System Feature Overview 19
• Capacity Plus does not use “request and grant” mechanism to allocate channels and
does not require any central controller to trunk the channels.
• The dynamic Rest Channel mechanism makes Capacity Plus very suitable for an
environment where channels are shared by multiple radio systems.
• The dynamic Rest Channel mechanism also improves the reliability of the Capacity
Plus system. In the event of a repeater failure, the other available repeaters
automatically reconfigure themselves and continue to work as the Capacity Plus
system.
The Capacity Plus system configuration of MOTOTRBO does not require any new hardware apart
from backend network devices such as routers. If a customer has multiple MOTOTRBO systems
working in digital repeater mode at the same site and wants to convert to a Capacity Plus system,
then the repeaters and radios should be updated with the new software, and the repeaters need to
be connected to an IPv4-based backend network. If one logical channel of a repeater is configured
to the Capacity Plus mode, then the other logical channel will also be in the same mode.
In a Capacity Plus configuration, MOTOTRBO systems support all previous digital repeater mode
features, with the exception of the following:
• Scan: Capacity Plus supports Group Scan, so a properly programmed radio listens for
multiple talkgroups within a single Capacity Plus system, but does not support scanning
channels of another system. Adding multiple talkgroups to the Receive list of a radio
allows the user to hear the conversations of those talkgroups, and reply within the call
hang time, regardless of the physical channel on which that call takes place.
• Emergency Revert Channel: Capacity Plus does not support a revert channel for
emergency because probability of all Trunked Channels becoming busy is low.
However, reverting to an emergency group is supported. This promotes a centralized
handling of an emergency situation.
• IP Site Connect configuration: Capacity Plus is a single site system and therefore
does not support features related to IP Site Connect configuration such as wide-area
coverage and automatic roaming. However, a radio can be programmed with multiple
channels in multiple zones, one of which could be a Capacity Plus system, another an
IP Site Connect System, and others could be MOTOTRBO conventional channels or
Analog conventional channels.
• Impolite calls: Capacity Plus supports impolite Emergency Call and impolite
transmissions (i.e. Group members can transmit over an ongoing call). A new call
always starts on an idle channel and therefore, a radio does not start a non-Emergency
Call impolitely.
• Talkaround mode: A radio can have a talkaround personality but in Capacity Plus
mode, there is no talkaround option.
• Monitoring of channels status: Monitoring is important in a conventional system,
where a radio stays on a channel. In Capacity Plus, a radio moves from one Rest
Channel to another. Most of the Rest Channels are in an idle state and therefore,
monitoring is not necessarily needed.
• Fragmentation of a Data Packet: Capacity Plus does not fragment a data packet
before transmitting over-the-air. Thus, the size of an IP datagram (including IP and UDP
headers) should be less than the maximum size of the Packet Data Unit. The value of
the Packet Data Unit is a CPS programmable parameter with a maximum size of 1500
bytes.
• Option Board: If the Option Board feature is enabled for Capacity Plus, then the feature
is automatically enabled for all trunked and revert channels of a Capacity Plus system.
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