Question 2/12 - Speech transmission characteristics and measurement methods for terminals and gateways interfacing packet-switched (IP) networks
(Continuation of Question 2/12)
Motivation
Traditionally, the analogue and digital telephones were interfacing switched-circuit 64 kbit/s PCM networks. With the fast growth of IP networks, terminals directly interfacing packet-switched networks (VoIP) are being rapidly introduced. Such IP network edge devices may include gateways, specifically designed IP phones, soft phones or other devices connected to the IP based networks and providing telephony service. Since the IP networks will be in many cases interworking with the traditional PSTN and private networks, many of the basic transmission requirements have to be harmonized with specifications for traditional digital terminals. However, due to the unique characteristics of the IP networks including packet loss, delay, etc. new performance specification, as well as appropriate measuring methods, will have to be developed. Also, the VoIP terminals may use other than 64 kbit/s PCM (G.711) speech algorithms, as well as may provide traditional narrow-band (300-3400 Hz) or wideband telephony.
A VoIP terminal can be considered as a kind of VoIP gateway with an additional acoustical frontend; by this, the requirements and measurement methodologies developed for VoIP gateways can easily be applied for VoIP terminals by defining a hypothetical reference point between the gateway function and the acoustical frontend. The latter falls under the responsibility of Question 3/12.
The following major Recommendations/Supplements/Handbooks, in force at the time of approval of this Question, fall under its responsibility:
Recommendation P.1010
Question
Study items to be considered include, but are not limited to:
- Which transmission characteristics need to be defined for VoIP gateways and the VoIP gateway part of VoP terminals?
- Which measurement methods are needed for for VoIP gateways and the VoIP gateway part of VoIP terminals?
- How can coding schemes other than G.711 best be taken into account (for narrowband telephony as well as for wideband telephony) ?
- How can an IP "half channel" adaptor, which may also be referred to as "reference codec" be defined ?
- Which measurement methodology is appropriate to quantify distortions that are typical for IP based devices ?
- Which reference connections in the chain from mouth-to-ear can be defined for VoIP ?
Tasks
Tasks include, but are not limited to:
- Enhancement of Recommendation P.1010 on Fundamental Voice Transmission Objectives for IP Terminals and Gateways regarding wideband telephony
- Production of a new Recommendation P.VOIP-MM on Measurement Methodologies for IP Terminals and Gateways
- Contribution to possible extensions or enhancements of Recommendations P.501 and P.502.
Note: P.VOIP-MM may be included into P.1010, this is for further discussion.
Relationships
Recommendations: P.310, P.311, P.340, P.342, P.501, P.502, G.107, G.108, G.109, G.177, G.799.1, M.2301, Y.1540, Y.1541
Questions: 3/12, 6/12, 9/12, 11/12, 12/12, 17/12
Study Groups: 4, 13, 15
Standardisation bodies: ETSI STQ, ETSI TISPAN, TIA TR-41, T1A1
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