Capacity maximization for OFDM two-hop relay system with separate power constraints

The combination of multihop relay system and orthogonal frequency division multiplexing (OFDM) modulation is a promising way to increase capacity and extend coverage area. For OFDM two-hop relay system with separate power constraints, we consider joint subcarrier matching and power allocation problem to maximize the system capacity, where the relay strategy is decode-and-forward. We formulate the optimal joint subcarrier matching and power allocation problem as an optimization problem, which is mixed binary integer programming problem and prohibitive to find global optimum in terms of complexity. By separating the subcarrier matching and power allocation, we provide the optimal scheme, i.e., optimal joint subcarrier matching and power allocation. Though simplifying the system architecture, the simulation proves that the one-to-one subcarrier matching is almost optimal.