Scheduling in Multimedia Wireless Networks

Wednesday, August 8, 2001 - 9:30am - 10:30am
Keller 3-180
Rajeev Agrawal (Motorola)
Wireless systems in the future will have to provide multimedia services where different users have different physical-layer and network-layer QoS requirements. We investigate the use of power control, processing gain, and scheduling in CDMA systems to accommodate these diverse service requirements. First, we derive the time-sharing capacity region for any channel state which is given in terms of the convex hull of the set of user bit rates that can be supported simultaneously subject to physical-layer QoS requirements. Therefore by choosing any bit rate vector in the time-sharing capacity region, we automatically satisfy the physical-layer QoS requirements. Thus, it is the control knob used by the scheduler to satisfy the network layer QoS requirements. We consider the problem of scheduling on fading channels where the channel state varies with time. We design a class of scheduling policies that guarantees system stability. We use simulation to compare the performance of various policies in this class. Specially, we show that the new Minimum Draining Time policy has certain desirable qualities vis-a-vis the Cone policy and Modified Cone policy. All three are special cases of the class of policies for which we show stability.