The Ieee 802.16 M The Harq Technology Research

In2005, IEEE introduced the IEEE802.16e standard with the characteristics of mobile, broadband and IP. As the request of users for the mobile transmission rate constantly rises, the IEEE802.16e standard show its limitations. Therefore, as the enhanced version of the IEEE802.16e, IEEE802.16m, which provides two times spectrum efficiency of IEEE802.16e, arises at the historic moment.HARQ is the key technology of wireless mobile communication and plays a very important role in realizing the mobile communication system with high throughput rate and high reliability. Therefore, HARQ is introduced to the standards IEEE802.16e and IEEE802.16m.The main work and achievements of this paper are briefly described as follows.First, the basic principles of HARQ and the HARQ technology used in IEEE802.16m standard are introduced in this dissertation.Second, we study the channel coding used in IEEE802.16m. The results of simulations show that with the increase of number of iterations, the performance of CTC improves, but the gain becomes smaller.Third, this dissertation designs a simulation platform of the HARQ system based on CTC code used in IEEE802.16m standard, involving CRC,CTC,HARQ retransmission,modulation and demodulation,constellation rearrange, AWGN channel and HARQ combination.Furthemore, we study the IR combination and Chases combination used in HARQ system.Through the simulating,we find that when we adopt a lower modulation order and a lower coding rate, the gain of IR combination compared with Chase combination is limited, but with the coding rate and modulation order increasing, the gain of IR combination compared to Chase combination increases gradually. This dissertation also introduces a method to reduce the delay of HARQ transmission which is proved to be effective.In the end, we study the AMC and HARQ combination technology.We adopt six kinds of MCS, including QPSK (1/2,3/4),16QAM (1/2,3/4) and64QAM (2/3,3/4).Compared with AMC technology, the gain of AMC-HARQ is limited when the adaptive accuracy is high, but it is considerable when the adaptive error is serious.