Wireless and Optical Channels Capacities

Abstract

This chapter is devoted to wireless channel and optical channel capacities. The chapter starts with definitions of mutual information and channel capacity, followed by the information capacity theorem. We discuss the channel capacity of discrete memoryless channels, continuous channels, and channels with memory. Regarding the wireless channels, we describe how to calculate the channel capacity of flat-fading and frequency-selective channels. We also discuss different optimum and suboptimum strategies to achieve channel capacity including the water-filling method, multiplexed coding and decoding, channel inversion, and truncated channel inversion. We also study different strategies for channel capacity calculation depending on what is known about the channel state information. Further, we explain how to model the channel with memory and describe McMillan-Khinchin model for channel capacity evaluation. We then describe how the forward recursion of the BCJR algorithm can be used to evaluate the information capacity of channels with memory. The next topic is related to the evaluation of the information capacity of fiber-optics communication channels with coherent optical detection. Finally, we describe how to evaluate the capacity of hybrid free-space optical (FSO)-RF channels, in which FSO and RF subsystems cooperate to compensate for the shortcoming of each other.