Adaptive Interleaving Schemes And It’s Performance Analysis In Wireless OFDM Systems

Orthogonal frequency division multiplexing is a communication technologywhich has been widespread used by wireless communication system in recent years.This technology could eliminate inter carrier interface by nature for it’s sub-carrierorthogonal property and effectively resist inter-symbol interface by inserting cp. Inhigh order modulation wireless OFDM system, the traditional fixed interleaving isincreasing unable to meet the system performance requirements, so disperse errorbits to maximum state by using channel state information to adaptive change theinterleaving scheme, then improving the channel decoding efficiency, and ultimately,increasing the system performance has been widely studied. In this background, thisthesis proposed a new adaptive interleaving scheme which not only gets theintertwined effect of past programs but also effectively adapts to deep fadingchannel environment and has a good resistance to interleaving scheme offset causedby channel estimation error.This paper firstly described the basic theory of OFDM system and channelestimation, several basic channel estimation method and analyzed the impact onsystem performance of these method. Then adaptive interleaving scheme design hasbeen studied as follows:Firstly studied the adaptive interleaving scheme and its principles, learned thetraditional adaptive interleaving scheme design ideas, analyzed the performance ofthe foundation program and improvement program in theory based on adaptiveinterleaving principles and the assumptions mechanism(good or bad channelnumber is equal in system) which leads to these adaptive interleaving schemes,especially highlighted its anti deep fading and channel estimation error on thedefects.Then based on the assumptions mechanism that leads to all those previousadaptive interleaving schemes, this article designed an optimal interleaving effectadaptive interleaving scheme, analyzed its pros and cons, pointed out the distinctionin interleaving effects with previous the adaptive interleaving scheme and indirectly,provided that although the previous adaptive interleaving schemes is not good withthe new designed scheme in interleaving effects, they have a lot of advantages insome other anti-jamming performance.Finally, with the traditional adaptive interleaving scheme design ideas, thispaper proposed a new adaptive interleaving scheme which focused on resisting deepchannel fading and channel estimation error based on a new assumptions mechanism(the number of four channel states is equal in system), explained thoseprevious adaptive interleaving schemes don’t maximumly make use of theassociativity of channel states that gives the advantage of the new adaptiveinterleaving scheme. This new adaptive interleaving scheme not only has the bestinterleave effect but also has the new advantage. So compared with the traditionaladaptive interleaving schemes, its simulation performance is been effectivelyimproved.