Dimensioning the contention channel of DOCSIS cable modem networks

Abstract

This paper presents an open queueing model with blocking that enables us to determine the optimal fraction c* of the uplink channel capacity that should be dedicated to the contention channel in order to minimize the mean response time in a DOCSIS cable network. To assess the performance of this queueing network we make use of a decomposition technique. One of the key components of the model exists in capturing the behavior of the conflict resolution algorithm by means of a single processor sharing queue. The model is validated in three successive steps by means of several simulation programs. We also explore the impact of a variety of systems parameters, e.g., the number of cable modems, the initial backoff window size, etc., on the optimum c*. © IFIP International Federation for Information Processing 2005.