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fixeria gerrit-no-reply at lists.osmocom.orgfixeria has submitted this change. ( https://gerrit.osmocom.org/c/osmo-gsm-manuals/+/22622 ) Change subject: TRXD: more information on PDU versioning and some highlights ...................................................................... TRXD: more information on PDU versioning and some highlights Change-Id: Idac4a1c73cc92bf030ea80474c71688bfb706421 Related: SYS#4895, OS#4941, OS#4006 --- M common/chapters/trx_if.adoc 1 file changed, 41 insertions(+), 9 deletions(-) Approvals: Jenkins Builder: Verified laforge: Looks good to me, but someone else must approve pespin: Looks good to me, approved diff --git a/common/chapters/trx_if.adoc b/common/chapters/trx_if.adoc index ef2740b..d1aa566 100644 --- a/common/chapters/trx_if.adoc +++ b/common/chapters/trx_if.adoc @@ -311,15 +311,16 @@ NOTE: In the example for `HVHH`, legacy TCH/H0 does not belong to a _VAMOS pair_, so it can be configured to use any Training Sequence Code without restrictions. +[[trx_if_pdu_version_nego]] ==== TRXD header version negotiation -Messages on DATA interface may have different header formats, defined by a -version number, which can be negotiated on the control interface. By default, -the Transceiver will use the legacy header version (0). +Messages on DATA interface may have different formats, defined by a version number, +which can be negotiated on the control interface. By default, the Transceiver will +use the legacy header version (0). See <<trx_if_pdu_versioning>>. -The header format negotiation can be initiated by the BTS using `SETFORMAT` -command. If the requested version is not supported by the transceiver, status -code of the response message should indicate a preferred (basically, the latest) +The format negotiation can be initiated by the BTS using `SETFORMAT` command. +If the requested version is not supported by the transceiver, status code of +the response message should indicate a preferred (basically, the latest) version. The format of this message is the following: ---- CMD SETFORMAT <ver_req> @@ -353,7 +354,38 @@ === TRXD protocol -Messages on the data interface carry one radio burst per UDP message. +PDUs on the data interface carry one radio burst per one UDP packet. +Two kinds of TRXD PDU exist: + +* `TRX -> L1` (from transceiver to the L1): Uplink messages received from the MS, +* `L1 -> TRX` (from the L1 to transceiver): Downlink messages sent to the MS. + +Depending on the origin and the version indicator, PDUs may have different structure. + +[[trx_if_pdu_versioning]] +==== PDU versioning + +The format of a PDU, i.e. presence and ordering of certain fields, is determined by +the version number indicated in the first octet. This is usually referred as +`TRXDvN`, where `N` is the version number (e.g. TRXDv0 or TRXDv1). A version number +indicates the message format to be used for both directions: `TRX -> L1` and +`L1 -> TRX`. The same version shall be used for all messages in both directions, +mixing in any way is not permitted. + +The version negotiation is optionally initiated by the `L1` on the control interface, +and expected to be performed before starting the transceiver (i.e. sending `POWERON` +command). See <<trx_if_pdu_version_nego>>. + +The current header allows to distinguish up to 16 different versions. +The following versions are defined so far: + +* TRXDv0 - initial version of TRXD protocol, inherited as-is from OpenBTS project. +* TRXDv1 (proposed in July 2019): +** Introduced the concept of protocol versioning; +** Introduced NOPE / IDLE indications; +** New field: MTS (Modulation and Training Sequence); +** New field: C/I (Carrier-to-interface) ratio; +** Downlink messages mostly unchanged. ==== Uplink Data Burst @@ -417,7 +449,7 @@ ---- VER: 4 bits:: -TRXD header version, v0 and v1 are specified so far. +TRXD header version, common for both `TRX -> L1` and `L1 -> TRX` directions. TN: 3 bits:: Timeslot number. @@ -542,7 +574,7 @@ ---- VER: 4 bits:: -TRXD header version, v0 and v1 are specified so far. +TRXD header version, common for both `TRX -> L1` and `L1 -> TRX` directions. TN: 3 bits:: Timeslot number. -- To view, visit https://gerrit.osmocom.org/c/osmo-gsm-manuals/+/22622 To unsubscribe, or for help writing mail filters, visit https://gerrit.osmocom.org/settings Gerrit-Project: osmo-gsm-manuals Gerrit-Branch: master Gerrit-Change-Id: Idac4a1c73cc92bf030ea80474c71688bfb706421 Gerrit-Change-Number: 22622 Gerrit-PatchSet: 2 Gerrit-Owner: fixeria <vyanitskiy at sysmocom.de> Gerrit-Reviewer: Jenkins Builder Gerrit-Reviewer: fixeria <vyanitskiy at sysmocom.de> Gerrit-Reviewer: laforge <laforge at osmocom.org> Gerrit-Reviewer: pespin <pespin at sysmocom.de> Gerrit-MessageType: merged -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.osmocom.org/pipermail/gerrit-log/attachments/20210213/1cc99756/attachment.htm>