Performance of hybrid ARQ using turbo code in W-CDMA high speed downlink packet access

摘要

This paper elucidates the performance of combining-based hybrid ARQ (HARQ) such as Type-I with packet combining (PC), and Type-II, applying Turbo code and multipath interference canceller (MPIC) in W-CDMA high speed downlink packet access. Simulation results demonstrate that the four modulation and coding scheme (MCS) sets of QPSK with the coding rate of R = 1/2, 16 QAM with R = 1/2 and 3/4, and 64 QAM with R = 3/4, and three MCS sets of QPSK with R = 3/4, 16 QAM with R = 5/6, and 64 QAM with R = 5/6 are needed for Type-I with PC and Type-II, respectively. Furthermore, Turbo code can improve the required average received E{sub}c/N{sub}0 and increase the peak throughput by more than approximately 5% (500 kbps) in 64 QAM compared with convolutional code, in both combining-based schemes. When the adaptive modulation and coding (AMC) is employed, the throughput performance is almost identical in the region where more than two MCS sets are selected according to the instantaneous SIR measurement results. However, in the high-received E{sub}c/N{sub}0 region where the MCS employing 64 QAM is selected in a high possibility, Type-II can increase the maximum throughout approximately 7% (800 kbps) compared with Type-I with PC.