Classical Water-Filling Power Allocation Algorithm

In this article, we provide a detailed examination of three distinct water-filling power allocation algorithms: the classical water-filling algorithm, iterative block water-filling algorithm, and carrier leakage-aware power allocation algorithm. We conduct throughput comparisons to analyze their respective advantages and limitations. For readers unfamiliar with these algorithms, we offer comprehensive explanations of each method's operational principles and practical applications, including key mathematical formulations such as the Lagrangian multiplier optimization for power constraints. The implementation typically involves sorting subchannel gains and iteratively calculating optimal power levels until the total power budget is satisfied. Additionally, we discuss scenario-specific suitability of these algorithms and their potential future developments. This article aims to enhance understanding of power allocation strategies in communication systems through practical code implementation insights and performance comparisons.