An Efficient Macrocell Power Control Algorithm for Enhancing Dense Picocell Deployments

The integration of picocells in cellular networks is a cornerstone for 4G cellular networks as a low power, low cost solution to offer high data rates to outdoor customers and simultaneously reduce the load of the macrocellular network. However, the massive and unplanned deployment of picocells will diminish their performance due to severe interference from the macrocells. In this paper, an efficient power allocation scheme is proposed, in which the downlink power of macro base stations (BSs) is optimized aiming at maximizing picocells sum-rate. The non-convex optimization problem is reformulated as a difference of two concave functions and the branch and bound (B&B) algorithm is applied to find the optimum numerically. The impact of deploying a number of pico BSs on the capacity and energy efficiency measured by [bit/s/W] is investigated. The numerical results show that the total capacity improves as the number of pico BSs increases. As the number of pico BSs exceeds a certain threshold, the energy efficiency decreases followed by a marginal increase in the total capacity. Moreover, the proposed scheme outperforms other sub-optimum power allocation schemes in terms of making more pico BSs attain the required capacity to improve the energy efficiency.