When operating in IP
Site Connect Mode, MOTOTRBO combines the logical channels of multiple MOTOTRBO
systems (operating in digital repeater mode at dispersed locations) into one
logical channel covering all locations. In this mode, repeaters across
dispersed locations exchange voice and data packets over an IPv4-based back-end
network.
When a new call starts at
one of the logical channel of a repeater, the repeater sends the call to all the
repeaters and all these repeaters repeat the call on their corresponding logical
channel. This allows a radio in the coverage area of any repeater to
participate in the call. Thus, the coverage area of an IP Site Connect system
is the sum of the coverage areas of all the repeaters. However, note that an IP
Site Connect configuration does not increase the capacity (i.e. number of calls
per hour) of the system. The capacity of one Wide Area Channel of an IP Site
Connect system is approximately the same as that of a single repeater working
in digital repeater mode.
In an IP Site Connect
configuration, MOTOTRBO radios support all the features that they already support
in digital repeater mode. Additionally, the radios are capable of automatically
roaming from one site to another.
The IP Site Connect
configuration of MOTOTRBO does not require any new hardware besides backend
network devices such as routers. If a customer has multiple MOTOTRBO systems working
in digital repeater mode at dispersed sites and wants to convert them into an
IP Site Connect system then the repeaters and the radios should be updated with
new software and the repeaters need to be connected to an IPv4-based backend
network.
MOTOTRBO has three security
features in the IP Site Connect configuration.
Þ Provides the confidentiality of voice and data
payloads by extending the privacy feature, whether Basic or Enhanced, to cover
the communication over the backend network.
Þ Ensures that all the messages between repeaters are
authentic.
Þ Supports Secure VPN (Virtual Private Network) based
communication between the repeaters for customers needing higher level of
security (protection against replay attack).
The backend network can be a dedicated network or most probably an
internet provided by an Internet Service Provider (ISP). ISPs provide a range
of technologies such as dial-up, DSL (typically, ADSL), cable modem, broadband
wireless access, ISDN, Frame Relay, Satellite Internet access, etc. The backend
network cannot be based on a dial-up connection (due to small bandwidth) or
Satellite Internet access (due to large delay).
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