Research Of M-ary Spread Spectrum Baseband System Based On FPGA

With the upgrading of communication systems, and the refreshment ofcommunication technologies, spread spectrum techniques have been widely used inboth military and civilian communications as a new means of communication. However,in many applications, the channel bandwidth is limited, spread spectrum systems can’tsatisfy certain requirements. In order to solve the problem of using the spectrumresource more effectively and transfering data in more highly speed, M-ary spreadspectrum system has become the research pot nowadays.This paper aims to design a M-ary spread spectrum baseband system ofdisplacement sequences. First of all, we review domestic and foreign studies on M-aryspread spectrum baseband system, compare several common M-ary spread spectrumbaseband system and spreading code design scheme. We ultimately choose to use them-displacement sequences as a M-ary spreading code. We finish the design ofhexadecimal spread spectrum baseband system.The main research include specific design solution to M-ary spread spectrumbaseband system of displacement sequence. For specific technical indicators ofbaseband system, we respectively analysis system performance under correspondingindicators, and we complete BER analysis. As to the synchronization problem, wedesign a feasible scheme which use the preferred pair of m-sequence to achieve the thesynchronization clock extraction, use sliding integrator for synchronization acquisitionand tracking.We divide the sending and receiving part into several modules based on thetop-down FPGA design process. Using the platform in the lab and analyzing thetechnical indicators of the system, we finish the simulation and verification of eachmodule in the baseband system, as well as the simulation and verification of each module.This M-ary spread spectrum baseband system of displacement sequence designedin this paper, is optimized on the basis of ordinary M-ary spread spectrum system. Fullyexploiting data’s synchronous tributaries, we propose a synchronize transmissionscheme which use the preferred pair of m-sequence to take the information of1bit, thusmaking the system based on structure of the hexadecimal spread spectrum carryingmore information.