Performance Of Constant Envelope OFDM In Cooperative Communication Systems

Constant envelope orthogonal frequency-division multiplexing (CE-OFDM) transforms the normalized OFDM signal, by way of phase modulation, to the phase of the carrier, and it not only mitigates the high peak-to-average power ratios with OFDM, but also maximizes power amplifier efficiency and preserves the advantages of OFDM such as the high datas rate and the capability to combat multi-path interference. Antenna diversity restrains error performance degradation due to fading channel effectively. Maximal-ratio combining(MRC), equal gain combining(EGC), select combining(SC) as well as the combination of SC at the transmitter/MRC at the receiver(SC/MRC) are common antenna diversity. Amplify-and-forward(AF) cooperative communications combat the influence of the fading and improve the reliability of transmissions effectively. Nakagami distribution is always used to model fading channels due to its great versatility and practical applicability. This thesis investigates the error performance of CE-OFDM system using EGC, combined SC/MRC and AF cooperative CE-OFDM system using SC, MRC, combined SC/MRC in Nakagami-m fading channels.Chapter1presents a brief review of CE-OFDM, antenna diversity and AF cooperative communication systems.Chapter2investigates the error performance of CE-OFDM system with antenna diversity, derives closed-form expressions for the lower bound of the average symbol error rate(SER) and bit error rate(BER) of combined SC/MRC CE-OFDM system with M-ary phase-shift keying(MPSK) and rectangular M-ary quadrature amplitude modulation(MQAM) over Nakagami-m flat fading channels with arbitrary fading index m. Both numerical and simulation results verify the accuracy of the derivation. Then, it investigate the error performance of CE-OFDM system using EGC over frequency-selective Nakagami-m fading channels, and show the simulation results.Chapter3investigates the error performance of AF cooperative CE-OFDM over Nakagami-m fading channels, firstly, derives the lower bound expressions for the error rate of MRC reception diversity variable gain multiple AF relays cooperative CE-OFDM system with MPSK and rectangular MQAM, secondly, derives the closed-form expressions for the average SER and BER of SC reception diversity variable gain single AF relay cooperative CE-OFDM system with binary phase-shift keying (BPSK) and rectangular MQAM, and then, derives the lower bound expressions for the error rate of MRC reception diversity fixed gain multiple AF relays cooperative CE-OFDM system with MPSK and rectangular MQAM, in addtion, derives the closed-form expressions for the average SER and BER of SC reception diversity fixed gain single AF relay cooperative CE-OFDM system with BPSK and rectangular MQAM, finally, derives the lower bound expressions for the error rate of combined SC/MRC variable gain AF cooperative CE-OFDM system with MPSK and rectangular MQAM. Both numerical and simulation results verify the accuracy of the derivation.Chapter5finishes the paper with conclusion.