Improving the system capacity of a cellular network with partial power equalization

We derive an expression for the system capacity of a cellular network in which power equalization (PE) is applied only to the mobile stations (MS) that have stronger channel, while there is no power equalization for those with weaker channel. Power equalization means adjustment of the transmit power of each MS in order to have the same received power at the base station (BS). Systems that use matched filter receiver need power equalization. In general, however, if another reception strategy is used, the system capacity is higher if there is no power equalization. Although this strategy is optimal for the sum rate capacity, it will give an advantage to users staying very close to the BS, and is not fair. In this paper we consider a combined model in which the power equalization is done partially, i.e., stations that are closer to the BS equalize their transmit powers, while the others do not. For that reason, we define a cut-off rate beyond which no MS can transmit. This corresponds to an equivalent cut-off radius in the cell within which the transmit power of the mobile stations has to be scaled down such that all of them have the same receive power. Outside the cut-off radius all users can transmit with their maximal power (i.e. no PE is applied to them), such that the overall system capacity is increased. We derive a closed form expression in terms of the hypergeometric functions for the system capacity when partial power equalization is applied and the channel is Gaussian.