Distributed Power Allocation for Coordinated Multipoint Transmissions in Distributed Antenna Systems

TL;DR

This paper presents a scalable distributed power allocation algorithm for CoMP in DAS, overcoming non-strict concavity issues and requiring only local information exchange, with proven convergence and robustness to channel variations.

Contribution

It introduces a novel distributed power allocation method that handles non-strict concavity and does not depend on channel coefficients, improving scalability and robustness.

Findings

Algorithm converges to optimal power allocation.

Requires only local information exchange.

Robust to different channel fading conditions.

Abstract

This paper investigates the distributed power allocation problem for coordinated multipoint (CoMP) transmissions in distributed antenna systems (DAS). Traditional duality based optimization techniques cannot be directly applied to this problem, because the non-strict concavity of the CoMP transmission's achievable rate with respect to the transmission power induces that the local power allocation subproblems have non-unique optimum solutions. We propose a distributed power allocation algorithm to resolve this non-strict concavity difficulty. This algorithm only requires local information exchange among neighboring base stations serving the same user, and is thus scalable as the network size grows. The step-size parameters of this algorithm are determined by only local user access relationship (i.e., the number of users served by each antenna), but do not rely on channel coefficients. Therefore, the convergence speed of this algorithm is quite robust to different channel fading coefficients. We rigorously prove that this algorithm converges to an optimum solution of the power allocation problem. Simulation results are presented to demonstrate the effectiveness of the proposed power allocation algorithm.