Matching Based Two-Timescale Resource Allocation for Cooperative D2D Communication (Technical Report).

We consider a cooperative device-to-device (D2D) communication system, where the D2D transmitters (DTs) act as relays to assist cellular users (CUs) in exchange for the opportunities to use the licensed spectrum. To reduce the overhead, we propose a novel two-timescale resource allocation scheme, in which the pairing between CUs and D2D pairs is decided at a long timescale and time allocation for CU and D2D pair is determined at a short timescale. Specifically, to characterize the long-term payoff of each potential CU-D2D pair, we investigate the optimal cooperation policy to decide the time allocation based on the instantaneous channel state mbox{information (CSI)}. We prove that the optimal policy is a threshold policy. Since CUs and D2D pairs are self-interested, they are paired only when they agree to cooperate mutually. Therefore, to study the behaviors of CUs and D2D pairs, we formulate the pairing problem as a matching game, based on the long-term payoff of each possible pairing. Furthermore, unlike most previous matching model in D2D networks, we allow transfer between CUs and D2D pairs to improve the performance. Besides, we propose an algorithm, which converges to an $epsilon$-stable matching.