Subject: [payload] new draft - RTP Payload Format for TETRA Audio Codec - pls review

From: REISENBAUER Andreas <[email-masked]>
Date: Tue, 16 Jan 2018 10:50:26 +0000

Dear IETF Payload WG,

I have recently uploaded a draft specifying TETRA Audio Codec payload in https://tools.ietf.org/html/draft-df-stecker-expertenforum-payload-tetra-00 

"This document specifies a Real-time Transport Protocol (RTP) payload
   format to be used for TETRA encoded speech signals.  The payload
   format is designed to be able to interoperate with existing TETRA
   transport formats on non-IP networks.  ..."

from chapter 3  "Media Format Background"
   "The TETRA codec is used as vocoder for TETRA systems.  The TETRA
   codec is designed for compressing 30ms of audio speech data into 137
   bits.  The TETRA codec is designed in such a way that on the air
   interface two of these 30ms samples are transported together (sub-
   block 1 and sub-block 2). ..."

Main motivation of this payload is to attach ground based applications (fixed terminal stations, control room applications) to TETRA networks. Those networks are still TDM based while ground based applications today are connected via IP. As typically control rooms consume a bunch of so called "TETRA talkgroups", it makes sense to use TETRA encoded audio (as it is realized as an ACELP encoder) to save high value quality of service bandwidth (8kBit/s net data rate rather than e.g. 64kBit/s with G.711) without any drawback in terms of decreased audio quality and _without_ any transcoding. TETRA codec anyhow is used as the one and only codec within the entire TETRA network (both the air as well as the ground infrastructure).

BTW: TETRA is still far away from being dead, it is still widely used and still expanded at authorities and civil services.

So I warmly invite you to review and give me your +1 on this draft that it can become an RFC sooner or later.

Many thanks
Andreas

----------------------------
Dipl. Ing. Andreas Reisenbauer
Principal Architect

FREQUENTIS AG
Address: A-1100 Wien, Innovationsstrasse 1