The Contention Behavior of DOCSIS in CATV Networks

In this paper, we study the contention behavior of DOCSIS in cable TV networks. Specifically, we focus on the behavior of TCP over DOCSIS. We determine the expected access delay for TCP transmissions in CATV networks. The access delay here is defined as the interval between the time when a data packet arrives at a cable modem (CM) and the time when that packet is successfully sent by the CM. The analytical model is comprised of two parts. The first part is to calculate the probability that a CM sends a request in a randomly selected minislot, and the second part is to derive the expected access delay based on the probability derived in the first part. The accuracy of the analytical model is validated by simulations. The results show that our analytical model can accurately model the contention behavior of DOCSIS in CATV networks.