Joint Slot and Sub-channel Allocation Scheme in Wireless Self-Backhaul HetNets

Due to the low cost and flexible deployment, wireless self-backhaul can be a promising backhaul solution for ultradense heterogeneous networks (HetNets). In this paper, we investigate the scheduling issues in wireless self-backhaul HetNets. To coordinate the inter-cell interference among small base stations (SBSs), a graph coloring algorithm is used to divide the SBSs into multiple SBS sets. SBSs belonging to the same set can receive or transmit data at the same time. We formulate a slot and sub-channel allocation optimization problem to maximize the downlink (DL) throughput of all SBSs subject to access-backhaul link matching constraints and user data rate requirements. Since the formulated problem is Integer Non Linear Program (INLP) whose solution is intractable, the solution is obtained by dividing the problem into two sub-problems. Firstly, a Linear Problem (LP) is formulated for solving the slot allocation problem, which roughly guarantee user data rate and access-backhaul link matching requirements. Secondly, two low-complexity heuristic algorithms for sub-channel allocation are proposed. Each base station (BS) will use corresponding sub-channel allocation algorithm in a distributed manner at working slot.