A comparative study of frequency domain HARQ Chase combining schemes for broadband single carrier MIMO CDMA communication

In this paper, we consider two turbo packet combining schemes for cyclic prefix (CP)-CDMA MIMO with Chase-type ARQ: i) In the first scheme, namely “chip-level turbo packet combining”, minimum-mean-square-error frequency domain equalization (MMSE FDE) and packet combining are jointly performed at the chip-level. ii) In the second scheme, namely “symbol-level turbo packet combining”, chip-level MMSE FDE and despreading are separately carried out for each transmission, then packet combining is performed at the level of the soft demapper. A comparative study, in term of implementation cost and performance evaluation, is presented. Using complexity analysis and throughput simulations, we demonstrate that the choice of the best combining technique depends on the system configuration.