Reliable Underlay Device-to-Device Communications on Multiple Channels

Device-to-device (D2D) communications provide a substantial increase in spectrum usage and efficiency by allowing nearby users to communicate directly without passing their packets through the base station (BS). In previous works, proper channel assignment and power allocation algorithms for sharing of channels between cellular users and D2D pairs, usually require exact knowledge of the channel-state-information (CSI). However, due to the non-stationary wireless environment and the need to limit the communication and computation overheads, obtaining perfect CSI in the D2D communication scenario is generally not possible. In this work, we propose a joint channel assignment and power allocation strategy for D2D pairs and cellular users to maximize the overall aggregate throughput, under imperfect knowledge of CSI, while guaranteeing the outage probability for all users and encouraging fairness among D2D pairs. The proposed solution does not restrict the D2D transmitters to operate on a single channel, allowing each D2D pair to simultaneously access multiple channels and increase the overall throughput. We propose both a centralized and a decentralized method to solve our problem, where the computation load of the BS is alleviated by decomposing our problem into several subproblems, each of them being solved iteratively at the individual D2D pairs. Numerical experiments corroborate the merits of the proposed schemes when compared with state-of-the-art alternatives.