Jointly optimal rate control and total transmission power for cooperative cognitive radio system

In this study, the authors apply the multi-objective optimisation (MOO) methods to the challenge posed by joint rate maximisation and total transmission power (TTP) minimisation in cooperative cognitive radio networks. The proposed MOO methods which are based on amplify and forward relaying strategy optimise the two conflicting objectives and, at same time, they maximise the rate quality and minimise the TTP allocated to the network relays simultaneously. The MOO problem under investigation is a non-convex non-linear combinatorial optimisation one that three MOO methods are presented for a desired solution. The explored methods are: weighted sum algorithm (which is based on a simplistic model), MOO fractional programming method (which has much in common with their MOO problem) and lexicographic algorithm (which is suitably adapted to complex combinatorial optimisation environments due to its robustness in avoiding trapping in local optima). Their simulation results confirm the proposed methods' effectiveness for simultaneous rate maximisation and TTP minimisation as well as their superiority over counterpart algorithms.