Amplify and forward relaying protocol design with optimum power and time allocation

Parameter optimization such as power and time allocation plays an important role in emerging cooperative relaying protocol designs, especially when the environment is congested and contested. However, most existing works on cooperative relaying protocol designs considered equal-time allocation scenario, i.e. equal time duration is assigned to each source and each relay. In our recent work, we developed a decode-and-forward (DF) relaying protocol with linear mapping, where a significant performance improvement can be achieved by jointly optimizing power and time allocation. In this paper, we would like to explore optimum power and time allocation in amplify-and-forward (AF) relaying protocol designs, which has been widely considered in military/commercial communication applications. First, we design an AF relaying protocol based on an linear mapping approach for re-encoding at the relay which has shown superiority in our prior study. Then, we develop an optimum linear mapping for the AF protocol to minimize the outage probability. Finally, based on the optimum linear mapping, we obtain an optimum strategy of power and time allocation. It shows that one should always allocate more energy and time resources at the source than at the relay to minimize the outage probability of the AF relaying protocol. Numerical and simulation results validate our theoretical development.