WO2007124635A1

WO2007124635A1 - A frame synchronization implement method in a wireless communication system

Info

Publication number: WO2007124635A1
Application number: PCT/CN2006/003761
Authority: WO
Inventors: Shuqiang Xia; Yong Li
Original assignee: Zte Corporation
Priority date: 2006-05-01
Filing date: 2006-12-30
Publication date: 2007-11-08
Also published as: CN101068127A; CN101068127B

Abstract

A frame synchronization implement method in a wireless communication system is applied to the transmission mode that the SCH signals are transmitted uniformly in a frame. At the transmitting terminal the sync channel signals and broadcast channel signals are transmitted in the time division multiplexing mode each of the broadcast channel signals is adjacent to a sync channel signal and advances or delays a defined time interval with respect to the adjacent sync channel signal. Present invention integrates the included information in the SCH signals and BCH signals.

Description

TECHNICAL FIELD The present invention relates to the field of digital communications, and in particular, to a method for implementing frame synchronization in a wireless communication system, which is applicable to OFDM (Orthogonal Frequency Division Multiplexing). LTE (long term evolution) system, CDMA2000 system, WCDMA system. BACKGROUND When a mobile station initially accesses a system or performs handover between cells, it is often an essential step for the mobile station to acquire frame synchronization with the system. Here, frame synchronization is defined as the frame start position at which the mobile station obtains received data. In the frame synchronization process, two channels are generally involved: a synchronization channel (SCH) and a broadcast channel (BCH 'broadcast channel). The SCH channel generally provides several possible locations for system frame synchronization, while the BCH provides a specific cell. Some related system information. When the SCH (or BCH)-frame is transmitted only once, a common method is to send the SCH (or BCH) signal at a fixed position of one frame, and after the mobile station captures the SCH (or BCH) signal, The frame synchronization of the mobile station and the system is also determined at the same time. However, when the frame length is relatively long (for example, the length of one frame is 10 ms), if the SCH-frame is transmitted only once, it takes 4 times for the mobile station to capture the SCH. Therefore, the actual system needs cannot be satisfied. Therefore, it is common practice to transmit the SCH signal multiple times within one frame time. When a frame time includes a plurality of SCH signals, the applicant has previously proposed a synchronization signal transmission method in this case. However, the method is only applicable to the case where the SCH signal is not uniformly transmitted within one frame. When the SCH signal is transmitted multiple times within one frame, and the SCH signal is uniformly transmitted, the foregoing The frame synchronization method cannot be directly applied. Since the SCH is the signal that the mobile station needs to capture first, when the SCH signal is uniformly transmitted within one frame, the mobile station can easily average the captured multiple SCH signals, which has implementation complexity. Low, the SCH signal is easy to capture, etc. Therefore, it is necessary to propose a frame synchronization method for the SCH transmission mode. Currently, there is no frame in the prior art that is suitable for uniformly transmitting the SCH signal in one frame. Synchronization method. SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for implementing frame synchronization such that frame synchronization is achieved when a frame includes a plurality of SCH signals and BCH signals, and the SCH signal is uniformly transmitted in a frame. In order to achieve the object of the present invention, the method of the present invention specifically includes the following steps: Let the time length of one frame be L, the number of transmission synchronization channel signals in one frame be N, and the number of intra-frame transmission broadcast channel signals be K. At the transmitting end: the synchronization channel signal and the broadcast channel signal are transmitted in a time division multiplex manner; and each of the broadcast channel signals is adjacent to a synchronization channel signal, leading or lags the adjacent synchronization channel signal by a certain time interval; the kth broadcast channel signal The timing of the synchronization channel signal relative to its neighbor is t[k], where k=l, 2...K, t[k] greater than 0 indicates that the broadcast channel signal leads the adjacent synchronization channel signal, and t[k] is less than 0 indicates broadcast. The channel signal lags the adjacent sync channel signal; t[k] satisfies the following requirements: a, abs{t[k]} <L/2N; b, vector T[l]=(t[l],t[2] After t[K]) is cyclically shifted by p bits, where p=2...K, the corresponding vector is T[pH;t[p],t[p+l], ..t[K], t [l],t[2]...t[pl]); Let T[p] and T[l] correspond to the same number of elements S[p], Thres; where, is a constant greater than i.

Abs{ t[k]} represents the absolute value of t[k], and Max{S[p]} represents the maximum value of S[p]. Through the above method for realizing frame synchronization, the information included in the SCH signal and the BCH signal is integrated, which has the advantages of high accuracy, simple implementation, and the like. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of a BCH and SCH signal transmission timing according to the present invention; FIG. 2 is a schematic diagram of another BCH and SCH signal transmission timing according to the present invention; FIG. 3 is a flowchart of a frame synchronization implemented by a receiving end according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to better understand the present invention, the following detailed description will be made in conjunction with the accompanying drawings and specific embodiments. For convenience of explanation, it is assumed that the length of one frame is L, the number of SCH signals transmitted in one frame is N, and the number of BCH signals in one frame is K, and generally N is greater than K. Figure 1 and Figure 2 show an LTE system based on OFDM technology. The frame length is 10 ms, and the number of BCH and SCH signals transmitted in one frame is twice. The SCH signal is represented by a rectangular frame including vertical lines in the figure, the numerals 1, 3 respectively indicate the first and second SCH symbols in one frame, and the reference numeral 5 indicates the first SCH signal in the next frame. Further, in this embodiment, the SCH signal is uniformly transmitted, and the SCH signal transmission interval is 5 ms; the BCH signal is represented by a rectangular frame including horizontal lines in the drawing. Reference numerals 2, 4 denote the first and second BCH symbols in one frame, respectively, and reference numeral 6 denotes the first BCH signal in the next frame. The method for implementing frame synchronization provided by the present invention needs to meet the following conditions when transmitting frame information at the transmitting end:

The SCH and BCH signals are transmitted in a time division multiplexed manner, and each BCH is placed next to a SCH and is advanced or lagging adjacent to the SCH-determined time interval. When the number of BCH transmissions in one frame is two, one leading, one hysteresis is preferable, as shown in Figs. Of course, the timing of the BCH phase ^"SCH does not require a certain advance, one" after the band, alternately appears. The kth (k = 1, 2 . . . K) BCH signals are timed relative to their neighboring SCH signals. [k] , t[k] greater than 0 indicates that the BCH leads the adjacent SCH signal, and t[k] is less than 0 indicates that the BCH lags the adjacent SCH signal. t[k] satisfies: ^2 requirements: (1), abs{t [k]} < L/2N;

(2), after the cyclic shift p(p=2. ..K) bits of the vector T[l] t[l], t[2] t[K]), the corresponding vector is T[p] t[ p], t[p+l]...t[K], t[l], t[2]...t[pl]). Let T[p] and T[l] correspond to the same number of elements as S[p], then

Is a constant greater than one. Where abs{ t[k]} represents the absolute value of t[k]. Max{S[p]} represents the maximum value of S[p], p=2...K. As can be seen from FIG. 1, the SCH signal and the BCH signal are time division multiplexed, and the timing of the first BCH relative to the adjacent SCH signal per frame is t[l]=-fms; the second BCH of each frame is relatively adjacent. The timing of the SCH signal is t[2]=f ms. Here r is a positive number and less than 2.5 ms (10/(2*2)). Figure 2 shows a schematic diagram of the transmission timing of the BCH and SCH signals including the present invention. The difference from FIG. 1 is as follows: The timing of the first BCH of each frame in FIG. 2 relative to the adjacent SCH signal is t{l\=^ ms\ The timing of the first BCH per frame relative to the adjacent SCH signal in FIG. 1 is t [2]==-rms. FIG. 3 is a flow chart showing a method for implementing frame synchronization by a mobile station at the receiving end. Step 301: The mobile station uses the SCH signal in the received signal to capture the SCH signal timing. The SCH signal is usually known to the mobile station, where the SCH signal is transmitted multiple times within one frame, so the timing of the SCH signal is relatively easy to capture. It should be noted that the method for capturing the SCH signal timing is not limited herein, and the methods in the prior art, such as the received signal and the local reference SCH signal match or other methods T are applied. Step 302: Initialize the loop variable m, m may take a value between [Ι, Κ] as the initial value of k, that is, m=k, m=l in this embodiment; Step 303: According to the timing vector of the BCH relative to the SCH T[m], extracts the received BCH signal. Taking Figure 1 as an example, T[l]-( t[l], t[2])=( ~ ^τ , ^τ )\ Τ[2] = ^r r Let the two consecutive SCH signals received by the mobile station be SCH signal 3 and SCH signal 5, the mobile station can extract data according to the timing vector T[l] of the BCH relative to the SCH: that is, extracting the received data with respect to the SCH signal 3 delay ^r ras; extracting the data with respect to the SCH signal 5 leading τ ms. Step 304: Demodulate and decode the received signal, and determine the correctness of the decoding result. Herein, the coding and decoding mentioned in the present invention belong to the prior art, and the coding method adopted by the receiver corresponds to the coding method used by the transmitter, for example, the transmitter adopts Turbo coding, and the receiver adopts Turbo decoding, of course. There are also many methods for decoding Turbo, so that you can choose the appropriate encoding and decoding method according to cost and performance. There are many methods for judging whether the decoding result is correct, such as detecting whether the decoding result can pass the CRC detection: if it can pass, it means that the decoding is correct; otherwise, it indicates the decoding error. Step 305: If the decoding is correct, the frame synchronization is completed, that is, the SCH signal corresponding to the first element t[m] in T[m] is realized as the mth SCH signal in one frame. Step 306: If the decoding is wrong, it is judged whether m is smaller than K (the transmission of the BCH signal in one frame) Number of times sent: If m is not less than K, the current channel is bad and frame synchronization detection fails. The mobile station re-executes the step detections 302-306 with the newly received data, and proceeds to step 302. If m is less than K, step 307 is performed. Step 307: Add m to the original base. Steps 303 - 306 are re-executed, that is, go to step 303. If the value of m is not 1 in step 302, then if the decoding result is incorrect, it is judged whether m is equal to k-1: If not, m=(m+l) Mod K , where Mod represents the modulo operation, then Go to step 303; if equal, initialize m=k, then go to step 302. In the case of the cartridge, when the initial value of m is not 1, step 306 adds a modulo operation, and when the initial value of m is equal to 1, the operation can be omitted. It should be understood by those skilled in the art that the above description is only the preferred embodiment of the present invention, and is not intended to limit the scope of the present invention; Covered.

Claims

Claim

1. A method for implementing frame synchronization in a wireless communication system, wherein the length of one frame is L, the number of transmission synchronization channel signals in one frame is N, and the number of intra-frame transmission broadcast channel signals is K, which is characterized by At the transmitting end:

The synchronization channel signal and the broadcast channel signal are transmitted in a time division multiplex manner; and each of the broadcast channel signals is adjacent to a synchronization channel signal, leading or lagging adjacent to the synchronization channel signal by a certain time interval; the kth broadcast channel signal is adjacent to the same The timing of the synchronization channel signal is t[k], where k=l, 2...K, and t[k] is greater than 0, indicating that the broadcast channel signal leads the adjacent synchronization channel signal, and t[k] is less than 0, indicating that the broadcast channel signal is adjacent to the lag. Synchronous channel signal; t[k] meets the following requirements:

a, abs{t[k]} < L/2N;

b, the vector T[l]=(t [ , t[2] t[K]) is cyclically shifted by p bits, where p=2...K, and the corresponding vector is T[pKt[p],t [p+l]...t[ ] ₅ t[l],t[2]...t[pl]); Let T[p] and T[l] correspond to the same number of elements as S[p] , then ^Max { ^S ^\ ; where Τ3⁄4Γ is a constant greater than 1, abs{ t[k]} represents the absolute value of t[k], and Max{S[p]} represents the maximum value of S[p].

2. The method for implementing frame synchronization according to claim 1, wherein when two broadcast channel signals are transmitted in one frame, one of the broadcast channel signals leads the synchronization channel signal, and the other broadcast channel signal lags the synchronization channel signal. .

The method for implementing frame synchronization according to claim 1 or 2, wherein the receiving end further comprises the following steps:

Step 1. The mobile station captures the synchronization channel signal from the received data to obtain the timing of the synchronization channel signal.

Step 2. Set the timing of the received broadcast channel signal relative to the synchronization channel signal to be T[m], m=k, and k is any value between [Ι, Κ];

Step 3: extracting the received broadcast channel signal according to the synchronization channel signal timing and the timing vector T[m] of the synchronization channel relative to the received synchronization channel signal; Step 4, demodulating and decoding the received broadcast channel signal, determining whether the decoded result is correct, if correct, the frame synchronization is completed; otherwise, going to step 5;

Step 5. Determine if m is equal to k-1: If not, let m=(m+l) Mod K, go to step 3, where Mod represents the modulo operation; otherwise, go to step 2.

The method for implementing frame synchronization according to claim 1 or 2, further comprising the following steps at the receiving end: Step 1. The mobile station captures a synchronization channel signal from the received data to obtain a timing of the synchronization channel signal. ;

Step 2. Set the timing of the received broadcast channel signal relative to the synchronization channel signal to be T[m], m=l;

Step 3. Extract the received broadcast channel signal according to the synchronization channel signal timing and the timing vector T[m] of the broadcast channel relative to the received synchronization channel signal;

Step 4: Demodulating and decoding the received broadcast channel signal, determining whether the decoded result is correct, if correct, the frame synchronization is completed; otherwise, going to step 5;

Step 5. Determine whether m is less than K: If m is less than K, let m=m+l, go to step 3; if m is not less than K, go to step 2.

The method of frame synchronization according to claim 3, wherein in the step 4, it is detected whether the decoding result can pass the CRC detection: if it can pass, the decoding is correct; if it fails, the decoding error is performed.

The method of frame synchronization according to claim 4, wherein in the step 4, it is detected whether the decoding result can pass the CRC detection: if it can pass, the decoding is correct; if it fails, the decoding error is performed.