SIMULATION OF AN ADAPTIVE RATE CONVOLUTIONALLY CODED MULTICARRIER DS/CDMA SYSTEM

Abstract

The radio link for mobile unit can be characterized, by time-varying multipath fading, which causes the transmission quality to vary with time. When the transmitter is provided with the channel state information, the transmission schemes can be adapted to it, allowing the available channel to be utilized more efficiently. During good channel condition, more information can be sent. As the channel condition become worse, lower information rates are applied in order to maintain adequate transmission quality. In this dissertation, simulation of an adaptive rate convolutionally coded Multicarrier Direct Sequence Code Division Multiple Access (MC-DS/CDMA) system has been carried out in MATLAB environment. In order to accommodate a number of coding rates easily and make encoder and decoder structure simple, Rate-Compatible Punctured Convolutional (RCPC) code has been used. The data throughput at several coding rates has been evaluated, and selection of coding rate which gives maximum throughput in the signal-to-interference and noise ratio (SINR) sense has been done. The SINR estimate is obtained by the soft decision viterbi decoding metric.