diff options
| author | Vadim Yanitskiy <vyanitskiy@sysmocom.de> | 2022-06-16 01:22:33 +0700 |
|---|---|---|
| committer | fixeria <vyanitskiy@sysmocom.de> | 2022-06-30 16:36:41 +0000 |
| commit | ff9d3a64dc8fec465140c244a816db22eea97b6b (patch) | |
| tree | 02c82c96b4f4de48a5e34f6d9f66410d3f10e343 /doc | |
| parent | 46fe68094415795a454ac049e7351cf779d03633 (diff) | |
lchan_select: prepare a list of timeslots once, iterate over it
The lchan_avail_by_type() attempts to find an unused lchan for the
given GSM_LCHAN_* value: TCH/F, TCH/H, or SDCCH. This is achieved
by looking up timeslots with compatible GSM_PCHAN_* values.
For instance, finding an unused SDCCH lchan may involve:
* attempt to find a timeslot with pchan=GSM_PCHAN_CCCH_SDCCH4,
* attempt to find a timeslot with pchan=GSM_PCHAN_CCCH_SDCCH4_CBCH,
* attempt to find a timeslot with pchan=GSM_PCHAN_SDCCH8_SACCH8C,
* attempt to find a timeslot with pchan=GSM_PCHAN_SDCCH8_SACCH8C_CBCH,
* attempt to find a timeslot with pchan=GSM_PCHAN_OSMO_DYN (switched),
* attempt to find a timeslot with pchan=GSM_PCHAN_OSMO_DYN (not switched).
Each attempt involves iterating over all timeslots of each TRX,
either in ascending or in descending order (see _lc_dyn_find_bts()
and _lc_find_trx()).
This patch simplifies the lookup logic by preparing a monolithic
array of timeslot pointers once, and then using that array for
each GSM_PCHAN_* lookup attempt. This change is required for the
upcoming dynamic channel allocation mode, which is fa more complex
than the existing ascending/descending ones.
A side effect of this change is that the interference aware mode
of allocation is not limited by the scope of a single TRX anymore.
Interference levels are now compared within the scope of the whole
BTS, so that lchans on the other TRXes may be picked if they are
better according to the interference reports from the BTS.
Change-Id: I7ccc56856bfd40fd7c63b7437736de60c2b516ff
Related: SYS#5460
Diffstat (limited to 'doc')
| -rw-r--r-- | doc/manuals/chapters/chan_alloc.adoc | 9 |
1 files changed, 5 insertions, 4 deletions
diff --git a/doc/manuals/chapters/chan_alloc.adoc b/doc/manuals/chapters/chan_alloc.adoc index 3a6d41ab5..d99512465 100644 --- a/doc/manuals/chapters/chan_alloc.adoc +++ b/doc/manuals/chapters/chan_alloc.adoc @@ -59,10 +59,11 @@ OsmoBSC(config-net-bts)# channel allocator avoid-interference ? 1 In channel allocation, prefer lchans with less interference. ---- -NOTE: Interference levels are compared within the scope of a single TRX, which -is selected with respect to the configured allocation mode. This means that -the selection logic would ignore channels on the other TRXes, even if they -are better according to the interference reports from the BTS. +NOTE: Interference levels are compared within the scope of the whole BTS. This +means that the selection logic may pick channels on the other TRXes, if they are +better according to the interference reports from the BTS. This feature makes +the allocation order non-deterministic and therefore nullifies the meaning of +channel allocation modes described above. ==== TCH sigalling policy |