Effect of backhaul constraints on uplink femtocell networks

One promising approach to expand the coverage and enhance the performance of cellular networks is to employ multitier cellular networks. In this paper, an uplink two-tier communication network is studied, in which macrousers, femtousers, and femto access points are geometrically located inside the coverage area of a macro base station according to a Poisson point process. Each femtocell is assumed to have a fixed backhaul constraint that puts a limit on the maximum number of femto and macrousers it can service. Under this backhaul constraint, the network adopts a special open-access policy in which each macrouser is either assigned to its closest femto access point or to the macro base station. The choice is made based on the ratio between the distance of the macrouser from the macro base station and its distance from its closest femto access point. Under this model, upper and lower bounds on the outage probabilities experienced by users serviced by femto access points are derived as functions of the distance between the macro base station and the femto access point serving them. Similarly, upper and lower bounds on the outage probabilities of the users serviced by the macro base station are obtained. The bounds in both cases are confirmed via simulation results.