Joint bandwidth, caching and association optimization for D2D assisted wireless networks

This paper aims to minimize the average delay via joint bandwidth allocation, caching placement and user association in a device-to-device (D2D) assisted heterogeneous network with cache-enabled D2D transmitters and helpers. The optimal bandwidth allocation is first derived in closed form. Then, we propose a low-complexity algorithm to obtain a suboptimal solution, where three subproblems are tackled iteratively. In each subproblem, the structure of the optimal caching placement or user association is derived according to the corresponding Karush-Kuhn-Tucker conditions. Simulation results show the superiority of the proposed scheme comparing to the existing caching scheme in terms of average delay.