The Simulation On Link Adaptation

The goal of wireless link adaptation technology is to achieve the best performance of communication by changing the parameters of transmitter and receiver according to the variation of the mobile channel dynamically, such as transmit power, modulation scheme, coding rate, length of frame and transmit times.After a brief introduction of the fade of wireless channel and the technology of estimation of channel and SNR, this thesis mainly investigated the basic principles of the Adaptive Modulation and Coding (AMC) and the application of AMC in Broadband Wireless Access(BWA) systems. Then, the relations of frame length adaptation and throughput, energy-efficient are briefly discussed.AMC is a technology which transmitter dynamically change modulation and coding scheme, in which using high-level modulation and high-rate coding when the condition of channel is good and using low-level modulation and low-rate coding when it is bad. According to the information that reflected the condition of channel, this thesis classified AMC into heuristic AMC and SNR-estimation AMC. The system that using the first one of AMC decide the scheme of modulation and coding according to the frame error ratio that reflected indirectly the condition of channel, while it using the another of AMC decide the scheme according to the SNR estimation. In this thesis, we compared the two class AMC through simulation, and analyzed their merits and flaws. Frame length adaptation is a technology which transmitter dynamically change the length of frame according to the condition of channel. When the channel is fading, the transmitter shortened the length of frame to improve the throughput, reduce the probability of transmission fail, save the energy of communication, and extend the range of transmission. This thesis not only analyzed the effect of the frame length adaptation, but also discussed the relation of it and AMC.The fifth chapter, we investigated and simulated the application of AMC in the IEEE 802.16 system, the SUI channel model, and the principles of coding and decoding of the Block Turbo Code, and compared the performance between BTC and RSV. In the end, we investigated the performance of AMC on SUI channel model.