Cambium Networks cnReach N500, User Manual

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cnReach N500 User Guide
Technical Reference
phn-4673_002v000 (March 2018)
3-9
Access Point Synchronization
It is common practice in large Ethernet SCADA communication systems to install multiple overlapping
wireless networks to mitigate poor performance and prioritize traffic for different traffic types and
mixed protocols.
Wireless Ethernet networks with many remote devices can experience low throughput and long latency.
Dividing large wireless networks into many smaller networks can increase throughput and reduce
latency; using PTP backhaul links for high throughput and PMP access links to interface various end
devices. Different traffic types can cause low priority data to block high priority data. Separating
networks for each application in a single area establishes guaranteed capacity for each traffic type.
For example, SCADA polling, video surveillance and internet access can each have individual networks
with the same or overlapping geographical coverage. Installing multiple radios at the same location or in
the same geographical area must be done carefully to prevent interference.
cnReach radios have a technology to prevent problems related to multiple radios installed at the same
location. With synchronization enabled, the radios in overlapping networks transmit and receive at the
same time, but on different frequencies as shown in the following hop sequence.
For every hop in the sequence, each radio sub-network; 1x Access Point and connected End Points will
transmit and receive on a unique frequency over the same time duration, therefore eliminating self-
interference.
MMS is a timing feature that allows multiple Access Point radios in co-located networks and/or
interconnected sub-networks to synchronize transmit and receive times to prevent self-interference.
Dividing the 902-928 MHz ISM band is not required since each Access Point in the network is timed to
precisely and simultaneously transmit using different frequency channels. The respective End Points
respond to their Access Points on the same channels before the entire system hops and the process
continues.