximum and predetermined threshold value
Compare.
Owing to the signal intensity of receiving sequence is different, when separation sequence do with local sequence slip relevant after power value difference
Different very big, it is difficult to judge the position of peak value by a unified threshold value, in order to solve this problem, it is preferable that calculating
During use normalized algorithm, peak value result of determination is limited between (0,1).
Wherein, normalization is the calculation of a kind of simplification, can have the expression formula of dimension, through conversion, changes into
Dimensionless expression formula, thus solve signal intensity and differ and cause judging the situation of peak value.
Step S112: if maximum is more than predetermined threshold value, then maximum is correlation peak, and time counter is clear
Zero.
Step S114: if maximum is less than or equal to predetermined threshold value, and time counter has been counted a full frame period, then
Update frequency deviation value, re-start the search of correlation peak.
Step S116: position master sync signal according to correlation peak.
Use the detection method of descending master sync signal in the LTE system of this embodiment, it is possible to position the position of PSS accurately
Put, and when big frequency deviation occurs in system, can automatically carry out frequency offset correction within the specific limits, it is ensured that the inspection of PSS signal
Surveying, meanwhile, the most relevant peak value fluctuation range occurred is the least, it is simple to quickly determine peak.
Embodiment two
This embodiment is the detection side of descending master sync signal in LTE system further preferred on the basis of embodiment one
Method, sees Fig. 2, and the method is specifically described as follows.
The first step, the generation of local sequence:
Owing to Zadoff-Chu sequence has the dependency of good frequency domain and time domain.In this embodiment, local sequence is by frequency domain
Zadoff-Chu sequence generates, and concrete method is as follows:
Wherein, u is the subscript of the root sequence of Zadoff-Chu, u=25,29,34, and different according to u value, generate three group 62 respectively
Then front 31 sequences are designated as d0 (n), the d1 (n) that rear 31 sequences are designated as by the local sequence of point.Because direct current does not transmit any
Information, therefore the centre of sequence needs to fill zero.For convenience of calculation, this sequence zero filling again benefit one 0 one-tenth is become 64 points, i.e.
[0, d1 (n), 0, d0 (n)], after IFFT converts, just creates the correlated series in three groups of time domains.
Second step, frequency offset processing module
First receiving sequence be X (n) be the I/Q data of one group of 30.72M, the present embodiment is straight at an I/Q data DDS(added behind
Connect digital frequency synthesizer) module, add a pre-frequency deviation value M for it, its sequence is mixed down sequence Y (n).
Wherein, n represents the length of data sequence, and the value of M is included in a look-up table, and as above table 1, this look-up table is big
Little and step value can be adjusted according to the needs of system.When not carrying out frequency offset correction, frequency deviation obtains between [-2k ,+2k]
To correlation peak or obvious, the super peak value that goes beyond the scope is inconspicuous.Wherein stepping is the biggest, and the time of frequency offset correction is more
Short, it is proposed that stepping value within 4.The scope [-8K ,+7k] of look-up table in this example, stepping is 1, represents 1K.
3rd step, 0.96M wave filter
Add the low pass filter of a 0.96M bandwidth in the rear end of Y (n), filter the data of other frequency bands, only retain centre
The data of 0.96M bandwidth, it is to avoid the interference of other signals, improve the accuracy of the detection of synchronizing signal.Filtered letter
Number sequence is Z (n), and sample rate is 3.84M.
4th step, 4 times down-sampled
Use 30.72M clock, gather a length of 2048 points of an OFDM symbol.Sample rate is reduced to 3.84M by the present embodiment,
The length gathering an OFDM symbol needs 256 points.And the local sequence generated is 64 points, accordingly, it would be desirable to Z (n) sequence is carried out 4
Extraction, produces the data sequence Z1 of 4 groups 64, Z2, Z3, Z4 again.
Owing to local clock crystal oscillator is unstable, the I/Q data collected of receiving terminal is caused to occur that periodic frequency offsets, for
Reducing the fluctuation of correlation peak, 4 groups of separation are all preserved by the present embodiment, do slip phase with three groups of this locality sequences respectively
Close.The parallel sequence one participating in slip relevant has 4*3=12 group so simultaneously.
5th step, normalization
Owing to the signal intensity of receiving sequence is different, when separation sequence do with local sequence slip relevant after performance number difference very
Greatly.Thus can not judge the position of peak value by a unified threshold value, in order to solve this problem, the present embodiment uses
Normalized algorithm: by separation sequence and locally associated sequence correlation power value divided by the energy value of separation sequence.
Specific formula for calculation is as follows:
Wherein,The result obtained after representing normalized,For one group in m group data sequence,For l
In the local sequence of group one group, u represents cell identification number, wherein, and u=25,29,34.
6th step, peak value searching module
Peak value searching process is concrete as it is shown on figure 3, the input of peak value searching module is 12 groups of normalized results, its be all (0,
1) value between, finds out maximum Fmax in these 12 groups of results, is compared with threshold value N by Fmax.When Fmax is more than N, peak
Value finds, and time counter timing resets；When Fmax is not more than N, and time counter has counted a full frame period
(10ms) time, illustrating that peak value does not occur, there is bigger frequency deviation in the I/Q data that at this moment receptor receives, needs to carry out frequency deviation school
Just.
Frequency deviation counter cnt adds 1, gives frequency deviation value M, after the I/Q data of receiving sequence is carried out frequency offset correction, sends into
The low pass filter of 0.96M, carries out follow-up new round peak value searching.
Fig. 4 is the peak value figure produced after 15dbm receiving sequence cross-correlation, and peak value is 0.84；Fig. 5 is that 0dbm receiving sequence is mutual
The peak value figure produced after Xiang Guan, peak value is 0.93；Fig. 6 is the peak value figure produced after-15dbm receiving sequence cross-correlation, and peak value is
0.94；Fig. 7 is the peak value figure produced after-30dbm receiving sequence cross-correlation, and peak value is 0.95.From Fig. 4, the knot of Fig. 5, Fig. 6, Fig. 7
Fruit is it can be seen that the peak ranges fluctuation using this embodiment to obtain is the least, and peak value is obvious.Peak value is by the intensity with receiving sequence
Affect little, be practical method.Signal between [-30db ,+15db], peak value all fluctuates between 0.84 to 1.
It is above the description that the detection method of master sync signal descending in LTE system provided by the present invention is carried out.Below will
In the LTE system provide the present invention, the detection device of descending master sync signal is described, it should be noted that this device can
For performing the detection method of descending master sync signal in any one LTE system above-mentioned.
Embodiment three
Corresponding with the detection method of descending master sync signal in the LTE system that the embodiment of the present invention one provides, the present invention implements
Example additionally provides the detection device of descending master sync signal in a kind of LTE system, sees Fig. 8, and this device can include at frequency deviation
Reason module 10, low pass filter 20, slip correlation module 30, peak value searching module 40 and master sync signal locating module 50.
Frequency offset processing module 10, for for one frequency deviation value of receiving sequence X (n) pre-add, synthesizes one group of sequence Y (n), its
In, n is the length of data sequence, and sequence X (n) is downlink data in LTE system；
Low pass filter 20, carries out low-pass filtering to obtain sequence Z (n) for sequence Y (n) being passed through；
Slip correlation module 30, extracts for sequence Z (n) is carried out x times, produces m group length and is the data sequence of y, wherein,
X, y and m are the positive integer more than 1, and select the z group sequence in m group data sequence, and sequence local with l group is slided respectively
Relevant, wherein, a length of y, z of local sequence are the positive integer more than 1 and less than or equal to m, and l is the positive integer more than 1；
Peak value searching module 40, for finding out maximum, and by maximum with default in the relevant all operation results that slide
Threshold value compares, and wherein, if maximum is more than predetermined threshold value, then maximum is correlation peak, and by time counter
Resetting, if maximum is less than or equal to predetermined threshold value, and time counter has counted a full frame period, then update frequency deviation value,
Re-start the search of correlation peak；
Master sync signal locating module 50, for positioning master sync signal according to correlation peak.
Preferably, frequency offset processing module 10 specifically performs following steps: frequency deviation value is inputted a DDS module, for sequence X
N () does frequency offset correction, wherein, DDS module is for carrying out phase modulation to sequence X (n), to obtain sequence Y (n).
Use the preferred embodiment, by the function of DDS module simulation DDS chip, it is achieved to receiving sequence X (n) phase modulation,
The features such as it has low cost, and resolution is high, and output frequency is many, switch speed is fast.
Preferably, described frequency deviation value is included in a look-up table, and described look-up table size and step value are according to system
Needs are adjusted, described frequency deviation value value condition in described look-up table by state machine according to the size of described correlation peak
Determine.
Preferably, low pass filter 20 is used for retaining the valid data of 0.96M bandwidth in the middle of sequence Y (n).
Use the preferred embodiment, filter the data of other frequency bands, only retain the valid data of middle 0.96M bandwidth, this
Sample improves the accuracy of synchronization signal detection
Preferably, x=4, m=4, y=64, z=4, l=3.
Preferably, peak value searching module 40 finds out the step of maximum in performing all operation results that slip is relevant
Time, specifically perform following steps: relevant all operation results are normalized by sliding；And in normalized
After the result that obtains determines maximum, wherein, normalized uses below equation to calculate:
Wherein,The result obtained after representing normalized,For one group in m group data sequence,For l
In the local sequence of group one group, u represents cell identification number, wherein, and u=25,29,34.
Use the preferred embodiment, solve signal intensity and differ and cause judging the situation of peak value.
Preferably, described device also includes local sequence generating module, for using following steps by the Zadoff-of frequency domain
Chu sequence generates three groups of this locality sequences:
Calculate according to below equation:
Wherein, u is the subscript of the root sequence of Zadoff-Chu, u=25,29,34, and different according to u value, generate three group 62 respectively
The local sequence of point；First 31 are designated as d0 (n), rear 31 d1 (n) being designated as；By sequence [0, d1 (n), 0, d0 (n)] through IFFT
After conversion, obtain the correlated series in three groups of time domains and be three groups of this locality sequences.
From the description of various embodiments above, it can be seen that the embodiment of the present invention achieves following technique effect: in system
When big frequency deviation occurs, can automatically carry out frequency offset correction within the specific limits, it is ensured that the detection of PSS signal.
It should be noted that said apparatus or system embodiment belong to preferred embodiment, involved unit and module are also
It is not necessarily necessary to the application.
Each embodiment in this specification all uses the mode gone forward one by one to describe, what each embodiment stressed is with
The difference of other embodiments, between each embodiment, identical similar part sees mutually.Dress for the application
For putting embodiment, due to itself and embodiment of the method basic simlarity, so describe is fairly simple, it is real that relevant part sees method
The part executing example illustrates.
The above, the only present invention preferably detailed description of the invention, but protection scope of the present invention is not limited thereto,
Any it is familiar with the people of this technology in the technical scope that disclosed herein, the change that can readily occur in or replacement, all should contain
Within protection scope of the present invention.Therefore, protection scope of the present invention should be as the criterion with scope of the claims.
Claims (10)
1. the detection method of descending master sync signal in a LTE system, it is characterised in that including:
For one frequency deviation value of receiving sequence X (n) pre-add, synthesizing one group of sequence Y (n), wherein, n is the length of data sequence, described
Sequence X (n) is downlink data in LTE system；
By described sequence Y (n) after low pass filter processes, obtain sequence Z (n)；
Described sequence Z (n) being carried out x times extract, produce m group length and be the data sequence of y, wherein, x, y and m are more than 1
Positive integer；
Select the z group sequence in described m group data sequence, do slip to l group this locality sequence respectively relevant, wherein, described this locality
The a length of y, z of sequence is the positive integer more than 1 and less than or equal to m, and l is the positive integer more than 1；
In the relevant all operation results that slide, find out maximum, and described maximum is compared with predetermined threshold value；
If described maximum is more than described predetermined threshold value, the most described maximum is correlation peak, and is reset by time counter；
If described maximum is less than or equal to described predetermined threshold value, and described time counter has been counted a full frame period, then
Update described frequency deviation value, re-start the search of described correlation peak；And
Master sync signal is positioned according to described correlation peak.
The detection method of descending master sync signal in LTE system the most according to claim 1, it is characterised in that for receiving
One frequency deviation value of sequence X (n) pre-add, the step synthesizing one group of sequence Y (n) specifically includes:
Described frequency deviation value being inputted a DDS module, does frequency offset correction for described sequence X (n), wherein, described DDS module is used for
Described sequence X (n) is carried out phase modulation, to obtain described sequence Y (n).
The detection method of descending master sync signal in LTE system the most according to claim 2, it is characterised in that described frequency
Value partially is included in a look-up table, and described look-up table size and step value are adjusted according to the needs of system, described frequency deviation
Value value condition in described look-up table is determined according to the size of described correlation peak by state machine.
The detection method of descending master sync signal in LTE system the most according to claim 1, it is characterised in that described low
Bandpass filter is used for retaining the valid data of 0.96M bandwidth in the middle of described sequence Y (n).
The detection method of descending master sync signal in LTE system the most according to claim 4, it is characterised in that x=4, m=
4, y=64, z=4, l=3.
The detection method of descending master sync signal in LTE system the most according to claim 5, it is characterised in that sliding
The step finding out maximum in relevant all operation results specifically includes:
By sliding, relevant all operation results are normalized；And
The result obtained after described normalized determines described maximum,
Wherein, described normalized uses below equation to calculate:
Wherein,The result obtained after representing normalized,For one group in described m group data sequence,
For one group in the local sequence of described l group, u represents cell identification number, wherein, u=25,29,34.
The detection method of descending master sync signal in LTE system the most according to claim 6, it is characterised in that use with
Lower step generates three groups of this locality sequences:
Calculate according to below equation:
Wherein, u is the subscript of the root sequence of Zadoff-Chu, u=25,29,34, and different according to u value, generate three group 62 respectively
The local sequence of point；
First 31 are designated as d0 (n), rear 31 d1 (n) being designated as；
By sequence [0, d1 (n), 0, d0 (n)] after IFFT converts, obtain the correlated series in three groups of time domains and be described three groups
Local sequence.
8. the detection device of descending master sync signal in a LTE system, it is characterised in that including:
Frequency offset processing module, for for one frequency deviation value of receiving sequence X (n) pre-add, synthesizes one group of sequence Y (n), and wherein, n is number
According to the length of sequence, described sequence X (n) is downlink data in LTE system；
Low pass filter, carries out low-pass filtering to obtain sequence Z (n) for described sequence Y (n) being passed through；
Slip correlation module, extracts for described sequence Z (n) is carried out x times, produces m group length and is the data sequence of y, its
In, x, y and m are the positive integer more than 1, and select the z group sequence in described m group data sequence, respectively sequence local with l group
Doing slip relevant, wherein, a length of y, z of described local sequence are the positive integer more than 1 and less than or equal to m, and l is more than 1
Positive integer；
Peak value searching module, for finding out maximum, and by described maximum with pre-in the relevant all operation results that slide
If threshold value compares, wherein, if described maximum is more than described predetermined threshold value, the most described maximum is correlation peak,
And time counter is reset, if described maximum is less than or equal to described predetermined threshold value, and described time counter is counted
A full frame period, then update described frequency deviation value, re-start the search of described correlation peak；And
Master sync signal locating module, for positioning master sync signal according to described correlation peak.
The detection device of descending master sync signal in LTE system the most according to claim 8, it is characterised in that described frequency
Partially processing module specifically performs following steps:
Described frequency deviation value being inputted a DDS module, does frequency offset correction for described sequence X (n), wherein, described DDS module is used for
Described sequence X (n) is carried out phase modulation, to obtain described sequence Y (n).
The detection device of descending master sync signal in LTE system the most according to claim 8, it is characterised in that described low
Bandpass filter is used for retaining the valid data of 0.96M bandwidth in the middle of described sequence Y (n).
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