Iterative multi-user power allocation: performance evaluation & modification

Crosstalk is the major limiting factor in DSL systems in terms of bit-rate or service coverage. Multiuser power control algorithms can be used to combat crosstalk degrading effects. The best ever known distributed power control solution is iterative water-filling (IWF). In this paper the performance of IWF in an ADSL system is considered in terms of offered rate-region and convergence speed. Then, two novel modifications are proposed to accelerate convergence (usually 100∼400%) without any performance loss. Therefore, it suits better in practical applications, since each iteration needs re-initialization of the modem.