CN102857457B - Time division duplexing-long term evolution (TDD-LTE) downlink synchronizing method - Google Patents

Abstract

The invention is applicable to the field of Time division duplexing-long term evolution (TDD-LTE) system communication and provides a TDD-LTE downlink synchronizing method. The method includes obtaining half-frame synchronization information and serial numbers in a cell identity (ID) group; determining a cyclic prefix (CP) type; subjecting a frequency domain secondary synchronization sequence to de-interleaving and descrambling to obtain an even sequence and an odd sequence respectively; subjecting the even sequence and a secondary original sequence to circular correlation and recording a coordinate corresponding to a peak value of correlation values as a first displacement coordinate; generating a third descrambling sequence according to the first displacement coordinate; descrambling the odd sequence and the third descrambling sequence, subjecting the odd sequence, the third descrambling sequence and the secondary original sequence to circular correlation, and recording a coordinate corresponding to a peak value of correlation values as a second displacement coordinate; and obtaining a cell ID group serial number and frame starting information according to the first displacement coordinate and the second displacement coordinate. According to the TDD-LTE downlink synchronizing method, m<0> and m<1> can be determined only by performing 31 times of cross-correlation calculation with the length of 31, so that TDD-LTE downlink synchronization information is obtained, and the calculation amount is greatly reduced.

Description

A kind of TDD-LTE down link synchronisation method

Technical field

The invention belongs to long evolving system (Time Division Duplexing-Long Term Evolution, the TDD-LTE) communications field of TDD mode, particularly relate to a kind of TDD-LTE down link synchronisation method.

Background technology

The physical layer of LTE system have employed OFDM (Orthogonal Frequency Division Multiplexing, OFDM) modulation technique, wherein, OFDM symbol is superposed by multiple sub-carrier signal and forms, and utilize orthogonality to distinguish between each subcarrier, thus TDD-LTE system is very responsive to the frequency shift (FS) of signal.But in actual applications, due to the radio frequency oscillator frequency deviation that transmitting-receiving two-end exists, and travelling carriage is in the Doppler Doppler frequency displacement produced in high-speed mobile environment, all can destroy the orthogonality between subcarrier, and then introducing subcarrier interference, cause systematic function significantly to reduce.Therefore, how to obtain synchronous in LTE system, namely how LTE terminal obtains time and the Frequency Synchronization between community and detects physical-layer cell ID, is the problem first needing to solve.

In TDD-LTE system, the radio frames (radio frame) of a 10ms is divided into 10 length to be the subframe of 1ms (subframe), and is configured up-downgoing resource in units of subframe.In order to realize the down-going synchronous of TDD-LTE system, when system, transmit master sync signal (PSCH) and auxiliary synchronous signals (SSCH) on the downlink channel respectively, wherein, master sync signal is mapped in the 3rd OFDM symbol of the 1st work song frame and the 6th work song frame, and auxiliary synchronous signals is mapped in last OFDM symbol of the 0th work song frame and the 5th work song frame.The realization flow of down-going synchronous is roughly: TDD-LTE terminal is according to the correlation detection master sync signal of master sync signal, obtain 5ms clock, i.e. field sync information, then according to the correlation detection auxiliary synchronous signals of auxiliary synchronous signals, obtain frame synchronization information and physical-layer cell ID.In existing auxiliary synchronizing process, according to the good autocorrelation of secondary synchronization sequences on frequency domain, auxiliary synchronizing information is obtained by the method itself and Received signal strength being done on frequency domain cross-correlation, but, said process needs 168 groups of secondary synchronization sequences to do the computing cross-correlation that length is 62 with receiving sequence respectively, amount of calculation is huge, causes system resource to be born large.

Summary of the invention

The object of the embodiment of the present invention is to provide a kind of TDD-LTE down link synchronisation method, and the auxiliary synchronizing process amount of calculation being intended to solve existing TDD-LTE down link synchronisation method is huge, causes the problem that system burden is large.

The embodiment of the present invention is achieved in that a kind of TDD-LTE down link synchronisation method, and described method comprises the steps:

By master sync signal and Received signal strength cross-correlation, obtain the interior numbering of group of field sync information and community ID;

By cyclic prefix CP data and master sync signal end CP length data cross-correlation, determine CP type;

Generate local scrambling sequence and auxiliary synchronous original series, described local scrambling sequence comprises the first scrambling sequence and the second scrambling sequence;

According to master sync signal initial time and CP type, extract time domain secondary synchronization sequences, and be converted to frequency domain secondary synchronization sequences;

By the deinterleaving of described frequency domain secondary synchronization sequences and respectively with described first scrambling sequence and described second scrambling sequence descrambling after, obtain even order and odd numbered sequences respectively;

By described even order and described auxiliary synchronous original series circular correlation, be the first shift coordinates by coordinate record corresponding for correlation peaks;

According to described first shift coordinates, generate the 3rd scrambling sequence;

After described odd numbered sequences and described 3rd scrambling sequence descrambling, with described auxiliary synchronous original series circular correlation, be the second shift coordinates by coordinate record corresponding for correlation peaks;

According to described first shift coordinates and described second shift coordinates, obtain community ID group #, and according to the relative position of described first shift coordinates with described second shift coordinates, calculating frame start information.

Another object of the embodiment of the present invention is to provide a kind of TDD-LTE downlink synchronization device, and described device comprises:

Main lock unit, for by master sync signal and Received signal strength cross-correlation, obtains the interior numbering of group of field sync information and community ID;

CP type determining units, for by cyclic prefix CP data and master sync signal end CP length data cross-correlation, determines CP type;

Local scrambling sequence and auxiliary synchronous original series generation unit, for generating local scrambling sequence and auxiliary synchronous original series, described local scrambling sequence comprises the first scrambling sequence and the second scrambling sequence;

Frequency domain secondary synchronization sequences acquiring unit, for according to master sync signal initial time and CP type, extracts time domain secondary synchronization sequences, and is converted to frequency domain secondary synchronization sequences;

Sequence of parity acquiring unit, for by the deinterleaving of described frequency domain secondary synchronization sequences and respectively with described first scrambling sequence and described second scrambling sequence descrambling after, obtain even order and odd numbered sequences respectively;

Coordinate record corresponding for correlation peaks, for by described even order and described auxiliary synchronous original series circular correlation, is the first shift coordinates by the first shift coordinates acquiring unit;

3rd scrambling sequence generation unit, for according to described first shift coordinates, generates the 3rd scrambling sequence;

Coordinate record corresponding for correlation peaks, for by after described odd numbered sequences and described 3rd scrambling sequence descrambling, with described auxiliary synchronous original series circular correlation, is the second shift coordinates by the second shift coordinates acquiring unit;

Community ID group # and frame start information acquiring unit, for according to described first shift coordinates and described second shift coordinates, obtain community ID group #, and according to the relative position of described first shift coordinates with described second shift coordinates, calculating frame start information.

The embodiment of the present invention is in the auxiliary synchronizing process of TDD-LTE system down-going synchronous, by obtaining corresponding even order and odd numbered sequences by after Received signal strength deinterleaving and descrambling, correspondingly complete the cross-correlation procedure of auxiliary synchronous signals and Received signal strength, greatly reduce the amount of calculation of auxiliary synchronizing process thus, alleviate system burden.

Accompanying drawing explanation

Fig. 1 is the realization flow figure of the TDD-LTE down link synchronisation method that first embodiment of the invention provides;

Fig. 2 is the structure chart of the TDD-LTE downlink synchronization device that second embodiment of the invention provides.

Embodiment

In order to make object of the present invention, technical scheme and advantage clearly understand, below in conjunction with drawings and Examples, the present invention is further elaborated.Should be appreciated that specific embodiment described herein only in order to explain the present invention, be not intended to limit the present invention.

The embodiment of the present invention is in the auxiliary synchronizing process of TDD-LTE system down-going synchronous, by obtaining corresponding even order and odd numbered sequences by after Received signal strength deinterleaving and descrambling, correspondingly complete the cross-correlation procedure of auxiliary synchronous signals and Received signal strength, greatly reduce the amount of calculation of auxiliary synchronizing process thus, alleviate system burden.

Namely the down-going synchronous process of TDD-LTE system is that subscriber equipment (User Equipment, UE) obtains time and Frequency Synchronization with residing community, and detects the process of the community ID of this community.In the physical layer of TDD-LTE system, there are 504 unique community ID, these communities ID is divided into 168 unique community ID groups, and each group comprises 3 unique community ID, therefore, and a community ID wherein, (scope is 0-167) and (scope is 0-2) represents respectively in community ID group # residing for the ID of this community and its group in the ID group of this community and numbers, when cicada with a community ID can be determined.

Meanwhile, because master sync signal is mapped in the 1st work song frame of TDD-LTE radio frames and the 3rd OFDM symbol of the 6th work song frame, therefore 5ms field sync information can be obtained by main synchronizing process; Auxiliary synchronous signals is mapped in the 0th work song frame of TDD-LTE radio frames and last OFDM symbol of the 5th work song frame, and it is different with the secondary synchronization sequences of the 5th work song frame to be mapped to the 0th work song frame, therefore can be got the border of 10ms by auxiliary synchronizing process, namely get 10ms frame synchronization information.

Fig. 1 shows the realization flow of the TDD-LTE down link synchronisation method that first embodiment of the invention provides, and details are as follows:

In step S101, by by master sync signal and Received signal strength cross-correlation, obtain the interior numbering of group of field sync information and community ID

Because master sync signal all has good autocorrelation in time domain and frequency domain, therefore, master sync signal and Received signal strength are carried out cross-correlation, and then search correlation peaks, obtain the positional information of master sync signal in Received signal strength thus, and obtain numbering in field sync information and community ID group further.

The idiographic flow of main synchronizing process is as follows:

1, the frequency domain Zadoff-Chu sequence being 62 according to length generates the main synchronizing sequence of frequency domain, and maps on 62 frequencies at subcarrier center.Wherein, Zadoff-Chu sequence is:

$d_u\left(n\right)=\left\{\begin{array}{cc}{e}^{-j\frac{\mathrm{\&pi;un}(n+1)}{63}}& n=\mathrm{0,1},...,30\\ e^{-j\frac{\mathrm{\&pi;u}(n+1)(n+2)}{63}}& n=\mathrm{31,32},...,61\end{array}\right.,$

And the index u of Zadoff-Chu root sequence is given by table 1:

Table 1

2, direct current subcarrier is inserted at subcarrier center; 5 subcarriers before and after main synchronizing sequence insert respectively 5 protection subcarriers; then the FFT under main synchronizing sequence zero padding to minimum bandwidth is counted (128 point); around revolving; do IFFT conversion, the main synchronizing sequence of frequency domain is converted to the main synchronizing sequence of time domain.

3, by down-sampled for Received signal strength to appropriate speed, from moment S, the data after down-sampled are stored 128 sampled points, do to 3 time-domain primary synchronization sequences relevant cumulative respectively.

4, starting point moment S is slided on the whole frame period, after having searched for a frame, numbering in the group of the record position at correlation peaks place and the master sync signal community ID of correspondence thereof.

Now, correlation peaks position is the original position of master sync signal, that is field sync information (5ms).

In step s 102, by by Cyclic Prefix (Cyclic Prefix, CP) data and main synchronizing sequence end CP length data cross-correlation, CP type is determined.

According to the generative process of OFDM symbol, after completing IFFT computing, need before in time domain, the data sequence of each OFDM symbol end CP length copies to this symbol, therefore, namely the data sequence of the CP length before master sync signal is the data sequence of the CP length at master sync signal end.According to this feature, the method can doing cross-correlation by the data sequence of the CP length by CP data sequence and main synchronizing sequence end determines CP type, and its idiographic flow is as follows:

1, respectively front 9 data sequences of main synchronizing sequence correlation peaks position and front 32 data sequences are preserved.

Because master sync signal is positioned at the 1st work song frame and the 6th work song frame of TDD-LTE radio frames, therefore when minimum bandwidth, the CP length under conventional CP pattern is 9, and the CP length under mode of extension is 32.

2, above-mentioned two data sequences are done relevant cumulative to 9 data at master sync signal end and 32 data respectively, judge its higher value, CP type can be determined.That is, when the relevant accumulated value of 9 data is larger, this CP type is conventional CP type, and when the relevant accumulated value of 32 data is larger, this CP type is expansion CP type.

In TDD-LTE system, the pseudo random sequence that auxiliary synchronous signals is 31 by two segment length is consisted of intertexture, cascade, lay respectively in the 0th work song frame of radio frames and last OFDM symbol of the 5th work song frame, different with the secondary synchronization sequences of the 5th work song frame owing to being mapped to the 0th work song frame, therefore can be got the border of 10ms by auxiliary synchronizing process, namely get 10ms frame synchronization information.

In step s 103, generate local scrambling sequence and auxiliary synchronous signals original series S (n), wherein, local scrambling sequence comprises the first scrambling sequence C ₀with the second scrambling sequence C ₁.

Wherein, local scrambling sequence C ₀and C ₁generation depend on master sync signal, by m sequence cyclic shift generates:

$c_0\left(n\right)=\tilde{c}\left((n+N_{\mathrm{ID}}^{\left(2\right)})\mathrm{mod}31\right)$

$c_1\left(n\right)=\tilde{c}\left((n+N_{\mathrm{ID}}^{\left(2\right)}+3)\mathrm{mod}31\right)$

Wherein, the interior numbering of group of community ID, now because main synchronizing process completes, therefore determine.

M sequence $\tilde{c}\left(i\right)=1-2x\left(i\right),$ 0≤i≤30， $x(\stackrel{\&OverBar;}{i}+5)=(x(\stackrel{\&OverBar;}{i}+3)+x\left(\stackrel{\&OverBar;}{i}\right))\mathrm{mod}\mathrm{2,0}\&le;\stackrel{\&OverBar;}{i}\&le;25,$ And the initial condition of x (i) is x (0)=0, x (1)=0, x (2)=0, x (3)=0, x (4)=1.

The generation of auxiliary synchronous signals original series S (n) is obtained by two kinds of m sequence s ~ (n) different cyclic shifts:

$s_0^{\left(m_0\right)}\left(n\right)=\tilde{s}\left((n+m_0)\mathrm{mod}31\right)$

$s_1^{\left(m_1\right)}\left(n\right)=\tilde{s}\left((n+m_1)\mathrm{mod}31\right)$

M sequence $\tilde{s}\left(i\right)=1-2x\left(i\right),$ 0≤i≤30， $x(\stackrel{\&OverBar;}{i}+5)=(x(\stackrel{\&OverBar;}{i}+2)+x\left(\stackrel{\&OverBar;}{i}\right))\mathrm{mod}\mathrm{2,0}\&le;\stackrel{\&OverBar;}{i}\&le;25,$ And the initial condition of x (i) is x (0)=0, x (1)=0, x (2)=0, x (3)=0, x (4)=1.

Wherein, m ₀and m ₁be derived from community ID group # its relation is as follows:

m ₀＝m′mod31

m ₁＝(m ₀+[m′/31]+1)mod31

$m^{\&prime;}=N_{\mathrm{ID}}^{\left(1\right)}+q(q+1)/2,q=\left[\frac{N_{\mathrm{ID}}^{\left(1\right)}+q^{\&prime;}(q^{\&prime;}+1)/2}{30}\right],q^{\&prime;}=[N_{\mathrm{ID}}^{\left(1\right)}/30]$

And community ID group # with m ₀and m ₁mapping relations can see table 2.

Table 2

In step S104, according to master sync signal initial time and CP type, from low low-rate reception signal, extract time domain secondary synchronization sequences, and time domain secondary synchronization sequences is converted to frequency domain secondary synchronization sequences.

In embodiments of the present invention, because CP type is determined in step s 102, therefore according to the correlation peaks position obtained in main synchronizing process, the position of secondary synchronization sequences in low low-rate reception signal can be calculated, thus extract time domain secondary synchronization sequences.

After getting time domain secondary synchronization sequences, by time domain secondary synchronization sequences being carried out the FFT conversion of 128, obtain the secondary synchronization sequences of frequency domain.

In step S105, by the deinterleaving of frequency domain secondary synchronization sequences, and by respectively with local scrambling sequence C ₀and C ₁descrambling, obtains even order e (n) and odd numbered sequences o (n).

In step s 106, even order e (n) and auxiliary synchronous signals original series are carried out circular correlation, the first shift coordinates of the frequency domain secondary synchronization sequences that record correlation peaks is corresponding.

In embodiments of the present invention, because even order e (n) is through m by original series ₀the cyclic shift of position obtains, and has good autocorrelation due to original series, and after therefore e (n) being done circular correlation with original series, the first shift coordinates of the frequency domain secondary synchronization sequences that its correlation peaks is corresponding is m ₀.

In step s 107, according to the first shift coordinates, generate the 3rd scrambling sequence wherein, the 3rd scrambling sequence by m sequence cyclic shift generates:

$z_1^{\left(m_0\right)}\left(n\right)=\tilde{z}\left((n+\left(m_0\mathrm{mod}8\right))\mathrm{mod}31\right)$

M sequence $\tilde{z}\left(i\right)=1-2x\left(i\right),$ 0≤i≤30，

$x(\stackrel{\&OverBar;}{i}+5)=(x(\stackrel{\&OverBar;}{i}+4)+x(\stackrel{\&OverBar;}{i}+2)+x(\stackrel{\&OverBar;}{i}+1)+x\left(\stackrel{\&OverBar;}{i}\right))\mathrm{mod}\mathrm{2,}$ Its initial condition is x (0)=0, x (1)=0, x (2)=0, x (3)=0, x (4)=1.

In step S108, by odd numbered sequences o (n) with after carrying out second time descrambling, carry out circular correlation with auxiliary synchronous original series, the second shift coordinates of the frequency domain secondary synchronization sequences that record correlation peaks is corresponding.

In embodiments of the present invention, because odd numbered sequences o (n) is through m by original series ₁the cyclic shift of position obtains, and has good autocorrelation due to original series, and after therefore o (n) being done circular correlation with original series, the second shift coordinates of the frequency domain secondary synchronization sequences that its correlation peaks is corresponding is m ₁.

Thus, in step S106 and step S108, only needing to carry out 31 length is the computing cross-correlation of 31, can determine m ₀and m ₁, need to carry out 168 length to be the computing cross-correlation of 62 compared to traditional auxiliary synchronizing process, greatly reduce operand, improve down-going synchronous efficiency, alleviate system burden.

In step S109, according to the first shift coordinates and the second shift coordinates, obtain community ID group #, according to the relative position of the first shift coordinates with the second shift coordinates, calculating frame start information.

In embodiments of the present invention, because the first shift coordinates is the m determined after synchronous ₀, the second shift coordinates is the m determined after synchronous ₁, therefore, according to m ₀and m ₁can determine community ID group #, its community ID group # obtains equation and is:

And according to determine community ID.Meanwhile, according to m ₀and m ₁relative position, frame start information can be calculated.

Fig. 2 shows the structure of the TDD-LTE downlink synchronization device that second embodiment of the invention provides, and for convenience of explanation, illustrate only part related to the present embodiment.

With reference to Fig. 2, this downlink synchronization device includes:

Main lock unit 21, for by master sync signal and Received signal strength cross-correlation, obtains the interior numbering of group of field sync information and community ID;

CP type determining units 22, for by cyclic prefix CP data and master sync signal end CP length data cross-correlation, determines CP type;

Local scrambling sequence and auxiliary synchronous original series generation unit 23, for generating local scrambling sequence and auxiliary synchronous original series, described local scrambling sequence comprises the first scrambling sequence and the second scrambling sequence;

Frequency domain secondary synchronization sequences acquiring unit 24, for according to master sync signal initial time and CP type, extracts time domain secondary synchronization sequences, and is converted to frequency domain secondary synchronization sequences;

Sequence of parity acquiring unit 25, for by the deinterleaving of described frequency domain secondary synchronization sequences and respectively with described first scrambling sequence and described second scrambling sequence descrambling after, obtain even order and odd numbered sequences respectively;

Coordinate record corresponding for correlation peaks, for by described even order and described auxiliary synchronous original series circular correlation, is the first shift coordinates by the first shift coordinates acquiring unit 26;

3rd scrambling sequence generation unit 27, for according to described first shift coordinates, generates the 3rd scrambling sequence;

Coordinate record corresponding for correlation peaks, for by after described odd numbered sequences and described 3rd scrambling sequence descrambling, with described auxiliary synchronous original series circular correlation, is the second shift coordinates by the second shift coordinates acquiring unit 28;

Community ID group # and frame start information acquiring unit 29, for according to described first shift coordinates and described second shift coordinates, obtain community ID group #, and according to the relative position of described first shift coordinates with described second shift coordinates, calculating frame start information.

And in main lock unit 21, specifically include:

The main synchronizing sequence of frequency domain generates subelement 211, for generating 3 main synchronizing sequences of frequency domain according to Zadoff-Chu sequence;

Time-domain primary synchronization sequence generates subelement 212, for main for frequency domain synchronizing sequence is converted to time-domain primary synchronization sequence;

First relevant cumulative subelement 213, for from master sync signal initial time, stores 128 sampled points by the Received signal strength after down-sampled, does relevant cumulative respectively to 3 time-domain primary synchronization sequences;

Acquisition subelement 214 is numbered in field sync information and community ID group, for described initial time is slided on the whole frame period, correlation peaks position is recorded as described field sync information, obtains the interior numbering of group of community ID corresponding to described correlation peaks position simultaneously.

And specifically include in CP type determining units 22:

Data preserve subelement 221, for preserving front 9 data of described correlation peaks position and front 32 data respectively;

Second relevant cumulative subelement 222, for doing relevant adding up to 9 data at master sync signal end and 32 data respectively by front 9 data of preserving and front 32 data;

Relevant accumulation result comparing unit 223, for being defined as corresponding CP type by the higher value of relevant accumulation result.

The TDD-LTE downlink synchronization device that second embodiment of the invention provides can be used in the TDD-LTE down link synchronisation method of aforementioned correspondence, and details, see the associated description of the invention described above first embodiment, do not repeat them here.

In embodiments of the present invention, by above-mentioned auxiliary synchronizing process, only needing to carry out 31 length is the computing cross-correlation of 31, can determine m ₀and m ₁, thus obtain the down-going synchronous information of TDD-LTE, greatly reduce operand, improve down-going synchronous efficiency, alleviate system burden.

The foregoing is only preferred embodiment of the present invention, not in order to limit the present invention, all any amendments done within the spirit and principles in the present invention, equivalent replacement and improvement etc., all should be included within protection scope of the present invention.

Claims (6)

1. a TDD-LTE down link synchronisation method, is characterized in that, described method comprises the steps:

By master sync signal and Received signal strength cross-correlation, obtain the interior numbering of group of field sync information and community ID;

By cyclic prefix CP data and master sync signal end CP length data cross-correlation, determine CP type;

Generate local scrambling sequence and auxiliary synchronous original series, described local scrambling sequence comprises the first scrambling sequence and the second scrambling sequence, and the generation of described auxiliary synchronous original series is by m sequence two kinds of different cyclic shifts obtain:

$s_0^{\left(m_0\right)}\left(n\right)=\tilde{s}\left((n+m_0)\mathrm{mod}31\right)$

$s_1^{\left(m_1\right)}\left(n\right)=\tilde{s}\left((n+m_1)\mathrm{mod}31\right)$

M sequence $\tilde{s}\left(i\right)=1-2x\left(i\right),$ 0≤i≤30， $x(\stackrel{\&OverBar;}{i}+5)=(x(\stackrel{\&OverBar;}{i}+2)+x\left(\stackrel{\&OverBar;}{i}\right))\mathrm{mod}\mathrm{2,0}\&le;\stackrel{\&OverBar;}{i}\&le;25,$ And the initial condition of x (i) is x (0)=0, x (1)=0, x (2)=0, x (3)=0, x (4)=1;

Wherein, m ₀and m ₁be derived from community ID group # m ₀be the first shift coordinates, m ₁be the second shift coordinates, its relation is as follows:

m ₀＝m′mod31

m ₁＝(m ₀+[m′/31]+1)mod31；

$m^{\&prime;}=N_{\mathrm{ID}}^{\left(1\right)}+q(q+1)/2,q=\left[\frac{N_{\mathrm{ID}}^{\left(1\right)}+q^{\&prime;}(q^{\&prime;}+1)/2}{30}\right],q^{\&prime;}=[N_{\mathrm{ID}}^{\left(1\right)}/30]$

According to master sync signal initial time and CP type, extract time domain secondary synchronization sequences, and be converted to frequency domain secondary synchronization sequences;

By the deinterleaving of described frequency domain secondary synchronization sequences and respectively with described first scrambling sequence and described second scrambling sequence descrambling after, obtain even order and odd numbered sequences respectively;

By described even order and described auxiliary synchronous original series circular correlation, be the first shift coordinates by coordinate record corresponding for correlation peaks;

According to described first shift coordinates, generate the 3rd scrambling sequence;

After described odd numbered sequences and described 3rd scrambling sequence descrambling, with described auxiliary synchronous original series circular correlation, be the second shift coordinates by coordinate record corresponding for correlation peaks;

According to described first shift coordinates and described second shift coordinates, obtain community ID group #, and according to the relative position of described first shift coordinates with described second shift coordinates, calculating frame start information.

2. the method for claim 1, is characterized in that, in the group of described acquisition field sync information and community ID, the step of numbering specifically comprises:

Generate 3 main synchronizing sequences of frequency domain according to Zadoff-Chu sequence, described Zadoff-Chu sequence is:

$d_u\left(n\right)=\left\{\begin{array}{cc}{e}^{-j\frac{\mathrm{\&pi;un}(n+1)}{63}}& n=\mathrm{0,1},...,30\\ e^{-j\frac{\mathrm{\&pi;u}(n+1)(n+2)}{63}}& n=\mathrm{31,32},...,61\end{array}\right.,$ Wherein, u is radical exponent, and in the group of community ID, the value of the u that numbering 0,1,2 is corresponding is respectively 25,29,34;

Main for frequency domain synchronizing sequence is converted to time-domain primary synchronization sequence;

From master sync signal initial time, the Received signal strength after down-sampled is stored 128 sampled points, do to 3 time-domain primary synchronization sequences relevant cumulative respectively;

Described initial time is slided on the whole frame period, correlation peaks position is recorded as described field sync information, obtain the interior numbering of group of community ID corresponding to described correlation peaks position simultaneously.

3. method as claimed in claim 2, it is characterized in that, the step of the described CP of determination type specifically comprises:

Preserve front 9 data of described correlation peaks position and front 32 data respectively;

Front 9 data of preserving and front 32 data are done relevant adding up to 9 data at master sync signal end and 32 data respectively;

The higher value of relevant accumulation result is defined as corresponding CP type.

4. a TDD-LTE downlink synchronization device, is characterized in that, described device comprises:

Main lock unit, for by master sync signal and Received signal strength cross-correlation, obtains the interior numbering of group of field sync information and community ID;

CP type determining units, for by cyclic prefix CP data and master sync signal end CP length data cross-correlation, determines CP type;

Local scrambling sequence and auxiliary synchronous original series generation unit, for generating local scrambling sequence and auxiliary synchronous original series, described local scrambling sequence comprises the first scrambling sequence and the second scrambling sequence, and the generation of described auxiliary synchronous original series is by m sequence two kinds of different cyclic shifts obtain:

$s_0^{\left(m_0\right)}\left(n\right)=\tilde{s}\left((n+m_0)\mathrm{mod}31\right)$

$s_1^{\left(m_1\right)}\left(n\right)=\tilde{s}\left((n+m_1)\mathrm{mod}31\right)$

M sequence $\tilde{s}\left(i\right)=1-2x\left(i\right),$ 0≤i≤30， $x(\stackrel{\&OverBar;}{i}+5)=(x(\stackrel{\&OverBar;}{i}+2)+x\left(\stackrel{\&OverBar;}{i}\right))\mathrm{mod}\mathrm{2,0}\&le;\stackrel{\&OverBar;}{i}\&le;25,$ And the initial condition of x (i) is x (0)=0, x (1)=0, x (2)=0, x (3)=0, x (4)=1;

Wherein, m ₀and m ₁be derived from community ID group # m ₀be the first shift coordinates, m ₁be the second shift coordinates, its relation is as follows:

m ₀＝m′mod31

m ₁＝(m ₀+[m′/31]+1)mod31；

$m^{\&prime;}=N_{\mathrm{ID}}^{\left(1\right)}+q(q+1)/2,q=\left[\frac{N_{\mathrm{ID}}^{\left(1\right)}+q^{\&prime;}(q^{\&prime;}+1)/2}{30}\right],q^{\&prime;}=[N_{\mathrm{ID}}^{\left(1\right)}/30]$

Frequency domain secondary synchronization sequences acquiring unit, for according to master sync signal initial time and CP type, extracts time domain secondary synchronization sequences, and is converted to frequency domain secondary synchronization sequences;

Sequence of parity acquiring unit, for by the deinterleaving of described frequency domain secondary synchronization sequences and respectively with described first scrambling sequence and described second scrambling sequence descrambling after, obtain even order and odd numbered sequences respectively;

Coordinate record corresponding for correlation peaks, for by described even order and described auxiliary synchronous original series circular correlation, is the first shift coordinates by the first shift coordinates acquiring unit;

3rd scrambling sequence generation unit, for according to described first shift coordinates, generates the 3rd scrambling sequence;

Coordinate record corresponding for correlation peaks, for by after described odd numbered sequences and described 3rd scrambling sequence descrambling, with described auxiliary synchronous original series circular correlation, is the second shift coordinates by the second shift coordinates acquiring unit;

Community ID group # and frame start information acquiring unit, for according to described first shift coordinates and described second shift coordinates, obtain community ID group #, and according to the relative position of described first shift coordinates with described second shift coordinates, calculating frame start information.

5. device as claimed in claim 4, it is characterized in that, described main lock unit comprises:

The main synchronizing sequence of frequency domain generates subelement, for generating 3 main synchronizing sequences of frequency domain according to Zadoff-Chu sequence;

Time-domain primary synchronization sequence generates subelement, for main for frequency domain synchronizing sequence is converted to time-domain primary synchronization sequence;

First relevant cumulative subelement, for from master sync signal initial time, stores 128 sampled points by the Received signal strength after down-sampled, does relevant cumulative respectively to 3 time-domain primary synchronization sequences;

Acquisition subelement is numbered in field sync information and community ID group, for described initial time is slided on the whole frame period, correlation peaks position is recorded as described field sync information, obtains the interior numbering of group of community ID corresponding to described correlation peaks position simultaneously.

6. device as claimed in claim 5, it is characterized in that, described CP type determining units comprises:

Data preserve subelement, for preserving front 9 data of described correlation peaks position and front 32 data respectively;

Second relevant cumulative subelement, for doing relevant adding up to 9 data at master sync signal end and 32 data respectively by front 9 data of preserving and front 32 data;

Relevant accumulation result comparing unit, for being defined as corresponding CP type by the higher value of relevant accumulation result.