ITU-T Study Group 12 is the expert group responsible for the development of international standards (ITU-T Recommendations) on performance, quality of service (QoS) and quality of experience (QoE). This work spans the full spectrum of terminals, networks and services, ranging from speech over fixed circuit-switched networks to multimedia applications over mobile and packet-based networks.
The evolution from circuit-switched to packet-based networks has introduced new challenges to the assessment of QoS/QoE, in large part stemming from the emergence of new multimedia services and applications. SG12 standards thus work to achieve the end-to-end performance levels required to support adequate QoS in an IP environment characterized by a wide array of user applications.
SG12’s standardization work targets operational aspects of performance, QoS and QoE; the end-to-end quality aspects of interoperability; and the development of both subjective and objective quality-assessment methodologies for multimedia services.
SG12 also leads ITU’s standardization work on services based on speech technology, voice aspects of car communications, hands-free communications in vehicles, and methods of minimizing technology-related driver distraction.
SG12 standards are designed to assess QoS across next-generation network’s (NGN) multiple network operators and, in some cases, unusual topologies and distances. A particular focus of SG12 is end-to-end quality, as perceived by the customer, delivered using paths that increasingly involve complex interactions between terminals and network technologies.
The ‘E-model’ for voice quality prediction (Recommendation ITU-T G.107) has seen widespread adoption, applicable in wireline and wireless scenarios based on both circuit-switched and packet-based technology. A second version of the model, the ‘Wideband E-model’ (Recommendation ITU-T G.107.1), predicts the quality of wideband speech services. The two models are an essential aid in transmission planning, helping operators to ensure that users will be satisfied with end-to-end transmission performance.
SG12’s work on QoS/QoE assessment of multimedia services has given rise to a recent highlight in the completion of a series of algorithmic models to monitor the quality of streamed audiovisual media (ITU-T P.1200 series). The model algorithms provide objective models for non-intrusive monitoring of the quality of video services, addressing both lower and higher resolution applications such as mobile TV and IPTV.
Recent SG12 achievements include technical requirements and test methods for the universal wired headset or headphone interface of digital mobile terminals (Recommendation ITU-T P.381), testing methods and QoE factors in web browsing (Recommendation ITU-T P.1501 and G.1031), and perceptual objective listening quality assessment (Recommendation ITU-T P.863 and P.863.1).
Another recent SG12 achievement was the completion of a standard addressing QoS in mobile networks (Recommendation ITU-T E.804), a methodology which looks at mobile QoS parameters from a user’s perspective. The standard defines QoS parameters and their computation for popular services in mobile networks such as e-mail, video streaming and voice; also describing the measurement procedures needed to perform the measurements of QoS parameters.