Error-rate analysis of switched diversity receivers in Weibull fading

Introduction: Diversity is an effective and widely used technique for mitigating the effects of multipath fading [1]. Among the well-known diversity techniques, switched and stay combining (SSC) is simple and cheap, though less efficient. In a dual-branch SSC receiver, if the instantaneous signal-to-noise ratio (SNR) of the first branch falls below a predefined switching threshold, the second branch is immediately selected, regardless of whether or not the SNR of that branch is above or below the predetermined threshold. The Weibull fading channel model is a flexible model providing good fit to experimental wireless channel measurements for both indoor [2] and outdoor [3] environments. Considering the performance of diversity receivers over Weibull fading channels, in [4] a study on dual-branch selection combining (SC) receiver performance over correlative Weibull fading has been presented. Another contribution related to the performance analysis of SSC receivers in Weibull fading has been presented in [5]. In [5], useful formulas for statistical parameters of the dual-branch SSC output SNR, such as the cumulative distribution function (cdf), the probability density function (pdf) and the moments have been derived. Capitalising on these expressions, the average output SNR, the amount of fading (AoF), the outage probability, the optimum switching threshold for maximum SNR and the switching rate (SR) of the combiner have been also obtained in closed forms. However, the error performance analysis was not presented in [5] due to space limitations. In this Letter, the symbol error rate performance of dual-branch SSC receivers in a Weibull fading environment is studied. Analytical expressions for the average symbol error probability (ASEP) for several binary and multilevel modulation schemes are extracted and the common switching threshold for maximum ASEP is obtained in closed form. The single-branch receiver performance in the Weibull channel is also investigated. Finally, selected numerical examples are presented to point out the effect of the fading severity and the switching threshold on the receiver’s performance.