Optimal Downlink Power Allocation in Cellular Networks

TL;DR

This paper proposes a convex optimization-based, distributed power allocation algorithm for cellular networks that prioritizes users with lower modulation schemes, ensuring fairness and efficiency in utility proportional fairness.

Contribution

It introduces a novel utility proportional fairness model using sigmoidal utility functions and develops a tractable, distributed algorithm for optimal power allocation considering modulation schemes.

Findings

The optimization problem is proven convex and tractable.

The algorithm ensures non-zero power to all users and prioritizes lower modulation schemes.

Traffic and modulation dependent pricing can be implemented to optimize network performance.

Abstract

In this paper, we introduce a novel approach for power allocation in cellular networks. In our model, we use sigmoidal-like utility functions to represent different users' modulation schemes. Each utility function is a representation of the probability of successfully transmitted packets per unit of power consumed by a user, when using a certain modulation scheme. We consider power allocation with utility proportional fairness policy, where the fairness among users is in utility percentage i.e. percentage of successfully transmitted packets of the corresponding modulation scheme. We formulate our network utility maximization problem as a product of utilities of all users and prove that our power allocation optimization problem is convex and therefore the optimal solution is tractable. We present a distributed algorithm to allocate base station (BS) powers optimally with priority given to users running lower modulation schemes while ensuring non-zero power allocation to users running higher modulation schemes. Our algorithm prevents fluctuation in the power allocation process and is capable of traffic and modulation dependent pricing i.e. charges different price per unit power from different users depending in part on their modulation scheme and total power available at the BS. This is used to flatten traffic and decrease the service price for users.