Investigation of Different Quality of Service Mechanisms in VoIP

Abstract

Voice over Internet Protocol (VoIP) has become a key technology of communication. Quality of Service (QoS) is fundamental to the operation of a Voice over Internet Protocol systems. It must provide a functionality and voice quality as a traditional telephone network. VoIP voice quality can be improved by adopting many Quality of Service (QoS) mechanisms. This research tries to find out which QoS mechanism provides the objective quality of voice in VoIP systems, investigating between three of most recently implemented techniques. Delay, Jitter and Packet loss are the basic metrics used in the above mentioned comparisons. In scenario one, various scheduler algorithms were investigated, simulation have shown that priority queuing (PQ) scheduler algorithm is the best algorithm can be applied in VoIP applications. Scenario two investigated RSVP which implemented only with Weighted Fair Queuing (WFQ) over different codecs. According to the achieved statistics G.723 recorded lowest statistics. Which means it is the best choice to improve performance. Scenario three investigated different scheduler algorithms over different codecs. The results indicated that PQ scheduler algorithm over codec G.723 is the best. As conclusion, the research declared which is the best in any mechanism. when more than one mechanism were merged good results were obtained, statistics show that G.723 is best codec and PQ is best algorithm also no doubt RSVP provide more quality, so PQ over codec G.723 is a good choice and RSVP over codec G.723 also are best choice.