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Research On Channel Estimation, Equalization And Coherent Detection Under Fading Channels

Posted on:2007-10-04Degree:MasterType:Thesis
Country:ChinaCandidate:X L ChengFull Text:PDF
GTID:2178360215997594Subject:Communication and Information System
Abstract/Summary:PDF Full Text Request
People show great interest in shortwave communication for its special merits such as flexibility,not easily be destroyed and long propagation distance. HF channel is a typical fading channel and signal passed throught it will be faded. Studies on the characterization of fading channels and reliable communication on these channels are concerned on. This paper discusses the technique of channel estimation, equalization and coherent detection on fading channels.After introducing the concept and status of shortwave communication, we analysize the characterization of fading multipath channels, give the realization of one typical channel model-Watterson channel model. The results of channel simulation show the means is feasible and well represents various features of shortwave channel such as Multi-path delay, Rayleigh fading, Doppler shift, Doppler spread, noise, etc. Furthermore, we discuss the methods of channel estimation in time domain, typical equalizers and their adaptive forms, coherent detection and carrier and symbol synchronization which is necessary. In the equalization part, we compare the performance of usual equalizers and give a indirect equalize scheme which associates channel estimation and adaptive equalization. It can compensate the shortage when only using fixed coefficients or adaptive equalizers and reach fast equalization while keeping the effect of equalization. In synchronization part, we analysize the characterization of PLL, the realization of several tracking loops. Furthermore, we suggest one acquiring and tracking scheme with which we can finish the whole phase of synchronization. Finally, we use Matlab/Simulink to design and simulate a digital baseband communication system which includes convolutional encode and decode, interleave and deinterleave,pilots generation and insertation, channel module, channel equalization, scramble and descramble, modulation and demodulation. Wo gived the performance curve as the simulation result.
Keywords/Search Tags:PLL, modulation and demodulation, interleave, synchronization, channel simulate, channel equalization
PDF Full Text Request
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