Elimination of limit cycles in wireless communication networks using three-level comparators

In this paper, the problem of interference management in the reverse channel (uplink) of CDMA2000 system is studied. Using a simple model for IS-856 uplink, the rate assignment in the network is formulated in the context of feedback control systems. A three-level quantization is employed for the characterization of the interference regulation error in the base station (as apposed to traditional two-level comparison). Using describing function analysis, it is shown that by adopting this type of comparison scheme the undesirable oscillation in the network can be eliminated. This, in turn, improves the performance of the network significantly, at the expense of a more complex implementation. Simulations are provided to demonstrate the efficiency of the proposed scheme.