Adaptive transmission techniques in wireless fading channels

Abstract

In this thesis, the application of two adaptive transmission techniques: transmitter power adaptation and adaptive modulation are considered and studied.Firstly, we develop a power control scheme for the interference-limited Nakagami fading channels to minimize the outage probabilities of users by using a modified SIR-balancing model. The upper and lower bounds are derived for the outage probability to help us solve the minimization problem. Secondly, we examine the performance of adaptive M-ary Quadrature Amplitude Modulation (MQAM) system in the presence of Nakagami fading, log-normal shadowing and co-channel interference, by deriving an approximate expression of the probability density function (PDF) for the received signal-to-interference ratio (SIR)Finally, a novel sub-optimal algorithm is derived for the problem of transmitter power allocation in multiple-input multiple-output (MIMO) system. The proposed algorithm is simpler in computation, while it presents a satisfying performance in terms of the achievable data throughput and the power efficiency.