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CN106953823B - A kind of wireless communication high-precision frame synchornization method based on synchronizing sequence - Google Patents

A kind of wireless communication high-precision frame synchornization method based on synchronizing sequence Download PDF

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Publication number
CN106953823B
CN106953823B CN201710137590.6A CN201710137590A CN106953823B CN 106953823 B CN106953823 B CN 106953823B CN 201710137590 A CN201710137590 A CN 201710137590A CN 106953823 B CN106953823 B CN 106953823B
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synchronization
wireless communication
synchronizing sequence
frame
sequence
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CN106953823A (en
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高君慧
黄志超
曹凡
姜培文
金石
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Southeast University
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Southeast University
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    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00Modulated-carrier systems
    • H04L27/26Systems using multi-frequency codes
    • H04L27/2601Multicarrier modulation systems
    • H04L27/2647Arrangements specific to the receiver only
    • H04L27/2655Synchronisation arrangements
    • H04L27/2656Frame synchronisation, e.g. packet synchronisation, time division duplex [TDD] switching point detection or subframe synchronisation

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Synchronisation In Digital Transmission Systems (AREA)

Abstract

本发明公开了一种基于同步序列的无线通信高精度帧同步方法,首先对基带信号进行低通滤波,之后分别进行粗同步和数据存储,粗同步输出带有一定误差的同步位置,数据存储是为了后续进行精同步做数据准备,精同步的要点是进行了非降采样下的互相关,利用了同步序列的所有信息,因而能够得到最精确的同步位置。本发明帧同步精度极高,适用于具有固定帧格式的无线通信系统。

The invention discloses a high-precision frame synchronization method for wireless communication based on synchronization sequences. First, low-pass filtering is performed on a baseband signal, and then coarse synchronization and data storage are respectively performed. The coarse synchronization outputs a synchronization position with a certain error, and the data storage is In order to prepare data for subsequent fine synchronization, the key point of fine synchronization is to perform cross-correlation under non-downsampling, using all the information of the synchronization sequence, so that the most accurate synchronization position can be obtained. The frame synchronization precision of the invention is extremely high, and is suitable for a wireless communication system with a fixed frame format.

Description

A kind of wireless communication high-precision frame synchornization method based on synchronizing sequence
Technical field
The present invention relates to a kind of wireless communication high-precision frame synchornization method based on synchronizing sequence, belongs to wireless communication skill Art.
Background technique
In wireless communication technique, especially with orthogonal frequency division multiplexing (Orthogonal Frequency Division Multiplexing, OFDM) technology be representative the modulation scheme with fixed frame structure, transmitting terminal and receiving end must be in skies The start position that the synchronization of progress radio frames in time on mouth, i.e. receiving end determine radio frames transmitted by transmitting terminal, thus Receiving end can distinguish the position of each different transmission symbols of entire radio frames, prepare for subsequent demodulation.Frame synchronization is main Have based on cyclic prefix and based on the two methods of synchronizing sequence, in the frame synchornization method based on synchronizing sequence: receiving Base band data carry out cross-correlation with the synchronizing sequence that is locally stored, the peak value for finding cross-correlation output valve corresponds to synchronous sequence The corresponding position of column, according to position of the synchronizing sequence in entire radio frames, to release the starting point of radio frames.
In order to match with the structure of radio frames, the length of synchronizing sequence is generally large;Simultaneously for transmission rate request High system, sample rate is higher, then the base band data rate of system is big.In order to reduce the calculation times of cross correlation algorithm, drop Low complex degree, current frame synchronization algorithm mostly can be down-sampled to base band data progress, then carry out cross-correlation.Although reducing in this way Complexity, but has lost the precision of frame synchronization, certain error is caused to system.
Summary of the invention
Goal of the invention: synchronous in order to solve frame synchronization (the being classified as thick synchronization below) bring done after above-mentioned reduction sample rate The inaccurate problem in position, while synchronous complexity is reduced as far as possible, the invention proposes a kind of based on the wireless of synchronizing sequence Communicate high-precision frame synchornization method, compared to slightly synchronize be simply added into the very low module of complexity can on thick synchronous foundation, Obtain accurate frame synchronization position.
In order to overcome the deficiencies in the prior art, the present invention provides one kind
Technical solution: to achieve the above object, the technical solution adopted by the present invention are as follows:
A kind of wireless communication high-precision frame synchornization method based on synchronizing sequence is used in a wireless communication system, to nothing Synchronizing sequence in line frame is detected, and accurately determines wireless frame start position, solves radio frames time domain in wireless communication On precise timing synchronization problem, while overcome the problems, such as general essence synchronous institute with resource consumption it is big;It specifically includes as follows Step:
(1) low-pass filtering is carried out to the base band data received, eliminates the interference of asynchronous sequence signal;Using based on following Ring prefix or frame synchornization method based on synchronizing sequence are slightly synchronized, and it is (i.e. thick synchronous to be navigated to obtain thick sync bit Synchronizing sequence is receiving the start position in data frame), the original synchronizing sequence obtained according to thick sync bit is stored, this is original The length of synchronizing sequence is L point;
(2) start the n-th point of original synchronizing sequence starting point forward, length is the data of L+2N+1 as base band number According to storing the base band data;
(3) base band data of the original synchronizing sequence to L point and L+2N+1 point carries out cross-correlation calculation and (it is mutual to carry out 2N+1 Close), the cross-correlation calculation is down-sampled to the progress of original synchronizing sequence, therefore contains all information of original synchronizing sequence, Improve the precision of precise synchronization position;
(4) peak value of cross correlation results is searched for, and finds the corresponding position of the peak value to get corresponding serial number is arrived;Mutually The serial number for closing result is counted from the starting point of base band data, corresponding 1~2N+1 of serial number;The corresponding position of the peak value found is turned It changes biasing into, i.e., subtracts N in serial number, so the range of biasing is (- N, N);
(5) thick sync bit is added with biasing, as a result as final smart sync bit.
Preferably, in the step (2), N is the absolute value of thick synchronous worst error, i.e., slightly synchronous worst error is ± N; Therefore, we are when positioning base band data, as long as expanding N number of point respectively before and after original synchronizing sequence may include all possibility Synchronizing sequence, so peak value must can be found when doing L point cross-correlation calculation.
In the present invention, firstly, certain requirement has been done in the initial position and length to base band data, so that the base band number taken out According to the range that can cover original synchronizing sequence completely;Secondly, using complete original synchronous sequence when carrying out cross-correlation calculation Column, so that whole sampling point informations of original synchronizing sequence are utilized in cross-correlation calculation, it is ensured that the synchronous accuracy of essence;Separately Outside, biasing is interpreted as the gap of smart sync bit Yu thick sync bit by we, and thick sync bit is added with biasing, can be obtained To smart sync bit.
It should be noted that transmitting terminal of the present invention in system, it is necessary to stringent to send the wireless communication with fixed frame format Number, and position of the synchronizing sequence in frame format cannot change
The utility model has the advantages that the wireless communication high-precision frame synchornization method provided by the invention based on synchronizing sequence, has as follows A little, this essence synchronized algorithm is accurately found out between thick sync bit and actual synchronization position on the basis of traditional thick synchronization Deviation, to calculate smart synchronous point, with it is thick it is synchronous compared be only added to 2N+1 L point cross-correlation, resource consumption is extremely low, together It is high to walk precision;The present invention has rational design, and synchronous effect is obvious, and algorithm complexity is low.
Detailed description of the invention
Fig. 1 is implementation flow chart of the invention;
Fig. 2 is the range schematic diagram for the base band data that the present invention stores.
Specific embodiment
Below with reference to LTE SISO system, the present invention will be further explained.
LTE SISO system is divided into 10ms using strictly frame format, one radio frames of system, and each radio frames are divided into 10 A subframe, each subframe are divided into 2 time slots, include 7 OFDM symbols in each time slot, each symbol uses 2048 point IFFT tune System, in addition cyclic prefix, a radio frames share 307200 points, and systematic sampling rate is 30.72MSamples/s, synchronizing sequence It is added in first OFDM symbol of radio frames, length L is 2048, and synchronizing sequence here selects PSS sequence, and bandwidth is 0.465MHz, transmitter in strict accordance with frame format and must continue to send the radio frames for having PSS sequence, and receiver just can be carried out Subsequent essence is synchronous.
In receiving end, by down coversion, base band data is obtained by ADC, filters out synchronizing sequence using low-pass filter first Out-of-band interference signal eliminates the influence to subsequent synchronisation algorithm, gives two moulds simultaneously by the signal of low-pass filter Block: thick synchronization module and base band data memory module, the selection of thick synchronization module is more, be based primarily upon at present it is down-sampled (can be with Selecting down-sampled 16 times) progress cross-correlation obtains thick sync bit to base band data later, and the length of cross-correlator at this time is removed for L It is here 128, which can generate certain error with down-sampled multiple;Base band data memory module is according to thick sync bit It sets, stores the base band data in synchronizing sequence location, but do not know that the starting point of synchronizing sequence is located at stored base band data Which point.
After storing data, the auto-correlation of L point is carried out, 2N+1 cross-correlation is carried out here, down-sampled 16 times the case where Under, worst error 8, so N=8, carries out 17 L point cross-correlation altogether.
The search that peak value is carried out after cross-correlation, finds the corresponding coordinate of peak value, and 0~2N+1 is converted into biasing ,-N~N, Thick sync bit is added with biasing again, the synchronous position of final essence can be obtained.
The above is only a preferred embodiment of the present invention, it should be pointed out that: for the ordinary skill people of the art For member, various improvements and modifications may be made without departing from the principle of the present invention, these improvements and modifications are also answered It is considered as protection scope of the present invention.

Claims (1)

1.一种基于同步序列的无线通信高精度帧同步方法,其特征在于:用于在无线通信系统中,对无线帧中的同步序列进行检测,确定无线帧起始位置,具体包括如下步骤:1. a wireless communication high-precision frame synchronization method based on a synchronization sequence, is characterized in that: for in a wireless communication system, the synchronization sequence in the wireless frame is detected, and the starting position of the wireless frame is determined, specifically comprising the steps: (1)对接收到的基带数据进行低通滤波,采用基于循环前缀或基于同步序列的帧同步方法进行粗同步,得到粗同步位置,存储根据粗同步位置得到的原始同步序列,该原始同步序列的长度为L个点;(1) Perform low-pass filtering on the received baseband data, and use the frame synchronization method based on cyclic prefix or synchronization sequence to perform coarse synchronization to obtain the coarse synchronization position, and store the original synchronization sequence obtained according to the coarse synchronization position. The original synchronization sequence The length of is L points; (2)将原始同步序列起点往前的第N个点开始的、长度为L+2N+1的数据作为基带数据,存储该基带数据;(2) the data with the length of L+2N+1 starting from the Nth point before the starting point of the original synchronization sequence is used as the baseband data, and the baseband data is stored; (3)对原始同步序列和基带数据进行互相关计算;(3) Cross-correlation calculation is performed on the original synchronization sequence and baseband data; (4)搜索互相关结果的峰值,并找到该峰值对应的位置,即得到对应的序号;互相关结果的序号从基带数据的起点算起,对应的序号为1~2N+1;将找到的峰值对应的位置转换成偏置,即在序号上减N,所以偏置的范围为(-N,N);(4) Search the peak value of the cross-correlation result, and find the position corresponding to the peak, that is, obtain the corresponding serial number; the serial number of the cross-correlation result is calculated from the starting point of the baseband data, and the corresponding serial number is 1~2N+1; The position corresponding to the peak value is converted into an offset, that is, N is subtracted from the serial number, so the offset range is (-N, N); (5)将粗同步位置与偏置相加,结果即为最终的精同步位置;(5) Add the coarse synchronization position and the offset, and the result is the final fine synchronization position; 所述步骤(2)中,N为粗同步最大误差的绝对值,即粗同步最大误差为±N。In the step (2), N is the absolute value of the maximum error of the coarse synchronization, that is, the maximum error of the coarse synchronization is ±N.
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CN109218247B (en) * 2018-11-27 2020-11-24 威胜信息技术股份有限公司 Timing synchronization method based on novel synchronization sequence
CN112398566B (en) * 2020-11-16 2022-05-24 中国电子科技集团公司第二十九研究所 A high-precision time-of-arrival calculation method and device for burst communication system
CN112702296B (en) * 2020-12-18 2022-11-11 上海微波技术研究所(中国电子科技集团公司第五十研究所) FPGA (field programmable Gate array) realization method and system for data synchronization parallelization in millimeter wave communication
CN114765528B (en) * 2021-01-15 2023-09-26 烽火通信科技股份有限公司 Frame synchronization method, device, equipment and readable storage medium
CN115333571B (en) * 2022-06-22 2023-12-19 飞芯智控(成都)科技有限公司 Synchronization processing method and device for frequency hopping communication system

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