Research On Link Adaptation Technology In Cdma2000 1x EV-DV System

Link adaptation technology is a key scheme for high speed packet data service in 3G mobile communication and beyond. By using link adaptation technology, we can track the change of wireless channels in time and obtain good transmission performance of links. In this dissertation, we mainly focus on adaptive modulation and coding (AMC) technology and hybrid automatic repeat query (HARQ) technology, which are key link adaptation technologies in 3G and beyond, based on the background of cdma2000 1xEV-DV system.Chapter 2 states simply the key technologies in cdma2000 1xEV-DV and the procedure of modeling simulation system of cdma2000 1xEV-DV. Then, tells how to simulating AMC and HARQ in the simulation system.In chapter 3, we illuminate the principle of AMC technology, and analyze the implemental scheme of AMC. The simulation results show that we can get better performance by using AMC, and more MCS, better performance. So we give the analysis.Then we propose a new AMC algorithm based on retransmission in this chapter. This algorithm takes the time diversity gain obtained by using HARQ into account, and selects the MCS that can maximize the throughput to transmit data. So, it can obtain good performance. The simulation results show it.In chapter 4, we introduce the basic principle and implement schemes of HARQ technology. And then analyze some HARQ schemes, which are fit for cdma2000 1xEV-DV, including Chase Combining (CC) and Incremental Redundancy based on N channels stop and wait (N-SAW). We compare their performance through theory analysis and computer simulation. Additionally, by using AMC and HARQ we obtain better performance than only by using AMC. At the same time we find that the difference between using different numbers of MCS in AMC may be reduced byHARQ, so we analyze the causes.