Research And Simulation Verification Of HARQ Technology For LTE-advanced

In order to make the LTE system can evolution to4G smoothly,3GPP finished the report of technology required for LTE-Advanced in2008June, which put forward the minimum requirement for LTE-Advanced:downlink peak rate is1Gbps and uplink peak rate is500Mbps, uplink and downlink peak spectrum utilization rate reached15Mbps/Hz and30Mbps/Hz. If we want achieve reliable data transmission in such a high data rate, the introduction of effective error control technology will be more and more important meaning and value. Hybrid automatic repeat request (HARQ) technology is able to compensate the influence on signal transmission caused by time varying of the wireless channel and multipath fading, has been widely used in the B3G system (such as LTE). HARQ make automatic retransmission request (ARQ) and forward error correction (FEC) organic combination, and give full play to the two technical advantages and make up their defects, thereby achieving a higher reliability than FEC and higher transmission efficiency than ARQ.This paper based on the LTE-Advanced specification, considered the characteristics of carrier aggregation, it can aggregate several continuous or discontinuous small bands into a larger band, in order to get wider bandwidth and better peak data rate, which meet the demand for frequency resource of system. At the same time, Relay is introduced through the relay node, can meet the high requirements for the cell edge user data rate and cell average throughput of LTE-Advanced. And on this basis, studied the HARQ under this two technology, and its performance was simulated by MATLAB. The main work and innovation are as follow:(1) In-depth study of three different types of HARQ:type I HARQ, type II HARQ and type III HARQ, discussed the advantages and disadvantages.(2) Research the two basic HARQ process mapping mechanisms under the Carrier Aggregation:fixed HARQ and variable HARQ. And put forward two improved scheme, and proves the feasibility and advantage of the improved scheme by the simulation.(3) Research two kinds of HARQ in traditional relay system:DF-HARQ and STBC-HARQ. Put forward a new HARQ scheme in Relay, and the simulation results show that the improve scheme can improve the system throughput and the retransmission efficiency of Relay.