Generalized type-II hybrid SR ARQ scheme using punctured convolutional coding and code combining technique in Multi-Carrier Code Division Multiple Access (MC-CDMA) systems

In this paper, we present the performance of the generalized type II hybrid selective repeat (SR) ARQ scheme using punctured convolutional coding and the code combining technique in Multi-Carrier Code Division Multiple Access (MC-CDMA) systems by computer simulations with different parameters. Multi-Carrier Code Division Multiple Access (MC-CDMA) allows high data rate transmission in a severe noisy channel without the need of a complex receiver implementation as it reduces the inter symbol interference (ISI) and exploits frequency diversity. With the code combining, at successive decoding attempts for a data packet, the decoder for error correction operates on a combination of all received sequences for that packet. It is found that the system throughput efficiency increases when the modulation level, starting code rate and h values decreases and while the size of CDMA code matrix increases. Besides, it is observed that the system performance depends on not only the level of modulation but also the type of modulation.