Providing reliable and efficient VoIP over WCDMA

摘要

The architecture of the IP Multimedia Subsystem (IMS) defined by the Third Generation Partnership Project (3GPP) provides a solid base for solutions for interconnecting fixed and wireless networks and supplying new services over them, such as voice over IP (VoIP). Compared with circuit-switched voice, the main end-user benefit of VoIP is the ease with which end users can enrich basic voice service with multimedia services during an ongoing session. Improved end-user flexibility will also probably lead to an increase in traffic and operator revenues. VoIP also has the potential to help operators lower their operating costs by converging their networks into a single all-IP network. The challenges associated with deploying VoIP over mobile systems include matching the efficiency and quality of circuit-switched voice service while maintaining the inherent flexibility of IP-based services. In the process, one must consider every aspect of the VoIP realization, from compression of IP header overhead to radio access bearer, including quality enhancements and the handling of jitter. The authors provide an overview of VoIP and its transmission over mobile radio links with available packet-based access (GPRS/EDGE, WCDMA) and dedicated bearers (HSDPA/E-UL). They also describe the capabilities a radio network must have to provide a flexible packet-switched voice service with adequate quality and capacity.