Simulation And Circuit Implement Of Direct Sequence Spread Spectrum Based On DS-UWB

UWB wireless technology has the advantage of high rate, low power consumption, low cost and so on. It has wide application prospect in LAN and is considered to be one of the key technology of next generation of wireless communication.This paper mainly discusses simulation and hardware realization of spread spectrum based on DS-UWB. First of all, analysis and comparison is done about code of spread spectrum. Because both self-correlation performance and cross-correlation performance affect dsss's bit error rate and multi-users performance directly, these two characters are analyzed elaborately here. Then the whole base band spread spectrum system with ternary code is simulated on Matlab platform with different codes and simulation result is given. The result suggests that M-BOK spread spectrum with ternary code can get higher system process gain and lower bit error rate.Secondly, detailed description is done to whole dsss module's hardware realization .Both algorithm and circuit design are given. Variable length of PN code and ternary code are used in spread spectrum circuit design The key part is design of all digital dsss synchronization module. This module makes use of characteristic of DS-UWB without carrier wave, so the whole synchronization system can work on chip rate. The design includes Digital Matched Filter, Delay-Locked Loop and Direct Digital Synthesizer modules. Control part is realized in Delay-Locked Loop module. Functional and timing simulations are done on Modelsim and Quartus software separately, and the simulation result is analyzed, codes's .The circuit's working frequency can reach up to 113M.Finally, this design is verified on Altera's cyclonell EP2C35F672C8 and waveform is measured by logic analyzer. The results shows that the circuit works well and satisfies the design . The synchronous precision is 1/4 chip.This circuit can be also applied in similar dsss communication system.