diff options
author | Vadim Yanitskiy <vyanitskiy@sysmocom.de> | 2022-06-23 05:47:59 +0700 |
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committer | Vadim Yanitskiy <vyanitskiy@sysmocom.de> | 2022-06-23 05:48:04 +0700 |
commit | b06fc255399e56d4cb75979242f6b819d6eec15d (patch) | |
tree | 720d31561b8b209a3c5fa4fda62170706eb1acf7 /doc/manuals/chapters | |
parent | 1f6a0deceeef25fef5bab92776b3a292d0f66736 (diff) |
doc/manuals: document channel allocation parameters
Change-Id: Ib77eb3d4ad896f1e37b52e549ca3c24f4980240b
Related: SYS#5460
Diffstat (limited to 'doc/manuals/chapters')
-rw-r--r-- | doc/manuals/chapters/chan_alloc.adoc | 79 | ||||
-rw-r--r-- | doc/manuals/chapters/interf_meas.adoc | 1 |
2 files changed, 80 insertions, 0 deletions
diff --git a/doc/manuals/chapters/chan_alloc.adoc b/doc/manuals/chapters/chan_alloc.adoc new file mode 100644 index 000000000..3a6d41ab5 --- /dev/null +++ b/doc/manuals/chapters/chan_alloc.adoc @@ -0,0 +1,79 @@ +== Channel allocation + +Radio resource management is one of the main tasks of the Base Station Controller. +This involves selection, activation, and deactivation of logical channels, which +are maintained by connected Base Stations. The number of usable logical channels +is limited by total number of radio carriers and may vary depending on the physical +channel combinations assigned to their timeslots. Thus a major goal of the this +task is to manage all the available resources in an efficient way, shifting the +balance between service quality and the overall capacity. + +=== Channel allocation parameters + +OsmoBSC's channel allocator can be configured via the VTY interface. All +relevant parameters are limited by the scope of a BTS node they belong to. +There is currently no way to define global configuration for all BTS. + +All parameters with their respective default values are listed below: + +---- +network + bts 0 + channel allocator ascending + channel allocator avoid-interference 0 + channel allocator tch-signalling-policy always +---- + +==== Channel allocation modes + +Currently only the following two simple channel allocation modes are supported: + +- ascending (default): allocates channels in ascending order, +starting from timeslot 0 of the first TRX (also called C0, the BCCH carrier); +- descending: allocates channels in descending order, +starting from timeslot 7 of the last TRX. + +NOTE: Regardless of the chosen mode, logical channels (sub-slots) are always +selected in ascending order. For example, if a timeslot is configured as SDCCH/8 +and all 8 sub-slots are not in use, then the first SDCCH(0) sub-slot will be +selected in both ascending and descending modes. + +The allocation mode to be used can be configured using the following VTY command: + +---- +OsmoBSC(config-net-bts)# channel allocator ? + ascending Allocate Timeslots and Transceivers in ascending order + descending Allocate Timeslots and Transceivers in descending order +---- + +==== Interference aware channel allocation + +The channel allocator can be configured to prefer logical channels with least +interference, based on interference measurements periodically sent by the BTSs +(see <<interf_rep>>). This is an optional feature, which is disabled by default. + +---- +OsmoBSC(config-net-bts)# channel allocator avoid-interference ? + 0 Ignore interference levels (default). Always assign lchans + in a deterministic order. + 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. + +==== TCH sigalling policy + +By default, in a situation when all SDCCHs are exhausted, OsmoBSC will be using TCH +channels for signalling (e.g for Location Updating or call establishment). This +behavior can be restricted to certain kinds of signalling or disabled completely. + +---- +OsmoBSC(config-net-bts)# channel allocator tch-signalling-policy ? + never Never allow TCH for signalling purposes + emergency Only allow TCH for signalling purposes when establishing an emergency call + voice Allow TCH for signalling purposes when establishing any voice call + always Always allow TCH for signalling purposes (default) +---- diff --git a/doc/manuals/chapters/interf_meas.adoc b/doc/manuals/chapters/interf_meas.adoc index c82ff4907..518a6e5c5 100644 --- a/doc/manuals/chapters/interf_meas.adoc +++ b/doc/manuals/chapters/interf_meas.adoc @@ -1,3 +1,4 @@ +[[interf_rep]] == Interference reporting According to 3GPP 48.058, section 6.1, the BTS shall periodically report the |