Voice transmission over IP (VoIP) presents many problems, mainly due to the high and unpredictable bandwidth variations of the current Internet. The paper shows that a net- work scenario where a portion of bandwidth is guaranteed for voice traffic is not sufficient to achieve good performance. For this reason the target of the paper is to propose a system architec- ture for voice transmission constituted by an IP network which reserves bandwidth for voice traffic and where routers use ac- tive queue management (AQM) techniques to provide feedback to voice sources regarding incoming congestion situations. Voice sources, based on Adaptive Multi-Rate (AMR) encoding tech- nique standardized by ETSI, implement a new rate-adaptation protocol, the Packet Size Adaptation Protocol (PSAP), to control their output rate in order to follow the bandwidth available on the network instant by instant. The system architecture proposed in the paper is then evaluated via simulation, and compared with a VoIP architecture widely used today. In the comparison, both source and destination side performance are considered, combin- ing network losses and perceived speech quality using the PESQ parameter recently standardized by ITU-T.
A New Adaptive-Rate Architecture for VoIP: Definition and Performance Evaluation
RUGGERI, Giuseppe;
2004-01-01
Abstract
Voice transmission over IP (VoIP) presents many problems, mainly due to the high and unpredictable bandwidth variations of the current Internet. The paper shows that a net- work scenario where a portion of bandwidth is guaranteed for voice traffic is not sufficient to achieve good performance. For this reason the target of the paper is to propose a system architec- ture for voice transmission constituted by an IP network which reserves bandwidth for voice traffic and where routers use ac- tive queue management (AQM) techniques to provide feedback to voice sources regarding incoming congestion situations. Voice sources, based on Adaptive Multi-Rate (AMR) encoding tech- nique standardized by ETSI, implement a new rate-adaptation protocol, the Packet Size Adaptation Protocol (PSAP), to control their output rate in order to follow the bandwidth available on the network instant by instant. The system architecture proposed in the paper is then evaluated via simulation, and compared with a VoIP architecture widely used today. In the comparison, both source and destination side performance are considered, combin- ing network losses and perceived speech quality using the PESQ parameter recently standardized by ITU-T.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
