Method for generating signals of low-interference multi-velocity multi-district quasi-synchronous CDMA communication system

Abstract

The invention discloses a signal generation method of a low-interference multispeed multi-cell quasi-synchronous code division multiple access (CDMA) communication system. The method comprises the steps: a spread spectrum sequence code group is an Hadamard matrix set with certain idealized characteristics formed by Bent functions and a Walsh-Hadamard orthogonal sequence set; a sequence set with the characteristic of a similar zero correlation zone (ZCZ) sequence is obtained by calculating with a pair of complementary sequence sets by utilizing the Hadamard matrix set; and a plurality groups of sequence sets with the similar ZCZ sequence characteristics are obtained by carrying out Cartesian convolution operation with the orthogonal sequence set by utilizing the similar ZCZ sequence set. When a system maximum synchronization error and a channel maximum multipath delay spread are in the stated range, the system interference can be reduced greatly. The parameters of the spread spectrum sequence code group and the system efficiency can be adjusted and flexibly selected according to the practical factors. Therefore, the requirements of power control and synchronization by the CDMA communication system are reduced, and the complexity of system realization is lowered.

Description

technical field [0001] The invention relates to a direct sequence spread spectrum wireless communication, in particular to a signal generation method of a low-interference multi-rate multi-cell quasi-synchronous CDMA communication system. Background technique [0002] Multi-rate is the basic requirement for the future personal mobile communication system, that is, in addition to supporting the existing voice and low-speed data services, it also needs to support a wider range of integrated services including high-resolution images and high-speed data. There are several implementation schemes for multi-rate in CDMA communication system: variable processing gain scheme, variable duty ratio scheme, multi-carrier CDMA scheme and multi-code CDMA scheme. [0003] Multicode Code Division Multiple Access is a parallel transmission technique. A basic rate and a constant chip rate are preset in the system, and the transmission of each basic rate data is carried by a spreading code. T...

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Problems solved by technology

[0008] When the sequence set with zero correlation zone is applied to multi-cell system, as long as the zero correlation zone is larger than the multipath delay and the access delay of adjacent base stations, good system performance can be obtained, but the zero correlation zone sequence is different from other sequences by Concatenating in the way of chip XOR will cause the loss of the characteristics of the zero correlation zone, and only using the zero correlation zone sequence for spreading will make the number of available code words insufficient, so we need multiple sets of zero correlation zone sequence sets

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