Research On Frequency Domain Pre-Equalization For MIMO Broadcast Wireless Channels

In the downlink of wireless communication, MIMO technology has gainedwidespread attention. In the frequency selective fading channel, MIMO-OFDM not onlycan increase the system bandwidth to improve spectrum efficiency, but also canexponentially increase the system capacity. Compared to OFDM technology, singlecarrier frequency domain equalization has many advantages such as lowerpeak-to-average power ratio and less sensitivity to carries frequency offsets. In addition,compared to the equalization in the receiver, the frequency domain pre-equalization hasnot brought the increase of the noise interference and also inherits from the frequencydomain equalization the property of relatively low complexity and error probability.For the MIMO downlink system, two types of frequency domain pre-equalizationtechnologies have been studied: traditional linear frequency domain pre-equalizationand nonlinear frequency domain pre-equalization. For nonlinear frequency domainequalization, three algorithms based on the “dirty paper” coding, successive THprecoding and parallel TH precoding are respectively introduced. Firstly, based on theminimum mean square error criterion, detailed algorithm description has beenresearched for a variety of frequency domain pre-equalization technology; Secondly, theperformance of various algorithms has been analyzed, especially considering the effectof several different ordering algorithms on the overall algorithms in the successive THprecoding frequency domain pre-equalization technology. Finally, all kinds ofalgorithms have been simulated. Simulation results have confirmed:1) in successive THprecoding frequency domain pre-equalization scheme, the performance with the randomordering algorithm is very close to that with the optimal ordering algorithm;2)successive TH precoding frequency domain pre-equalization algorithm has betterperformance than parallel TH precoding frequency domain pre-equalization algorithm;3)TH precoding frequency domain pre-equalization technique can achieve significantperformance improvement compared to linear frequency domain pre-equalization andtraditional DPC-FDPE system;4) channel prediction can effectively improve theperformance of the frequency domain pre-equalization system.