Adaptive Coded Modulation Performance and Channel Estimation Tools for Flat Fading Channels

Abstract

The need for spectrally efficient transmission on mobile and wireless channels is prevalent. A promising scheme for such transmission is adaptive coded modulation. In this thesis, techniques for assessing the performance of such systems are presented. One of the vulnerable points of such systems is the need for a reliable feedback channel. Channel prediction is proposed as a technique to combat the harmful effects of feedback delay.

The Nakagami distribution is often employed in a model for the fading envelope of a wireless channel; this leads to a gamma-distributed signal-to-noise ratio. Nakagami (1960) provides expressions for the probability density function (PDF) of the product, sum, and ratio of two correlated gamma-distributed random variables (RVs). However, such an expression for the difference between two such RVs has not been provided by Nakagami. Anew expression for this PDF is provided in this dissertation, and it is shown that it is closely related to a distribution first described by McKay (1932). Applications of the new PDF include outage probability calculation in an environment with self-interference and assessment of the quality of certain channel estimation techniques.