On Millimeter Wave 5G Backhaul Link Scheduling

Heterogeneous networks that consist of densely deployed base stations of different (macro and small-cell) tiers are envisioned to be among the key technologies for providing the high data rates required in 5G systems. Moreover, interconnecting small-cell base stations via millimeter-wave (mm-wave) backhaul links is a flexible and cost-effective alternative to fiber optic backhauling. Given a set of mm-wave backhaul links, this paper addresses the problem of scheduling all links in the minimum number of time slots such that the subset of links scheduled to each time slot can be activated simultaneously. In particular, a set of links can be activated simultaneously if all link signal-to-interference-plus-noise-ratio (SINR) targets are satisfied, and the number of RF chains of every base station is not exceeded. We give a succinct optimization-based formulation of the problem, capturing both SINR constraints and number of RF chains limitations. Using reduction from the set-cover problem, we devise a provably good polynomial-time algorithm for the problem. Our numerical results further indicate the significant superiority of the presented approach.