Policy Driven Scheduling to Provide Differentiated QoS for Delay Sensitive Services in HSDPA

Increasing demand for high data-rate multimedia real time services has led to the use of asynchronous time shared channels in the forward link for real-time services in 3G wireless networks, such as HSDPA, EV-DO and EV-DV. While network service providers would like to impose operational policies on the packet schedulers based on QoS requirements by real-time services to maximize profit, existing schedulers are not capable to deal with such challenge due to time varying channel conditions and constraints on the total forward link transmit power. In this paper, we consider the problem of scheduling users on the forward link in a multiuser system where multiple users can be scheduled during each interval. We introduce a delay aware policy driven scheduling algorithm SPS-Delay (Strict Policy Scheduling for Delay) to support differentiated QoS requirements in the form of tolerable latency specified by the user applications. We developed an HSDPA system in OPNET, and implemented our scheduling algorithm along with other well- known algorithms. Our simulations show that SPS-Delay reduces packet drop rate by as much as 80% and increases the number of satisfied users by as much as 32% when compared to PF.