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Trunked Radio Features Operation
(cont.)
Radios that operate in a SmartZone system will enjoy the benefits that
SmartZone brings over AMSS operation. Like AMSS, SmartZone is a wide-area
coverage system that will allow up to 50 sites to be operational in the system.
SmartZone brings several enhancements over AMSS operation such as:
Dynamic Site Assignment - Allows the zone controller to dynamically assign
channels at sites where required, as opposed to bringing up channels at all of
the sites as AMSS systems do.
Variable Density Sites - SmartZone allows sites to have varying numbers of
channel resources to accommodate low-density areas as well as high-density
areas.
Automatic Site Registration/De-registration - SmartZone radios automatically
send in their unit IDs and current mode selections upon power up, power
down, site switches, mode changes, and when they exit emergency operation.
This allows the zone controller to know where the radio is at all times, and also
what mode the radio has selected.
Critical Site Assignment - One or more sites can be designated as critical sites.
This will instruct the zone controller to ensure that, before a channel grant is
given to a radio that has been identified as a critical site user, every site that is
designated as a critical site must have available channel resources, otherwise
a busy signal will be sent to the unit.
Busy Override - This feature allows a SmartZone radio to send a busy-override
request if a busy is issued. The zone controller will send a grant even though
not all of the sites may have available channel resources.
Enhanced Automatic Site Switching - SmartZone radios will use received signal
strength indication (RSSI) to determine if the radio should switch to another
site; this will be transparent to the user. In addition, the zone controller
continuously transmits up to seven adjacent site IDs (along with their active
control modes) to the radios, so that the radio, at any time, will be able to
quickly switch to the next site that has the highest RSSI rating, since the
control mode and site ID is known in advance. This is an enhancement over
AMSS systems.
Preferred Site—SmartZone radios can program certain sites to be always
preferred, most preferred, or least preferred. This gives the user the flexibility
to keep a radio on a particular site, regardless of the presence of a stronger
signal from an adjacent site. This also forces the radio to always look for its
preferred site and use it whenever possible.
Site Trunking—If the zone controller loses communication with any site, that
site will revert to what is known as "site trunking." While in this condition,
radios will still be able to operate in the trunking mode, but trunking operations
will be limited to the site only.
Enhanced Failsoft Operation—If a site experiences a complete failure, it will
revert to failsoft operation like today's SMARTNET system. A SmartZone radio,
however, can be programmed to automatically migrate to the lowest failsoft
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