Study And Design On Equalizers For Wireless Communications

In wireless communication system, Inter-symbol Interference is serious and signal is distorted extremely because of fading channel resulted in by the effect of multipath.The adaptive equalizer should be used in order to compensate channel characteristic and recover received signal correctly.Blind equalizers can compensate channel characteristic and reduce Inter-symbol Interference without training sequence,so are used widely in many fields such as digital communication system,radar system,earthquake and image processing system and so on.The characterization of the wireless communication channel and the appearance of ISI are discussed in this paper firstly.Then, the adaptive equalization technology are summarized. This paper analyses and simulates the common blind equalization algorithms based on Bussgang family.In the computer simulation part of the channel equalizer, this paper simulate the CMA by the MATLAB software.The effect of noise and step-size to the convergence are discussed with the module.Then we establish the QPSK modulation plat with the Simulink tool.In the AWGN and multi-path channels,the eye diagram,the constellation diagram and the BER curve are discussed furtherly.During the process of the implementation, we establish the FPGA hardware plat,and VHDL code had been coded to implement blind equalizer of DDLMS algorithm based on TOP-DOWN digital design methodology. Design principle,structures and VHDL implementations of modules in enhancement blind equalizer are described in detail in follow sections. Each section closed with the structure graph and the test results of module in verification.This thesis investigates the design technologies of EDA (Electronic Design Automation) by means of designing and implementing blind equalizer. It provides preliminary study for large scale SOPC (System on Programmable Chip) in wireless communication system field.