Optimal Resource Allocation for Multi-D2D Links Underlying OFDMA-Based Communications

This paper analyzes the optimal resource allocation for multi-D2D(Device-to-Device) links underlying OFDMA-based networks with the target of reaching maximum sum-throughput of D2D transmission. In order to guarantee QoS (Quality of Service) of cellular users, the rate loss of cellular users is limited by a lower-bound constraint RLC. Meanwhile, the D2D link is allowed to use a sub-carrier only when the throughput from spectrum reusing exceeds a certain threshold. Since the primal problem is non-convex, we solve it through a subgradient-based algorithm by applying Lagrangian dual theory. The numerical results demonstrate the effectiveness and convergence of the algorithm by comparison with water-filling-based method. Besides, the subcarrier-specific RLC is more relaxed than the user-specific RLC for D2D transmission, which means D2D transmission can reach higher throughput under the latter constraint.