Contention resolution algorithms for CATV networks based on the DVB/DAVIC protocol

In a bi-directional Community Antenna Television (CATV) Network the use of a Contention Resolutions Algorithm (CRA) is essential in order to allocate the bandwidth of the multiaccess medium in the upstream direction between the active stations. Two of the CRAs known as exponential backoff algorithm and splitting tree algorithm, have recently been adopted by the Digital Video Broadcasting (DVB)/Digital Audio-Visual Council (DAVIC) Cable Television Protocol. In this paper we present a performance analysis and a comparison of both algorithms in terms of mean access delay and system throughput for different traffic source scenarios (i.e. Internet traffic, Voice over IP, and mixed traffic). The analysis focuses on changes in performance when selecting different backoff bounds for the exponential backoff algorithm and different values for the Entry-Spreading factor of the splitting tree algorithm. The results presented here show that an increase over 10% in system performance can be obtained by selecting the splitting tree algorithm for different traffic sources.