diff options
author | Vadim Yanitskiy <vyanitskiy@sysmocom.de> | 2021-06-28 23:15:43 +0200 |
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committer | fixeria <vyanitskiy@sysmocom.de> | 2021-07-05 12:17:59 +0000 |
commit | 997a257f8dabe5dd940a1271e56e676a871896d7 (patch) | |
tree | 75488bca836fefd2d2ff5543e7a3ce5065c92e6c /doc | |
parent | ced29cf94cc0bfa82cf62a7b1fa48202145f3fb6 (diff) |
power_control: constrain BS power reduction on BCCH carrier
BS Power Control is not allowed on the BCCH/CCCH carrier, unless
the BTS is operating in the BCCH carrier power reduction mode.
Allow constrained BS power reduction (up to 6 dB) on active logical
channels iff BCCH carrier power reduction mode is enabled.
Take into account that the maximum power difference between a timeslot
used for BCCH/CCCH and the timeslot preceding it shall not exceed 3 dB.
Change-Id: I2cc6a86731984f586ef35b43a8d3de631f7d8a2f
Related: SYS#4919, SYS#4918
Diffstat (limited to 'doc')
-rw-r--r-- | doc/manuals/chapters/power_control.adoc | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/doc/manuals/chapters/power_control.adoc b/doc/manuals/chapters/power_control.adoc index bb87c850c..d456484ea 100644 --- a/doc/manuals/chapters/power_control.adoc +++ b/doc/manuals/chapters/power_control.adoc @@ -357,6 +357,30 @@ TIP: If you're using OsmoBTS, make sure that it reports feature #021 "BCCH carri power reduction mode" in the feature vector. This can be checked by issuing `show bts` command in OsmoBSC's VTY interface. +==== Interworking with static and dynamic power control + +The key difference between BCCH carrier power reduction and the BS power control +is that the former affects *inactive* timeslots (or sub-channels), so only dummy +bursts are affected. The later depends on the Downlink measurement reports sent +by the MS, and thus applies to *active* channels only. However, both features +are interconnected: the maximum BCCH carrier power reduction value constrains +the BS Power value that can be used for dynamic or static BS power control. + +BS power control on the BCCH carrier will not be enabled unless the BTS is in BCCH +carrier power reduction mode of operation. Once it is, the BS power reduction +value in either of `dyn-bts` or `static` modes would be constrained by currently +applied BCCH power reduction value, and thus would never exceed the maximum of 6 dB. + +For example, consider a BTS with BS power control configured to use _dynamic_ mode +and the maximum power reduction of 16 dB. Once this BTS is switched into the BCCH +carrier power reduction mode with the maximum attenuation of 4 dB, the maximum +power reduction value for the BS power loop on the C0 carrier would be 4 dB. + +Moreover, according to 3GPP TS 45.008, between a timeslot used for BCCH/CCCH and +the timeslot preceding it, the difference in output power actually transmitted by +the BTS shall not exceed 3 dB. This means that on some timeslots the power +reduction value can be constrained even further. + ==== Managing BCCH carrier power reduction The BCCH carrier power reduction can be controlled via the CTRL and VTY interfaces. |