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Feature #4546

closed

baseband frequency hopping support for osmo-bts-trx

Added by laforge almost 4 years ago. Updated over 3 years ago.

Status:
Resolved
Priority:
Normal
Assignee:
Category:
osmo-bts-trx
Target version:
-
Start date:
05/12/2020
Due date:
% Done:

100%

Spec Reference:

Description

The idea of baseband frequency hopping is to "commutate" the bursts among the available TRX.

So we have a BTS with e.g. 4 TRX. TRX0 carries the CCCH and hence cannot do hopping. However, TRX1 to TRX3 can implement baseband hopping.

This works by having each of the TRX on a fixed ARFCN (no tuning or actual hopping of the carrier frequency). The trick is to then assign dedicated channels (TCH + SDCCH) not on one ARFCN but on a hopping sequence that "hops" between those three ARFCN, basically jumping to a different ARFCN for every burst.

This feature would be implemented in osmo-bts. It has four separate streams of bursts to/from the four TRX in the example above, and it needs to re-order them according to the hopping sequences before passing them into the convolutional decoder.


Files

osmo-bts-trx.dot osmo-bts-trx.dot 1.49 KB fixeria, 06/06/2020 12:13 PM

Checklist

  • pass the hopping parameters (MAIO, HSN, ...) over the PCU socket so the PCU knows about them (common part)
  • handle/parse hopping channels on A-bis OML + RSL (common part)
  • commutator between "gsm_bts_trx" and "radio carrier" doing the actual hopping
  • automatic TTCN3 testing of frequency hopping configurations

Related issues

Related to OsmocomBB - Bug #4658: Wrong burst order in a multi-trx setupStalledfixeria07/08/2020

Actions
Related to OsmoBTS - Bug #4708: Various SMSCB test cases fail with frequency hopping enabledResolvedfixeria08/13/2020

Actions
Precedes OsmoPCU - Feature #4547: support for frequency hopping in osmo-pcuResolvedfixeria05/13/2020

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