Hybrid ARQ Technique Employing a Signal Constellation Rearrangement Based on 256-QAM

In this paper,we introduce a Hybrid ARQ (HARQ) technique based on 256-QAM.By employing signal constellation rearrangement,the diversity of bit reliabilities caused by M-QAM signal constellation can be reduced,thus the corresponding performance of HARQ could be enhanced.We present the standard signal constellation (Gray Mapping) of 256-QAM,in which 3 signal constellations are rearranged to derived 4 types of constellation mapping rules of 256-QAM.The simulation results show that the proposed technique performs a noticeable gain in HARQ performance with a lower complexity.This will be favorable to the application of 256-QAM (for example,in HSDPA and HSUPA),and provide great value in reference and practical application.