Resource allocation in downlink of dual-hop OFDM relaying systems

In this paper, the main objective is to maximize the spectral efficiency in the downlink of dual-hop Orthogonal Frequency Division Multiplexing (OFDM) relaying systems. We propose an algorithm which jointly allocates transmission power and transmission interval in a system consisting of a source, multiple relays and a destination which utilizes Decode-and-Forwarded (DF) relaying. Two different sets of constraints are considered in this algorithm. In the first one, base and relay stations have independent power constraints while in the second one, there is a total power constraint. The algorithm is then extended to the case of multiple users where in addition to power and time, subcarrier allocation is also conducted. Numerical results are also provided which verify the performance improvement by adopting of the proposed algorithms.