4736

4455

كارشناسي ارشد

مخابرات

اصفهان: دانشگاه صنعتي اصفهان، دانشكده برق و كامپيوتر

1388

هشت،95،[II]ص.: مصور، جدول،نمودار

ص.ع. به فارسي و انگليسي

علي محمد دوست حسيني

محمد جواد اميدي

88/8/16

محمود مدرس هاشمي

مهندسي برق و كامپيوتر

ID4455

به فارسي و انگليسي: قابل رويت در نسخه ديجيتالي

Design of a Blind Adaptive Decision Feedback Equalizer for Time Varying Channels Iman Moazzen i moazzen@ec iut ac ir Date of Submission April 27 2009 Department of Electrical and Computer Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Supervisor Ali Mohammad Doost Hosseini alimdh@cc iut ac ir Abstract A great interest in high rate communications has developed recently InterSymbol Interference ISI is the main restricition in such systems In order to circumvent ISI to reach high rate data transmission application of the equalization methods seems unavoidable The function of an equalizer is to improve the performance in retrieving the transmitted data symbols by compensating the ISI without excessive noise magnification in these systems Equalizers are divided into two main groups Linear and Nonlinear Decision Feedback Equalizer DFE is nonlinear and uses previously detected symbols in order to estimate their interference and consequently reduce ISI in the current symbol Regarding low realization complexity it is appropriate to use such an equalizer in high rate applications On the other hand It is well known that the error propagation phenomenon is the main drawback of DFE and it is not used very often in practice in severe channels like wireless channels The weighted DFE WDFE is proposed to limit this problem and is presented in this report However the design of an optimal equalizer is based upon a prior knowledge of the channel impulse response as well as some statistical characteristics of the noise and input signals which are not available in most practical situations So common equalizers utilize training sequences which are known to the receiver They can substantially solve the problem but decrease the effective bit rate especially under substantial channel variations requiring frequent training sequences transmission In some cases transmitting a training sequence is imopossible or difficult So in recent decades Blind Equalization BE without training has emerged significantly attractive and is addressed in this work Furthermore particularly in severely fading channels Single Inpute Multi Output SIMO transmission is widely replacing Single Input Single Output SISO approach to enhance the performance via diversity combining Hence SIMO systems are also considered pdfMachine Is a pdf writer that produces quality PDF files with ease Produce quality PDF files in seconds and preserve the integrity of your original documents Compatible across nearly all Windows platforms if you can print from a windows application you can use pdfMachine Get yours now

علي محمد دوست حسيني

محمد جواد اميدي

محمود مدرس هاشمي