Optimal Uplink Power Control in Two-Cell Systems with Rise-over-Thermal Constraints

Joint assignment of transmit powers to users through basestation cooperation improves system capacity. In this letter, we study the optimal power allocation for sum capacity in a two-cell system with an individual rise-over-thermal constraint per basestation. It is proven that the optimal power allocation to any pair of users resides in one of five discrete power assignments, each of which corresponds to at least one constraint being binding. We propose a joint proportional fairness scheduler across two cells that extends the optimal power allocation to multi-user systems. Simulations show that the combined power allocation and proportional fairness scheduler achieves significant gains over a conventional round-robin scheduler, in terms of both cell average and cell edge throughput.