tailieunhanh - Báo cáo hóa học: " DSC and universal bit-level combining for HARQ systems"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: DSC and universal bit-level combining for HARQ systems | Lv et al. EURASIP Journal on Wireless Communications and Networking 2011 2011 66 http content 2011 1 66 o EURASIP Journal on Wireless Communications and Networking a SpringerOpen Journal RESEARCH Open Access DSC and universal bit-level combining for HARQ systems Tiejun Lv Jinhuan Xia and Feichi Long Abstract This paper proposes a Dempster -Shafer theory based combining scheme for single-input single-output SISO systems with hybrid automatic retransmission request HARQ referred to as DSC in which two methods for soft information calculations are developed for equiprobable EP and non-equiprobable NEP sources respectively. One is based on the distance from the received signal to the decision candidate set consisting of adjacent constellation points when the source bits are equiprobable and the corresponding DSC is regarded as DSC-D. The other is based on the posterior probability of the transmitted signals when the priori probability for the NEP source bits is available and the corresponding DSC is regarded as DSC-APP. For the diverse EP and NEP source cases both DSCD and DSC-APP are superior to maximal ratio combining the so-called optimal combining scheme for SISO systems. Moreover the robustness of the proposed DSC is illustrated by the simulations performed in Rayleigh channel and AWGN channel respectively. The results show that the proposed DSC is insensitive to and especially applicable to the fading channels. In addition a DS detection-aided bit-level DS combining scheme is proposed for multiple-input multiple-output-HARQ systems. The bit-level DS combining is deduced to be a universal scheme and the traditional log-likelihood-ratio combining is a special case when the likelihood probability is used as bit-level soft information. Keywords Basic probability assignment BPA Bit-level combining Dempster -Shafer D -S evidence theory Hybrid automatic retransmission request HARQ Multiple-input multiple-output MIMO Maximum-ratio combining MRC I