M. Nazih El-Derini and Mahmoud R. El-Sakka, "On The Selection Between Using the VT-CSMA or the P-VT-CSMA Protocol'', International Conference on Communication, Control, Computers, Energy, and Electronics, COMCONEL'1991, pp. 174-178, December 1991, Cairo, Egypt.


In some network applications, the success of transmitting packets depends not only on the correct transmission of data, but also on the transmission delay. In such cases, protocols which handle packet-based priorities and time constrain are needed. But those protocols favor to transmit high priority packets over low priority packets.

In this paper, a weighting function between using Virtual time CSMA (VT-CSMA) and Prioritized Virtual Time CSMA (P-TV-CSMA) protocols is introduced. By using this function, we can decide which protocol is better to use for a given load. Simulation results show that as the ratio between the cost of losing high priority to low priority packets increases, or as the ratio between the number of high priority to low priority packets increases, the threshold between using VT-CSMA and P-VT-CSMA protocols occurs at lower load.