Joint routing and scheduling in dense small cell networks using 60 GHz backhaul

This paper addresses the problem of joint routing and backhaul link scheduling in a dense small cell network using 60GHz multi-hop backhaul, coordinated by a local Cloud-RAN central unit. Our objective is to optimally select the backhaul links and paths to be activated in time domain to enhance the cell throughput and to minimize the total delay, considering the backhaul channel conditions and the Quality of Service requirements. This problem is formulated as a generalized vehicle routing problem and decoupled into two sub-problems: channel-aware path selection and queue-aware link scheduling. The path selection sub-problem is solved optimally using Branch-and-Cut exact algorithm for a given number of paths with per-link delay bounds. Subsequently, the scheduling sub-problem is solved using back-pressure scheduling.