Study Of The Link Adaptive Transmission And Multi-Antenna Technology In IEEE 802.16m System

After nearly thirty years dramatic development, wireless communication technique has brought deep change to our life and working style. Although 3G network coverage is becoming complete, user traffic has more challenge for transmission rate, so 4G becomes the inevitable trend in the future. IEEE 802.16m as the evolution version of WiMAX together with LTE's evolution version LTE-Advanced becomes the two main criteria of 4G candidate techniques. In order to obtain higher transfer rates, smaller error rates, lower latency and better quality of service, multi-antenna technology and link-adaptive transmission technology have became the focus of the assessment, here this paper will give detailed introduction and research on these two key techniques based on IEEE 802.16m system.For the multi-antenna technology part, we get inspiration from TCBP scheme in 16m system, integrate two ports CBP and GOB based adaptive beamforming technique, a DOA plus CBP beamforming scheme technique is proposed using eight dual-polarized antennas with 45 degree plus or minus at the base station side to form double parallel codewords, also six new improved downlink broadcast weight schemes are given. Simulation results suggest that compared with SRS based EBB scheme, the DOA plus CBP scheme can achieve better performance, compromise of the cost and complexity, also with new broadcast weight, system can obtain better control channel coverage.For content about link-adaptive transmission, an AARAA scheme is proposed based on existing rank adaptive method, it takes full advan- tage of ACK/NACK information from user's HARQ feedback channel to achieve closed-loop control, and the throughput in RI prediction process is mapped in to effective one, so the AARAA can take control of the error transmission probability for the first time. Simulation results show that the AARAA scheme excels the current sheme in several channel scenarios.