A heuristic for dynamic bandwidth allocation with preemption and degradation for prioritized requests

Bandwidth allocation is a fundamental problem in communication networks. The problem of bandwidth allocation is further intensified when the requested bandwidth exceeds the available unused bandwidth and so not all requests can be completely served. This research examines on-line bandwidth allocation, where the decision for acceptance or rejection of the request has to be made when future requests and their arrival statistics are not known. A request can be defined as a flow of information from a source to a destination with a certain amount of bandwidth, a priority level, a utility function that is based on the bandwidth received and a worth that is based on the utility function and the priority level. The goal of this research is to develop a scheduling heuristic for an overloaded system that attempts to schedule the requests such that the sum of the worths of the requests satisfied in a fixed interval of rime is the maximum. The scheduling heuristic can preempt or degrade already-scheduled requests. Three different types of utility functions (step, linear, and concave) are examined. Other parameters being considered include network loading and the relative weights of the different priority levels. The heuristic variations developed are shown to perform well compared to a complete sharing policy and an upper bound.