Spectrum allocation for wireless backhauling of 5G small cells

Abstract

The anticipated massive deployment of the small cells entail wireless backhauling for 5G cellular networks. However, the scarcity of radio frequency (RF) spectrum in the licensed bands is a major limitation which necessitates efficient spectrum planning for backhaul/access links of 5G small cells. This paper investigates the problem of channel assignment in the backhaul/access of small cells. We first formulate a problem to maximize the common achievable rate at the backhaul and access links of the small cells. Due to the NP-hard nature of the problem, we transform the original problem into a less complex convex programming problem and solve it numerically. We then propose and comparatively analyze the performance of two simple distributed backhaul channel allocation criteria, namely, maximum received signal power (max-RSP) and minimum received signal power (min-RSP) criteria. For these criteria, we theoretically derive the number of allocated backhaul channels and coverage probability for a given target rate of each small cell given its distance from the centralized wireless backhaul hub. Simulation results provide insights about the performance gap between the centralized and distributed schemes. Further, it is observed that the min-RSP criterion outperforms the max-RSP criterion which implies that more backhaul channels should be allocated to small cells that are located near the cell-edge.