Interference-aware routing and spectrum allocation for millimeter wave backhaul in urban picocells

The exponential growth in demand for mobile data requires significant increases in spatial reuse, motivating an evolution towards picocellular architectures with densely deployed base stations. Providing backhaul for such a network is a key challenge, because of the high access link rates, and the cost and difficulty of running optical fiber to base stations that might be opportunistically placed on lampposts and rooftops. Wireless backhaul using millimeter (mm) wave spectrum is therefore an attractive and flexible approach, given the plentiful availability of spectrum and the possibility of synthesizing highly directive, steerable links. In this paper, we formulate and investigate the problem of joint resource allocation and routing on such a mm wave backhaul network, providing a linear programming formulation that accounts for mutual interference across simultaneously active links. While the number of variables grows exponentially in network size, it is possible to prune the problem size so that it is manageable for moderately sized networks. Numerical results and design implications are briefly discussed.