The Research And Implementation Of Adaptive Equalizer Based On FPGA

Nowadays,the communication systems undertake an important business in the digital and information era of the information growing day by day,which demands the digital communication systems toward to the development of more high-speed and more high-reliability.But,the non-ideal characteristic of channel is the main obstacle. Equalization is one important technique in communication system.It can excellent compensate the non-ideal characteristic of channel,which reduces signal distortion and error-coding probability.It makes high quality transmission possible.Especially in the field of high-speed communication and wireless communication,the signal distortion is more severe.So the equalization technique is indispensible.The adaptive equalization can automatically adjust coefficient,track the channel environment.It's one critical and applicative technique in communication system.The author researches the structure and algorithm performance of adaptive equalizer in multipath fading channel and implements adaptive equalizer based on FPGA.First of all,it elaborates the reasons of ISI(inter-symbol interference) and mathematical model,introduces the theory of equalizer.Then,introduces two kinds of common adaptive algorithm—LMS and RLS algorithm and their improvement form.Also simulates them by MATLAB and analyses the advantages and disadvantages of these adaptive algorithm.The author also detailed designs the time-domain,linear and horizontal structure adaptive equalizer based on LMS adaptive algorithm in the environment of IES 9.2i that is easy to implement by FPGA.Also simulates them by MODELSIM SE 6.0.Finally,the adaptive equalizer is successfully conducted in the XUP Xilinx Virtex-ⅡPro development system board.The adaptive equalizer in this paper can automatically track the channel, compensate the non-ideal characteristic of channel and reduce error code.This system meets practical need.All the performance is completed under the theory of soft radio in thie paper.The adaptive equalizer,which is implemented by FPGA,has smaller volume,faster convergence rate,easier to implement and flexible.The adaptive equalizer could be used widely in digital radio communication systems.