WO2003036836A1 - Method and device for the capturing of down synchronization in the cdma communication system - Google Patents

Method and device for the capturing of down synchronization in the cdma communication system Download PDF

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Publication number
WO2003036836A1
WO2003036836A1 PCT/CN2001/001486 CN0101486W WO03036836A1 WO 2003036836 A1 WO2003036836 A1 WO 2003036836A1 CN 0101486 W CN0101486 W CN 0101486W WO 03036836 A1 WO03036836 A1 WO 03036836A1
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Prior art keywords
synchronization
signal
code
preamble sequence
frame
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PCT/CN2001/001486
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French (fr)
Chinese (zh)
Inventor
Chen Ji
Daoben Li
Yongsheng Zhang
Liwen Shi
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Linkair Communications,Inc.
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Priority to CNA018228577A priority Critical patent/CN1493124A/en
Priority to PCT/CN2001/001486 priority patent/WO2003036836A1/en
Publication of WO2003036836A1 publication Critical patent/WO2003036836A1/en

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/69—Spread spectrum techniques
    • H04B1/707—Spread spectrum techniques using direct sequence modulation
    • H04B1/7073—Synchronisation aspects
    • H04B1/7075—Synchronisation aspects with code phase acquisition
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J13/00—Code division multiplex systems
    • H04J13/0007—Code type
    • H04J13/004—Orthogonal
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B2201/00—Indexing scheme relating to details of transmission systems not covered by a single group of H04B3/00 - H04B13/00
    • H04B2201/69—Orthogonal indexing scheme relating to spread spectrum techniques in general
    • H04B2201/707—Orthogonal indexing scheme relating to spread spectrum techniques in general relating to direct sequence modulation
    • H04B2201/70701—Orthogonal indexing scheme relating to spread spectrum techniques in general relating to direct sequence modulation featuring pilot assisted reception

Definitions

  • the present invention relates to the technical field of wireless spread spectrum communication and the technical field of digital mobile communication, and in particular, to a method and an apparatus for downlink synchronization acquisition in a wireless spread spectrum communication system. Background of the invention
  • CDMA technology is being widely used in wireless communication systems. Because of its unique advantages such as large capacity, soft capacity, soft handover, high voice quality and low transmit power, as well as anti-interference and privacy, CDMA systems have developed rapidly and become the technology of choice for third-generation cellular communication systems.
  • CDMA is a modulation and multiple access technology based on spread-spectrum communications.
  • signals used by different users to transmit information are not distinguished by different frequencies or time slots, but by different coding sequences.
  • the receiver correlator can select a signal using a predetermined pattern among a plurality of CDMA signals. Other signals using different code patterns cannot be demodulated because they are different from the code patterns generated locally by the receiver.
  • a base station transmitter or a mobile station transmitter uses a spreading code to spread the digital information
  • the receiving device uses a local spreading code to despread the spread spectrum signal to find useful information.
  • Synchronization means that the local spreading code and the received spreading code are completely consistent in structure, frequency, and phase.
  • a CDMA system is unique to spreading code synchronization. Therefore, the synchronization problem of the spread spectrum system is more complicated than the general digital communication system.
  • a clock source with high accuracy and stability is used in the transmitter and receiver. Many frequency and phase instabilities can be removed. However, objectively, there are many uncertain factors that cannot be estimated in advance, especially in mobile communications. These uncertain factors are random and cannot be compensated in advance. They can only be eliminated by a synchronous system. Therefore, the synchronization system is indispensable and very important in the CDMA system.
  • the synchronization of the spreading code is divided into two steps: First, capturing, that is, coarsely adjusting the frequency and phase of the local spreading code, so that the phase difference between the local spreading code and the receiving spreading code is less than one symbol width Tc.
  • the second is tracking, which automatically adjusts the phase of the local spreading code to accurately synchronize the frequency and phase of the received spreading code. Therefore, as the transmission rate requirements for digital mobile communication systems become higher and higher, and the capacity becomes larger, the requirements for synchronization accuracy become higher and higher.
  • the bit synchronization, chip synchronization, symbol synchronization, and frame synchronization of the system must be guaranteed to achieve the despreading of the spread spectrum signal and the correct reception and processing of the signal.
  • a spread spectrum multiple address code coding technology a coding method for a spread spectrum multiple access code is disclosed.
  • the frequency code has good auto-correlation and cross-correlation characteristics.
  • a spreading code is simply referred to as a LA code.
  • the LA code consists of polarized basic pulses with a normalized amplitude and width of 1.
  • the number of basic pulses depends on the number of users required.
  • the actual factors such as the number of orthogonal pulse compression codes used, the number of orthogonal frequencies that can be used, the system bandwidth, and the maximum signal transmission rate of the system are determined.
  • the intervals of the basic pulses on the time coordinate are different and different.
  • the pulse positions and pulse polarities are arranged and coded at different intervals. Taking the above design, it provides a clear and fast design method for the spread spectrum address code for the spread spectrum technology and digital multiple access technology.
  • the characteristics of this LA code are: first: the main peaks of the autocorrelation function are equal to the number of basic pulses, and also the number of orthogonal codewords in the code group; second: the subpeaks of the autocorrelation and cross-correlation functions are only + 1 ,-1 and 0 are three possible values.
  • the LA code can be used to identify different cells. The description about the encoding method of the spread spectrum multiple access code is omitted here, and the document is incorporated herein by reference.
  • the inventor Li Daoben and the invention name "A Spread Spectrum Multiple Access Coding Method with Zero Correlation Window", a spread spectrum
  • the address code is called the LS code. Since the LS code is composed of the C code and the S code, it is also called the CS code.
  • the method for generating the LS code (CS code) is described in detail in PCT / CN00 / 00028. be omitted.
  • the designed spread-spectrum multi-address code with "zero correlation window" has the following two characteristics: First: The auto-correlation function of each spread-spectrum address code is zero except for the origin, that is, it has the most ideal characteristics.
  • each spreading address code is completely orthogonal to any non-zero delay except for the zero delay.
  • the cross-correlation function between spread-spectrum address codes has a "zero correlation window" near the origin. From the perspective of orthogonality, the relative delay between the spreading address codes is completely orthogonal when the relative delay is smaller than the width of the "zero correlation window".
  • the above-mentioned method for generating the LS code is a method for designing a spread spectrum address code, so that the correlation function of the newly formed spread spectrum address code forms a "no interference window (IFW)" near the origin, thereby making the corresponding bidirectional Synchronous CDMA systems do not have the fatal near-far effect in traditional CDMA systems, that is, there is no multiple-access interference (MAI) and inter-symbol interference (ISI), which lays the foundation for establishing a large-capacity wireless digital communication system.
  • MAI multiple-access interference
  • ISI inter-symbol interference
  • the multi-user interference and neighboring cell interference and the high-speed mobile fading environment in the mobile communication system increase the difficulty of synchronization. Therefore, there must be a high-precision synchronous capture method, which can quickly and accurately realize synchronous capture, and meet the requirements of the system.
  • downlink synchronization capture method mentioned in the application number PCT / CN00 / 00142 and the invention name "Downlink Synchronization Capture Method in Code Division Multiple Access System" is mainly through the use of broadcast channels and matched filtering. And sliding related technologies. The implementation of this method includes the following steps:
  • a broadcast channel is added to the downlink, and a unique code is placed in a fixed time slot in the broadcast channel frame; when the mobile station broadcast channel receiver detects the unique code, the frame positioning information can be determined.
  • the broadcast channel synchronization loop In order to overcome the influence of the multipath fading channel, the broadcast channel synchronization loop first finds the position of the energy concentration where the main peak of each symbol appears, and then determines the decision time of the broadcast channel receiver for each symbol according to the position. Correctly, when the unique code matching filter detects the unique code, it can give an accurate synchronization information.
  • an object of the present invention is to provide a new method and device for downlink synchronization capture in a code division multiple access communication system.
  • a downlink synchronization capture method in a commercial CDMA system based on a LA and LS spread-spectrum address coding method includes the following steps: Prefix the data segment with a fixed-length preamble sequence; choose different spreading code sequences that are as orthogonal to each other as possible for the preamble sequence and the traffic channel; execute the preamble sequence codeword on the baseband sampled signal at the receiver Matching filtering to obtain I and Q signals; calculate the signal energy value by performing a square operation on the I and Q signals; accumulate all the sampled values in the data length of a frame; take the largest value in the data length of a frame Sampling values, capturing the maximum energy correlation peak; and estimating the accurate arrival time of the preamble sequence based on the captured maximum energy correlation peak, thereby achieving forward chip synchronization and frame synchronization.
  • the invention also provides a device for performing downlink synchronization acquisition in a commercial CDMA communication system based on the LA and LS spread-spectrum address coding methods.
  • the device includes a matched filter for sampling the baseband at the receiving end.
  • the signal performs filtering that matches the preamble sequence code word to obtain I and Q signals; a device that calculates the signal energy value by performing a square operation on the I and Q signals; accumulates all of the data length of a frame Accumulation device of sampling values; a device that takes the maximum sampling value within one frame of data to capture the maximum energy-related peak; and the maximum energy-related peak that is captured to estimate the accurate arrival time of the pre-synchronization sequence to achieve forward Device for chip synchronization and frame synchronization.
  • the downlink synchronization capture method of the present invention is mainly realized by a matched filter using a preamble sequence.
  • the method adopted by the present invention is to add a fixed-length preamble sequence before a given length of data segment, and select a spreading code of the data segment and the preamble sequence to make the signal of the data segment and the preamble sequence as orthogonal as possible.
  • the maximum energy-related peak is captured through a matched filter of the pre-synchronization sequence, thereby achieving chip and frame synchronization capture.
  • FIG. 1 is a frame structure used for implementing the method of the present invention.
  • FIG. 2 is a schematic diagram of the overall signal processing of a synchronization capture device designed according to the method of the present invention.
  • FIG. 3 is a schematic diagram of a synchronization detection module for maximum correlation window of captured energy according to the present invention.
  • FIG. 4 is a schematic diagram of a preamble sequence designed according to the method of the present invention.
  • Figure 5 shows the auto-correlation and cross-correlation characteristics using the LS code as a preamble sequence according to the method of the present invention.
  • the frame structure includes a preamble sequence and a data segment sequence (0, the preamble sequence and the data segment sequence are time-multiplexed.
  • the preamble sequence ( ⁇ ) and the data segment signal (0
  • the preamble sequence and data segment signals can use different LS code group and LA code group, and ⁇ 0 has the autocorrelation characteristic of the impact form, which can also be achieved by LS code and LA code.
  • FIG. 2 the figure shows a schematic diagram of the overall signal processing of the synchronization capture device.
  • the parts before the synchronization detection device 207 are similar to the conventional spread-spectrum communication system. Those skilled in the art can easily understand that details will not be described again.
  • This synchronization capture device includes an analog down-converter 201, a band-pass filter 202, a digital-to-analog converter A / D203, a digital down-converter 204, a down-sampler 205, a matched filter 206, and a synchronization detection device 207.
  • the analog down conversion converter 201 down converts the received radio frequency signal RF into an intermediate frequency analog signal.
  • the output of the down-converter 201 is provided to a band-pass filter 202, which performs band-pass filtering on the input intermediate frequency analog signal, and the band-pass filtered intermediate frequency analog signal is provided to the analog A-to-digital converter A / D203 converts into a digital signal containing Nsl samples in each symbol, obtains the baseband signal through digital down-converting converter 204, and a downsampler 205 samples the input baseband signal so that each symbol With Ns2 samples, the sampling result is input to the matched filter 206 that matches the preamble sequence, and the I and Q values output by the matched filter 206 are sent to the synchronization detection device 207.
  • FIG. 3 shows a schematic diagram of a synchronization detection module of the present invention.
  • the received signal often contains several multipath delay components with different propagation delays and channel fading.
  • the capture energy is used in commercial CDMA systems based on the LA and LS spread-spectrum address coding methods. Method of maximum correlation window.
  • the I and Q channels are squared in the arithmetic unit 301, the signal energy values are calculated, and then N are performed in the module 302
  • the maximum value is taken within a frame of data length, and the position of the maximum value is determined. The determined maximum position is used to capture the maximum energy correlation window, thereby obtaining frame positioning information, and obtaining frame positioning. After that, an accurate phase of the spreading code can be obtained, and the signal despreading processing and timing tracking can be performed.
  • the downlink service channel of the data segment is superimposed on 32 independent code channels, and each code channel uses a 128-bit LS code. Therefore, a code sequence should be found in the preamble sequence in each cell, and the 32 LS codes used by the traffic channel should be as orthogonal to each other as possible.
  • the receiver performs matching filtering on the preamble sequences of different cells, and selects the one with the strongest energy as the correct selected cell. Therefore, the preamble sequences of neighboring cells should also have better mutual interaction.
  • the relevant characteristics are as orthogonal as possible to avoid interference between neighboring cell pre-synchronization sequences, so as to correctly extract synchronization information and perform cell selection.
  • the preamble sequences of different cells use different LA interval gaps and the preamble sequence codeword sequences constructed by the LA polarity, which have better autocorrelation and cross-correlation characteristics, and the presync structured in this way
  • the sequence and data segment downlink traffic channels also have good cross-correlation characteristics.
  • a method for constructing a preamble sequence using the LS + LA code in a LAS-CDMA system is given below in conjunction with FIG. 3 and FIG. 4.
  • the first symbol sequence This symbol sequence will be spread using a short LS code.
  • the gray area in the figure is the interval between two adjacent symbols. The interval is generated according to the LA arrangement.
  • FIG 4 is given in the structure of a short code LS, assume that the total code length of 81 ⁇ , pre-gap length interval I ⁇ C code length 2L 15 in spaced opposed gap length code length 2L 13 S ⁇ 21, rear spacer
  • the gap length is added to the code with a protective interval gap of the same length as the C code and the S code.
  • the purpose of the gap is to prevent the C code and the S code from colliding, thereby providing a zero correlation window as large as possible for auto-correlation and cross-correlation.
  • the zero correlation window is-2L1-2L1.
  • composition of LA Composition of LA:
  • the LA code can be regarded as a concatenation method of the LS code.
  • each cell uses the same LS code set, so different cells need to use different LAs to distinguish them.
  • the interval between two LA code spread symbols in a LA sequence is the LA interval Gap, and the sequence of the sequential LA interval Gap is called the LA array.
  • the selection of symbol, ... is called LA polarity.
  • LS + LA code preamble sequence with excellent auto-correlation and cross-correlation characteristics.
  • Figure 5 shows the auto-correlation and cross-correlation characteristics of 4 preamble synchronization sequences using 8 symbols in each of which a total of 43 chip long gap gaps are added between 32-bit LS code spreading symbols.
  • Tables 1 and 2 show the selection methods of the LA interval and LA polarity of the four preamble sequences, respectively.
  • the auto-correlation of the preamble sequence 1 and the cross-correlation characteristics with the preamble sequences 2, 3, and 4 are shown in order.
  • the chip amplitude is taken to be 1.
  • the maximum side peak amplitude of the auto-correlation and cross-correlation is 1/8 of the main peak of the auto-correlation, and the energy difference is about 18 dB.
  • the main peak can be easily distinguished, whether it is auto-correlation There is still cross correlation, and there are zero correlation windows of -2L1 _ 2L1.
  • Preamble sequences 2, 3, 4 have the same characteristics as sequence 1. Table 1: LA permutations
  • the transmission power of the preamble sequence can be increased to be equivalent to the signal power of the data channel service channel at full load.

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

Abstract

In the digital mobile communication system, especially in the Code Division multiple Access mobile system, it is most important to achieve accurate synchronization. In order to capture chip synchronization and frame synchronization quickly and exactly, the present invention provides a scheme which captures the maximum energy correlation window to acquire sync information by inserting the prefix synchronizing sequence. The present invention also provides a method to constitute the prefix synchronizing sequence in the multi-cell down channel in the commercial CDMA system based on LA and LS spread spectrum address encoded mode. The receiver use filter matched with the preamble synchronizing sequence codeword to achieve the capture of down synchronization.

Description

CDMA通信***下行链路同步捕获方法和装置 技术领域  Method and device for downlink synchronization acquisition of CDMA communication system
本发明涉及无线扩频通信技术领域和数字移动通信技术领域， 特别涉及 无线扩频通信***的下行链路同步捕获方法和装置。 发明背景  The present invention relates to the technical field of wireless spread spectrum communication and the technical field of digital mobile communication, and in particular, to a method and an apparatus for downlink synchronization acquisition in a wireless spread spectrum communication system. Background of the invention
众所周知， 近年来， 随着移动通信的高速发展， CDMA技术正在被广泛地 应用到无线通信***中。 CDMA ***由于具有大容量、 软容量、 软切换、 高话 音质量和低发射功率以及抗干扰和保密等独特的优势， 使它得以迅速发展 , 并成为第三代蜂窝通信***的首选技术。  As we all know, in recent years, with the rapid development of mobile communications, CDMA technology is being widely used in wireless communication systems. Because of its unique advantages such as large capacity, soft capacity, soft handover, high voice quality and low transmit power, as well as anti-interference and privacy, CDMA systems have developed rapidly and become the technology of choice for third-generation cellular communication systems.
CDMA是一种以扩频通信为基础的调制和多址连接技术。 在 CDMA通信系 统中， 不同用户传输信息所用的信号不是靠频率不同或时隙不同来区分， 而 是用各自不同的编码序列来区分。 接收机用相关器可以在多个 CDMA信号中 选出使用预定码型的信号。 其它使用不同码型的信号因为与接收机本地产生 的码型不同而不能被解调。  CDMA is a modulation and multiple access technology based on spread-spectrum communications. In a CDMA communication system, signals used by different users to transmit information are not distinguished by different frequencies or time slots, but by different coding sequences. The receiver correlator can select a signal using a predetermined pattern among a plurality of CDMA signals. Other signals using different code patterns cannot be demodulated because they are different from the code patterns generated locally by the receiver.
通常， 在 CDMA***中, 无论是基站发射机或移动站发射机均用扩频码对 传输的数字信息扩展频谱， 而接收设备利用本地扩频码对扩频信号相关解 扩， 解出有用的信息。 同步就是要实现本地扩频码与接收到的扩频码在结构 上、 频率和相位上完全一致。 CDMA ***除了有一般的数字通信***的载波同 步、 位同步、 帧同步外， 扩频码的同步是它所特有的。 因此， 扩频***的同 步问题比一般的数字通信***更为复杂。  Generally, in a CDMA system, whether a base station transmitter or a mobile station transmitter uses a spreading code to spread the digital information, and the receiving device uses a local spreading code to despread the spread spectrum signal to find useful information. information. Synchronization means that the local spreading code and the received spreading code are completely consistent in structure, frequency, and phase. In addition to the carrier synchronization, bit synchronization, and frame synchronization of a general digital communication system, a CDMA system is unique to spreading code synchronization. Therefore, the synchronization problem of the spread spectrum system is more complicated than the general digital communication system.
一般说来， 在发射机和接收机中采用高精度和高稳定度的时钟频率源， 可以去掉许多频率和相位的不稳定性。 但是， 由于客观上存在着许多事先无 法估计的不确定因素， 尤其是在移动通信中， 这些不确定因素都带有随机性， 不能预先补偿， 只能通过同步***来消除。 因此同步***在 CDMA ***中是 不可缺少的， 而且是非常重要的。 Generally speaking, a clock source with high accuracy and stability is used in the transmitter and receiver. Many frequency and phase instabilities can be removed. However, objectively, there are many uncertain factors that cannot be estimated in advance, especially in mobile communications. These uncertain factors are random and cannot be compensated in advance. They can only be eliminated by a synchronous system. Therefore, the synchronization system is indispensable and very important in the CDMA system.
概括起来， 引起不确定性的主要有时间不确定性和频率不确定性， 归纳 如下：  To sum up, the main causes of uncertainty are time uncertainty and frequency uncertainty, which are summarized as follows:
1、 收发信机间的距离引起传播的延迟所产生的相位差；  1. The phase difference caused by the propagation delay caused by the distance between the transceivers;
2、 收发信机时钟频率的相对不稳定性 I起的频差；  2. Relative instability of transceiver clock frequency Frequency difference from I;
3、 收发信机相对运动引起的多谱勒频移； 以及  3. Doppler frequency shift caused by relative motion of the transceiver; and
4、 多径效应引起的频率和相位的变化。  4. Frequency and phase changes caused by multipath effects.
扩频码的同步分成两个步骤： 一是捕获， 即粗调本地扩频码的频率和相 位， 使本地扩频码与接收扩频码相位差小于一个码元宽度 Tc。 二是跟踪， 即 自动调整本地扩频码的相位， 使其与接收扩频码频率和相位精确同步。 因此， 当对数字移动通信***的传送速率要求越来越高， 容量越来越大时， 对同步 精度的要求也越来越高。 尤其在无线扩频通信***中， 必须保证***的位同 步， 码片同步， 符号同步和帧同步， 才能实现扩频信号的解扩， 进行信号的 正确接收和处理。  The synchronization of the spreading code is divided into two steps: First, capturing, that is, coarsely adjusting the frequency and phase of the local spreading code, so that the phase difference between the local spreading code and the receiving spreading code is less than one symbol width Tc. The second is tracking, which automatically adjusts the phase of the local spreading code to accurately synchronize the frequency and phase of the received spreading code. Therefore, as the transmission rate requirements for digital mobile communication systems become higher and higher, and the capacity becomes larger, the requirements for synchronization accuracy become higher and higher. Especially in a wireless spread spectrum communication system, the bit synchronization, chip synchronization, symbol synchronization, and frame synchronization of the system must be guaranteed to achieve the despreading of the spread spectrum signal and the correct reception and processing of the signal.
在申请号为 PCT/CN98/ 00151、 发明人为李道本、 发明名称为 "一种扩频 多地址码编码技术" 的 PCT专利申请中， 公开了一种扩频多址码的编码方法， 这种扩频码具有良好的自相关和互相关特性， 为简明起见， 以下在本发明的 描述中将这种扩频码简称为 LA码。  In the PCT patent application with the application number PCT / CN98 / 00151, the inventor Li Daoben, and the invention name "a spread spectrum multiple address code coding technology", a coding method for a spread spectrum multiple access code is disclosed. The frequency code has good auto-correlation and cross-correlation characteristics. For the sake of brevity, in the description of the present invention, such a spreading code is simply referred to as a LA code.
LA码是由归一化幅度与宽度均为 1的、 具有极性的基本脉冲所組成， 基 本脉冲的个数根据所要求的用户个数， 能够利用的脉冲压缩码的个数、 能够 利用的正交脉冲压缩码的个数、 能够利用的正交频率的个数、 ***带宽、 系 统最大传信率这些实际因素确定， 基本脉冲在时间坐标上的间隔不等且不 同， 利用这种间隔不等且不同的脉冲位置和脉冲极性排列编码。 釆取以上设 计， 为扩频技术和数字多址技术提供了一种筒明、 快捷的扩频地址码的设计 方法。 该 LA码的特点是： 第一： 自相关函数的主峰等于基本脉冲的个数， 也等于码组中正交码字的个数， 第二： 自相关及互相关函数的副峰只有 + 1， - 1及 0三个可能值。 该 LA码可以被用来实现对不同小区的识别。 有关该扩 频多址码的编码方法的描述在此从略， 引用该文件在此作为参考。 The LA code consists of polarized basic pulses with a normalized amplitude and width of 1. The number of basic pulses depends on the number of users required. The number of pulse compression codes that can be used. The actual factors such as the number of orthogonal pulse compression codes used, the number of orthogonal frequencies that can be used, the system bandwidth, and the maximum signal transmission rate of the system are determined. The intervals of the basic pulses on the time coordinate are different and different. The pulse positions and pulse polarities are arranged and coded at different intervals. Taking the above design, it provides a clear and fast design method for the spread spectrum address code for the spread spectrum technology and digital multiple access technology. The characteristics of this LA code are: first: the main peaks of the autocorrelation function are equal to the number of basic pulses, and also the number of orthogonal codewords in the code group; second: the subpeaks of the autocorrelation and cross-correlation functions are only + 1 ,-1 and 0 are three possible values. The LA code can be used to identify different cells. The description about the encoding method of the spread spectrum multiple access code is omitted here, and the document is incorporated herein by reference.
在申请号为 PCT/CN00/00028、 发明人为李道本、 发明名称为 "一种具有 零相关窗的扩频多址编码方法" 的 PCT专利申请中， 公开了一种具有零相关 窗的扩频多地址码， 称为 LS码， 由于 LS码由 C码和 S码两部分组成， 因此 又称为 CS码， LS码（CS码）的生成方法在 PCT/CN00/00028中有详细描述， 在此从略。 所设计的具有 "零相关窗口" 的扩频多地址码具有以下两个特点： 第一： 各个扩频地址码的自相关函数除原点外处处为零， 即其具有最理想的 特性。 从正交性的观点来讲， 各个扩频地址码与其自身除零时延处外， 对任 何非零时延都完全正交。 第二： 扩频地址码间的互相关函数在原点附近存在 一个 "零相关窗口"。 从正交性观点讲， 各扩频地址码之间在相对时延小于 该 "零相关窗口" 宽度时是完全正交的。  In the PCT patent application with the application number PCT / CN00 / 00028, the inventor Li Daoben, and the invention name "A Spread Spectrum Multiple Access Coding Method with Zero Correlation Window", a spread spectrum The address code is called the LS code. Since the LS code is composed of the C code and the S code, it is also called the CS code. The method for generating the LS code (CS code) is described in detail in PCT / CN00 / 00028. be omitted. The designed spread-spectrum multi-address code with "zero correlation window" has the following two characteristics: First: The auto-correlation function of each spread-spectrum address code is zero except for the origin, that is, it has the most ideal characteristics. From the perspective of orthogonality, each spreading address code is completely orthogonal to any non-zero delay except for the zero delay. Second: The cross-correlation function between spread-spectrum address codes has a "zero correlation window" near the origin. From the perspective of orthogonality, the relative delay between the spreading address codes is completely orthogonal when the relative delay is smaller than the width of the "zero correlation window".
上述发明的 LS码的生成方法是一种扩频地址码设计方法， 使新形成的扩 频地址码的相关函数在原点附近形成一个 "无干扰窗口 （IFW )，，。 从而使所 对应的双向同步码分多址***不存在传统码分多址***中致命的远近效应， 即不存在多址干扰（MAI )及符号间干扰（ ISI )。 为建立起大容量的无线数 字通信***奠定基础。 在一种基于 LA和 LS扩频地址编码方式的商用 CDMA***中，由于扩频码 字的零相关窗口特性， 必须保证下行和上行信道的严格同步。 而移动通信系 统中的多用户干扰和邻小区干扰及高速移动衰落环境， 又增加了同步的困 难。 因此必须有一种高精度的同步捕获方法， 能快速准确地实现同步捕获， 满足***的要求。 The above-mentioned method for generating the LS code is a method for designing a spread spectrum address code, so that the correlation function of the newly formed spread spectrum address code forms a "no interference window (IFW)" near the origin, thereby making the corresponding bidirectional Synchronous CDMA systems do not have the fatal near-far effect in traditional CDMA systems, that is, there is no multiple-access interference (MAI) and inter-symbol interference (ISI), which lays the foundation for establishing a large-capacity wireless digital communication system. In a commercial CDMA system based on the LA and LS spreading address coding methods, due to the zero correlation window characteristic of the spreading codeword, strict synchronization of the downlink and uplink channels must be guaranteed. The multi-user interference and neighboring cell interference and the high-speed mobile fading environment in the mobile communication system increase the difficulty of synchronization. Therefore, there must be a high-precision synchronous capture method, which can quickly and accurately realize synchronous capture, and meet the requirements of the system.
另外， 在申请号为 PCT/CN00/00142， 发明名称为 "码分多址***中下行 链路的同步捕捉方法" 中提到的下行链路同步捕捉方法， 主要是通过使用广 播信道、 匹配滤波器和滑动相关技术来实现的。 该方法的实现包括以下步骤： In addition, the downlink synchronization capture method mentioned in the application number PCT / CN00 / 00142 and the invention name "Downlink Synchronization Capture Method in Code Division Multiple Access System" is mainly through the use of broadcast channels and matched filtering. And sliding related technologies. The implementation of this method includes the following steps:
1 )在下行链路中加入广播信道， 并在广播信道帧中的固定时隙放独特码； 当移动站广播信道接收机检测到独特码， 就能确定帧定位信息。 1) A broadcast channel is added to the downlink, and a unique code is placed in a fixed time slot in the broadcast channel frame; when the mobile station broadcast channel receiver detects the unique code, the frame positioning information can be determined.
2 ) 为了克服多径衰落信道的影响， 广播信道同步环路首先找出每个符号 的主峰出现的能量集中的位置， 然后根据该位置确定广播信道接收机对每个 符号的判决时刻， 若判决正确， 当独特码匹配滤波器检测到独特码后， 就可 以给出一个准确的同步信息。  2) In order to overcome the influence of the multipath fading channel, the broadcast channel synchronization loop first finds the position of the energy concentration where the main peak of each symbol appears, and then determines the decision time of the broadcast channel receiver for each symbol according to the position. Correctly, when the unique code matching filter detects the unique code, it can give an accurate synchronization information.
但在用户数较大， 低信扰比和高速移动的环境中， 该方法无法克服^ [艮多 业务用户的干扰， 而且广播信道的自相关较差， 匹配滤波器检测同步峰值较 为困难， 检测时间较长， 检测精度不能满足高速移动的需要。' 发明内容  However, in the environment of large number of users, low signal-to-interference ratio, and high-speed movement, this method cannot overcome the interference of multi-service users, and the auto-correlation of the broadcast channel is poor. It is more difficult for the matched filter to detect the synchronization peak. It takes a long time, and the detection accuracy cannot meet the needs of high-speed movement. '' Summary of the Invention
为解决现有技术中所存在的上述问题和缺陷， 本发明的目的在于提供一 种新的用于码分多址通信***中的下行链路同步捕捉方法和装置。  In order to solve the above-mentioned problems and defects in the prior art, an object of the present invention is to provide a new method and device for downlink synchronization capture in a code division multiple access communication system.
为了实现上述目的，按照本发明， 在基于 LA和 LS扩频地址编码方式的 商用 CDMA ***中的一种下行链路同步捕捉方法包括以下步骤：在给定长度的 数据段前加上固定长度的前置同步序列；对前置同步序列和业务信道选择尽 可能相互正交的不同的扩频码序列；在接收端对基带采样信号执行和前置同 步序列码字相匹配的滤波， 获得 I路和 Q路信号；通过对 I路值和 Q路信号 执行平方运算计算出信号能量值；累加一帧数据长度中的所有采样值;在一帧 数据长度内取最大采样值，捕获最大能量相关峰；以及根据捕获的最大能量相 关峰来估计前置同步序列的准确到达时间， 从而实现前向码片同步和帧同 步。 In order to achieve the above object, according to the present invention, a downlink synchronization capture method in a commercial CDMA system based on a LA and LS spread-spectrum address coding method includes the following steps: Prefix the data segment with a fixed-length preamble sequence; choose different spreading code sequences that are as orthogonal to each other as possible for the preamble sequence and the traffic channel; execute the preamble sequence codeword on the baseband sampled signal at the receiver Matching filtering to obtain I and Q signals; calculate the signal energy value by performing a square operation on the I and Q signals; accumulate all the sampled values in the data length of a frame; take the largest value in the data length of a frame Sampling values, capturing the maximum energy correlation peak; and estimating the accurate arrival time of the preamble sequence based on the captured maximum energy correlation peak, thereby achieving forward chip synchronization and frame synchronization.
本发明同时还提供了一种在基于 LA和 LS扩频地址编码方式的商用 CDMA 通信***中执行下行链路同步捕获的装置，该装置包括：一个匹配滤波器，用 于在接收端对基带采样信号执行和前置同步序列码字相匹配的滤波，获得 I 路和 Q路信号；通过对 I路值和 Q路信号执行平方运算计算出信号能量值的 装置；累加一帧数据长度中的所有采样值的累加装置；在一帧数据长度内取最 大采样值，从而捕获最大能量相关峰的装置；以及才 居捕获的最大能量相关峰 来估计前置同步序列的准确到达时间，从而实现前向码片同步和帧同步的装 置。  The invention also provides a device for performing downlink synchronization acquisition in a commercial CDMA communication system based on the LA and LS spread-spectrum address coding methods. The device includes a matched filter for sampling the baseband at the receiving end. The signal performs filtering that matches the preamble sequence code word to obtain I and Q signals; a device that calculates the signal energy value by performing a square operation on the I and Q signals; accumulates all of the data length of a frame Accumulation device of sampling values; a device that takes the maximum sampling value within one frame of data to capture the maximum energy-related peak; and the maximum energy-related peak that is captured to estimate the accurate arrival time of the pre-synchronization sequence to achieve forward Device for chip synchronization and frame synchronization.
本发明的下行链路同步捕捉方法主要是通过使用前置同步序列的匹配滤 波器来实现的。 本发明采取的方法是在给定长度的数据段前加上固定长度的 前置同步序列， 选择数据段和前置同步序列的扩频码使数据段的信号和前置 同步序列尽可能正交， 通过前置同步序列的匹配滤波器捕获最大能量相关 峰， 从而实现码片同步和帧同步的捕获。  The downlink synchronization capture method of the present invention is mainly realized by a matched filter using a preamble sequence. The method adopted by the present invention is to add a fixed-length preamble sequence before a given length of data segment, and select a spreading code of the data segment and the preamble sequence to make the signal of the data segment and the preamble sequence as orthogonal as possible. The maximum energy-related peak is captured through a matched filter of the pre-synchronization sequence, thereby achieving chip and frame synchronization capture.
通过以下对 CDMA 通信***下行链路同步捕捉方法及实现该方法的装置 的具体描述就能更深入地理解本发明的目的和优点。 附图说明 作为本发明的一部分的附图和本说明一起用于说明本发明的实施例， 用于解释本发明的原理。 The purpose and advantages of the present invention can be understood more deeply through the following detailed description of the downlink synchronization capture method of a CDMA communication system and a device for implementing the method. BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of this invention, serve to explain embodiments of the invention and to explain the principles of the invention.
图 1是实施本发明方法所采用的帧结构。 图 2是依据本发明方法设计的同步捕获装置的总体信号处理示意图。 图 3给出了本发明捕获能量最大相关窗同步检测模块的示意图。 图 4为依据本发明方法设计的一个前置同步序列的示意图。 图 5为依据本发明方法使用 LS码作为前置同步序列的自相关和互相关特 性。  FIG. 1 is a frame structure used for implementing the method of the present invention. FIG. 2 is a schematic diagram of the overall signal processing of a synchronization capture device designed according to the method of the present invention. FIG. 3 is a schematic diagram of a synchronization detection module for maximum correlation window of captured energy according to the present invention. FIG. 4 is a schematic diagram of a preamble sequence designed according to the method of the present invention. Figure 5 shows the auto-correlation and cross-correlation characteristics using the LS code as a preamble sequence according to the method of the present invention.
具体实施方式 图 1 是一示意图， 示出了根据本发明所采用的帧结构。 参见图 1 , 在该 帧结构中， 包括一前置同步序列 和一数据段序列 (0 , 前置同步序列和 数据段序列时分复用。 其中前置同步序列 (ί)和数据段信号 (0应保证充分 正交， 可以使前置同步序列和数据段信号选用不同的 LS码組和 LA码组， 并 且 ^0具有冲击形式的自相关特性， 这也可以通过 LS码和 LA码来实现。 1 is a schematic diagram showing a frame structure used in accordance with the present invention. Referring to FIG. 1, the frame structure includes a preamble sequence and a data segment sequence (0, the preamble sequence and the data segment sequence are time-multiplexed. Among them, the preamble sequence (ί ) and the data segment signal (0 Should be fully orthogonal, the preamble sequence and data segment signals can use different LS code group and LA code group, and ^ 0 has the autocorrelation characteristic of the impact form, which can also be achieved by LS code and LA code.
参见图 2 , 图中表示同步捕获装置的总体信号处理示意图，其中在同步检 测装置 207 之前的各部分与常规的扩频通信***类似，本领域的技术人员很 容易理解，细节不再赘述。 这一同步捕获装置包括模拟下变频变换器 201,带 通滤波器 202,数-模转换器 A/D203,数字下变频器 204,下采样器 205,匹配滤 波器 206和同步检测装置 207。 模拟下变频变换器 201将接收的射频信号 RF 下变频成中频模拟信号。下变频变换器 201的输出提供给一个带通滤波器 202, 对输入的中频模拟信号进行带通滤波， 带通滤波后的中频模拟信号提供给模 -数转换器 A/D203,变换成每个符号中包含 Nsl 个采样的数字信号，经过数字 下变频变换器 204得到基带信号， 一个下采样器 205对输入的基带信号进行 采样， 使每个符号具有 Ns2 个采样，将采样结果输入与前置同步序列相匹配 的匹配滤波器 206，最后将匹配滤波器 206输出的 I路和 Q路值送入同步检测 装置 207。 Referring to FIG. 2, the figure shows a schematic diagram of the overall signal processing of the synchronization capture device. The parts before the synchronization detection device 207 are similar to the conventional spread-spectrum communication system. Those skilled in the art can easily understand that details will not be described again. This synchronization capture device includes an analog down-converter 201, a band-pass filter 202, a digital-to-analog converter A / D203, a digital down-converter 204, a down-sampler 205, a matched filter 206, and a synchronization detection device 207. The analog down conversion converter 201 down converts the received radio frequency signal RF into an intermediate frequency analog signal. The output of the down-converter 201 is provided to a band-pass filter 202, which performs band-pass filtering on the input intermediate frequency analog signal, and the band-pass filtered intermediate frequency analog signal is provided to the analog A-to-digital converter A / D203 converts into a digital signal containing Nsl samples in each symbol, obtains the baseband signal through digital down-converting converter 204, and a downsampler 205 samples the input baseband signal so that each symbol With Ns2 samples, the sampling result is input to the matched filter 206 that matches the preamble sequence, and the I and Q values output by the matched filter 206 are sent to the synchronization detection device 207.
图 3 表示本发明的同步检测模块的示意图。 在移动通信环境中， 接收信 号往往包含了若干个不同传播时延与信道衰落的多径时延分量。 在移动台进 行 Rake 接收时， 所面临的是一个完整的工作窗口内的多径， 而不是某个单 径， 因此，在基于 LA和 LS扩频地址编码方式的商用 CDMA ***中采用了捕获 能量最大相关窗的方法。 将匹配滤波器 206送出的 I路， Q路信号送入同步 检测模块 207后， 先在运算器 301中对 I路、 Q路进行平方运算， 计算信号 能量值， 然后在模块 302中进行 N个样值的累加， 在模块 303中， 再在一帧 数据长度内取最大值， 并确定最大值位置， 用该确定的最大值位置捕获能量 最大相关窗，从而获取帧定位信息，在获取帧定位后， 就可以取得准确的扩频 码相位， 进行信号的解扩处理和定时跟踪。  FIG. 3 shows a schematic diagram of a synchronization detection module of the present invention. In a mobile communication environment, the received signal often contains several multipath delay components with different propagation delays and channel fading. When a mobile station performs Rake reception, it is faced with a multipath within a complete working window, rather than a single path. Therefore, the capture energy is used in commercial CDMA systems based on the LA and LS spread-spectrum address coding methods. Method of maximum correlation window. After the I and Q signals sent by the matched filter 206 are sent to the synchronization detection module 207, the I and Q channels are squared in the arithmetic unit 301, the signal energy values are calculated, and then N are performed in the module 302 For the accumulation of samples, in module 303, the maximum value is taken within a frame of data length, and the position of the maximum value is determined. The determined maximum position is used to capture the maximum energy correlation window, thereby obtaining frame positioning information, and obtaining frame positioning. After that, an accurate phase of the spreading code can be obtained, and the signal despreading processing and timing tracking can be performed.
在基于 LA和 LS扩频地址编码方式的商用 CDMA***中， 数据段下行业务 信道为 32个独立的码道相叠加， 每个码道使用 1个 128位的 LS码。 因此在 每一个小区内前置同步序列应找到一个码序列，和业务信道所使用的 32个 LS 码尽可能相互正交。 在移动台进行小区搜索时， 接收机对不同小区的前置同 步序列作匹配滤波， 选择其中能量最强者作为正确选定小区， 因此相邻小区 的前置同步序列也应该具有较好的互相关特性， 即尽可能相互正交， 以避免 邻小区前置同步序列相互间的干扰， 从而正确提取同步信息， 进行小区选择。 经分析和实际测试， 使用短 LS 码扩频并在不同的扩频符号间*** LA 间隔 gap , 不同小区的前置同步序列使用不同的 LA 间隔 gap并利用 LA极性所构 造出的前置同步序列码字序列， 具有较好的自相关和互相关特性， 而且这样 构造的前置同步序列和数据段下行业务信道也有较好的互相关特性， 下面结 合图 3、 图 4给出一种在 LAS- CDMA***中使用 LS+LA码来构造前置同步序列 的方法。 In a commercial CDMA system based on the LA and LS spread-spectrum address coding methods, the downlink service channel of the data segment is superimposed on 32 independent code channels, and each code channel uses a 128-bit LS code. Therefore, a code sequence should be found in the preamble sequence in each cell, and the 32 LS codes used by the traffic channel should be as orthogonal to each other as possible. When the mobile station performs cell search, the receiver performs matching filtering on the preamble sequences of different cells, and selects the one with the strongest energy as the correct selected cell. Therefore, the preamble sequences of neighboring cells should also have better mutual interaction. The relevant characteristics are as orthogonal as possible to avoid interference between neighboring cell pre-synchronization sequences, so as to correctly extract synchronization information and perform cell selection. After analysis and actual test, use short LS code to spread spectrum and insert LA interval between different spreading symbols gap, the preamble sequences of different cells use different LA interval gaps and the preamble sequence codeword sequences constructed by the LA polarity, which have better autocorrelation and cross-correlation characteristics, and the presync structured in this way The sequence and data segment downlink traffic channels also have good cross-correlation characteristics. A method for constructing a preamble sequence using the LS + LA code in a LAS-CDMA system is given below in conjunction with FIG. 3 and FIG. 4.
图 4 为一个同步序列的示意图， 其中 ^mb0/。， symbol, ^ symbol, (符号数 ^ = 2 = 1,2,3...)从¾/^0/。开始的符号序列， 这个符号序列将使用短 LS 码扩 频， 图中灰色区域为两个相邻符号之间的间隔， 该间隔依据 LA排列生成。 FIG. 4 is a schematic diagram of a synchronization sequence, where ^ mb 0 /. , Symbol, ^ symbol, (number of symbols ^ = 2 = 1,2,3 ...) from ¾ / ^ 0 /. The first symbol sequence. This symbol sequence will be spread using a short LS code. The gray area in the figure is the interval between two adjacent symbols. The interval is generated according to the LA arrangement.
短 LS码的构成方法：  How to make short LS code:
在图 4中给出了一个短 LS码的结构， 假设总码长为 81^，前置间隔 gap长 I^ C码长 2L15中置间隔 gap长 2L13 S码长 21^，后置间隔 gap长 在码中加 入和 C码 S码等长的保护性间隔 gap的目的是使 C码和 S码不相碰， 从而为 自相关和互相关提供一个尽可能大的零相关窗， 在这里零相关窗为- 2L1— 2L1。 FIG 4 is given in the structure of a short code LS, assume that the total code length of 81 ^, pre-gap length interval I ^ C code length 2L 15 in spaced opposed gap length code length 2L 13 S ^ 21, rear spacer The gap length is added to the code with a protective interval gap of the same length as the C code and the S code. The purpose of the gap is to prevent the C code and the S code from colliding, thereby providing a zero correlation window as large as possible for auto-correlation and cross-correlation. Here The zero correlation window is-2L1-2L1.
LA的构成方法：  Composition of LA:
LA码可以看成是 LS码的一种级联方式， 在 CDMA***中， 各个小区使用 相同的 LS码集， 因此不同的小区需要使用不同的 LA来加以区分。  The LA code can be regarded as a concatenation method of the LS code. In a CDMA system, each cell uses the same LS code set, so different cells need to use different LAs to distinguish them.
如图 4所示，一个 LA序列中前后两个一 LA码扩频的符号之间的间隔为 LA 间 隔 Gap， 顺序的 LA 间隔 Gap 的排列称为 LA 排列 ， 序歹' j 中 [symbol, , symbol,…… 的选取方式称为 LA极性。 进一步的 LA码的构成方 法可以参考上述有关专利。  As shown in FIG. 4, the interval between two LA code spread symbols in a LA sequence is the LA interval Gap, and the sequence of the sequential LA interval Gap is called the LA array. The selection of symbol, ... is called LA polarity. For the method of forming the LA code, please refer to the related patents.
在构造不同小区的前置同步序列时， 针对不同的具体情况， 可以灵活使 用 LA排列和 LA极性， 充分利用 LS+LA码的特性， 可以构造初试和小区组网 6 使用的具有优良自相关和互相关特性的 LS+LA码前置同步序列。 下面给出了一个具体构造 LS+LA码前置同步序列的例子。 附图' 5为 4个使用 8个符号， 每个符号以 32位 LS码扩频符号间共加入 43个 chip长间隔 gap的前置同步序列自相关和互相关特性。 以下的表 1和 表 2分别表示这 4个前置同步序列的 LA间隔和 LA极性的选取方式。 图中依 次为前置同步序列 1的自相关及和前置同步序列 2 , 3, 4的互相关特性， 在 这里取码片幅度为 1。 从图上可以看出， 采用 8个符号的 LA序列， 自相关和 互相关的最大副峰幅度为自相关主峰的 1/8 , 能量相差约 18dB,可以很容易 区分出主峰， 无论是自相关还是互相关， 均存在 -2L1_2L1 的零相关窗。 前置 同步序列 2 , 3 , 4和序列 1的特性相同。 表 1: LA排列的分配 When constructing the preamble sequence of different cells, according to different specific situations, you can flexibly use the LA arrangement and LA polarity, and make full use of the characteristics of LS + LA code to construct a preliminary test and cell networking. 6 LS + LA code preamble sequence with excellent auto-correlation and cross-correlation characteristics. An example of constructing a LS + LA code preamble sequence is given below. Figure 5 shows the auto-correlation and cross-correlation characteristics of 4 preamble synchronization sequences using 8 symbols in each of which a total of 43 chip long gap gaps are added between 32-bit LS code spreading symbols. The following Tables 1 and 2 show the selection methods of the LA interval and LA polarity of the four preamble sequences, respectively. In the figure, the auto-correlation of the preamble sequence 1 and the cross-correlation characteristics with the preamble sequences 2, 3, and 4 are shown in order. Here, the chip amplitude is taken to be 1. It can be seen from the figure that using the 8-symbol LA sequence, the maximum side peak amplitude of the auto-correlation and cross-correlation is 1/8 of the main peak of the auto-correlation, and the energy difference is about 18 dB. The main peak can be easily distinguished, whether it is auto-correlation There is still cross correlation, and there are zero correlation windows of -2L1 _ 2L1. Preamble sequences 2, 3, 4 have the same characteristics as sequence 1. Table 1: LA permutations
1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8
前置同步序 Preamble
0 2 4 6 8 10 12 1  0 2 4 6 8 10 12 1
列 1 Column 1
前置同步序 Preamble
0 2 4 6 8 10 12 1  0 2 4 6 8 10 12 1
列 1 Column 1
前置同步序 Preamble
0 2 4 6 8 10 12 1  0 2 4 6 8 10 12 1
列 3 Column 3
前置同步序 Preamble
0 2 4 6 8 10 12 1  0 2 4 6 8 10 12 1
列 4 Column 4
表 2: LA极性的分配  Table 2: LA Polarity Assignment
■1 2 3 4 5 6 7 8  1 2 3 4 5 6 7 8
前置同步序 Preamble
1 1 1 1 1 1 1 1  1 1 1 1 1 1 1 1
列 1 Column 1
前置同步序 Preamble
1 -1 1 - 1 1 -1 1 -1 列 2  1 -1 1-1 1 -1 1 -1 Row 2
前置同步序 Preamble
1 1 - -1 - 1 1 1 -1 -1 列 3  1 1--1-1 1 1 -1 -1 row 3
前置同步序 Preamble
1 1 1 1 - 1 -1 -1 -1 列 4 为了降低组网环境中相邻小区数据段业务信道的对捕获能量最大相关窗的干 扰， 可以提高前置同步序列的发信功率， 使之与数据段业务信道满负荷时的 发信功率相当。 1 1 1 1-1 -1 -1 -1 Row 4 In order to reduce the interference of the data channel service channel of the adjacent cell on the maximum correlation window of captured energy in the networking environment, the transmission power of the preamble sequence can be increased to be equivalent to the signal power of the data channel service channel at full load.

Claims

权利要求 Rights request
1.在基于 LA和 LS扩频地址编码方式的商用 CDMA***中，一种下行链路 同步捕捉方法包括以下步骤： 1. In a commercial CDMA system based on the LA and LS spread-spectrum address coding methods, a downlink synchronization capture method includes the following steps:
(a)在给定长度的数据段前加上固定长度的前置同步序列；  (a) Prefix a data segment of a given length with a fixed-length preamble sequence;
(b)对前置同步序列和业务信道选择尽可能相互正交的不同的扩频码序 列；  (b) Select different spreading code sequences for the preamble sequence and the traffic channel as mutually orthogonal as possible;
(c)在接收端对基带采样信号执行和前置同步序列码字相匹配的滤波， 获得 I路和 Q路信号；  (c) Perform filtering at the receiving end on the baseband sampled signal to match the preamble sequence codeword to obtain I and Q signals;
(d)通过对 I路值和 Q路信号执行平方运算计算出信号能量值；  (d) Calculate the signal energy value by performing a square operation on the I and Q signals;
(e)累加一帧数据长度中的所有采样值；  (e) accumulate all samples in the data length of one frame;
(f)在一帧数据长度内取最大采样值,捕获最大能量相关峰;以及  (f) taking the maximum sampled value within a frame of data length to capture the maximum energy-related peak; and
(g)根据捕获的最大能量相关峰来估计前置同步序列的准确到达时间， 从 而实现前向码片同步和帧同步。  (g) The accurate arrival time of the preamble sequence is estimated according to the captured maximum energy correlation peak, thereby realizing forward chip synchronization and frame synchronization.
2.按照权利要求 1 的下行链路同步捕捉方法，其特征是：上述步骤（c)包 括在接收端对不同小区的前置同步序列作匹配滤波， 选择其中能量最强者作 为正确选定小区。  2. The downlink synchronization capture method according to claim 1, characterized in that the step (c) includes matching filtering on the preamble sequence of different cells at the receiving end, and selecting the one with the strongest energy as the correct selected cell .
3.在基于 LA和 LS扩频地址编码方式的商用 CDMA通信***中的一种下行 链路同步捕获装置包括:一个匹配滤波器，用于在接收端对基带采样信号执行 和前置同步序列码字相匹配的滤波，获得 I路和 Q路信号；通过对 I路值和 Q 路信号执行平方运算计算出信号能量值的装置；累加一帧数据长度中的所有 采样值的累加装置；在一帧数据长度内取最大釆样值，从而捕获最大能量相关 峰的装置；以及根据捕获的最大能量相关峰来估计前置同步序列的准确到达 时间，从而实现前向码片同步和帧同步的装置。 3. A downlink synchronization acquisition device in a commercial CDMA communication system based on the LA and LS spread-spectrum address coding methods includes: a matched filter for performing baseband sampling signals at the receiving end and preamble sequence code Word-matched filtering to obtain I and Q signals; a device that calculates the signal energy value by performing a square operation on the I and Q signals; an accumulation device that accumulates all the sampled values in the data length of a frame; Device for taking maximum sample value within frame data length to capture maximum energy correlation peak; and device for estimating accurate arrival time of preamble sequence based on captured maximum energy correlation peak, thereby realizing forward chip synchronization and frame synchronization .
4. 按照权利要求 3的下行链路同步捕获装置，其特征是还包括用于将接 收的射频信号下变频成中频模拟信号的模拟下变频变换器；对上述中频模拟 信号进行低通滤波的低通滤波器；将上述低通滤波后的中频模拟信号变换成 釆样数字信号的模 -数转换器;将上述采样数字信号变换成基带信号的数字下 变频变换器；以及对基带信号再进行采样的下采样器。 4. The downlink synchronization acquisition device according to claim 3, further comprising an analog down-converter for down-converting the received radio frequency signal into an intermediate-frequency analog signal; and a low-pass filter for performing low-pass filtering on the intermediate-frequency analog signal. A pass filter; an analog-to-digital converter that converts the low-pass filtered intermediate frequency analog signal into a sample-like digital signal; a digital down-converter that converts the sampled digital signal into a baseband signal; and resamples the baseband signal Downsampler.
PCT/CN2001/001486 2001-10-18 2001-10-18 Method and device for the capturing of down synchronization in the cdma communication system WO2003036836A1 (en)

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