QoS analysis of VoIP traffic for different codecs and frame counts per packet in multimedia environment using OPNET

Voice over IP (VoIP) is nowadays a common component of multimedia converged networks. In this paper, Quality of Service (QoS) analysis of VoIP traffic is presented in a multimedia network having other types of network traffic also deployed i.e. video, database and web. In such traffic occupied network, VoIP is configured with different codecs and frame counts per packet to observe the effect of these variations on the QoS of VoIP in terms of queuing delay, jitter, packet end-to-end delay and packet delay variation (end-to-end jitter) metrics. The significance of this paper is the emphasis on QoS evaluations in a VoIP deployment while observing the effects of variations in voice codecs and packet lengths. Many previous research papers focus on the perceived speech quality and packet losses; whereas queuing delays and end-to-end latency are usually not considered when analysis is done for different codecs and packet lengths at a time. We consider three main voice codecs (G.711, G.729 and G.723.1) and three frame counts per packet values (10, 25 and 50 voice frames per packet) under each codec. The simulation results show that G.723.1 voice encoding experiences higher queuing delays and queue delay variations (jitter) for higher numbers of frames per packet. However, the least packet end-to-end delay is observed in voice packets encoded with G.729 codec for all configured values of frames per packet.