More Digital Receiver Technology Of Wireless Spread Spectrum Communication System And Its FPGA Implementation

Spread Spectrum technology has the advantages of low probability of intercepting, high immunity to interference, hiding the useful information and multiple-access communication ability. It was used in many aspects including anti-jamming communications, satellite communications, navigation, secrecy communications and orientation. On the other hand, with the rapid development of VLSI, digital receiver and software defined radio have become a popular area in modern communication systems.In this dissertation, a DS-CDMA communication system has been built based on digital technology and software defined radio.This dissertation researches on the key technologies of DS-CDMA system, especially on the spread spectrum codes and its synchronization technology. A whole simulation platform is constructed base on the research. Also, the dissertation gives an implementation of the whole DS-CDMA system with FPGA. The system has implemented successfully by testing both the modules and the whole system.The main contents are presented as follows:1. The basic concepts and development trends of spread spectrum technology and software-defined radio are briefly introduced.2. The theory of DSSS technology and the key technologies related in this system are discussed. Those technologies contain the characteristics of spread spectrum sequence and the selection of it, acquisition and tracking of spread spectrum sequence and the adaptive threshold.3. A DS-CDMA system is designed and realized. This dissertation proposes algorithms which are adapted to this system. First it describes the scheme and parameters of this system. Then it describes the design and realization of physical level and data-link level. Physical level is divided into transmitter and receiver. Data-link level is divided into some sub-level such as serial to parallel transformation, RS coding and decoding, frame forming and so on. A lot of simulation results are showed in this chapter. The results prove that the algorithms are correct and the performance can satisfy the requirements. 4. The hardware platform and hardware structure of this system are showed. Some chips used are introduced and the configurations of them are analyzed. The flow and tools of developing FPGA are summarized. At last, the test scheme and results are presented.The DS-CDMA system has already implemented and works well at present. The system uses the method of blocking designing, which makes it flexible, compatible and valuable in practice.