Table of Contents
Advertisement
MN004527A01-AG
Chapter 2: Services and Features
Local Site Trunking (LST) is a feature enabling a Base Station to operate stand-alone. The Base
Station may enter the mode when the link from the local cell to the central switch has gone down. The
radio limits functionality when the cell is in this mode.
NOTICE: Whether a radio can register on cells in LST depends on the codeplug settings.
If system broadcasts indicate that system-wide services are not available (LST) on a cell, the radio
registers on this cell only if there are no system-wide cells available.
Depending on the infrastructure settings, when the radio is operating on an LST cell, the radio may
prevent you from invoking the following services:
•
Private call
•
Phone call
•
Private Automatic Branch Exchange (PABX) call
•
Packet data
Depending on the codeplug configuration, the radio may indicate entering the LST with the following
notifications:
•
Visible and audible
•
Visible
•
Audible
•
None
To avoid unnecessary roaming and reduce congestion, Local Site Trunking Ignoring feature can be
enabled. When Local Site Trunking Ignoring feature is enabled, the radio temporarily ignores the
LST/WST parameter when selecting a site. However, the radio still takes other parameters such as the
Radio Signal Strength Indicator (RSSI) level of the cell into consideration when deciding on roaming.
2.19.12
Cell Surveillance and Monitoring Threshold
The radio constantly calculates a normalized value that represents the signal strength of a cell. This
value is used by the radios to determine if the cell is usable and when to leave the cell.
In the default case, when the radio is camped on a cell, it initiates link failure procedures, such as leave
the cell, if this normalized signal strength value falls below zero. However, it is possible to configure the
radio to allow this normalized value to be processed below zero using the Customer Programming
Software (CPS); value can be set in 1 db steps up to -5 db. Reducing this value below zero allows the
radio to maintain service on a weak cell where the radio is unable to roam to a better cell.
2.20
Supplementary Services
Following is the description of the TETRA Supplementary Services (SS) that the radio supports in the
Trunked Mode Operation (TMO).
2.20.1
Dynamic Group Number Assignment
The radio supports dynamic addition and removal of talkgroups in its talkgroup list through TETRA
Dynamic Group Number Assignment (DGNA) and De-assignment signaling (SS-DGNA).
The radio responds to DGNA directed to it or to DGNA directed to a group the radio is attached to even
if the talkgroup is not programmed in the codeplug.
62
Advertisement
Table of Contents
