Performance evaluation of maximal ratio combining in Shadowed-Rician fading land mobile satellite channels with estimated channel gains

The maximal ratio combining (MRC) scheme for Shadowed-Rician (SR) fading land mobile satellite (LMS) channels with estimated channel gains is studied, in this paper. It is assumed that satellite contains a single antenna and earth station (ES) has multiple antennas. For this set-up, a maximum-likelihood decoder is derived under assumption that perfect channel state information (CSI) is known; then the perfect CSI is replaced with estimated CSI in decision metric at ES. The MRC scheme for SR fading LMS channels has been studied in existing literature mostly with perfect CSI assumption. We derive approximate closed-form expressions of the probability density function, cumulative distribution, moment generating function (MGF), and analytical diversity order for the MRC based receiver in independent and identically distributed SR fading LMS channels with estimated channel gains. The author also provides approximate closed-form expressions of the outage probability and capacity of the considered scheme with estimated channel gains. Next, the author considers correlated SR fading LMS links and derive approximate bit error rate of the satellite system with estimated channel gains. It is shown from analysis and simulation that channel estimation error and correlation do not affect the diversity order but reduce the capacity of the considered system.