An optimization scheme for dual-hop device-to-device (DH-D2D) transmission

In this paper, we consider a relay enhanced device to device communication under Decode and Forward (DF) communication mode. The power allocation at the source as well as at the relay nodes is optimized in both cellular and D2D systems to enhance the sum throughput of the system. A joint power optimization problem for orthogonal frequency division multiplexing (OFDM) based transmission is formulated. The joint optimization problem is transformed into set of two convex subproblems. A novel water filling solution is derived from KKT conditions. Simulations results are presented to observe the gains of the proposed scheme over the non-optimized power allocation scheme. Results demonstrate that the proposed optimal scheme exhibits much better throughput as compared to the non optimal technique.