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Time synchronous method for multi-carrier CDMA system

A code division multiple access and time synchronization technology, applied in code division multiplexing systems, multi-frequency code systems, transmission systems, etc., can solve the problems of low transmission efficiency, difficult to ensure the correctness of time synchronization, and accuracy impact.

Inactive Publication Date: 2003-11-12
BEIJING UNIV OF POSTS & TELECOMM +1
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AI Technical Summary

Problems solved by technology

The accuracy of timing estimation depends on the length of the cyclic prefix. The longer the length, the more accurate the timing estimation. However, the longer the cyclic prefix, the lower the transmission efficiency of the system. It can be seen that there is a contradiction between the two
In addition, in a multipath fading channel, the cyclic prefix is ​​extremely susceptible to multipath interference, and the accuracy of timing estimation will be greatly affected, so it is difficult to guarantee the correctness of time synchronization based on the cyclic prefix synchronization method

Method used

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  • Time synchronous method for multi-carrier CDMA system
  • Time synchronous method for multi-carrier CDMA system
  • Time synchronous method for multi-carrier CDMA system

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Embodiment Construction

[0019] The present invention will be described in detail below with reference to the accompanying drawings.

[0020] figure 1 is a block diagram of the MC-CDMA baseband processing system, which includes a transmitter 101 and a receiver 102 . The transmitter 101 provides user data to be sent, and after passing through the spreading unit 103, the user data is combined with a synchronization training sequence from a frame synchronization training sequence source 104 into a frequency-domain multi-carrier OFDM symbol frame. Each frequency-domain multi-carrier OFDM symbol is converted into a time-domain multi-carrier OFDM symbol by the IFFT (Inverse Fast Fourier Transform) unit 105, and sent to the multi-path channel 107 to complete the baseband transmission process. In the receiver 102, the synchronization training sequence is first extracted from the received multi-carrier OFDM symbols in the time domain, and sent to the time synchronization unit 108, and the acquisition of frame...

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Abstract

The method includes: 1) storing the known synchronous train sequence IFFI changing result into buffer storage in advance, 2) carrying on correlation for received synchronous train sequence with synchronous time slot and train sequence in buffer storage and within search window, carrying on correlation operation to obtain a serial correlation output result, 3) derivating out energy of correlation output result, 4) utilizing a filter set to carry on filter processing for a serial obtained energy, 5) arranging filtered correlation output energy in sequence from big to small and starting cancellation sidelobe for correlation peak value from the maximum value, 6) searching out frame head position by searching forward and 7) adjusting framke boundary as per framke head position and removing cyclic prefix of OFDM data symbol to restore initial position for it.

Description

technical field [0001] The invention relates to a multi-carrier code division multiple access (MC-CDMA) system, in particular to a time synchronization method for the multi-carrier code division multiple access system. Background technique [0002] MC-CDMA technology combines the advantages of Orthogonal Frequency Division Multiplexing (OFDM) technology and Code Division Multiple Access (CDMA) technology, which can effectively resist multipath fading, improve spectrum utilization and reduce data transmission rate. Because of these advantages, MC-CDMA technology is considered to be one of the most effective technologies for wireless broadband communication in the future. However, the MC-CDMA system also inherits another feature of the OFDM system, which is very sensitive to frequency offset. Therefore, synchronization technology is a key issue of MC-CDMA system. [0003] Synchronization techniques include time synchronization (symbol synchronization, frame synchronization) ...

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Application Information

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IPC IPC(8): H04B7/26H04J13/00H04L7/00H04L27/26
Inventor 张平阮丹刘乐
Owner BEIJING UNIV OF POSTS & TELECOMM
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