This change implements an additional channel allocation mode, which
can be employed during a TCH channel allocation for assignment.
Selection between ascending and descending order is performed
depending on pre-configured parameters:
* Uplink RxLev threshold and number of samples for averaging,
* C0 (BCCH carrier) channel load threshold.
This is useful in setups where Tx power of the RF carriers cannot be
adjusted +dynamically at run-time and thus BS Power Control cannot
be performed. In such setups the BCCH carrier is transmitting at
relatively higher power than the other RF carriers. The key idea
is to allocate channels in a smarter way, so that UEs with poor signal
would get channels on carriers with high Tx power, while UEs with good
signal could use carriers with lower Tx power.
Change-Id: I1b7a0d706976b73cc5c30a8714b830811addfe8d
Related: osmo-ttcn3-hacks.git Ia522f37c1c001b3a36f5145b8875fbb88311c2e5
Related: SYS#5460
A follow-up patch implements a special channel allocation mode, which is
only working for assignment (basically TCH selection for a voice call).
This mode cannot be employed for initial CHANNEL REQUEST or handover due
to the absence of an already established lchan.
Adding this mode to the existing VTY command syntax would be confusing:
channel allocator (ascending|desscending|dynamic)
^^^^^^^
so this patch extends the VTY syntax in a way that it becomes possible
to configure different channel allocator modes for different cases:
OsmoBSC(config-net-bts)# channel allocator mode ?
set-all Set a single mode for all variants
chan-req Channel allocation for CHANNEL REQUEST (RACH)
assignment Channel allocation for assignment
handover Channel allocation for handover
The old command syntax, which is basically 'set-all', is kept for
backwards compatibility, but marked as deprecated.
Change-Id: I3ae73b36ee9433cc768376b56f0765e5f416162f
Related: SYS#5460
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
Vadim Yanitskiy