Weidmuller WI-I/O-9-U2: Wireless Mesh I/O & Gateway User Manual V1.2.2 - Manual (Page 22)

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A spread-spectrum transmission offers some advantages over a fixed-frequency
transmission.

Spread-spectrum signals are more resistant to narrowband interference.

They are difficult to intercept or eavesdrop because of the pseudorandom
transmission sequences.

Transmissions can share a frequency band with other types of conventional
transmissions with minimal interference.
2.3.2 869 MHz Fixed Frequency radio (EU Country Code)
This radio operates in the unlicensed fixed frequency band of 869 MHz. There are two
frequencies, the first operating at 869.525 MHz with a maximum transmit power level of
500 mW and is regulated with a 10% duty cycle on the channel. This duty cycle limit
requires that the module does not transmit for more than 10 % of the total operating
time which means other users of the unlicensed frequency are able to transmit without
interference. The second frequency operates at 869.875MHz with a transmit power
level of 5mW and no duty cycle regulation on the channel which means the module can
freely transmit as often as is needed.
Note: Care must be taken to ensure the duty cycle limit is not exceeded when
using the 869.525MHz frequency.
2.3.3 Meshing capability
The WEIDMULLER WIBMesh protocol is based on the “Ad hoc On Demand Distance
Vect
or” (AODV) routing algorithm which is a routing protocol designed for ad hoc
networks.
AODV is capable of unicast routing and is an on demand algorithm, meaning that it
builds and maintains these routes only as long as they are needed by the source
devices.
The Protocol creates a table, which shows the connection routes to other device in the
system. The Protocol uses sequence numbers to ensure the routes are kept as current
as possible. It is loop-free, self-starting, and can scale to a large numbers of nodes.
See section 3.4 “WIBMesh” for more details on configuration.
2.4 Antenna
The WI-I/O 9-U2 module will operate reliably over large distances. The distance that
can be reliably achieved will vary with each application and depend on the type and
location of antennas, the degree of radio interference, and obstructions (such as hills or
trees) to the radio path.