Επίδοση συστημάτων συνεργατικής επικοινωνίας με δύο επαναλήπτες, σε περιβάλλον με συσχετισμένες διαλείψεις σκίασης

Abstract

A cooperative diversity system with multiple relays where the receiver com-bines the relayed and direct paths consists of a practical and useful configuration when the communication channels suffer from fading. This diploma thesis presents novel analytical formulas and numerical results on the performance of a cooperative diversity system with two relays in arbitrary positions over correlated lognormal channels (Chapter 4). The two relays form a di-amond-shaped cooperative system. The Fixed Relaying cooperative protocol and both the Time Domain Multiple Access (TDMA/half duplex relay) and the Space Do-main Multiple Access (SDMA/ full duplex relay) schemes are considered in the present contribution. The destination receiver combines the multiple versions of the received signal utilizing either the Selection Combining (SC) or the Maximal Ratio Combining (MRC) techniques. The performance of the proposed system is compared with a basic coopera-tive system with only one relay (triangle-shaped cooperative configuration) which is presented in chapter 3 and a direct link system, in order to investigate the benefits of cooperation. The proposed expressions for the outage probability can be directly applied to various propagation scenarios where the lognormal distribution is used to describe the large scale fading effects such as, indoor, urban and on body propaga-tion environments. Finally, the impact of the lognormal parameters (including correlation) on the cooperative system performance is investigated through extended numerical results. Index Terms