User's Manual

2-17 July 23, 2002
General CreataLink2 XT Hardware Integrator’s Guide
Air Interface
ReFLEX Network Operation
All two-way messaging networks that support two-way data communications with
CreataLink2 XT device use the ReFLEX protocol. The network can be viewed as
two separate one-way networks. For messages directed to the data transceiver, the
network controller routes the messages to one of many high power transmitter sites.
For messages from the data transceiver, a higher density of receiver sites are
provided to compensate for the lower transmit power of the data transceiver.
The Global Positioning System (GPS) synchronizes the downlink and uplink paths,
allowing downlink control of the uplink communications path. The network control-
ler schedules all transmissions from the data transceiver for optimal utilization of
the uplink communications path.
Downlink messages are delivered at a time when the data transceiver is guaranteed
to be listening, as defined by the data transceiver battery-save mode/collapse value.
Each unit is assigned certain frames in which its messages can be received. The
personal address collapse and information services collapse values are used to
schedule those frames a unit must decode for messages. If you use these collapsed
frames, you are trading battery life for the more frequent delivery of messages.
Therefore, collapse frame use provides a battery-save mode and defines the per
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centage of the time the data transceiver is listening to the channel for messages.
The remainder of the time the data transceiver is in a low-power state, and is not
listening to the carrier channel for messages. It is important for the data transceiver
and network controller to remain synchronized in order for messages to be delivered
successfully.
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The downlink is also referred to as the forward path. The uplink is also referred to
as the reverse path.