Optimal Power Allocation Strategies in Two-Hop X-duplex Multi-source Relay Channel

The aim of this thesis is to find an optimal power allocation strategy for the transmitting nodes in a network scenario which comprises two sources, a single relay and a single destination. The main problem which is present in such network configurations is the self-interference phenomenon created by the relay, which attempts to transmit and receive at the same time on the same frequency band. Finding the correct power level (both at sources and relay) which allows the overall rate maximization is a theme of great interest, since many wireless applications present this problem and the use of relays is expected to increase in the near future. The strategy found in this work contemplates the use of Half-Duplex or Full-Duplex transmission modes at the relay. Moreover it is proved that such strategy has interesting performances with respect to other solutions provided in similar scenarios, but which require more precise information about the relay to be known at the sources. The novelty introduced here is the presence of multiple sources, which raises issues of fairness. The fairness concern is addressed and integrated into the system model provided. All these topics are mathematically described and solved, and the theoretical part is supported with numerical results which confirm the validity of the provided model.