The Key Techniqe And Accomplishment Of Iterative Equalization

In recent years, with the rapid growth of the user’s requirements, therequirements of the wireless communication system capacity andperformance are increasing. However, due to the inter-symbol interferencearising from the multipath effect of wireless communication channel, thesignal will suffer from the interference effect and leads to the decodingfailure at the receiver end.The traditional equalization algorithms are restricted by the systemcomplexity and performance, so they are not suitable for applying to thereal system directly. Iterative equalizer, combining Turbo iterativedecoding technique with equalization algorithm, could benefit from softinformation exchanging between the equalizer and channel decoder. Thesystem complexity and performance of Turbo equalizer both haveimproved a lot compared with traditional equalizer and ready to be appliedto the actual system.In this paper, the principles and algorithms of equalizer and Turboequalization are introduced and conducted at the beginning. Then for asingle-carrier frequency domain iterative equalization algorithm, first wedo some calculation simplification to reduce the complexity on hardwarecomputing platform. Then the algorithm is simulated and verified basingon floating data. While for application system, the data type is fix-pointdata, so we change the floating algorithm to fix-point algorithm bycalculating the signal various range with scientific analysis methods. Atlast we compare the fix-point and floating algorithm simulation results,and see the performance decline is in reasonable range. For the signal collision problem caused by the hidden terminals inwireless communication systems, we propose an Iterative CollisionRecovery (ICR) algorithm basing on iterative equalization principle. ICRalgorithm recovers collision packets by reconstructing and eliminatingsignal interference in the collision to get an estimation of the transmittedsignal. Then soft information of the signal is exchanged betweeninterference cancelation module and channel decoder module to improvethe accuracy of the recovery result. In this way, the algorithm could getperformance increasing and achieve the purpose of collision recoveryunder hidden terminal situation.Finally, for the application of iterative collision recovery algorithm inreal system, we carried out a series of performance analysis and simulationto show that the algorithm could largely increase system capacity andadapt to various situation, so the algorithm has a great value in systemapplication.