diff options
Diffstat (limited to 'doc/manuals/abis/rtp.adoc')
| -rw-r--r-- | doc/manuals/abis/rtp.adoc | 33 |
1 files changed, 33 insertions, 0 deletions
diff --git a/doc/manuals/abis/rtp.adoc b/doc/manuals/abis/rtp.adoc new file mode 100644 index 00000000..dde56515 --- /dev/null +++ b/doc/manuals/abis/rtp.adoc @@ -0,0 +1,33 @@ +== User-Plane Traffic via RTP + +RTP (Realtime Transfer Protocol) is a protocol for streaming audio +and video data. It is specified by IETF RFC 1889. + +OsmoBTS A-bis/IP implements RTP as transport medium for circuit-switched +user-plane traffic, contrary to the E1 sub-slot based transport +specified in 3GPP TS 08.60. + +The RTP transport endpoint parameters are configured using the RSL User +Plane Transport Management procedures described in <<user_plane_txp_mgmt>>. + +RTCP is implemented in addition to RTP, on a UDP port number of the RTP +port incremented by one. + +=== RTP Payload Formats + +The RTP payload format depends on the voice codec used on the radio +channel. The OsmoBTS is simply passing the GSM speech frames between +the Um radio interface channels and the RTP payload (and vice-versa). + +No transcoding function is implemented in the BTS! + +.RTP Payload formats +[options="header",width="60%",cols="15%,15%,70%"] +|=== +| TCH | Codec | RTP payload format specification +| TCH/F | FR | IETF RFC 3551 Section 4.5.8 +| TCH/F | EFR | IETF RFC 3551 Section 4.5.9 +| TCH/F | AMR | IETF RFC 4867 +| TCH/H | HR | IETF RFC 5993 +| TCH/H | AMR | IETF RFC 4867 +|=== |