This commit extends existing VTY and RSL infrastructure to configure and
manage MS Power Parameters used in MS Power Control loop, by adding
support to set up Carrier-to-Interference (CI) parameters.
Using C/I instead of existing RxQual is preferred due to extended
granularity of C/I (bigger range than RxQual's 0-7).
Furthermore, existing literature (such as "GSM/EDGE: Evolution and Performance"
Table 10.3) provides detailed information about expected target values,
even different values for different channel types. Hence, it was decided
to support setting different MS Power Parameters for different channel
types.
These MS Power Parameters are Osmocom specific, ie. supported only by
newish versions of osmo-bts. Older versions of osmo-bts should ignore
the new IEs added just fine. The new IEs containing the MS POwer
Parameters are not send for non osmo-bts BTSs, hence this commit is
secure with regards to running osmo-bsc against an ip.access BTS such
as nanoBTS.
Related: SYS#4917
Depends: libosmocore.git Change-Id Iffef0611430ad6c90606149c398d80158633bbca
Change-Id: I7e76ec47b323d469f777624b74b08752d1f5584f
The BCCH carrier (sometimes called C0) of a BTS shall maintain
discontinuous Downlink transmission at full power in order to
stay 'visible' to the mobile stations. Because of that, early
versions of 3GPP TS 45.008 prohibited BS power reduction on C0.
However, starting from version 13.0.0 (2015-11) there is a feature
called 'BCCH carrier power reduction operation'. This is a special
mode of operation, where the variation of RF level for some
timeslots is relaxed for the purpose of energy saving.
In BCCH carrier power reduction operation, for timeslots on the
C0 carrier, except timeslots carrying BCCH/CCCH, the output power
may be lower than the output power used for timeslots carrying
BCCH/CCCH. In this case the maximum allowed difference in output
power actually transmitted by the BTS is 6 dB.
Introduce a VTY command to turn on and off the BCCH carrier power
reduction operation. Also introduce a CTRL command. On the
A-bis/RSL, abuse the BS POWER CONTROL message by setting
the Channel Number IE to 0x80 (RSL_CHAN_BCCH).
Currently, only osmo-bts-trx is supported. A value greater than
zero makes it reduce the power on *inactive* timeslots of the
BCCH carrier. Sending zero disables the BCCH power reduction
mode completely.
For more details, see 3GPP TS 45.008, section 7.1, and 3GPP TR 45.926.
Change-Id: I047fce33d4d3e4c569dd006ba17858467a2f4783
Related: SYS#4919
sysmoBTS is a BTS model sold by Sysmocom, which runs osmo-bts.
The later may also work with some other back-ends, including
the genaral purpose SDR hardware. Therefore, it's more
logical to call it 'osmo-bts'.
Change-Id: I93ab4dbf483e0786c35685b75ee4ea83bd591f7b
Pau Espin
Vadim Yanitskiy