Iterative Water-filling for Load-balancing in Wireless LAN or Microcellular Networks

This paper presents an efficient iterative load-balancing algorithm for time and bandwidth allocation among access points (APs) and users subject to heterogeneous fairness and application requirements. The algorithm can be carried out either at a central network switch with site-specific propagation predictions, or in a decentralized manner. The algorithm converges to maximum network resource utilization from any starting point, and usually converges in 3 to 9 iterations in various network conditions including users joining, leaving, and moving within a network and various network sizes. Such a fast convergence allows real-time implementations of our algorithm. Simulation results show that our algorithm has merits over other schemes especially when users exhibit clustered patterns: Our algorithm, when assuming multiple radios at each user, achieves 48% gain of median throughput as compared with the max-min fair load-balancing scheme (also with the multi-radio assumption) while losing 14% of fairness index; we also achieve 26% gain of median throughput and 52% gain of fairness index over the strongest-signal-first scheme (which assumes each user has only a single radio). When only a single radio is used, our algorithm is similar to the max-min fairness scheme, and is still better than SSF with 44% gain of 25-percentile throughput and 37% gain of fairness index