Minimal Delay Violation-Based Cross-Layer Scheduler and Resource Allocation for DSL Networks

The quality of service of many modern communication systems depends on the delay performance of the underlying network. In digital subscriber line (DSL) networks, for example, crosstalk introduces competition for data rate among users, which influences the delay distribution. In such a competitive environment, delay performance is largely determined by the manner in which resources are dynamically allocated to the different users. A common approach to this allocation problem is through a cross-layer scheduler. Such a scheduler violates the OSI model by allowing communication between different layers, in order to steer the physical layer towards operating points that maximize some upper layer performance metric. In this paper, we present a new cross-layer scheduler and resource allocation algorithm in the context of DSL networks, referred to as the minimal delay violation (MDV) scheduler, which aims to minimize the number of delay violations and achieve a high throughput. Rather than solving a linear network utility maximization problem, as most other schedulers from literature, we consider a problem that is reciprocal with the service rate, allowing the scheduler to allocate the data rates at a finer level, while still maintaining good performance. Through simulations, we show that the MDV scheduler performs better than cross-layer scheduling algorithms from literature with respect to packet loss ratio, delay and throughput performance for various scenarios, and often operates closely to an ideal scheduler.