SIPPING Ravi Raviraj Internet-Draft Psytechnics Expires: December 29, 2007 June 29, 2007 Session Initiation Protocol Package for Voice Quality Reporting Event draft-raviraj-sipping-endpoint-mos-00 Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on December 29, 2007. Copyright Notice Copyright (C) The IETF Trust (2007). Raviraj Expires December 29, 2007 [Page 1] Internet-Draft endpoint-mos February 2007 Abstract This document introduces the concept of Mean Opinion Score (MOS) and briefly describes the types and variations of MOS within an end point, thus justifying the need for a perceptual-objective-MOS SIP event package. Table of Contents 1. Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Mean Opinion Score (MOS) . . . . . . . . . . . . . . . . . . 3 3. MOS variations . . . . . . . . . . . . . . . . . . . . . . . 3 4. MOS reporting . . . . . . . . . . . . . . . . . . . . . . . . 4 5. References . . . . . . . . . . . . . . . . . . . . . . . . . 4 Raviraj Expires December 29, 2007 [Page 2] Internet-Draft endpoint-mos February 2007 1. Overview Over the last few years, a number of perceptual media quality measures have been standardized by ITU-T. For example, MOS-LQO, MOS-CQO, etc. Many of these quality measures could have a number of variations like narrow-band/wide-band, electrical/acoustical, full reference/no- reference, algorithm types etc. When applied within a network end- point, each media direction (ingress/egress) could have one or more of these values associated with it. We need a way to report these values efficiently without any ambiguity. These MOS values could be sent/distributed as perceptual objective quality SIP events. In this way, all the advantages of SIP like mobility, etc. will be pulled in. 2. Mean Opinion Score (MOS) The abbreviation MOS (Mean Opinion Score) is defined in ITU-T Rec. P.10/G.100[1] in the following way: The mean opinion scores, i.e., of the values on a predefined scale that subjects assign to their opinion of the performance of the telephone transmission system used either for conversation or for listening to spoken material. The ITU-T Rec. P.800.1[2] extends this further by saying the following. Apart from subjective opinion, the abbreviation MOS is also used for scores that originates from objective models or network planning models. In effect, it categorizes MOS into three broad groups: subjective MOS; scores given by human subjects, objective MOS; objective prediction of subjective MOS and estimation MOS; estimation by a network planning model. Additionally, it also defines another three orthogonal categories: listening MOS, Talking MOS and conversational MOS. Combining these two categories results in nine different types of MOS. 3. MOS variations The MOS type described above could have many variations: - Up to four variations based on the audio bandwidth: narrow-band, wide-band, uper-wide-band and full-band. - Variations in the algorithm used. For example, ITU-T Rec. P.564[3] defines two different compliance classes. - Variations based on stream direction. Within a simple endpoint where there are two directional streams (ingress and egress direction), there may be MOS for each direction. This particular variation does not apply to conversational MOS types. However, conversational MOS could have two other types of variations; local end conversational quality and remote end conversational quality. - Variations based on the measurement point; electrical, acoustical or packet-level. - Variations based on reference usage/availability; full reference or no reference. Raviraj Expires December 29, 2007 [Page 3] Internet-Draft endpoint-mos February 2007 The above list is not exhaustive and it is important to realize that, all these variations are within a simple end point. End points with multiple streams like conference stations may have additional variations. Although there are many possible combinations, not all are practical. Some combinations are already well defined, some are being defined and others are expected to be defined in the near future. A given end point will not support all well defined combinations. Instead, they can be expected to support a small subset of them. This subset will vary depending on the network and operating scenario. 4. MOS reporting Real-time reporting of various objective MOS types is an immediate requirement. An obvious method to send these MOS values is to use a SIP event. A perceptual objective MOS SIP event could report these values efficiently and without any ambiguity. 5. References [1] ITU-T recommendation P.10/G.100, "Vocabulary for performance and quality of service", July 2006. [2] ITU-T recommendation P.800.1, "Mean Opinion Score (MOS) terminology", July 2006. [3] ITU-T recommendation P.564, "Conformance testing for narrowband voice over IP transmission quality assessment models", July 2006. Author's Address Ravi Raviraj Psytechnics Ltd. Fraser House 23 Museum Street Ipswich, Suffolk IP1 1HN UK Phone: +44 1473 261866 Email: ravi.raviraj@psytechnics.com URI: http://www.psytechnics.com Raviraj Expires December 29, 2007 [Page 4] Internet-Draft endpoint-mos February 2007 Full Copyright Statement Copyright (C) The IETF Trust (2007). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. 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