Adaptive scheduling in DOCSIS-based CATV networks

This paper studies the effect of the DOCSIS MAC layer on the performance of two-way TCP transfers in hybrid fiber coax (HFC) networks. We propose a new adaptive scheduling scheme called long packet deferment (LPD) at the headend to improve TCP performance in DOCSIS-based HFC networks. LPD reduces the frequency of transmission of long packets and, if such long packets are transmitted, they are scheduled towards the end of each transmission period. Thus, it allows the system to behave as in a symmetric network earlier, reduces the round trip delay of sending data packets, and improves the aggregate downstream throughput. We have conducted simulations using network simulator ns-2 to compare the simple first-come-first-served scheduling of DOCSIS and IEEE 802.14 like mechanism with LPD. The results show that LPD has better performance in terms of higher aggregate downstream throughput and shorter access delay.