Outage Performance of Uplink Two-tier Networks Under Backhaul\n Constraints

Multi-tier cellular communication networks constitute a promising approach to\nexpand the coverage of cellular networks and enable them to offer higher data\nrates. In this paper, an uplink two-tier communication network is studied, in\nwhich macro users, femto users and femto access points are geometrically\nlocated inside the coverage area of a macro base station according to Poisson\npoint processes. Each femtocell is assumed to have a fixed backhaul constraint\nthat puts a limit on the maximum number of femto and macro users it can\nservice. Under this backhaul constraint, the network adopts a special open\naccess policy, in which each macro user is either assigned to its closest femto\naccess point or to the macro base station, depending on the ratio between its\ndistances from those two. Under this model, upper and lower bounds on the\noutage probabilities experienced by users serviced by femto access points are\nderived as functions of the distance between the macro base station and the\nfemto access point serving them. Similarly, upper and lower bounds on the\noutage probabilities of the users serviced by the macro base station are\nobtained. The bounds in both cases are confirmed via simulation results.\n