  Picocellular architectures are essential for providing the spatial reuse
required to satisfy the ever-increasing demand for mobile data. A key
deployment challenge is to provide backhaul connections with sufficiently high
data rate. Providing wired support (e.g., using optical fiber) to pico base
stations deployed opportunistically on lampposts and rooftops is impractical,
hence wireless backhaul becomes an attractive approach. A multihop mesh network
comprised of directional millimeter wave links is considered here for this
purpose. The backhaul design problem is formulated as one of joint routing and
resource allocation, accounting for mutual interference across simultaneously
active links. A computationally tractable formulation is developed by
leveraging the localized nature of interference and the provable existence of a
sparse optimal allocation. Numerical results are provided for millimeter (mm)
wave mesh networks, which are well suited for scaling backhaul data rates due
to abundance of spectrum, and the ability to form highly directional,
electronically steerable beams.
