Scheduling of Voice Packets in a Low-Bandwidth Shared Medium Access Network

This paper addresses the schedulability of VoIP packets in a low-bandwidth shared medium broadband access network. We show that EDF (Earliest Deadline First) without preemption is an optimal scheduling algorithm for the case where the size of the packets and the tolerated jitter are equal for all the packets, in the sense that no other algorithm, with or without preemption, may schedule more packets on time. We then employ this algorithm in order to concentrate upon two issues related to the effect of VoIP codec functionality on the schedulability of VoIP packets: packetization delay and silence suppression. We show that in both cases there are two counter-forces affecting the schedulability of the VoIP packets, and we use simulations in order to get in-depth understanding of these counter-forces under different conditions.