LTE-Advanced and Next Generation Wireless Networks: Channel Modelling and Propagation

Chapter 4

Outdoor Channels

Petros Karadimas

University of Bedfordshire, UK

4.1 Introduction

In outdoor wireless environments, the received signal is subject to spatial and temporal variations due to several inherent propagation mechanisms. According to the nature of the environment, the transmitted signal bandwidth and the overall distance that electromagnetic waves travel from the transmitting antenna to the receiving antenna, propagation can be confined within resolved clusters [1]. A resolved cluster is uniquely determined by its joint directional and delay characteristics [1]. The number of resolved clusters increases when the transmitted signal bandwidth increases or/and the scatterers¹ are more densely distributed (e.g., in an urban environment compared to a suburban). A generic modeling approach characterizing spatial and temporal variations of the received signal forms the subject of this chapter. The latter is carried out by considering the outdoor propagation channel to be jointly frequency selective, time selective and space selective at both the transmitter and receiver sides. Several common channel categories encountered in the literature such as time varying mobile and mobile-to-mobile channels are seen as special cases of the model adopted here.

In future wireless networks, the requirements for increased capacity and data rates will be met through combating propagation effects and transforming them into mechanism providing benefits. The latter is achieved through ...