Feature #4941


VAMOS support in OsmoBTS

Added by laforge about 2 years ago. Updated 11 months ago.

Target version:
Start date:
Due date:
% Done:


Spec Reference:


This ticket should document what needs to be done in terms of supporting VAMOS from OsmoBTS, and to track its status via check-lists and possibly sub-issues.

Our implementation will be focusing on osmo-bts-trx as none of the "proprietary PHY" we support implement any VAMOS support.

This likely includes (at least)
  1. Indication of [which level of] VAMOS support the BTS has via OML attributes to BSC
  2. Implementation of "shadow TRX" concept in data structures
  3. Implementation of VAMOS related RSL extensions on Abis
  4. Implementation of a new TRXDv2 protocol from/to the TRX
  5. VAMOS-aware uplink + downlink power control
  6. generation of one set of downlink symbols from the real + shadow timeslot/lchan

The corresponding BSC related work is tracked in #4940


  • CMI mapping as per 3GPP TS 45.009, section

Related issues

Related to OsmoBSC - Feature #4940: VAMOS support in OsmoBSCStalledneels01/12/2021

Related to Cellular Network Infrastructure - Feature #4006: TRX protocol: wind of changeStalledfixeria05/17/2019

Blocked by Cellular Network Infrastructure - Bug #5112: osmo-gsm-manuals: build verification is brokenResolvedfixeria04/10/2021

Actions #1

Updated by laforge about 2 years ago

Actions #2

Updated by Hoernchen about 2 years ago

According to chapter 4 random pairings with scpir=0 should be fine for the time being.

Actions #3

Updated by fixeria about 2 years ago

  • Status changed from New to In Progress
Actions #4

Updated by fixeria almost 2 years ago

Actions #5

Updated by fixeria almost 2 years ago

  • Blocked by Bug #5112: osmo-gsm-manuals: build verification is broken added
Actions #6

Updated by fixeria almost 2 years ago

  • % Done changed from 0 to 20

I've submitted a bunch of TRXDv2 related changes to Gerrit: osmo-bts-trx: cosmetic: TRXD 'header version' -> 'PDU version' osmo-bts-trx: remove outdated TRXD protocol documentation osmo-bts-trx: cosmetic: use '#pragma once' in trx_if.h osmo-bts-trx: reduce and share TRXC message buffer size osmo-bts-trx: move TRXD message length to trx_if.h osmo-bts-trx: 'burst type' is actually modulation type osmo-bts-trx: move MTS parser into trx_data_parse_mts() osmo-bts-trx: discard TRXD PDUs with unexpected version osmo-bts-trx: move TDMA frame number check to trx_data_read_cb() osmo-bts-trx: cosmetic: get rid of TRX_CHDR_LEN macro osmo-bts-trx: refactor handling of version specific TRXD parts osmo-bts-trx: implement TRXDv2 protocol support

together with other L1SAP/RSL related changes (all of them have been merged): protocol/gsm_08_58.h: add RSL_CMOD_SP_{GSM4,GSM5,GSM6} protocol/gsm_08_58.h: add more 'Channel rate and type' values protocol/gsm_08_58.h: add asymmetric CSD data rates l1sap: fix incorrect pointer cast in l1sap_chan_act() rsl: rename, fix and refactor lchan_tchmode_from_cmode() rsl: add missing Channel Mode values to rsl_handle_chan_mod_ie()

Actions #7

Updated by fixeria over 1 year ago

  • % Done changed from 20 to 60

For some reason, the related changes are not appearing here automatically, so adding manually:

remote: [VAMOS] osmo-bts-trx: rework and split up bts_sched_fn() [NEW]
remote: [VAMOS] osmo-bts-trx: implement and enable PDU batching for TRXDv2 [NEW]
remote: [VAMOS] osmo-bts-trx: indicate MTS in Downlink TRXDv2 PDUs [NEW]
remote: [VAMOS] common/scheduler: unify symbol names for training sequences [NEW]
remote: [VAMOS] struct gsm_lchan: store Training Sequence Code/Set [NEW]
remote: [VAMOS] scheduler: add new GMSK training sequences from 3GPP 45.002 [NEW]
remote: [VAMOS] Implement the concept of 'shadow' transceiver [WIP]
remote: [VAMOS] l1sap_chan_act(): handle Osmocom specific Training Sequence IE [NEW]

Actions #8

Updated by fixeria over 1 year ago

  • Status changed from In Progress to Feedback
  • % Done changed from 60 to 90

Everything is implemented except "VAMOS-aware uplink + downlink power control", but some patches got stuck in Gerrit:

Actions #9

Updated by fixeria over 1 year ago

  • Status changed from Feedback to Stalled
  • Priority changed from Urgent to Normal
Actions #10

Updated by fixeria 11 months ago

  • Checklist item CMI mapping as per 3GPP TS 45.009, section added

3GPP TS 45.009, section defines different TDMA frame numbers for channels in VAMOS mode. See tables{3,4}.


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