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| -rw-r--r-- | doc/manuals/chapters/chan_alloc.adoc | 79 | ||||
| -rw-r--r-- | doc/manuals/chapters/interf_meas.adoc | 1 | ||||
| -rw-r--r-- | doc/manuals/osmobsc-usermanual.adoc | 2 |
3 files changed, 82 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 diff --git a/doc/manuals/osmobsc-usermanual.adoc b/doc/manuals/osmobsc-usermanual.adoc index 0afa0158c..f83552584 100644 --- a/doc/manuals/osmobsc-usermanual.adoc +++ b/doc/manuals/osmobsc-usermanual.adoc @@ -24,6 +24,8 @@ include::{srcdir}/chapters/bts-examples.adoc[] include::{srcdir}/chapters/bsc.adoc[] +include::{srcdir}/chapters/chan_alloc.adoc[] + include::{srcdir}/chapters/power_control.adoc[] include::{srcdir}/chapters/interf_meas.adoc[] |