CN1642057A - Initial synchronizing method for community search for CDMA communication system - Google Patents

Abstract

The invention discloses an initial synchronization method in the subzone searching of the code division multiple access system. Each of the base station of the system is strictly synchronization. The number of all of the mutual pairwise orthogonal spread spectrum code words have L the received signal is taking amplog digital transformation and integral; and its result is inputted to matched filter; the matched filter is used one spread spectrum code word at each of two frames; the spread spectrum code is tested and the service subzone is selected by the judgment unit; the time slot position of the service slot is gained; and according to it the boundary of the frame is gained. The invention can quickly realize the down link subzone searching and initial synchronization; its synchronization precision is high; its method is simple, and easy to realize.

Description

Initial synchronization method in the subzone search of CDMA communication system

Technical field

The present invention relates to the initial synchronization method in the search of a kind of code division multiple access (CDMA) communication system cell, belong to wireless communication technology field.

Background technology

Fast development of information technology, mobile communication has been proposed how new business demand, the multimedia service and the high-speed data service that combine with data as image, speech, cdma system is owing to have big capacity, high spectrum utilization, low transmitting power, characteristics such as strong security are developed rapidly, become the mainstream technology of 3G (Third Generation) Moblie.

Usually in cdma system, receiving equipment utilizes local spreading code to the relevant despreading of spread-spectrum signal, solves Useful Information.Spreading code will realize exactly that synchronously local spreading code and the spreading code that receives are in full accord on structure, frequency and phase place.Spreading code is that spread spectrum system is peculiar synchronously, does not have spreading code synchronous, and the reception of spread-spectrum signal is not known where to begin.

Travelling carriage one start need be carried out Cell searching in the cdma system, and Cell searching promptly will search the information of sub-district He its adjacent sub-district at travelling carriage place, and the initial synchronisation of travelling carriage comprises that PN sign indicating number (pseudo noise code) is synchronous, sign synchronization, and frame synchronization and scrambler are synchronous etc.The initial synchronisation of WCDMA TDD system, undertaken by " three step prize laws ", the first step: slot synchronization, obtain the slot synchronization of a sub-district by the synchronization codes of synchronizing channel, adopt a matched filter that mates with synchronization codes, the synchronous code here all is identical for all sub-districts, obtains slot synchronization by the peak value that detects matched filter output.Second step, frame synchronization and code character indication, UE adopts the auxiliary synchronous code of synchronizing channel to obtain frame synchronization and the code character of all sub-districts of determining to find in the first step, received signal need be carried out coherent computing with the different spreading codes of all possible auxiliary synchronization channel, and definite maximum related value, determine frame synchronization and scrambler group number.The 3rd step, scrambler identification.After scrambler code character under the second step base station is determined, need further to determine the identity code-descending scrambler of base station, by possible scrambler is carried out exhaustive search, it is synchronous to set up scrambler.

WCDMA TDD adopts all sub-districts identical synchronizing pulse train to carry out slot synchronization, under objects at high speed situation of movement around travelling carriage or the travelling carriage, Doppler frequency-shift can cause the pulse energy big rise and fall, the identical synchronizing pulse train of each sub-district can disturb, add the influence of interchannel noise and various declines, it is big that the flase drop of each frame of sub-district slot synchronization is surveyed probability.

The Cell searching of TD-SCDMA system and initial synchronisation were divided into for four steps, the first step: descending pilot frequency time slot DwPTS search, in the down channel of TD-SCDMA, comprise descending pilot frequency time slot, travelling carriage uses a matched filter searching downlink channel, find the descending pilot frequency time slot of the strongest base station of signal by the output that receives matched filter, thereby find SYNC identifier (ID), and the code character of corresponding scrambler of SYNC ID and training sequence, each code character contains eight scramblers.Second step, scrambler and the identification of basic training sequences sign indicating number.The main purpose of this step is to find employed basic training sequences sign indicating number in this sub-district and the scrambler corresponding with it.Found the code character at this training sequence code place because of the first step, so this moved further platform only need be judged to the correlation of symbol by using four basic training sequences sign indicating numbers to carry out symbol respectively, just can determine which in four sign indicating numbers this training sequence be, and each scrambler is corresponding with specific basic training sequences sign indicating number, and then just can determine scrambler.In the 3rd step, realize that multi-frame is synchronous.The particular location of multi-frame head is to be determined by n continuous pilot channel QPSK phase code, and downlink pilot frequency channel adopts QPSK (quaternary PSK) modulation, therefore it comprises QPSK phase code information, and travelling carriage just can search the multi-frame head by solving this coded message.The 4th step: read broadcast channel (BCH).Travelling carriage utilizes the scrambler that former steps have identified, the basic training sequences sign indicating number, and the multi-frame head reads the BCH broadcast channel information, thereby obtains the public informations such as configuration of sub-district.The search utility of TD-SCDMA is more quick than the cell search procedure of WCDMA TDD, but the cell searching mode of WCDMA TDD can make the arrangement of descending Common Control Channel more flexible.The TD-SCDMA different districts adopts different synchronizing pulse trains to carry out slot synchronization, reduce the interference of the lock-out pulse of adjacent sub-district, but when multi-frame is synchronous, adopt the mode of demodulation QPSK information to search the multi-frame head, do not having under the situation of carrier synchronization, if carrier wave frequency deviation is very big, the error rate of QPSK is very high, influences the multi-frame net synchronization capability.

Summary of the invention

The object of the present invention is to provide a kind of initial synchronization method that is used for subzone search of CDMA communication system more accurately and fast.

The objective of the invention is to be achieved through the following technical solutions:

Initial synchronization method in a kind of subzone search of CDMA communication system, each base station strict synchronism in this cdma communication system, descending synchronous signal channel in same sub-district has most equally spaced time slots, and the equal in length of each time slot, the spreading code code word of total L mutual pairwise orthogonal, and per two code words ratio of the submaximum of cross-correlation and main peak in twos is characterized in that smaller or equal to 1/8th this method may further comprise the steps at least:

1) carries out analog to digital conversion and integration to received signal, and the result is imported matched filter

2) per two frames of matched filter use a spreading code code word, detect spreading code and select Serving cell by decision unit, and obtain the time slot position of Serving cell

3) obtain the frame boundaries of Serving cell according to the time slot position of Serving cell.

Preferable, step 2) matched filter uses the spreading code of a pair of pairwise orthogonal to detect respectively to two frames of each sub-district of receiving in, the descending synchronous code pairwise orthogonal that former frame is used, the descending synchronous code pairwise orthogonal that back one frame uses.

Preferable, the even frame of last sub-district is identical with the code word of the strange frame of one sub-district, back.

Preferable, wherein, step 2) may further comprise the steps:

2a) form No. 1 (1=1,2 ... L) correlation peak of each frame of code word can duration set and maximum value position set

2c) choose effective P ₁ ^l(i) and corresponding peak value energy V ₁ ^l(i) form set

2d) calculate average energy V in the l Number character energy duration set ₁ ^l, V ₂ ^lWith maximum value position P in the selected maximum value position set ₁ ^l, P ₂ ^l

If 2e) obtain average energy and maximum value position, then enter step 2f) more than or equal to I code word; If not then making l=l+1 return step 2a).Wherein I determines according to the neighbor cell number in the honeycomb of networking

The mean value V of the correlation peak of 2f) selection maximum ₁ ^l, V ₂ ^lA pair of code word corresponding district as Serving cell.

Preferable, step 2a), further may further comprise the steps 2c): 2b) the time slot position P of former frame in per two frames of l number is searched in initialization ₁ ^l, peak energy mean value V ₁ ^lThe time slot position P of back one frame ₂ ^l, peak energy mean value V ₂ ^l

Preferable, step 2a) matched filter obtains the correlation peak energy duration set V of each code word to each code word poll N time in ₁ ^l(i), V ₂ ^l(i) and maximum value position set P ₁ ^l(i), P ₂ ^l(i), wherein, N by system according to filter effect and Cell searching time set, i=1,2 ... N.

Preferable, step 2c) judges in the maximum value position set of l Number character and be no less than M maximum value position P ₁ ^l(i) absolute value of relative position difference and is no less than M maximum value position P less than P in twos ₂ ^l(i) absolute value of relative position difference then continues step 2d less than P in twos), wherein M is the integer of setting, i=1,2 ... N, the relativity shift * frame length of P=timer clock frequency; If do not satisfy then make l=l+1 return step 2a).

Preferable, step 2d) calculate in the l Number character can duration set in average energy be to the former frame correlation peak of l Number character can duration set in all V ₁ ^l(i) ask average, obtain V ₁ ^l, and to all V in the back frame correlation peak energy duration set of l Number character ₂ ^l(i) ask average, obtain V ₂ ^l, i=1 wherein, 2 ... N;

Preferable, step 2d) maximum value position P in the selected maximum value position set in ₁ ^lBe the time in the former frame maximum value position set of l Number character to be gone up a last maximum value position assignment that obtains give P ₁ ^l, maximum value position P in the selected maximum value position set ₂ ^lBe the time in the back frame maximum value position set of l Number character to be gone up a last maximum value position assignment that obtains give P ₂ ^l

Preferable, step 2f) selecting Serving cell is according to peak energy mean value V by decision unit ₁ ^l, V ₂ ^lCorresponding code word finds out frame number, finds the respective cell sequence number according to frame number again.

Preferable, step 2f) decision unit is according to maximum value position P ₁ ^l, P ₂ ^lDetermine the Serving cell time slot position.

Preferable, step 3) comprises the correspondence position value of the interregional integral multiple every a slot length of slip accumulator input 2 times of frame lengths before and after time slot position, and output the result enter in the moving average accumulator, the position of the output correspondence of moving average accumulator is the frame boundaries position.

Preferable, time slot the first half time slot of descending synchronous signal channel does carrier synchronization and channel estimating is used, half time slot of back breath of delivering a letter.

The present invention uses two frames to carry out spreading code and detects, so can realize the Cell searching and the initial synchronisation of down link fast.And, select Serving cell by multiframe peak energy mean value and maximum value position, improved synchronization accuracy, method is simple, is easy to realize.

Description of drawings

The present invention will be described in detail below by drawings and the specific embodiments.

Fig. 1 is the structural representation of mobile radio station descending synchronous signal channel receiver of the present invention.

Fig. 2 is the flow chart of synchronization loop of the present invention.

Fig. 3 is the downstream synchronization code word sequence number tabulation schematic diagram that parity frame is distinguished in each sub-district of the present invention.

Fig. 4 is correlation peak of the present invention and list of locations schematic diagram.

Fig. 5 is the slip accumulator that the present invention designs.

Fig. 6 is the moving average accumulator that the present invention designs.

Embodiment

In the cdma communication system of the present invention, the total L of a travelling carriage mutually orthogonal spreading code code word, and per two code words in twos the ratio of the submaximum of cross-correlation and main peak smaller or equal to 1/8th.And descending synchronous signal channel carries out the time-division in this cdma communication system, and most equally spaced time slots are arranged.In the same sub-district, the equal in length of each time slot of descending synchronous signal channel, and the first half time slot of descending synchronous signal channel breath of not delivering a letter, half time slot of back breath of delivering a letter.Like this, the first half time slot is used for carrier synchronization and channel estimating; Half time slot of back also is utilized effectively.In addition, each base station strict synchronism in this cdma communication system.The sub-frame of downlink synchronization of idol frame and the sub-frame of downlink synchronization of strange frame be the length that the length of a frame deducts a sub-frame of downlink synchronization at interval, if long enough at interval, the interference of the downstream synchronization code word that even frame and strange frame are non-orthogonal can be ignored.At this, No. 1 sub-district, No. 2 sub-districts, No. 3 sub-districts, No. 4 sub-districts ... the L sub-district is a neighbor cell.

Referring to Fig. 1, the down-going synchronous receiver by analog to digital conversion (A/D) 12 conversion and integration washer (IDF) 13, is sent into matched filter 14 with received signal 11.In the present embodiment, the output speed of integration washer (IDF) 13 is 2fc.The output I road of matched filter 14, Q road value, after quadratic sum computing 15, output signal is sent into synchronization loop 20.Handle through synchronization loop, search is also selected Serving cell, realizes slot synchronization, obtains frame boundaries, receives broadcast channel at last.Matched filter of the present invention can be a correlator also, as sliding correlation detector.

Referring to figs. 2 and 3, step 110 is to carry out analog to digital conversion and integration to received signal, and the result is imported matched filter.

Step 140 is to detect spreading code and select Serving cell.Suppose to have in the communication system L base station, L is given birth to L base station of frequency spreading code division dispensing with a code word, common property in each base station.Matched filter 14 per two frames use the coefficient of same spread spectrum code word as matched filter 14, and per two frames are changed the coefficient of a matched filter.In Fig. 3 illustrated the corresponding relation between sub-district and strange frame and the even frame.This corresponding relation is stored in the judgment device on upper strata.When matched filter 14 is started working, receive a strange frame of No. 1 sub-district, matched filter 14 uses No. 1 spread spectrum code word to handle; Then, to an even frame of No. 1 sub-district receiving and the strange frame of No. 2 sub-districts, matched filter 14 uses No. 2 spread spectrum code words to handle; Similarly, to the even frame of No. 2 sub-districts receiving and the strange frame of No. 3 sub-districts, matched filter 14 uses No. 3 spread spectrum code words to handle.To the strange frame of the L sub-district that receives, matched filter 14 uses L spread spectrum code words to handle; To the even frame of the L sub-district that receives, matched filter 14 uses No. 1 spread spectrum code word to handle.Wherein, the downstream synchronization code word of strange frame is mutually orthogonal in twos, and the downstream synchronization code word of even frame is mutually orthogonal in twos, but the downstream synchronization code word of even frame and strange frame can be non-orthogonal also can quadrature.As can be seen, the present invention carries out matched filtering to the parity frame of same sub-district with the code word of a pair of pairwise orthogonal, makes things convenient for the identification of parity frame.As long as it is a pair of in the code word certain to detect L, just can discerns this to the code word corresponding district, and can distinguish the parity frame of this sub-district.With reference to the accompanying drawings 3, the strange frame that use each sub-district and the code word of even frame are fixed, when the code word sequence number of the maximum correspondence of the correlation peak of the former frame that detects two consecutive frames and after the code word sequence number of maximum correspondence of correlation peak of a frame in the tabulation of accompanying drawing 3, just can determine the Serving cell at place and the parity frame of Serving cell according to this a pair of code word sequence number pairing cell id, here former frame might be strange frame or even frame, can judge that according to the code word sequence number of former frame former frame is strange frame or even frame.

Describe the concrete steps that detect spreading code and select Serving cell in detail below in conjunction with Fig. 2 and Fig. 4.Fig. 4 is to be that example describes with the corresponding No. 3 strange frame sign indicating number sequence numbers in No. 3 sub-districts among Fig. 3 and No. 4 even frame sign indicating number sequence numbers.

Step 201: the correlation peak that forms each each frame of code word can duration set and maximum value position set.

If use the l number (l=1,2 ... L, L are the numbers of all code words of the poll of wanting) as the filter factor of matched filter, maximum (peak value) note of former frame that is polled to two frames of l number for the i time is made V ₁ ^l(i), corresponding peaked position note is made P ₁ ^l(i); The maximum note of back one frame is made V ₂ ^l(i), corresponding peaked position note is made P ₂ ^l(i); After all code word of matched filter poll, repeat polling operation, polled N time of each code word obtains V ₁ ^l(i), P ₁ ^l(i), V ₂ ^l(i), P ₂ ^l(i), (l=1,2 ... L; I=1,2 ... N).

In Fig. 4, with the coefficient of 3 Number characters as matched filter, then the first time, the second time and the N time detection obtain the correlation peak energy V of back one frame ₂ ³(1), V ₂ ³(2), V ₂ ³(N) and maximum value position P ₂ ³(1), P ₂ ³(2), P ₂ ³(N).With the coefficient of 4 Number characters as matched filter, then the first time, the second time and the N time detection obtain this code word correlation peak energy duration set V of former frame ₁ ⁴(1), V ₁ ⁴(2), V ₁ ⁴(N) and correlation peak location set P ₁ ⁴(1), P ₁ ⁴(2), P ₁ ⁴(N).The code word 1,2 that the matched filter poll is all ... L, and polled N time of each code word, obtaining correlation peak can duration set and the set of correlation peak location.

Step 202: the maximum value position P of former frame in two frames of l number is searched in initialization ₁ ^l=0, peak energy mean value V ₁ ^l=0.0; The maximum value position P of back one frame ₂ ^l=0, peak energy mean value V ₂ ^l=0.0.

Step 203: choose effective P ₁ ^l(i) and corresponding peak value energy V ₁ ^l(i) form set.

Set integer M (M＜N) and P, the wherein relativity shift * frame length of P=timer clock frequency (chips).Ideally, if the matched filter coefficient of any two frames or multiframe is identical, the position of the correlation peak of the matched filter of the frame that matched filter coefficient is identical output should be identical so, consider the influence of the time slot position skew that multipath and clock frequency deviation bring, the correlation peak of continuous two time slots of descending synchronous signal channel should not surpass P.If the N of code word l P ₁ ^l(i) have in above M P ₁ ^lThe absolute value of the difference of relative position in twos (i) is less than P, and then code word 1 may be the code word of Serving cell, with this more than or equal to M P ₁ ^l(i) and corresponding energy value V ₁ ^l(i) form set.Otherwise, make l=l+1, return step 201, form the maximum energy duration set and the maximum value position set of each frame of l+1 Number character, up to l=L.Equally, if the N of code word 1 is a P ₂ ^l(i) have in above M P ₂ ^lThe absolute value of the difference of relative position in twos (i) is less than P, then with this more than or equal to M P ₂ ^l(i) and corresponding energy value V ₂ ^l(i) form set.Otherwise, make l=l+1, return step 201, form the maximum energy duration set and the maximum value position set of each frame of l+1 Number character, up to l=L.

Step 204: calculating energy mean value V ₁ ^l, V ₂ ^lWith maximum value position P ₁ ^l, P ₂ ^l

When calculating former frame average energy and maximum value position, the energy value V of condition in the step 203 will be satisfied ₁ ^l(i) form an energy duration set, the V in the calculating energy set ₁ ^l(i) mean value V ₁ ^lThe position P of condition in the step 203 will be satisfied ₁ ^l(i) form a location sets, P ₁ ^lEqual the P of the maximum i value in the location sets ₁ ^l(i), that is, and the maximum value position of last acquisition on the time in location sets.One group of V of a code word correspondence ₁ ^l, P ₁ ^lStore in the RAM.Can obtain set (P like this less than the L group ₁ ^l, V ₁ ^l), (1＜L).

When calculating back one frame average energy and maximum value position, the energy value V of condition in the step 203 will be satisfied ₂ ^l(i) form an energy duration set, the V in the calculating energy set ₂ ^l(i) mean value V ₂ ^lThe position P of condition in the step 203 will be satisfied ₂ ^l(i) form a location sets, P ₂ ^lEqual the P of the maximum i value in the location sets ₂ ^l(i).One group of V of a code word correspondence ₂ ^l, P ₂ ^lStore in the RAM.Can obtain set (P like this less than the L group ₂ ^l, V ₂ ^l), (l＜L).With correlation peak location average through multiframe, peak energy is average through multiframe, can resist decline and adjacent area interference and The noise, the false detection rate of reduction slot synchronization and Cell searching.

Step 205: whether obtain average energy and maximum value position more than or equal to I code word.If no, then return step 201; If obtain, then enter step 206.Wherein I determines according to the neighbor cell number in the honeycomb of networking.

Step 206: select correlation peak average energy V ₁ ^l, V ₂ ^lMaximum a pair of code word corresponding district is as Serving cell.

The former frame of per two frames and back one frame obtain set (P respectively in the abovementioned steps ₁ ^l, V ₁ ^l), (P ₂ ^l, V ₂ ^l), the number of set interior element is less than L.With certain time slot of descending synchronous signal channel the corresponding correlation peak average energy V of maximum value position ₁ ^lAnd V ₂ ^lRespectively by from big to small rank order, then with the former frame V of per two frames ₁ ^lWith back one frame V ₂ ^lBe combined into a new set (V ₁ ^L1, V ₂ ^L2) whether (can be understood as is with V ₁ ^lIn maximum and V ₂ ^lIn maximum be combined into one group of (V of new set ₁ ^L1, V ₂ ^L2), again with V ₁ ^lIn second largest value and V ₂ ^lIn second largest value be combined into a group of new set?), l ₁, l ₂Be positive integer, represent corresponding code word less than L.New set (V ₁ ^L1, V ₂ ^L2) in every couple of code character l ₁, l ₂Order identical with its sorting position in tabulation.For example, obtaining qualified former frame peak energy mean value in step 204 is V ₁ ¹, V ₁ ², V ₁ ³, V ₁ ⁴, back one frame peak average energy is V ₂ ², V ₂ ³, V ₂ ⁴, V ₂ ⁵, obtain V after sorted ₁ ¹, V ₁ ², V ₁ ³, V ₁ ⁴And V ₂ ², V ₂ ³, V ₂ ⁴, V ₂ ⁵Form new set (V ₁ ¹, V ₂ ²) (V ₁ ², V ₂ ³) (V ₁ ³, V ₂ ⁴) (V ₁ ⁴, V ₂ ⁵).Synchronization loop is according to from high to low order, at new set (V ₁ ^L1, V ₂ ^L2) in find out and meet parity frame tabulation of each sub-district, as shown in Figure 3, in all to (l ₁, l ₂), and meeting in parity frame tabulation of each sub-district all to (l ₁, l ₂) report to decision unit, form the sequence number l of code word ₁, l ₂, to maximum value position that should code word and tabulation that correlation peak average energy that should maximum value position is formed.In the last example, corresponding code character is (1,2), (2,3), (3,4), (4,5).Decision unit is selected the mean value V of correlation peak respectively ₁ ^l, V ₂ ^lThe maximum V of intermediate value ₁ ^l, V ₂ ^lCorresponding code word is judged corresponding district according to some in each sub-district parity frame tabulation to effective code word, and promptly the sub-district that energy is the strongest is as Serving cell.In the last example, V ₁ ¹And V ₂ ²Be maximum, so select code character (1,2) corresponding district, No. 1 sub-district is Serving cell.Again for example, maximum V among Fig. 4 ₁ ^lBe V ₁ ⁴, corresponding code word is 4; Maximum V ₂ ^lBe V ₂ ³, corresponding code word is 3.It is 4 that decision unit finds even frame code word in each sub-district parity frame tabulation, and strange frame code word is 3, and qualified sub-district is No. 3 sub-districts.Therefore, selecting No. 3 sub-districts is Serving cell.Simultaneously, decision unit is distinguished parity frame according to this to code word, and the parity frame of finishing all possible sub-district in the tabulation detects and slot synchronization.P ₁ ^l, P ₂ ^lPrecision be Tc/2 (Tc be chip long), P ₁ ^lOr P ₂ ^lValue be the position of last Tc/2 chip of a time slot, if know the position of last chip of time slot, promptly realized slot synchronization.The parity frame of determining the sub-district is according to former frame maximum V by decision unit ₁ ^lCorresponding code word and back one frame maximum V ₂ ^lCorresponding code word judges that according to each sub-district parity frame tabulation former frame is strange frame or even frame find respective cell in each sub-district parity frame tabulation after again, judges that then back one frame is even frame or strange frame.For example, behind selected No. 3 sub-districts, can determine that former frame is even frame; Back one frame is strange frame.The time of a correlation peak of every extraction is the time of a frame.

Step 207: the frame boundaries that obtains Serving cell.

Step 206 has been finished slot synchronization and the parity frame that Cell searching and institute might the sub-district and has been detected, two matched filters of next step travelling carriage use, and one of them matched filter is used for the frame boundaries position of search service sub-district.The only position work of a down-going synchronous frame before and after the determined position of slot synchronization of matched filter by a slip accumulation window, is found a maximum in window, peaked position promptly is the position of frame boundaries.Another matched filter is used for the frame boundaries position of the adjacent sub-district of poll.

Determined the position P of certain time slot of the descending synchronous signal channel of Serving cell by step 201-206 _Slot, P wherein _SlotPromptly be maximum average value V in the tabulation newly-generated in the step 205 ₁ ^lOr V ₂ ^lThe position of correlation peak.At this, with positional precision by Convert the precision of sample value level to.At P _SlotW (chips) opens a window in zone before and after this position, all values in this window (all values be the interval of sample value at interval, be assumed to here

) be designated as V _Slot-4W, V _Slot-4W+1... .V _Slot...., V _Slot+4W-1, V _Slot+4WThe respective value of the slot length integral multiple in interval enters in the slip accumulator successively before and after all values of this window.The slip accumulator is a techniques well known, and this not tired stating, Fig. 4 just provides a schematic structure chart.Suppose that a sub-frame of downlink synchronization has N time slot, maximizing V in the output of slip accumulator in the time of the sub-frame of downlink synchronization of twice _FrameAnd write down corresponding position P (i), _Frame(i):

$P_1^l-\mathrm{Slot}\_\mathrm{Length}/2+\mathrm{Slot}\_\mathrm{Length}\×i,$

$P_1^l-\mathrm{Slot}\_\mathrm{Length}/2+1+\mathrm{Slot}\_\mathrm{Length}\×i,$ $P_1^l+\mathrm{Slot}\_\mathrm{Length}/2+2+\mathrm{Slot}\_\mathrm{Length}\×i\·\·\·$

$P_1^l+\mathrm{Slot}\_\mathrm{Length}/2+\mathrm{Slot}\_\mathrm{Length}\×i,i=-N\_\mathrm{Slot},-N\_\mathrm{Slot}+1,......N\_\mathrm{Slot}$

, the N continuous _ Frame of the output of a slip accumulator P _Frame(i), i=1,2 ... N_Frame enters the moving average accumulator, as shown in Figure 5.The moving average accumulator is a techniques well known, and this not tired stating, Fig. 5 just provides a schematic structure chart.Value of each frame output of moving average accumulator, from starting working, N_Frame output valve and later output valve are effective values, a value of the average accumulator output of each frame slip is the frame boundaries position of every frame.The synchronizing information that this position receives as service signal.Wherein, the influence of multipath and channel fading is mainly considered in the selection of N_Frame.

Step 208: receive the system information among the broadcast channel BCCH.

The frame boundaries position of the Serving cell that obtains according to step 207 receives the system information among the broadcast channel BCCH, comprising the information such as tabulation of adjacent sub-district.

Step 209: carry out CRC check.

Continuous most frame CRC check mistake is then returned step 201.Otherwise enter step 210.

Step 210: Cell searching and initial synchronisation success.

Though above described the present invention by embodiment, those of ordinary skills know, the present invention has many distortion and variation and does not break away from spirit of the present invention, appended claim will comprise these distortion and variation.

Claims (13)

1. the initial synchronization method in the subzone search of CDMA communication system, each base station strict synchronism in this cdma communication system, descending synchronous signal channel in same sub-district has most equally spaced time slots, and the equal in length of each time slot, the spreading code code word of total L mutual pairwise orthogonal, and per two code words ratio of the submaximum of cross-correlation and main peak in twos is characterized in that smaller or equal to 1/8th this method may further comprise the steps at least:

1) carries out analog to digital conversion and integration to received signal, and the result is imported matched filter

2) per two frames of matched filter use a spreading code code word, detect spreading code and select Serving cell by decision unit, and obtain the time slot position of Serving cell

3) obtain the frame boundaries of Serving cell according to the time slot position of Serving cell.

2. the initial synchronization method in the subzone search of CDMA communication system according to claim 1 is characterized in that:

Step 2) matched filter uses the spreading code of a pair of pairwise orthogonal to detect respectively to two frames of each sub-district of receiving in, the descending synchronous code pairwise orthogonal that former frame is used, the descending synchronous code pairwise orthogonal that back one frame uses.

3. as the initial synchronization method in the subzone search of CDMA communication system as described in the claim 2, it is characterized in that:

The even frame of last sub-district is identical with the code word of the strange frame of one sub-district, back.

4. as the initial synchronization method in the subzone search of CDMA communication system as described in the claim 2, it is characterized in that:

Wherein, step 2) may further comprise the steps:

2a) form l number (l=1,2 ... L) correlation peak of each frame of code word energy duration set and maximum value position set;

2c) choose effective maximum value position and corresponding peak value energy composition set from the set of l Number character maximum value position;

2d) calculation procedure 2c) average energy V in the set of l Number character peak energy in ₁ ^l, V ₂ ^lWith maximum value position P in the selected maximum value position set ₁ ^l, P ₂ ^l

2e) whether obtain average energy and maximum value position, if then enter step 2f) more than or equal to I code word; If not then making l=l+1 return step 2a), wherein I determines according to the neighbor cell number in the honeycomb of networking;

The average energy V of the correlation peak of 2f) selection maximum ₁ ^l, V ₂ ^lA pair of code word corresponding district as Serving cell.

5. as the initial synchronization method in the subzone search of CDMA communication system as described in the claim 4, it is characterized in that:

Wherein, further may further comprise the steps 2c step 2a)): 2b) the time slot position P of former frame in per two frames of l number is searched in initialization ₁ ^l, peak energy mean value V ₁ ^lThe time slot position P of back one frame ₂ ^l, peak energy mean value V ₂ ^l

6. as the initial synchronization method in the subzone search of CDMA communication system as described in the claim 4, it is characterized in that:

Step 2a) matched filter obtains the correlation peak energy duration set V of each code word to each code word poll N time in ₁ ^l(i), V ₂ ^l(i) and maximum value position set P ₁ ^l(i), P ₂ ^l(i), wherein, N by system according to filter effect and Cell searching time set, i=1,2 ... N.

7. as the initial synchronization method in the subzone search of CDMA communication system as described in the claim 4, it is characterized in that:

Step 2c) is no less than M maximum value position P in the maximum value position set of judgement l Number character ₁ ^l(i) absolute value of relative position difference and is no less than M maximum value position P less than P in twos ₂ ^l(i) absolute value of relative position difference then continues step 2d less than P in twos), wherein M is the integer of setting, i=1,2 ... N, the relativity shift * frame length of P=timer clock frequency; If do not satisfy then make l=l+1 return step 2a).

8. as the initial synchronization method in the subzone search of CDMA communication system as described in the claim 4, it is characterized in that:

Step 2d) average energy is to all V in the former frame correlation peak energy duration set of l Number character in the middle calculating l Number character energy duration set ₁ ^l(i) ask average, obtain V ₁ ^l, and to all V in the back frame correlation peak energy duration set of l Number character ₂ ^l(i) ask average, obtain V ₂ ^l, i=1 wherein, 2 ... N;

9. as the initial synchronization method in the subzone search of CDMA communication system as described in the claim 8, it is characterized in that:

Step 2d) maximum value position P in the selected maximum value position set in ₁ ^lBe the time in the former frame maximum value position set of l Number character to be gone up a last maximum value position assignment that obtains give P ₁ ^l, maximum value position P in the selected maximum value position set ₂ ^lBe the time in the back frame maximum value position set of l Number character to be gone up a last maximum value position assignment that obtains give P ₂ ^l

10. as the initial synchronization method in the subzone search of CDMA communication system as described in the claim 4, it is characterized in that:

Step 2f) selecting Serving cell is according to peak energy mean value V by decision unit ₁ ^l, V ₂ ^lCorresponding code word finds out frame number, finds the respective cell sequence number according to frame number again.

11. the initial synchronization method as in the subzone search of CDMA communication system as described in the claim 4 is characterized in that:

Step 2f) decision unit is according to maximum value position P ₁ ^l, P ₂ ^lDetermine the Serving cell time slot position.

12. the initial synchronization method in the subzone search of CDMA communication system according to claim 1 is characterized in that:

Step 3) comprises the correspondence position value of the interregional integral multiple every a slot length of slip accumulator input 2 times of frame lengths before and after time slot position, and output the result enter in the moving average accumulator, the position of the output correspondence of moving average accumulator is the frame boundaries position.

13. the initial synchronization method in the subzone search of CDMA communication system according to claim 1 is characterized in that:

Time slot the first half time slot of descending synchronous signal channel is done carrier synchronization and channel estimating and is used, half time slot of back breath of delivering a letter.

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