Efficient mmWave wireless backhauling for dense small-cell deployments

Dense small-cell deployments of 5G networks require a wireless backhaul to efficiently connect the small cells to the macro base station (BS). We envision a wireless backhaul architecture where cells are grouped into clusters. One small cell per cluster plays the role of a cluster head connecting the rest of the small cells to the macro cell via a mmWave MIMO link. We formulate the problem of jointly selecting the cluster heads and the number of BS antennas dedicated to each mmWave MIMO link between the BS and each cluster head as a mixed integer nonlinear program (MINLP) and prove its NP-hardness. We propose a Alternate Convex Search Heuristic (ACSH) to handle the tradeoff between having faster backhaul links versus having more cluster heads and show it is near-optimal via extensive simulations. Last, we show that our heuristic has a 20%–50% performance gain compared to prior work.