Research And Implementation Of Equalization Technique In Software Receiver

In digital communication systems, distortion and aberration of band-limitedchannel can cause signal inter-symbol interference (ISI) and spectral leakage, therebyseriously affecting the quality of communication. In order to recover the transmittedsignal totally on the receiving end, the channel should be compensated efficiently byadaptive equalization technology.This paper describes the structure of software receiver and the principles of vectorsignal analysis, based on which the software radio-based receiver design is proposed. Itincludes signal acquisition, signal processing and signal display module. The paper alsogives the details of the signal processing module: frequency conversion, resampling,symbol and carrier synchronization, quadrature demodulation. The position and therelation with other modules of adaptive equalizer module are also defined.Basic principle and architectures of adaptive equalization and interrelatedequalization algorithms are described in this paper detailedly. Through study of softwarereceiver and in-depth understanding of various equalization algorithms, structures andperformance analysis, the linear adaptive equalizer, which uses the variable step-sizeConstant Module Algorithm(CMA) and Decision Directed-Least Mean Squarealgorithm(DD-LMS), is finally chosen. It completes equalization on a variety of digitalmodulation format signals and satisfies the requirement of the system.