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Bug #2734

Feature #2724: Improve default timers

RF channel teradown timers (T3109) way too large

Added by laforge 12 months ago. Updated 11 months ago.

Status:
Closed
Priority:
Normal
Assignee:
Category:
-
Target version:
-
Start date:
12/10/2017
Due date:
% Done:

100%

Spec Reference:

Description

When the BSC wants to tear down a logical channel, it
  1. sends a RR CHANnel RELease to the MS via the LAPDm link (RLL on Abis)
  2. deactivates the SACCH locally on the BSS side
  3. waits for 20s, and only then issues a RF CHANnel RELease on RSL which deactivates the channel

This means that a MS that is not responding to the RR CHAN REL (because it is out of range, was switched off, is broken, has lost radio signal) causes us to use the scarce radio channel for 20s more than needed.

According to 3GP TS 44.018 Section 3.4.13, this is timer T3109 (between RR CHAN REL and RF CHAN REL). It is set to 19 seconds in our default, which is ridiculously long.

There's also T3111 which should be started when the main signalling link is disconnected.


Related issues

Related to OsmoBSC - Bug #1610: RF channel release skipping T3109Resolved2016-02-23

History

#1 Updated by laforge 12 months ago

  • Subject changed from RF channel teradown timers way too large to RF channel teradown timers (T3109) way too large

#2 Updated by laforge 12 months ago

  • Related to Bug #1610: RF channel release skipping T3109 added

#3 Updated by laforge 12 months ago

  • Status changed from New to In Progress

I could find several recommendations in the magnitude of 5s

#4 Updated by laforge 12 months ago

  • % Done changed from 0 to 80

https://gerrit.osmocom.org/#/c/5283/ implements a change to a default of 5s

#5 Updated by laforge 11 months ago

  • Status changed from In Progress to Closed
  • % Done changed from 80 to 100

patch now merged.

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