ETSI - TS 102 929
Speech and multimedia Transmission Quality (STQ); Procedures for the identification and selection of common modes of de-jitter buffers and echo cancellers
|Publication Date:||1 March 2018|
De-jitter buffers and echo cancellers have a major effect on voice and data transmission quality in telecommunication networks. They affect the three service categories of PSTN/ISDN voice, voiceband data (due to PSTN modem and fax calls), and ISDN circuit mode data. Since the requirements for the settings of de-jitter buffers differ for different services, the present document describes the activation and mode switching procedures of de-jitter buffers and echo cancellers, including the requirement for in-band tone activating and other control mechanisms.
It is assumed that the clock accuracy of all elements involved is sufficiently high for application of the present document.
The scope of the present document is considering de-jitter buffer usage in circuit-to-IP media gateways, such as residential, access or trunking gateways in context of NGN/IMS.
The notion of circuit relates to a PSTN analog line or an ISDN 1x64 bearer channel.
The current version of the present document contains additional de-Jitter Buffer requirements for the transmission of V.152, Echo Canceller Tests and de-Jitter Buffer Tests.
The requirements for Echo Cancellers and de-Jitter Buffers in for speech transmission are out of scope in the present document. These requirements are covered in ETSI ES 202 718 [i.27].
The present document is:
a1) to circuit-to-IP media gateways and communication services with a gateway interworking function operating at the level of a synchronous byte-stream, such as:
- service "voice-over-IP" (VoIP) without or with silence suppression;
- service "voiceband data-over-IP" (VBDoIP); and
- service "circuit-mode data-over-IP" (CMDoIP);
a2) to IP-to-IP media gateways for dedicated interworking services between two IP domains, such as:
- service "IPDV reduction between two IP domains" with different Grade of Service (GoS) as e.g. described in Recommendation ITU-T G.799.3 [i.22];
- service "RTP IPDV reduction between two RTP domains", which may be subject of an "RTP transport translator" topology (see IETF RFC 5117 [i.23] and Recommendation ITU-T H.248.88 [i.24]);
- but IP-to-IP media gateways are basically out of scope of the present document due to its focus on circuit-to-IP gateway types; and is:
b) not applicable, because de-jitter buffers are not required:
b1) to circuit-to-IP media gateways and communication services with a gateway interworking function operating at the level of individual packets as atomic units (i.e. an asynchronous packet-stream), such as:
service "facsimile-over-IP" (FoIP) according to [i.7];
service "text-over-IP" (ToIP) according to [i.25]; and
service "data-over-IP" (MoIP) according to [i.26];
b2) to IP-to-IP media gateways in general.
Additionally the present document contains Transmission Requirements for Media Gateways (MGWs) with respect to voiceband data (VBD) and 64 kbit/s transparent data service.