A Combined Interleaving Technique for Trellis Coded MPSK Systems in Rayleigh Fading Channels |
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Authors: | Öztürk Ersin Aygölü Ümit |
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Affiliation: | (1) NETA, Alemda, Cad. 81244 Umraniye, Istanbul, Turkey;(2) Faculty of Electrical-Electronics Eng., Istanbul Technical University, 80626 Maslak, stanbul, Turkey |
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Abstract: | Freedom of mobility is the latesttrend in the evolution of digital communicationsystems. In these systems bandwidth and powerconstraints limit the mobility of the users. TCM(trellis coded modulation) is a combined coding andmodulation scheme which increases the productivity ofa digital communication system without increasing thetransmitted power or the required bandwidth. A mobilecommunication channel is affected from noise andfading because of the multipath propagation. On aRayleigh fading channel, coding should be used withtechniques which uncorrelate the received energy ofeach consecutive coded symbol. Interleaving is one ofthese techniques and used to make burst errors intorandom errors which can be corrected by errorcorrecting codes. In this paper, the trellis codingsystem which combines a regular convolutional encoder,bit interleaver, coordinate interleaver, and anappropriate decoder is considered. The analytical biterror probability upper bounds are derived for the8-PSK TCM system whose diversity is increased by usinga regular 2/3 rate convolutional code followed bythree bit interleavers and a 8-PSK signal mapperfollowed by two coordinate interleavers. Theanalytical and simulation results show that toincrease the diversity of the trellis coded M-PSKsystems in Rayleigh fading channels is the primary keyfor reliable transmission of high quality voice anddigital data. |
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Keywords: | fading channels interleaving trellis codedmodulation diversity suboptimal decoder |
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