WO2004066532A1 - Procede et dispositif de mise en oeuvre pour sous-systeme de synchronisation de liaison descendante - Google Patents

Procede et dispositif de mise en oeuvre pour sous-systeme de synchronisation de liaison descendante Download PDF

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Publication number
WO2004066532A1
WO2004066532A1 PCT/CN2003/000061 CN0300061W WO2004066532A1 WO 2004066532 A1 WO2004066532 A1 WO 2004066532A1 CN 0300061 W CN0300061 W CN 0300061W WO 2004066532 A1 WO2004066532 A1 WO 2004066532A1
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WIPO (PCT)
Prior art keywords
initial
cell
carrier frequency
frame boundary
tracking
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PCT/CN2003/000061
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English (en)
French (fr)
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WO2004066532A8 (fr
Inventor
Li Fang
Chen Ji
Jingbo Liu
Yongsheng Zhang
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Linkair Communications,Inc.
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Application filed by Linkair Communications,Inc. filed Critical Linkair Communications,Inc.
Priority to AU2003211659A priority Critical patent/AU2003211659A1/en
Priority to CN03805483.3A priority patent/CN1640041A/zh
Priority to PCT/CN2003/000061 priority patent/WO2004066532A1/zh
Publication of WO2004066532A1 publication Critical patent/WO2004066532A1/zh
Publication of WO2004066532A8 publication Critical patent/WO2004066532A8/zh

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Classifications

    • 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
    • H04B1/70735—Code identification
    • 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
    • H04B1/7077—Multi-step acquisition, e.g. multi-dwell, coarse-fine or validation
    • 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
    • H04B1/7083—Cell search, e.g. using a three-step approach
    • 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
    • H04B2201/70702—Intercell-related aspects

Definitions

  • the present invention relates to the field of wireless communication technologies, and in particular, to a CDMA system, and in particular, to a method and an apparatus for implementing a downlink synchronization subsystem. Background technique
  • the frequency accuracy of a mobile station crystal oscillator is generally around a few ppm, and it operates in the 2GHz frequency band, and the carrier frequency deviation is generally between 1K ⁇ to 10K ⁇ .
  • LA polar sequences of different cells cannot be accurately identified, and despreading up to 874Tc cannot be used. Therefore, it is necessary to find an implementation method and device for implementing downlink synchronization acquisition and cell identification in the TD-LAS system. Furthermore, a method and device for implementing downlink synchronization acquisition and cell identification that are generally effective for a general CDMA system are obtained. Summary of the invention
  • An object of the present invention is to provide a method and a device for implementing a downlink synchronization subsystem, which are used to implement frequency acquisition in a CDMA system, and simultaneously realize downlink synchronization acquisition and cell identification, and provide multipath information for receiving a service channel, and Carrier frequency tracking is performed to ensure the accuracy of the timing frequency and has the characteristics of simplicity and practicality.
  • a method for implementing a downlink synchronization subsystem includes the following steps: detecting an initial frame boundary;
  • the detection of the initial frame boundary refers to: In the initial frame boundary detection, the relevant peaks are extracted through a filter that matches the physical channel downlink synchronization of all cells to implement frame boundary detection; because all cells use different bipolar LAs Polarity sequence, so the downlink synchronization matching filter can only perform matching filtering on time slots, and perform LA non-coherent combining on the entire downlink synchronization physical channel.
  • the initial frequency acquisition refers to: After the initial frame boundary detection is completed, the mobile station can obtain the starting timing positions of one or more downlink synchronization physical channels from different cells that may exist; The frame boundary information of a cell is strong, the carrier frequency deviation is obtained by using the downlink synchronization physical channel, and the VC0 of the radio frequency needs to be adjusted to complete the initial carrier frequency acquisition
  • the performing cell search and selection refers to: searching all cells / sectors with sufficient signal strength, and establishing downlink synchronization with the selected cell.
  • Multi-path searching and tracking refers to receiving signals received by a mobile station through multiple paths after receiving frame synchronization, code synchronization, and carrier synchronization and determining a target cell. Select the appropriate path and provide it to the RAKE receiver.
  • the carrier frequency tracking means that: the initial carrier frequency acquisition unit reduces the initial frequency difference to less than 500 Hz, and the cell identification unit obtains the LA + LS combination used by the cell; the mobile station uses the downlink continuous pilot channel for frequency tracking , Reduce the remaining frequency difference to less than 100Hz, to meet the needs of demodulation.
  • the described timing frequency tracking refers to:
  • the timing frequency tracking is detected by using a mobile station
  • the frame period is compared with the exact period to extract the clock error.
  • the mobile station After the mobile station is powered on, it first performs initial frame boundary detection. If no downlink synchronization physical channel can be detected, it will always perform frame boundary detection;
  • initial carrier frequency acquisition and cell search and selection are performed until the cell search and selection is successful. If the time for cell search and selection is greater than a certain parameter M, the initial frame boundary detection is performed again;
  • the polar sequence of the serving cell, the Cel ID, is obtained, and the LS + LA code group of the cell / sector is obtained;
  • the multipath search and tracking loop starts to work, and transmits the multipath information of the received signal to the upper layer.
  • the timing tracking loop, carrier tracking loop, and BCH channel reception can run and perform CRC check.
  • the invention also provides a device for implementing a downlink synchronization subsystem, which is characterized by comprising: an initial frame boundary detection device, an initial carrier frequency acquisition device, a cell search and selection device, a multipath search and tracking device, and a carrier frequency tracking device , Timing frequency tracking device;
  • An input signal enters the initial frame boundary detection device, and after detecting a downlink synchronization physical channel, the information of the initial frame boundary is sent to the initial carrier frequency acquisition device and the cell search and selection device;
  • the initial carrier frequency acquisition device and the cell search and selection device perform initial carrier acquisition and cell search selection by using information of an initial frame boundary and a received signal of a downlink synchronization channel, until the cell search and selection succeeds, the initial carrier frequency
  • the output signal of the capture device is the initial carrier frequency difference
  • the output signal of the cell search and selection device is the energy and arrival delay of each cell searched, and this information is reported to the upper layer;
  • the multipath search device and tracking device use the time of arrival of the frame and the received signal of the downlink synchronization channel to find multipath information for the timing frequency tracking device and the carrier frequency tracking device.
  • the initial frame boundary detection device includes: Input: the received signal (4 / c) after passing through the baseband filter;
  • the initial frequency acquisition device includes:
  • Input the downlink synchronization channel received signal (4 / c) passing the baseband filter, the position of the frame boundary;
  • the cell search and selection device includes:
  • Input the downlink synchronization channel received signal (4c) after passing through the baseband filter, the position of the frame boundary;
  • Output Frame boundary position and energy of each cell.
  • the multi-path signal searching and tracking device includes:
  • Input receive the signal (4) through the downlink synchronization channel of the baseband filter, the frame boundary position of the selected cell;
  • Multi-path search and tracking is performed after the mobile station obtains frame synchronization, code synchronization, and carrier synchronization, and determines the target cell, then selects an appropriate path among the received signals that reach the mobile station through multiple paths, and provides it to the RAKE receiver.
  • the carrier frequency tracking device includes:
  • Input The received signal (4 / c) of the downlink traffic channel through the baseband filter, the position of the two paths; Output: the carrier frequency deviation (-500Hz, 500Hz);
  • the initial carrier frequency acquisition unit reduces the initial frequency difference to less than 500Hz, and the cell identification unit obtains the LA + LS combination used by the cell; the mobile station uses the downlink continuous pilot channel for frequency tracking, and reduces the remaining frequency difference to less than 100Hz To meet the needs of demodulation.
  • the timing frequency tracking device includes:
  • Timing frequency deviation (-200Hz, 200Hz); Timing frequency tracking uses the frame period detected by the mobile station to compare with the accurate period to extract the clock error. .
  • the device according to the present invention further comprises: a baseband filter, a splitter, an RF VC0, a BB VCO, and a CRC check device;
  • the baseband received signal passes through the 4fc baseband filter and enters the initial frame boundary detection device.
  • the information of the initial frame boundary is sent to the initial carrier frequency acquisition device and A cell search and selection device, the initial carrier frequency acquisition device and the cell search and selection device use initial frame boundary information and a received signal of a downlink synchronization channel to perform initial carrier acquisition and cell search selection until the cell search and selection is successful.
  • the output signal of the initial carrier frequency acquisition device is an initial carrier frequency difference, which is used to adjust the VC0 of the radio frequency.
  • the output signal of the cell search and selection device is the energy and arrival delay of each cell that is searched.
  • the downlink multipath search and tracking device uses the frame arrival time and the received signal of the downlink synchronization channel to find multipath information for the timing frequency tracking device, the carrier frequency tracking device, and the reception and detection of the BCH channel.
  • Said CRC checking device said An output signal of the frequency tracking means for adjusting the timing of the baseband VC0; of the carrier frequency tracking apparatus using multi-path information and the downlink pilot signals received continuous pilot channel, to calculate the carrier frequency difference, for adjusting the radio frequency VC0.
  • a beneficial effect of the present invention is that, by providing a method and device for implementing a downlink synchronization subsystem, the method is used for frequency acquisition in a CDMA system, and simultaneously realizes downlink synchronization acquisition and cell identification, and provides multipath information for receiving a service channel.
  • the carrier frequency is tracked to ensure the accuracy of the timing frequency, and has the characteristics of simple and practical. among them:
  • Initial frame boundary detection A frame boundary of a cell may be detected
  • Initial frequency acquisition Use the result of the initial frame boundary detection to obtain the frame start position of the downlink synchronization physical channel, perform partial despreading of the LS code, use the FFT algorithm to implement frequency acquisition, and reduce the carrier frequency deviation from the KHz range to less than 500Hz;
  • Multi-path signal search and tracking After cell search and selection, the mobile station uses the downlink synchronization channel to search and track multi-path signals to provide multi-path information for the reception of traffic channels;
  • Carrier frequency tracking Since the reception of the service channel requires the deviation of the carrier frequency to be less than 100Hz, it is necessary to continuously track the carrier frequency. Using continuous pilot channels and using differential detection to track the carrier frequency is simple and practical;
  • Timing frequency trace VC0 used by the mobile station for baseband timing and sampling has an initial deviation from the VC0 of the base station. Large deviations are likely to cause slip codes and affect the reception quality of the service channel. Therefore, the frequency of VC0 needs to be constantly adjusted to ensure the timing frequency. Accurate.
  • FIG. 1 is a subframe structure diagram of a downlink synchronization channel
  • Figure 2 is a control flowchart of the downlink synchronization subsystem
  • Figure 3 is a structural block diagram of the downlink synchronization subsystem.
  • DETAILED DESCRIPTION The present invention provides a method and device for implementing a downlink synchronization subsystem, including algorithms such as initial frame boundary detection, initial carrier acquisition, cell search and selection, multipath signal search and tracking, carrier tracking, and timing tracking. Through simulation, the feasibility is verified, which provides a reference and basis for the synchronization implementation of the CDMA system.
  • the following uses the TD-LAS system as an example and in conjunction with the drawings to explain the specific implementation of the present invention in detail.
  • the downlink synchronization subsystem of the TD-LAS system needs to complete the following tasks:
  • the specific implementation of the present invention is mainly a set of solutions for the downlink synchronization subsystem designed for the physical layer specification of the TD-LAS system, including initial frame boundary detection, initial carrier acquisition, cell search and selection, multipath signal search and tracking. , Carrier tracking, timing frequency tracking, etc.
  • the downlink synchronization sub-frame has a total of 8 time slots, and the length of each time slot refers to Table 2.
  • Each time slot transmits a downlink synchronization pulse of 72 Chips in length, which includes the C code of 24 chips and the S code of 24 chips. A guard band of 24 chips is reserved in the middle.
  • the downlink synchronization pulse is transmitted at the beginning of each time slot.
  • the LS code used for the downlink synchronization channel is complex digital, and the corresponding spreading and despreading is similar to QPSK, as shown in Table 4.
  • the 8 slots of the downlink synchronization subframe can transmit 8 modulation symbols.
  • a total of 8 bipolar mutually orthogonal code sequences can be obtained, such as each row or column of the 8 x 8 Wal sh matrix.
  • These code sequences are called LA polar sequences (see Table 3).
  • 8 orthogonal LA polar sequences can support 8-cell / sector networking; to support a larger network size, consider combining with other cell identification methods such as continuous pilot cell identification, or you can Make different cell / sector clusters use different LA guard intervals to expand the signal set of D-SYNPCH. Table 1.
  • LA slot (TS,) 0 1 2 3 4 5 6 7
  • the initial carrier frequency offset is less than 500Hz.
  • the LA polarity sequence of different cells can be accurately identified, and the downlink synchronization physical channel can be despread over the entire 874Tc. Therefore, the downlink synchronization physical channel matching each cell is used.
  • the filter can implement downlink synchronization acquisition and cell identification at the same time, and does not need to adjust the carrier frequency.
  • the frequency accuracy of a mobile station crystal oscillator is generally around a few ppm, working in the 2GHz band, and the carrier frequency deviation is generally between ⁇ to ⁇ . Under this condition, the LA polar sequences of different cells cannot be accurately identified, and despreading up to 874Tc cannot be used. Therefore, the initial carrier must be performed before the algorithm for downlink synchronization acquisition and cell identification is implemented in the TD-LAS system. Capture so that the frequency deviation is less than 500Hz.
  • the process of the downlink synchronization subsystem is as follows:
  • Multi-path signal search and tracking After the cell is searched and selected, the mobile station uses the downlink synchronization channel to search and track the multi-path signal to provide multi-path information for the reception of the service channel;
  • Carrier frequency tracking Because the reception of the service channel requires the deviation of the carrier frequency to be less than 100Hz, it is necessary to continuously track the carrier frequency.
  • the continuous pilot channel is used to track the carrier frequency by differential detection. It is simple and practical ;
  • Timing frequency tracking The VC0 used by the mobile station for baseband timing and sampling has an initial deviation from the VC0 of the base station. The large deviation easily generates slip codes and affects the reception quality of the service channel. Therefore, the frequency of VC0 needs to be constantly adjusted to ensure the timing. Accurate frequency.
  • the control of the downlink synchronization subsystem process is shown in Figure 2.
  • the mobile station first performs initial frame boundary detection after power-on. If no downlink synchronization physical channel can be detected, frame boundary detection will always be performed. After the frame boundary detection is completed, initial carrier frequency acquisition and cell search and selection are performed until the cell search and selection is successful. If the time for cell search and selection is greater than a certain parameter M, the initial frame boundary detection is performed again. After the initial carrier frequency acquisition and cell search and selection are successful, the LA polar sequence of the serving cell, the Cel ID, and the LS + LA code group of the cell / sector are obtained. After that, the multipath search and tracking loop began to work, and the multipath information of the received signal was transmitted to the upper layer. The timing tracking loop, the carrier tracking loop, and the BCH channel reception could be run, and a CRC check was performed.
  • the structure of the receiver of the downlink synchronization subsystem is shown in Figure 3.
  • the baseband received signal passes through the 4 / c baseband filter and enters the IFBD (Initial Frame Boundary Detection) unit.
  • the information of the initial frame boundary is sent to the initial carrier frequency acquisition unit and cell.
  • Search and selection unit, initial carrier frequency acquisition unit and cell search and selection unit use initial frame boundary information and received signals of the downlink synchronization channel to perform initial carrier acquisition and minimization.
  • the output signal of the initial carrier frequency capture unit is the initial carrier frequency difference, which is used to adjust the vco of the radio frequency
  • the output signal of the zone search and selection unit is the energy and arrival of each cell searched The delay is reported to the upper house.
  • the downlink multipath search and tracking unit uses the frame arrival time and the received signal of the downlink synchronization channel to find multipath information for the timing frequency tracking unit, the carrier frequency tracking unit, and the reception and CRC of the BCH channel.
  • the output signal of the checking unit and the timing frequency tracking unit is used to adjust the baseband timing VC0;
  • the carrier frequency tracking unit uses the multipath information and the received signal of the downlink continuous pilot channel to calculate the carrier frequency difference and is used to adjust the VC0 of the radio frequency;
  • downlink The description of each point in the receiver structure of the synchronization subsystem is shown in Table 5, and the input and output description of each module is shown in Table 6. Table 5. Explanation of points in the receiver structure of the downlink synchronization subsystem
  • Received signal (4 / C ) of the initial frame edge passing through the baseband filter The position detected by the initial frame boundary of the cell with the strongest energy searched, Range: (0,30720 * 4)
  • the initial carrier is received through the downlink synchronization channel of the baseband filter Signal carrier frequency deviation (_5KHz, 5KHz) capture (4c), position of frame boundary
  • the relevant peaks are extracted through a filter that matches the physical channel downlink synchronization of all cells to implement frame boundary detection. Because all cells use different LA polar sequences, the downlink synchronization matching filter can only perform matching filtering on time slots and perform LA non-coherent combining on the entire downlink synchronization physical channel.
  • the despreading length of the downlink synchronization physical channel on the time slot is 72Tc, and the corresponding 3dB performance loss point is 8KHz. Therefore, the maximum frequency deviation tolerated by this algorithm is [-8KHz, 8KHz].
  • the mobile station can obtain the starting timing positions of one or more downlink synchronization physical channels from different cells that may exist.
  • the mobile station selects the frame boundary information of a cell with the strongest energy, uses the FFT algorithm to calculate the carrier frequency deviation, and constantly adjusts the VC0 of the radio frequency to complete the initial carrier frequency acquisition. After this step is completed, the carrier frequency deviation will drop below 500Hz.
  • the signal despreading length used in the algorithm is 48Tc, and the multiplied signal is estimated, so the frequency deviation range that the algorithm can estimate is [-5KHz, 5KHz].
  • the purpose of cell search is to find all cells / sectors with sufficient signal strength and establish downlink synchronization with the selected cell.
  • the service channels of different cells use different LS spreading code groups and different LA intervals.
  • the mobile station In order for a mobile station to correctly demodulate the signal of a certain cell / sector and establish communication, it must obtain the information of the LS code group and LA interval arrangement of the traffic channel of this cell / sector. Therefore, in the cell search, the mobile station must search all possible cell ID sequences in the downlink synchronization physical channel, detect all cells / sectors with sufficient signal strength, and further obtain the destination cell / sector use.
  • the algorithm uses matched filtering on the entire downlink synchronization channel 874chip. Therefore, the frequency deviation range required by the algorithm is [-500Hz, 500Hz].
  • the prerequisite for carrier frequency tracking is that timing synchronization has been established between the mobile station and the base station, and the initial downlink carrier acquisition has reduced the carrier frequency deviation from a maximum of 6KHz to less than 500Hz.
  • carrier frequency tracking algorithms including FFT, DMP-FED, DD (differential frequency Rate detection). Because downlink continuous pilot channels are used in the TD-LAS system, frequency tracking can be achieved by using downlink continuous pilot channels.
  • LA initial carrier frequency capturing unit by the initial frequency difference is reduced to less than 5 00Hz, cell-cell recognition unit used to obtain the present composition + LS.
  • the mobile station can use the downlink continuous pilot channel for frequency tracking, reduce the remaining frequency difference to less than 100Hz, and meet the demodulation requirements.
  • Multi-path search and tracking is performed after the mobile station obtains frame synchronization, code synchronization, and carrier synchronization, and determines the target cell, then selects an appropriate path among the received signals that reach the mobile station through multiple paths, and provides it to the RAKE receiver.
  • a transmitter sends signals to a receiver via different paths.
  • the signal of each path undergoes different random amplitude attenuation and phase rotation, and different time delays. After these signals reach the receiver, the complex signals cause fading due to the addition of the complex numbers.
  • the existence of signals on these paths is also random. It exists at some moments, disappears at some moments, some moments are stronger than other path signals, and some moments may have stronger path signals.
  • a RAKE receiver including multiple branches can be used to combat multipath fading.
  • the RAKE receiver uses a search unit to detect multiple paths with strong signals and assigns them to each branch.
  • Each branch is responsible for synchronizing with a path signal and demodulating the signal in it, and then combining the path information according to certain rules.
  • Timing frequency tracking uses the frame period detected by the mobile station to compare with the accurate period to extract the clock error.
  • the frame period of the downlink signal be T.
  • T 30720T C.
  • the clock frequency of the mobile station and the base station is the same, the frame period measured by the mobile station is also T.
  • the clock frequency difference between the mobile station and the base station is 4, the sampling rate will change and the measured frame period will also change.
  • the periodic change be l, then ⁇ , where f is the exact clock frequency. Therefore, through detection, l can be used to modify the sampling clock.
  • the multipath search unit uses a code matching filter to detect the position of the D-SYNCH channel corresponding to each path in the received signal sampling sequence. Since D-SYNCH is in every downstream The signal frame position is fixed. When there is no clock error, the detected position is also unchanged. Therefore, using the position change given by the multipath search unit, the clock change can be detected, and the clock frequency difference can be calculated.
  • the multipath search unit should always give the information of the path that arrives first, and assume that the corresponding ⁇ is the same path, otherwise errors will be introduced.
  • the clock frequency tracking unit must also perform multi-frame accumulation and smoothing on the calculated frequency difference to reduce the influence of the multipath position error.
  • a beneficial effect of the present invention is that, by providing a method and device for implementing a downlink synchronization subsystem, the method is used to implement frequency acquisition, and simultaneously realize downlink synchronization acquisition and cell identification, provide multipath information for receiving a service channel, and perform carrier
  • the frequency tracking ensures the accuracy of the timing frequency and has the characteristics of simple and practical.

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Description

一种下行链路同步子***实现方法及装置 技术领域 本发明涉及无线通信技术领域， 特别涉及 CDMA ***， 具体的讲是一种 下行链路同步子***实现方法及装置。 背景技术
目前 C画 A技术发展迅速， 在对采用 LAS码的 CDMA***的 TDD模式的 研究过程中 （如： 在连宇通信有限公司的 LinkAirll l TD- LAS实验***中）， 可以得出： ***设计和实现的初始的载波频率偏移小于规范值 500Hz, 此 时不同小区的 LA极性序列可以准确识别， 而且下行同步物理信道可以在整 个 874Tc 上解扩， 因此使用匹配于各个小区下行同步物理信道的滤波器， 就可以同时实现下行同步捕获和小区识别， 不需要进行载波频率的调整。 在商用 LAS-CDMA TDD***中， 移动台晶体振荡器的频率准确度一般在 几个 ppm左右， 工作在 2GHz频段上， 载波频率偏差一般在 ΙΚΗζ到 ΙΟΚΗζ 之间。 在这种条件下， 不同小区的 LA极性序列不能准确识别， 而且不能使 用长达 874Tc的解扩， 因此， 需找到在 TD- LAS***中实现下行同步捕获和 小区识别的实现方法及装置， 进而得到对于一般的 CDMA***普遍有效的下 行同步捕获和小区识别的实现方法及装置。 发明内容
本发明的目的在于， 提供一种下行链路同步子***实现方法及装置， 用以在 CDMA***中实现频率捕获， 同时实现下行同步捕获和小区识别， 为 业务信道的接收提供多径信息， 并进行载波频率的跟踪， 保证定时频率的 准确， 且具有简单实用的特点。
本发明的技术方案为： 一种下行链路同步子***实现方法， 其特征在于包括以下步骤： 对初始帧边界进行检测；
利用初始帧边界检测的结果， 进行初始频率捕获；
进行小区搜索和选择；
进行多径信号的搜索和跟踪；
进行载波频率跟踪；
进行定时频率跟踪。
所述的对初始帧边界进行检测是指： 在初始帧边界检测中， 通过和所 有小区下行同步物理信道匹配的滤波器提取相关峰， 实现帧边界检测； 由 于所有小区使用不同的双极性 LA极性序列， 所以下行同步匹配滤波器只能 在时隙上进行匹配滤波， 在整个下行同步物理信道上进行 LA非相干合并。
所述的进行初始频率捕获是指： 在初始帧边界检测完成后， 移动台就 可以得到一个或多个可能存在的来自不同小区的下行同步物理信道的起始 定时位置； 移动站选择一个能量最强的一个小区的帧边界信息， 利用下行 同步物理信道得到载波频率偏差， 且需调整射频的 VC0 , 完成初始载波频 率捕获
所述的进行小区搜索和选择是指： 搜索到所有具有足够信号强度的小 区 /扇区， 并且和选定的小区建立下行同步。
所述的进行多径信号的搜索和跟踪是指： 多径搜索和跟踪是在移动台 获得帧同步、 码同步和载波同步， 并确定目标小区后， 在经过多条路径到 达移动台的接收信号中选择合适的路径， 提供给 RAKE接收机。
所述的进行载波频率跟踪是指： 由初始载波频率捕获单元将初始频差 减小到 500Hz以内， 小区识别单元获得本小区所用的 LA+LS组合； 移动台 利用下行连续导频信道作频率跟踪， 将剩余频差减小到 100Hz 以内， 满足 解调需要。
所述的进行定时频率跟踪是指： 定时频率跟踪是利用移动台检测到的 帧周期与准确的周期比较， 来提取时钟误差。
本发明所述的方法， 其特征在于， 其步骤进一步包括：
移动台开机后首先进行初始帧边界检测， 如果没能检测到任何下行同 步物理信道， 将一直进行帧边界检测；
在帧边界检测完成后， 进行初始载波频率捕获和小区搜索和选择， 直 到小区搜索和选择成功， 如果小区搜索和选择的时间大于某一参数 M, 则 重新进行初始帧边界检测；
初始载波频率捕获和小区搜索和选择成功以后， 得到服务小区的 极 性序列， Cel l ID, 并取得该小区 /扇区的 LS+LA码組；
多径搜索和跟踪环开始工作， 将接收信号的多径信息传送给上层， 定 时跟踪环和载波跟踪环以及 BCH信道接收可以运行，并进行 CRC校验。
本发明还提供了一种下行链路同步子***实现装置， 其特征在于包括： 初始帧边界检测装置， 初始载波频率捕获装置， 小区搜索和选择装置， 多 径搜索和跟踪装置， 载波频率跟踪装置， 定时频率跟踪装置；
输入信号进入所述的初始帧边界检测装置， 检测到下行同步物理信道 以后， 将初始帧边界的信息送入所述的初始载波频率捕获装置和所述的小 区搜索和选择装置；
所述的初始载波频率捕获装置和小区搜索和选择装置利用初始帧边界 的信息和下行同步信道的接收信号， 进行初始载波捕获和小区搜索选择， 直到小区搜索和选择成功， 所述的初始载波频率捕获装置的输出信号是初 始载波频差； 所述的小区搜索和选择装置的输出信号是搜索到的各个小区 的能量和到达延迟， 这些信息报告给上层；
所述的多径搜索装置和跟踪装置利用帧到达时刻和下行同步信道的接 收信号， 寻找多径信息用于所述的定时频率跟踪装置以及所述的载波频率 跟踪装置。
所述的初始帧边界检测装置包括： 输入： 经过基带滤波器的接收信号（4/c) ;
输出：搜索的能量最强小区的初始帧边界的位置，范围： ( 0, 30720*4 所述的初始频率捕获装置包括：
输入： 经过基带滤波器的下行同步信道接收信号（4/c) , 帧边界的位 置；
输出： 载波频率偏差， 范围： （- 5 z, 5KHz )。
所述的小区搜索和选择装置包括： '
输入： 经过基带滤波器的下行同步信道接收信号（4 c) , 帧边界的位 置；
输出： 各个小区的帧边界位置和能量。
• 所述的多径信号的搜索和跟踪装置包括：
输入： 经过基带滤波器的下行同步信道接收信号（4 )， 选定小区的帧 边界位置；
输出： 两径的位置；
多径搜索和跟踪是在移动台获得帧同步、 码同步和载波同步， 并确定 目标小区后， 在经过多条路径到达移动台的接收信号中选择合适的路径， 提供给 RAKE接收机。
所述的载波频率艮踪装置包括：
输入： 经过基带滤波器的下行业务信道接收信号（4/c) , 两径的位置； 输出： 载波频率偏差（- 500Hz，500Hz) ;
由初始载波频率捕获单元将初始频差减小到 500Hz 以内， 小区识别单 元获得本小区所用的 LA+LS 组合； 移动台利用下行连续导频信道作频率跟 踪， 将剩余频差减小到 100Hz以内， 满足解调需要。
所述的定时频率艮踪装置包括：
输入： 第一径的位置；
输出： 定时频率偏差（- 200Hz, 200Hz) ; 定时频率跟踪是利用移动台检测到的帧周期与准确的周期比较， 来提 取时钟误差。 .
本发明所述的装置， 其特征在于还包括： 基带滤波器， 分路器， RF VC0, BB VCO, CRC校验装置；
移动台开机后， 基带接收信号经过 4fc基带滤波器后， 进入所述的初 始帧边界检测装置， 检测到下行同步物理信道以后， 将初始帧边界的信息 送入所述的初始载波频率捕获装置和小区搜索和选择装置， 所述的初始载 波频率捕获装置和小区搜索和选择装置利用初始帧边界的信息和下行同步 信道的接收信号， 进行初始载波捕获和小区搜索选择， 直到小区搜索和选 择成功， 所述的初始载波频率捕获装置的输出信号是初始载波频差， 用于 调整射频的 VC0, 所述的小区搜索和选择装置的输出信号是搜索到的各个 小区的能量和到达延迟， 这些信息报告给上层， 下行多径搜索和跟踪装置 利用帧到达时刻和下行同步信道的接收信号 , 寻找多径信息用于所述的定 时频率跟踪装置、 所述的载波频率跟踪装置以及 BCH信道的接收和所述的 CRC 校验装置， 所述的定时频率跟踪装置的输出信号用于调整基带定时 VC0; 所述的载波频率跟踪装置利用多径信息和下行连续导频信道的接收信 号， 计算出载波频差， 用于调整射频的 VC0。
本发明的有益效果在于， 通过提供一种下行链路同步子***实现方法 及装置， 用以实现 CDMA***中的频率捕获， 同时实现下行同步捕获和小区 识别， 为业务信道的接收提供多径信息， 并进行载波频率的跟踪， 保证定 时频率的准确， 且具有筒单实用的特点。 其中：
初始帧边界检测： 检测到可能存在小区的帧边界；
初始频率捕获： 利用初始帧边界检测的结果， 得到下行同步物理信道 的帧起始位置， 进行 LS码的部分解扩， 利用 FFT算法实现频率捕获， 将载 波频率偏差从 KHz范围缩小到 500Hz以下；
小区搜索和选择： 当载波频率偏差降到 500Hz以下时， 利用 LS+LA的 匹配滤波， 下行同步物理信道在整个 874Tc 上解扩， 可以同时实现下行同 步捕获和小区识别；
多径信号的搜索和跟踪： 当小区搜索和选幹后， 移动站利用下行同步 信道进行多径信号的搜索和跟踪， 为业务信道的接收提供多径信息；
载波频率跟踪：由于业务信道的接收要求载波频率的偏差要小于 100Hz， 因此需要不断的进行载波频率的跟踪， 利用连续导频信道， 采用差分检测 的方法进行载波频率的跟踪， 筒单实用；
定时频率艮踪： 移动站用于基带定时和采样的 VC0与基站的 VC0有初 始的偏差， 偏差大容易产生滑码， 影响业务信道的接收质量， 因此需要不 断的调整 VC0的频率， 保证定时频率的准确。
附图说明
图 1为下行同步信道的子帧结构图；
图 2为下行同步子***的控制流程图；
图 3为下行同步子***的结构框图。 具体实施方式 本发明提供了一种下行链路同步子***实现方法及装置， 包括初始帧 边界检测、 初始载波捕获、 小区搜索和选择、 多径信号的搜索和跟踪、 载 波跟踪和定时跟踪等算法， 通过仿真验证了其可行性， 为 CDMA***的同步 实现提供了参考和依据。 下面以 TD- LAS ***为例， 并结合附图， 详细说 明本发明的具体实施方式。
TD-LAS ***的下行同步子***要完成以下任务：
1 )初始帧边界检测；
2 )初始载波捕获；
3 ) 小区搜索和选择；
4 ) 多径信号的搜索和跟踪； 5 )载波频率跟踪； 、
6 )定时频率跟踪。
本发明的具体实施方式主要针对 TD-LAS***的物理层规范设计的下行 同步子***的一套解决方案， 包括初始帧边界检测、 初始载波捕获、 小区 搜索和选择、 多径信号的搜索和跟踪、 载波跟踪、 定时频率跟踪等。
在 TD- US***中， 下行同步信道的结构如图 1所示； 所有小区的算法 使用相同的 LS 扩频码 （参见表 1) , 不同的调制符号码组来区分小区。 下 行同步子帧共有 8 个时隙， 每个时隙长度参照表 2, 每个时隙传输一个长 度为 72Chips的下行同步脉冲， 包含 24chips的 C码和 24chips的 S码， 中间保留 24chips 的保护带， 下行同步脉冲在每个时隙的起始开始传送。 用于下行同步信道的 LS 码是复数码， 相应的扩频和解扩类似于 QPSK, 如 表 4所示。 下行同步子帧的 8个时隙可以传送 8个调制符号， 总共可以得 到 8个双极性相互正交的码序列， 如 8 x 8Wal sh矩阵的每一行或每一列， 在 TD - LAS***中称这些码序列为 LA极性序列（参见表 3)。 8个正交的 LA 极性序列可以支持 8小区 /扇区的組网； 要支持更大的组网规模， 可以考虑 和其他小区识别的方法如连续导频小区识別相结合， 另外也可以使不同的 小区 /扇区簇使用不同的 LA保护间隔， 扩大 D-SYNPCH的信号集。 表 1. 下行同步信道的扩频码（LS码） （j = ^I )
Figure imgf000009_0001
其中： A = (+j + + + -) , = (- j - + + -) , C = (-j—— +) , D = ( · _ + + -) 表 2. 下行同步信道的子帧时隙长度
LA时隙（TS,) 0 1 2 3 4 5 6 7
长度 (Tc) 96 98 100 102 104 106 108 80 表 3. 下行同步信道的 LA极性码
Figure imgf000010_0001
表 4. 下行同步信道的 LA极性码
Figure imgf000010_0002
在***中， 初始的载波频率偏移小于 500Hz , 此时不同小区的 LA极性 序列可以准确识别， 而且下行同步物理信道可以在整个 874Tc 上解扩， 因 此使用匹配于各个小区下行同步物理信道的滤波器， 就可以同时实现下行 同步捕获和小区识别， 不需要进行载波频率的调整。但是商用 CDMA***中， 移动台晶体振荡器的频率准确度一般在几个 ppm左右，工作在 2GHz频段上， 载波频率偏差一般在 ΙΚΗζ到 Ι ΟΚΗζ之间。 在这种条件下， 不同小区的 LA 极性序列不能准确识别， 而且不能使用长达 874Tc的解扩， 因此，在 TD- LAS ***中实现下行同步捕获和小区识別的算法之前必须进行初始载波捕获， 使频偏小于 500Hz。 下行同步子***的流程如下所列：
1 )初始帧边界检测： 检测到可能存在小区的桢边界；
2 )初始频率捕获： 利用初始帧边界检测的结果， 得到下行同步物理信 道的帧起始位置， 进行 LS码的部分解扩， 利用 FFT算法实现频率捕获， 将 载波频率偏差从 KHz范围缩小到 500Hz以下；
3 ) 小区搜索和选择： 当载波频率偏差降到 500Hz以下时， 利用 LS+LA 的匹配滤波， 下行同步物理信道在整个 874Tc 上解扩， 可以同时实现下行 同步捕获和小区识别；
4 ) 多径信号的搜索和跟踪： 当小区搜索和选择后， 移动站利用下行同 步信道进行多径信号的搜索和跟踪， 为业务信道的接收提供多径信息；
5 )载波频率跟踪： 由于业务信道的接收要求载波频率的偏差要小于 100Hz, 因此需要不断的进行载波频率的跟踪， 利用连续导频信道， 采用差 分检测的方法进行载波频率的跟踪， 筒单实用；
6 )定时频率跟踪： 移动站用于基带定时和采样的 VC0与基站的 VC0有 初始的偏差， 偏差大容易产生滑码， 影响业务信道的接收质量， 因此需要 不断的调整 VC0的频率， 保证定时频率的准确。
下行同步子***流程的控制如图 2 所示。 移动台开机后首先进行初始 帧边界检测， 如果没能检测到任何下行同步物理信道， 将一直进行帧边界 检测。 在帧边界检测完成后， 进行初始载波频率捕获和小区搜索和选择， 直到小区搜索和选择成功， 如果小区搜索和选择的时间大于某一参数 M， 则 重新进行初始帧边界检测。 初始载波频率捕获和小区搜索和选择成功以后， 得到服务小区的 LA极性序列， Cel l ID, 并取得该小区 /扇区的 LS+LA码组。 之后多径搜索和跟踪环开始工作， 将接收信号的多径信息传送给上层， 定 时跟踪环和载波跟踪环以及 BCH信道接收可以运行，并进行 CRC校验。
下行同步子***的接收机的结构如图 3 所示。 移动台开机后， 基带接 收信号经过 4/c基带滤波器后， 进入 IFBD (初始帧边界检测）单元， 检测到 下行同步物理信道以后， 将初始帧边界的信息送入初始载波频率捕获单元 和小区搜索和选择单元， 初始载波频率捕获单元和小区搜索和选择单元利 用初始帧边界的信息和下行同步信道的接收信号， 进行初始载波捕获和小 区搜索选择， 直到小区搜索和选择成功， 初始载波频率捕获单元的输出信 号是初始载波频差， 用于调整射频的 vco， 小区搜索和选择单元的输出信 号是搜索到的各个小区的能量和到达延迟， 这些信息报告给上屋， 下行多 径搜索和跟踪单元利用帧到达时刻和下行同步信道的接收信号， 寻找多径 信息用于定时频率跟踪单元、载波频率跟踪单元以及 BCH信道的接收和 CRC 校验单元， 定时频率跟踪单元的输出信号用于调整基带定时 VC0; 载波频 率跟踪单元利用多径信息和下行连续导频信道的接收信号， 计算出载波频 差， 用于调整射频的 VC0; 下行同步子***的接收机结构中各点的说明如 表 5, 各模块的输入和输出说明如表 6。 表 5. 下行同步子***的接收机结构中各点的说明
Figure imgf000012_0001
表 6. 下行同步子***的接收机结构中各模块的输出和输入说明 模块 输入 输出
初始帧边 经过基带滤波器的接收信号 (4/C) 搜索的能量最强小区的初始帧边界 界检测 的位置， 范围：（0,30720*4) 初始载波 经过基带滤波器的下行同步信道接收信号 载波频率偏差 (_5KHz,5KHz) 捕获 (4 c), 帧边界的位置
小区搜索 经过基带滤波器的下行同步信道接收信号 各个小区的帧边界位置和能量 和选择 (4/c), 帧边界的位置
多径搜索 经过基带滤波器的下行同步信道接收信号 两径的位置
和跟踪 (4/c), 选定小区的帧边界位置
载波频率 经过基带滤波器的下行业务信道接收信号 载波频率偏差 (_500Hz,500Hz) 跟踪 (4/c), 两径的位置
定时频率 第一径的位置 定时频率偏差 (-200Hz,200Hz) 跟踪 在初始帧边界检测算法中， 通过和所有小区下行同步物理信道匹配的 滤波器提取相关峰， 实现帧边界检测。 因为所有小区使用不同的欢极性 LA 极性序列， 所以下行同步匹配滤波器只能在时隙上进行匹配滤波， 在整个 下行同步物理信道上进行 LA非相干合并。
如图 1所示， 下行同步物理信道在时隙上的解扩长度为 72Tc, 对应的 3dB性能损耗点为 8KHz ,因此此算法容忍的最大频率偏差为 [- 8KHz, 8KHz]。
在第一步初始帧边界检测完成后， 移动台就可以得到一个或多个可能 存在的来自不同小区的下行同步物理信道的起始定时位置。 移动站选择一 个能量最强的一个小区的帧边界信息， 利用 FFT 算法计算载波频率偏差， 不断调整射频的 VC0 , 完成初始载波频率捕获。 此步完成后， 载波频率偏 差将会降至 500Hz以下。
算法中采用的信号解扩长度为 48Tc , 而且估计的是倍频信号， 因此该 算法所能估计的频率偏差范围是 [- 5KHz， 5KHz]。
小区搜索的目的是搜索到所有足够信号强度的小区 /扇区， 并且和选定 的小区建立下行同步。 TD- LAS***中， 不同小区的业务信道使用不同的 LS 扩频码组和不同的 LA间隔排列。 移动台要正确解调某一小区 /扇区的信号， 并建立通信， 就必需得到这个小区 /扇区业务信道的 LS码组和 LA间隔排列 的信息。 因此在小区搜索中， 移动台必需在下行同步物理信道中， 搜索所 有可能的小区标志序列（Cel l ID sequence) , 检测到所有足够信号强度的 小区 /扇区， 进一步得到目的小区 / 扇区使用的 LS码组和 LA间隔排列的信 为了提高可靠性， 算法中采用在整个下行同步信道 874chip上匹配滤 波， 因此该算法要求的频率偏差范围是 [- 500Hz, 500Hz]。
实现载波频率跟踪的前提是移动台和基站之间已经建立了定时同步， 而且初始下行载波捕获已经将载波频率偏差从最大 6KHz 降低至 500Hz 以 下。 目前已经有一些载波频率跟踪算法， 包括 FFT, DMP-FED, DD (差分频 率检测）。 由于 TD-LAS ***中使用了下行连续导频信道， 因此可以利用下 行连续导频信道实现频率跟踪。
由初始载波频率捕获单元将初始频差减小到 500Hz 以内， 小区识別单 元获得本小区所用的 LA+LS 组合。 这样移动台就可以利用下行连续导频信 道作频率跟踪， 将剩余频差减小到 100Hz以内， 满足解调需要。
多径搜索和跟踪是在移动台获得帧同步、 码同步和载波同步， 并确定 目标小区后， 在经过多条路径到达移动台的接收信号中选择合适的路径， 提供给 RAKE接收机。
在移动通信环境中， 发射机发送信号经过不同路径到达接收机。 每条 路径的信号经历不同的随机的幅度衰减和相位旋转， 以及不同的时间延迟。 这些信号到达接收机后， 因为复数相加， 引起合成信号的衰落。 这些路径 上的信号的存在也是随机， 在某些时刻存在， 某些时刻消失， 某些时刻比 其它路径信号强， 某些时刻可能有更强的路径信号。 在 CDMA通信***中， 可以利用包括多个分支的 RAKE接收机来对抗多径衰落。
RAKE接收机是利用一个搜索单元检测多个信号较强的路径， 分配给每 个分支。 每个分支负责与一条路径信号同步， 并解调其中的信号， 而后将 各路径信息按一定规则合并。
定时频率跟踪是利用移动台检测到的帧周期与准确的周期比较， 来提 取时钟误差。
设下行信号帧周期为 T, TD-LAS ***中， T=30720TC。 当移动台与基站 的时钟频率相同， 则移动台测量的帧周期也为 T。 当移动台与基站的时钟 频差为 4 , 采样速率将发生变化， 测量的帧周期也会发生变化。 设周期变 化为 l ， 则有 ί, 其中 f为准确的时钟频率。 所以， 通过检测 , 可以得到 l 用来修正采样时钟。
在 TD- LAS***中， 多径搜索单元利用码匹配滤波器检测每个路径对应 的 D-SYNCH信道在接收信号采样序列的位置。 由于 D- SYNCH在每一个下行 信号帧位置是固定的， 当没有时钟误差， 检测到的位置也是不变的。 所以 利用多径搜索单元给出的位置变化， 可以检测时钟变化， 从而计算出时钟 频差。
由于多径信道的随机变化， 多径搜索单元应始终给出最先到达的一径 信息， 并假设对应^是同一条路径， 否则会引入误差。 时钟频率跟踪单元 也要对计算出的频差做多帧的累加平滑， 来减小多径位置误差的影响。
本发明的有益效果在于， 通过提供一种下行链路同步子***实现方法 及装置， 用以实现频率捕获， 同时实现下行同步捕获和小区识别， 为业务 信道的接收提供多径信息， 并进行载波频率的跟踪， 保证定时频率的准确， 且具有简单实用的特点。
以上具体实施方式以 TD-LAS***为例对本发明进行了说明， 但本具体 实施方式绝非用于限定本发明， 因为本发明不限于 TD- LAS***， 其一般性 原理和技术以及相应的实现方法和装置对于一般的 CDMA***均有效。

Claims

权 利 要 求
1. 一种下行链路同步子***实现方法， 其特征在于包括以下步骤： 对初始帧边界进行检测；
利用初始帧边界检测的结果， 进行初始频率捕获；
进行小区搜索和选择；
进行多径信号的搜索和跟踪；
进行载波频率跟踪；
进行定时频率跟踪。
2. 根据权利要求 1所述的方法， 其特征在于， 所述的对初始帧边界进 行检测是指： 在初始帧边界检测中， 通过和所有小区下行同步物理信道匹 配的滤波器提取相关峰， 实现帧边界检测； 由于所有小区使用不同的双极 性 LA极性序列， 所以下行同步匹配滤波器只能在时隙上进行匹配滤波， 在 整个下行同步物理信道上进行 LA非相干合并。
3. 根据权利要求 1所述的方法， 其特征在于， 所述的进行初始频率捕 获是指： 在初始帧边界检测完成后， 移动台就可以得到一个或多个可能存 在的来自不同小区的下行同步物理信道的起始定时位置； 移动站选择一个 能量最强的一个小区的帧边界信息， 利用下行同步物理信道得到载波频率 偏差， 且需调整射频的 VC0 , 完成初始载波频率捕获。
4. 根据权利要求 1所述的方法， 其特征在于， 所述的进行小区搜索和 选择是指： 搜索到所有具有足够信号强度的小区 /扇区， 并且和选定的小区 建立下行同步。
5. 根据权利要求 1所述的方法， 其特征在于， 所述的进行多径信号的 搜索和跟踪是指： 多径搜索和跟踪是在移动台获得帧同步、 码同步和载波 同步， 并确定目标小区后， 在经过多条路径到达移动台的接收信号中选择 合适的路径， 提供给 RAKE接收机。
6. 根据权利要求 1所述的方法， 其特征在于， 所述的进行载波频率跟 踪是指： 由初始载波频率捕获单元将初始频差减小到 500Hz 以内， 小区识 別单元获得本小区所用的 LA+LS 组合； 移动台利用下行连续导频信道作频 率跟踪， 将剩余频差减小到 100Hz以内， 满足解调需要。
7. 根据权利要求 1所述的方法， 其特征在于， 所述的进行定时频率跟 踪是指： 定时频率跟踪是利用移动台检测到的帧周期与准确的周期比较， 来提取时钟误差。
8. 根据权利要求 1所述的方法， 其特征在于， 其步骤进一步包括： 移动台开机后首先进行初始帧边界检测， 如果没能检测到任何下行同 步物理信道， 将一直进行帧边界检测；
在帧边界检测完成后， 进行初始载波频率捕获和小区搜索和选择， 直 到小区搜索和选择成功， 如果小区搜索和选择的时间大于某一参数 M, 则 重新进行初始帧边界检测；
初始载波频率捕获和小区搜索和选择成功以后， 得到服务小区的 LA极 性序列， Cel l ID, 并取得该小区 /扇区的 LS+LA码组；
多径搜索和跟踪环开始工作， 将接收信号的多径信息传送给上层， 定. 时跟踪环和载波跟踪环以及 BCH信道接收可以运行，并进行 CRC校验。
9. 一种下行链路同步子***实现装置， 其特征在于包括： 初始帧边界 检测装置， 初始载波频率捕获装置， 小区搜索和选择装置， 多径搜索和跟 踪装置， 载波频率跟踪装置， 定时频率跟踪装置；
输入信号进入所述的初始帧边界检测装置， 检测到下行同步物理信道 以后， 将初始帧边界的信息送入所述的初始载波频率捕获装置和所述的小 区搜索和选择装置；
所述的初始载波频率捕获装置和小区搜索和选择装置利用初始帧边界 的信息和下行同步信道的接收信号， 进行初始载波捕获和小区搜索选择， 直到小区搜索和选择成功， 所述的初始载波频率捕获装置的输出信号是初 始载波频差； 所述的小区搜索和选择装置的输出信号是搜索到的各个小区 的能量和到达延迟， 这些信息报告给上层；
所述的多径搜索装置和跟踪装置利用帧到达时刻和下行同步信道的接 收信号 , 寻找多径信息用于所述的定时频率跟踪装置以及所述的载波频率 跟踪装置。
10. 根据权利要求 9 所述的装置， 其特征在于， 所述的初始帧边界检 测装置包括：
输入： 经过基带滤波器的接收信号；
输出：搜索的能量最强小区的初始帧边界的位置，范围： ( 0, 30720*4
11. 根据权利要求 9 所述的装置， 其特征在于， 所述的初始频率捕获 装置包括：
输入： 经过基带滤波器的下行同步信道接收信号， 帧边界的位置； 输出： 载波频率偏差， 范围： （- 5KHz, 5KHz )。
12. 根据权利要求 9 所述的装置， 其特征在于， 所述的小区搜索和选 择装置包括：
输入： 经过基带滤波器的下行同步信道接收信号， 帧边界的位置； 输出： 各个小区的帧边界位置和能量。
13. 根据权利要求 9 所述的装置， 其特征在于， 所述的多径信号的搜 索和跟踪装置包括：
输入： 经过基带滤波器的下行同步信道接收信号， 选定小区的帧边界 位置；
输出： 两径的位置；
多径搜索和跟踪是在移动台获得帧同步、 码同步和载波同步， 并确定 目标小区后， 在经过多条路径到达移动台的接收信号中选择合适的路径， 提供给 RAKE接收机。
14. 才艮据权利要求 9 所述的装置， 其特征在于， 所述的载波频率跟踪 装置包括：
输入： 经过基带滤波器的下行业务信道接收信号， 两径的位置； 输出： 载波频率偏差（-500Hz, 500Hz) ;
由初始载波频率捕获单元将初始频差减小到 500Hz 以内， 小区识别单 元获得本小区所用的 LA+LS 组合； 移动台利用下行连续导频信道作频率跟 踪， 将剩余频差减小到 100Hz以内， 满足解调需要。
15. 根据权利要求 9所述的装置， 其特征在于， 所述的定时频率跟踪 装置包括：
输入： 第一径的位置；
输出： 定时频率偏差（-200Hz, 200Hz) ;
定时频率跟踪是利用移动台检测到的帧周期与准确的周期比较， 来提 取时钟误差。
16. 根据权利要求 9 所述的装置， 其特征在于还包括： 基带滤波器， 分路器， RF VCO, BB VCO, CRC校验装置；
移动台开机后， 基带接收信号经过 4 基带滤波器后， 进入所述的初 始帧边界检测装置， 检测到下行同步物理信道以后， 将初始帧边界的信息 送入所述的初始载波频率捕获装置和小区搜索和选择装置；
所述的初始载波频率捕获装置和小区搜索和选择装置利用初始帧边界 的信息和下行同步信道的接收信号， 进行初始载波捕获和小区搜索选择， 直到小区搜索和选择成功， 所述的初始载波频率捕获装置的输出信号是初 始载波频差， 用于调整射频的 VC0;
所述的小区搜索和选择装置的输出信号是搜索到的各个小区的能量和 到达延迟， 这些信息艮告给上层， 下行多径搜索和跟踪装置利用帧到达时 刻和下行同步信道的接收信号， 寻找多径信息用于所述的定时频率跟踪装 置、 所述的载波频率跟踪装置以及 BCH信道的接收和所述的 CRC校验装置； 所述的定时频率跟踪装置的输出信号用于调整基带定时 VC0; 所述的载波频率跟踪装置利用多径信息和下行连续导频信道的接收信 号， 计算出载波频差， 用于调整射频的 vco。
PCT/CN2003/000061 2003-01-23 2003-01-23 Procede et dispositif de mise en oeuvre pour sous-systeme de synchronisation de liaison descendante WO2004066532A1 (fr)

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