Scheduling Algorithms for Multi-Carrier Wireless Data Systems

We consider the problem of scheduling wireless data in systems such as 802.16 (WIMAX). Each scheduling decision involves constructing a frame of one or more time slots. Within each time slot multiple carriers must be assigned to users. The important aspect of our problem is that a scheduler knows the channel rates across all users and all carriers whenever a scheduling decision is made. Hence there is no need to treat each carrier in complete isolation. This gives a potential for enhancing performance by allocating multiple carriers simultaneously. We analyze this problem in a situation where finite queues are fed by a data arrival process. We generalize the well-known MaxWeight algorithm for the single-carrier setting to accommodate a number of natural optimization problems in the multi-carrier setting. We state the hardness of these problems and present simple algorithmic solutions with provable performance bounds. We also validate our algorithms via numerical examples.