CN101383634B - Method and apparatus for searching downlink synchronous sequence - Google Patents

Abstract

The invention provides a method for searching a down synchronizing sequence and a device thereof. The device comprises a preprocessor, a first correlator, a first decision circuit, a second correlator and a second decision circuit, wherein the preprocessor is used for converting down synchronous codes into complex down synchronous codes, and divides all complex down synchronous codes into at least one group, respectively sums up each group of complex down synchronous codes and then gets the average to generate composite down synchronous codes; the first correlator is used for causing all composite down synchronous codes to respectively perform the sliding correlation operation with receiving signals; the first decision circuit is used for causing the position of the biggest maximum correlation peak obtained by the first correlator to be used as the position of the down synchronizing sequence; the second correlator is used for causing all complex down synchronous codes to respectively perform the correlation operation with signals of the down synchronizing sequence; and the second decision circuit is used for causing down synchronous codes corresponding to the maximum correlation peak obtained by the second correlator to be used as down synchronous codes used by a current access cell. The invention can fast and accurately search the down synchronous codes, and can ensure the functionality under the condition of small-signals and burst interference.

Description

A kind of method of searching downlink synchronous sequence and device

Technical field

The invention belongs to moving communicating field, particularly a kind of mobile terminal device is confirmed the method and the device of downlink synchronous sequence in initial cell search procedure.

Background technology

In GSM, mobile terminal device need carry out initial Cell searching after start.A free-revving engine of search of initial zone be exactly realize terminal and base station synchronously, and a lot of realizing through searching downlink synchronous sequence (descending pilot frequency) synchronously of mobile communication system terminal and base station.Realize confirming comprising synchronously of descending pilot frequency its position in downstream signal and the descending synchronous code of detection current area.

In traditional method and apparatus; Usually adopt with all descending synchronous codes with receive signal slide one by one the descending synchronous code that the method for asking relevant confirms to use the position with yard number; But this method operand is very big; Especially the operand that increases along with the code character of descending synchronous code increases rapidly, and this method requires more hardware resource, thereby causes the mobile terminal-opening search network time long.

Shortcoming based on said method; Someone has proposed the method for simplifying---and the power detection method (such as: the power features window method that is applied to the TD-SCDMA system); Arithmetic speed can be than comparatively fast under the desirable situation of signal; But this method can not accurately find the position of descending synchronous code under low-power level signal, and under the situation that the especially periodic bursty interference of bursty interference is arranged, can cause the position error detection of descending synchronous code, so its practical application has certain limitation.

Summary of the invention

The method and the device that the purpose of this invention is to provide a kind of searching downlink synchronous sequence solve behind the existing mobile terminal-opening in initial Cell searching the searching downlink synchronous sequence overlong time, at small-signal with the problem that the location is forbidden the bursty interference signal is under arranged.

For solving the problems of the technologies described above, the present invention provides technical scheme following:

A kind of device of searching downlink synchronous sequence comprises:

Preprocessor is used for converting basic descending synchronous code to the complex values descending synchronous code, and all complex values descending synchronous codes are divided at least one group, to making even all after every group of complex values descending synchronous code summation, generates corresponding composite downstream synchronous code respectively;

First correlator is used for all composite downstream synchronous codes are done the slip related operation with the reception signal respectively;

First decision device is used for first correlator is done the position of the position of the maximum correlation peak that the slip related operation obtains as downlink synchronous sequence;

Second correlator is used for all complex values descending synchronous codes are carried out related calculation with the downlink synchronous sequence signal respectively;

Second decision device is used for second correlator descending synchronous code that the corresponding descending synchronous code of the maximum correlation peak that obtains uses as present access subzone that carries out related calculation.

A kind of method of searching downlink synchronous sequence comprises the steps:

A, convert basic descending synchronous code to the complex values descending synchronous code, and all complex values descending synchronous codes are divided at least one group, to making even all after every group of complex values descending synchronous code summation, generate corresponding composite downstream synchronous code respectively;

B, with all composite downstream synchronous codes respectively with receive signal and do the slip related operation, and with position, the position of the maximum correlation peak that obtains as downlink synchronous sequence;

C, all complex values descending synchronous codes are carried out related calculation with downlink synchronous signal respectively, and the descending synchronous code that uses as present access subzone of the descending synchronous code that the maximum correlation peak that obtains is corresponding.

Compared with prior art, descending synchronous code can be searched quickly and accurately, and functional under small-signal and bursty interference situation can be guaranteed through the present invention.

Method and apparatus of the present invention is applied to contain in the frame structure in the GSM (for example, TD-SCDMA and TD-LTE) of downlink synchronous sequence (descending pilot frequency).

Description of drawings

Fig. 1 is the method flow diagram of the searching downlink synchronous sequence of the embodiment of the invention;

Fig. 2 is the structure drawing of device of the searching downlink synchronous sequence of the embodiment of the invention.

Embodiment

For making the object of the invention, technical scheme and advantage clearer, describe the present invention below in conjunction with accompanying drawing and specific embodiment.

With reference to Fig. 1, the method for the searching downlink synchronous sequence of the embodiment of the invention mainly comprises the steps:

Step 101: convert basic descending synchronous code to the complex values descending synchronous code;

In this step, all basic descending synchronous codes of system are carried out the plural number processing.If s is one of them basic descending synchronous code;

is corresponding complex values descending synchronous code, and conversion formula is following:

$\stackrel{\→}{s}\left(n\right)={\left(j\right)}^n{s}_n,$ S _n∈ 1 ,-1}, n=down-going synchronous code bit number.

Thus it is clear that, the complex values descending synchronous code

Element s _nBe that actual situation alternately occurs.

For example, in TD SDMA (TD-SCDMA) system, descending synchronous code is one, and one has 32 by 64 predetermined PN sequences of system, that is: n=1, and 2 ..., 64, s=(s ₁, s ₂..., s ₆₄).After the plural numberization processing, obtain 32 complex values descending synchronous codes.

Step 102: all complex values descending synchronous codes are divided at least one group, to making even all after every group of complex values descending synchronous code summation, generate corresponding composite downstream synchronous code respectively;

According to the quantity of basic descending synchronous code and relevance principle divide into groups (quantity of 1≤code character quantity≤descending synchronous code), to the equal computing of suing for peace, make even of the complex values descending synchronous code of each group.Available following formulate:

N ₁+N ₂+…+N _m＝N

Wherein, N is total sequence number of descending synchronous code, and m is the packet count of descending synchronous code; N _mSequence number for the place code character of descending synchronous code.

The composite downstream synchronization code sequence of summation, all back generations of making even is:

${\stackrel{\→}{s}}_m\left(n\right)=\frac{1}{N_m}\underset{i=0}{\overset{N_m-1}{\mathrm{\Σ}}}{\stackrel{\→}{s}}_i\left(n\right),$ N=down-going synchronous code bit number.

Certainly, also can the complex values descending synchronous code only be divided into one group (being equivalent to not carry out dividing into groups).For example; In the TD-SCDMA system; Can only produce a composite downstream synchronization code sequence; Then the composite downstream synchronization code sequence is made even by all (promptly 32) complex values descending synchronous code sequence

addition summations again and is all generated, as follows:

$\stackrel{\→}{s}\left(n\right)=\frac{1}{32}\underset{i=0}{\overset{31}{\mathrm{\Σ}}}{\stackrel{\→}{s}}_i\left(n\right),$ n＝1，2，…，64

Complex values descending synchronous code sequence and composite downstream synchronization code sequence can be to generate, and be stored in the portable terminal according to step 101,102 method in advance.It is thus clear that above-mentioned steps 101,102 is not all to need after each start to carry out

During initial ranging, carry out follow-up step 103,104 again behind the mobile terminal-opening.

Step 103: with all composite downstream synchronous codes respectively with receive signal and do the slip related operation, and with position, the position of the maximum correlation peak that obtains as downlink synchronous sequence;

The reception signal of same frame of composite downstream synchronization code sequence or two continuous frames is done the slip related operation, because the composite downstream synchronization code sequence

Shorter, and it is longer to receive signal, so

Connect and collect mail number $\stackrel{\→}{R}=R_I+j{R}_Q$ With 1 chip is that step-length is slided, and when sliding, carries out related calculation:

$c\left(n\right)=R\{\stackrel{\→}{R},\stackrel{\→}{S}\}$

Because must contain in all descending synchronous codes in the signal that receives, with the composite downstream synchronization code sequence do relevant after, can obtain a maximum correlation peak.So, the position of maximum correlation peak is exactly the position of this descending synchronous code, just the position of descending pilot frequency.

Step 104: all complex values descending synchronous codes are carried out related calculation with the downlink synchronous sequence signal respectively, and the descending synchronous code that the maximum correlation peak that obtains is corresponding is as the descending synchronous code of present access subzone use.

The downlink synchronous signal that detects the position carries out related calculation with all complex values descending synchronous codes respectively:

$c_1=R\{\stackrel{\→}{R}\′,{\stackrel{\‾}{S}}_1\},$

…，

$c_N=R\{\stackrel{\→}{R}\′,{\stackrel{\→}{S}}_N\}$

c ₁～c _NIn the corresponding code word of maximum promptly be the employed descending synchronous code of present access subzone.

Corresponding to the method for above-mentioned searching downlink synchronous sequence, the present invention also provides a kind of device of realizing said method.

With reference to Fig. 2, the device of the searching downlink synchronous sequence of the embodiment of the invention comprises: preprocessor 10, first correlator 20, first decision device 30, second correlator 40 and second decision device 50.

Preprocessor 10 comprises: plural numberization unit 11, be used for converting basic descending synchronous code to the complex values descending synchronous code, and the complex values descending synchronous code is the sequence that basic descending synchronous code actual situation replaces; Grouped element 12 is used for all complex values descending synchronous codes are divided at least one group, can divide into groups to the complex values descending synchronous code according to the quantity and the correlation of basic descending synchronous code; Sum unit 13 is used for respectively to making even all after every group of complex values descending synchronous code summation.

First correlator 20 is used for all composite downstream synchronous codes are done the slip related operation with the reception signal respectively.Particularly, all composite downstream synchronous codes are done the slip related operation with the reception signal of a frame or two continuous frames respectively, the slip cycle of slip related operation is 1 chip.

First decision device 30 is used for first correlator is done the position of the position of the maximum correlation peak that the slip related operation obtains as downlink synchronous sequence.Because must contain in the composite downstream synchronization code sequence with the corresponding descending synchronous code of received signal, so there is the maximal correlation peak value in the result after relevant, the position that the corresponding sequence of maximum correlation peak is slided promptly is the position of descending synchronous code in received signal.

Second correlator 40 is used for all complex values descending synchronous codes are carried out related calculation with the downlink synchronous sequence signal respectively.

Second decision device 50 is used for second correlator descending synchronous code that the corresponding descending synchronous code of the maximum correlation peak that obtains uses as present access subzone that carries out related calculation.All complex values descending synchronous codes are done relevant successively with the downlink synchronous signal that detects the position, still maximum correlation peak can occur, and the corresponding code word of maximum correlation peak promptly is the employed descending synchronous code of present access subzone.

Should be noted that at last; Above embodiment is only unrestricted in order to technical scheme of the present invention to be described; Those of ordinary skill in the art is to be understood that; Can make amendment or be equal to replacement technical scheme of the present invention, and not break away from the spirit of technical scheme of the present invention, it all should be encompassed in the middle of the claim scope of the present invention.

Claims (9)

1. the device of a searching downlink synchronous code is characterized in that, comprising:

Preprocessor is used for converting basic descending synchronous code to the complex values descending synchronous code, and all complex values descending synchronous codes are divided at least one group, to making even all after every group of complex values descending synchronous code summation, generates corresponding composite downstream synchronous code respectively;

First correlator is used for all composite downstream synchronous codes are done the slip related operation with the reception signal respectively;

First decision device, the position that is used for first correlator is done the maximum correlation peak that the slip related operation obtains is as the position that receives the signal descending synchronous code;

Second correlator is used for all complex values descending synchronous codes are carried out related calculation with the descending synchronous code that receives signal respectively;

Second decision device is used for second correlator descending synchronous code that the corresponding descending synchronous code of the maximum correlation peak that obtains uses as present access subzone that carries out related calculation.

2. the device of searching downlink synchronous code as claimed in claim 1 is characterized in that, said preprocessor comprises:

The plural numberization unit is used for converting basic descending synchronous code to the complex values descending synchronous code;

Grouped element is used for all complex values descending synchronous codes are divided at least one group;

Sum unit is used for respectively to making even all after every group of complex values descending synchronous code summation.

3. the device of searching downlink synchronous code as claimed in claim 2 is characterized in that:

Said grouped element divides into groups to the complex values descending synchronous code according to the quantity and the correlation of basic descending synchronous code.

4. the device of searching downlink synchronous code as claimed in claim 1 is characterized in that:

Said first correlator is done the slip related operation with the reception signal of a frame or two continuous frames respectively with all composite downstream synchronous codes.

5. the device of searching downlink synchronous code as claimed in claim 4 is characterized in that:

The slip cycle that said first correlator is done the slip related operation is 1 chip.

6. the method for a searching downlink synchronous code is characterized in that, comprises the steps:

A, convert basic descending synchronous code to the complex values descending synchronous code, and all complex values descending synchronous codes are divided at least one group, to making even all after every group of complex values descending synchronous code summation, generate corresponding composite downstream synchronous code respectively;

B, with all composite downstream synchronous codes respectively with receive signal and do the slip related operation, and with the position of the maximum correlation peak that obtains as the position that receives descending synchronous code in the signal;

C, all complex values descending synchronous codes are carried out related calculation with the descending synchronous code that receives in the signal respectively, and the descending synchronous code that uses as present access subzone of the descending synchronous code that the maximum correlation peak that obtains is corresponding.

7. the method for searching downlink synchronous code as claimed in claim 6 is characterized in that:

In the steps A, the complex values descending synchronous code is divided into groups based on the quantity and the correlation of basic descending synchronous code.

8. the method for searching downlink synchronous code as claimed in claim 6 is characterized in that:

Among the step B, all composite downstream synchronous codes are done the slip related operation with the received signal of a frame or two continuous frames respectively.

9. the method for searching downlink synchronous code as claimed in claim 8 is characterized in that:

Among the step B, the slip cycle of said slip related operation is 1 chip.

Images