Baseband Receiver Design for Wireless MIMO-OFDM Communications, 2nd Edition

Chapter 5

Signal Propagation and Channel Model

Wireless communication signals experience many adverse effects as they travel through the transmitter and receiver electronics, the antennas, and the radio-frequency channel. Understanding these effects and modeling them accurately will lay solid foundations to wireless receiver design.

5.1 Introduction

Wireless communication systems offer many advantages, such as mobility, easy access, and installation; however, they also suffer more limitations than wireline transmission systems, such as limited capacity, spectrum shortage, and service quality uncertainties. In the wireless communication systems, signals are transmitted over the air in the radio-frequency (RF) band. There are numerous non-ideal factors that affect the quality of the received signals and thus the reliability of wireless communication. As a result, these wireless channel effects place some fundamental limitations on the capability of wireless communication systems. For example, we have derived the capacity of MIMO systems in Chapter 3; however, in practice, the unavoidable spatial correlation caused by limited antenna spacing degrades that capacity.

Wireless radio channels are extremely dynamic and time-varying owing to channel variations and user movement. Making matters worse is the fact that wireless transmission is usually off and on owing to the inconsistent nature of the wireless channels. Hence, most analysis and estimation of the wireless channels must ...