Cost-efficient deployment of mmW small cells with hybrid backhauls

Hybrid backhaul networks with millimeter wave (mmW) technologies are widely viewed as promising solutions to support next-generation ultradense mobile networks. In this paper, we propose a cost-efficient deployment framework of mmW small cells with hybrid backhaul, with the aim of providing useful insights on the optimal deployment of small cells for mmW mobile network planning. We investigate the trade-off between the deployment cost and the number of user equipments that can be admitted while considering 2 kinds of base stations (BSs) in mmW networks: backhaul aggregate nodes (BANs) and wireless backhaul BSs (WBSs). We derive the deployment cost of mmW networks including BSs and wired backhaul links as a function of the number of BANs and WBSs and investigate the relationship between the number of BSs and the number of admitted user equipments. We formulate an optimization problem to maximize cost efficiency subject to the constraint of wireless backhaul link capacity and derive the optimal number of WBSs per BAN cluster as well as the optimal number of deployed BANs. Numerical results validate the effectiveness of our proposed BS deployment framework.