Performance modeling of adaptive modulation coding schemes on rayleigh fading channels

Abstract

Adaptive modulation coding schemes (MCSs) are important techniques in wireless data communication to minimize the bit-error-rate (BER) and maximize throughput. Usually, the adaptive system consists a few MCSs that will intelligently adapt to channel variation. At the receiver, the MCS transition is decided by link quality analysis and the result is sent to transmitter via acknowledgement data. Therefore, the system performance cannot rely on a single MCS. This research developes a methodology to estimate an adaptive MCS performance using Markov model. The model concerns type I Hybrid automatic repeat request (ARQ) system which is a combination of forward error control (FEC) and ARQ under the Rayleigh fading condition. The two-state Markov model performance estimation (MMPE-2) and four-state Markov model performance estimation (MMPE-4) are proposed, where the system performance are estimated based on packet error probability and level crossing probability of the Rayleigh fading condition. Performance comparison between estimation models and simulation using International Radio Consultative Committee (CCIR) 520-2 channel model is made and the results shows that MMPE-4 are comparable for fade duration longer than the packet length. From the models, the analysis on traffic and acknowledgement data in term of bit BER and throughput can be done theoretically prior to any simulation and experiment. This can save a lot of time and the modification on the system can be done before proceeding for further evaluation or implementation. By using the estimation models as tools, several new adaptive MCSs are evaluated and the best adaptive system is proposed for high frequency data communication system.