Performance, dimensioning and interference tradeoffs for two-tier wireless networks

The paper considers a two-tier wireless network structure, where the edge of a Macrocell is underlaid by a number of uniformly deployed femtocells, and studies the impact of interference to flow-level performance. A careful examination of the factors associated with interference and the use of appropriate modeling techniques from the theory of Processor Sharing systems give rise to a simple methodology for determining the values of important flow-level performance metrics. Two forms of interference are taken into account: cross-tier interference from the Macrocell to femtocells and co-tier interference between neighboring femtocells. The model developed by the paper is capable of capturing the combined impact of both these types. Numerical results investigate various tradeoffs between system parameters and indicate, among other findings, that in scenarios where the potential for cross-tier interference is more pronounced, increasing the number of femtocells above some threshold leads to performance degradation. The proposed methodology allows for a full quantification of such effects.