New approach to bit loading and power minimization using mercury/waterfilling

This paper investigates mercury/waterfilling (MWF) power distribution policy for multi-carrier systems and its potential benefits. Comparing the performance in terms of bit error rate with conventional bit loading algorithm for practical systems, like Levin Campello (LC), we demonstrated that its power distribution is not optimal as widely believed due to the gap approximation inaccuracy for low constellation sizes. This fact can be used to improve system stability by achieving lower bit error rates or decreasing noise margin. Furthermore, we proposed a new formulation for throughput optimization seen as a combinatorial problem due to discrete nature of modulations used in practical systems. Moreover, we developed a new bit loading algorithm based on MWF as solution to this problem that gives higher throughput than LC under the same set of constraints. We also developed an algorithm for power minimization that enables power savings compared to LC while keeping the same quality of service as before. These strategies can be beneficial to operators in reduction of their operational costs.