Lifetime maximization in multihop mixed AF-DF relay networks

In this paper, we study the problem of the lifetime maximization in a new type of multi-hop relay network where the amplify-and-forward (AF) and the decode-and-forward (DF) relay nodes are alternatingly cascaded. In order to cope with the general frequency selective fading channel, the orthogonal frequency division multiplexing (OFDM) modulation is adopted over each hop. We formulate the optimization problem as maximizing the network lifetime subject to the constraint of minimum end-to-end rate requirement, while each relay node is constrained to its limited battery energy as well as the maximum power supply. Under certain assumptions, we transform the original problem into the standard convex optimization problem and solve it from the dual decomposition technique. Simulation results are provided to corroborate the proposed strategy.