Performance Analysis of Two-Tier Wireless Networks With Dynamic Traffic, Backhaul Constraints, and Terminal Mobility

Over the past few years, mobile cellular networks have witnessed an enormous growth in the carried data-traffic volume. The current networks' features are not enough to cope with this traffic trend, and the concept of small cells has emerged as a feasible solution to increase the network capacity. However, the deployment of small cells introduces several technical challenges, such as the cross-tier interference between the macrocell and the small cells or the use of the subscriber landline to send the backhaul data. In this paper, an analytical model is proposed to study the impact that the user traffic dynamics, the mobility of macrocell users, the scheme chosen to associate macrocell users to the small cells, and the changing available capacity of the small-cell backhaul have on the system performance. To make the solution of the model computationally feasible, we exploit the time-scale decomposition approach. In most practical scenarios, the arrival and departure rates of traffic flows are much larger than the rate of events associated with the mobility of macrocell users. Then, flows perceive that macrocell users are still. This model is applied to identify the scheme to associate macrocell users to the small cells, which maximizes the performance perceived by the small-cell users.