4292

4063

كارشناسي ارشد

مخابرات

اصفهان: دانشگاه صنعتي اصفهان، دانشكده برق وكامپيوتر

1387

يازده، 123، [II]ص.: مصور، جدول، نمودار

ص. ع. به : فارسي وانگليسي

محمد جواد اميدي

محمود مدرس هاشمي

23/07/1387

1396/09/04

كتابنامه

مهندسي برق و كامپيوتر

ID4063

به فارسي وانگليسي: قابل رويت در نسخه ديجيتال

Abstract It is well known that Code Division Multiple Access CDMA scheme is robust tofrequency selective fading and has been successfully introduced in commercial cellularmobile communications such as IS 95 and 3G systems Also Orthogonal FrequencyDivision Modulation OFDM scheme is inherently robust to frequency selective fading however it has some drawbacks such as difficulty in subcarrier synchronization sensitivity to frequency offset and nonlinear amplification CDMA scheme despiterobustness against frequency selective fading has problems in high speed transmissionsituations For example in multi path channels for good reception of the signal it isnecessary to use RAKE receiver with many arms equal to number of paths and thiswould be a challenge to implement as it would lose some signal energy The success of thespread spectrum techniques for second generation mobile radio and OFDM for digitalbroadcasting and wireless LANs motivated many researchers to investigate thecombination of both techniques The combination of CDMA and multi carrier modulationwas independently proposed by three different groups in 1993 So far Multi CarrierCDMA system has drawn a lot of attention and many research activities have started onthis subject Today the MC CDMA system is considered to be the most importantcandidate as a physical layer protocol for 4G mobile communications Therefore thenecessity of study and research on this topic is clear The purpose of this thesis is first to recognize the basics of MC CDMA and to becomefamiliar with its transmitter and receiver model Since MC CDMA is a multi carriermodulation it suffers from inter carrier interference due to different reasons such as non synchronize oscillators in transmitter and receiver or Doppler shift in multi path channels One way to combat this problem is to use Viterbi algorithm as a useful method to detectthe Maximum Liklihood ML path which is investigated in this thesis Using the receiverinformation about transmitted signal can be used to reduce the computational complexityof Viterbi algorithm and speed it up The way to unify both Viterbi algorithm and equalizerwhich would result in hardware reduction in receiver is described at the end

محمد جواد اميدي

محمود مدرس هاشمي