OFDM Downlink Scheduling for Delay-Optimality: Many-Channel Many-Source Asymptotics With General Arrival Processes
The authors consider the downlink of an OFDM system for supporting a large number of delay-sensitive users. The OFDM scheduling problem can be modeled as a discrete-time multisource multi-server queuing system with time-varying connectivity. For such a system, the Max-Weight policy is known to be throughput-optimal and the Server-Side Greedy (SSG) policy has been recently shown to achieve small queue lengths for i.i.d. arrival processes. However, there is often significant difference between queue-length optimality and delay optimality, and there exist arrival patterns such that algorithms with small queue backlog can still lead to large delay.