The effects of user mobility on usage parameter control (UPC) in wireless ATM systems

Wireless asynchronous transfer mode (WATM) networks pose new traffic management problems. One example is the effect of user mobility on usage parameter control (UPC). If the UPC algorithm resets after each handoff between wireless-cells, then users can cheat on their traffic contract. In brief, UPC is analogous to a digital filtering operation, with an associated convergence time. If a user changes wireless-cells before the UPC algorithm converges then UPC can not determine whether that user complied with their traffic contract. This paper derives explicit relationships between a user's traffic parameters (peak cell rate, sustained cell rate and maximum burst size), their transit time per wireless-cell, their maximum sustained cheating-rate and the generic cell rate algorithm's (GCRAs) limit (L) parameter. It also shows that the GCRA can still effectively police constant bit rate (CBR) traffic, but not some types of realistic variable bit rate (VBR) traffic. Finally, it discusses three solutions for this new network impairment.