ABSTRACT
Wireless channels are simultaneously affected by short-term fading and long-term fading (shadowing) [1]. The short-term signal variation has been described by several distributions such as Hoyt, Rayleigh, Rice, Nakagami- https://www.w3.org/1998/Math/MathML"> m , κ - μ , η - μ , α - μ https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9780429086496/6f2a715f-b5a8-4e0b-b00c-7c28bfe4886f/content/eq986.tif" xmlns:xlink="https://www.w3.org/1999/xlink"/> , and Weibull (see Chapter 2). Various techniques for reducing short-term fading effect are used in wireless communication systems [2]. An efficient method for amelioration system’s quality of service (QoS) by using multiple receiver antennas is called space diversity. The main goal of space diversity techniques is to upgrade transmission reliability without increasing transmission power and bandwidth while increasing channel capacity. Several principal types of combining techniques can be generally performed by their dependence on complex restrictions put on the communication system and the amount of channel-state information available at the receiver. In order to implement combining techniques such as maximum ratio combining (MRC) and equal gain combining (EGC), it is not only necessary to know all or some of the channel state information (CSI) of the received signal, but also the receiver chain for each branch of the diversity system. It increases the complexity of the system. Unlike previous combining techniques, a selection combining (SC) receiver processes only one of the diversity branches and is much simpler and cheaper for practical realization (see Chapter 4).
