Time synchronization method for multi-carrier CDMA system

Abstract

The present invention provides a time synchronization method for a multi-carrier code division multiple access system, comprising steps: (i) pre-store the IFFT transformation result of a known synchronous training sequence in a buffer; (ii) search Within the window, correlate the synchronous training sequence of the received synchronous time slot with the training sequence in the buffer, the correlation operation is controlled by a given threshold TH, and then continue to slide in the search window for correlation, thus obtaining a series of correlation output results ; (iii) Find the energy of the correlation output result; (iv) Use the first-order infinite impulse response digital filter bank to filter the obtained series of correlation output energies; (v) Filter the correlation output energy from large to small Sort, start from the largest value, delete the relevant peak side lobe, until the first m values ​​are found, remember these m values ​​and their corresponding sampling point positions; (vi) among these m values, use the largest value The corresponding sampling point position is the reference, and the frontmost position within W from the reference is searched forward, that is, the frame header position; (vii) adjust the frame boundary according to the determined frame header position, remove the cyclic prefix of the OFDM data symbol, and restore the OFDM data The starting position of the symbol.

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) ...

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

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