3-8
IM 04L51B01-41EN
3.4.2
Network Scale Setup
This function enables parameter setup for each of the three available network sizes (1 to
30 units, 31 to 60 units, and 61 to 100 units) so that you can use the optimal parameter
setup. The transmission frequency of control packets is adjusted according to the network
size in order to perform stable network communication. Note that if a parameter that does
not match the actual network configuration size is selected, congestion may occur in the
network, and in the worst case, routers may be disconnected from the network.
3.4.3
Monitoring Unit Time of Radio Transmission
If used outside Japan, there is no limit to the transmission time.
The wireless multi-hop network function complies with ARIB STD-T108, a standard defined
by Association of Radio Industries and Businesses (ARIB).
Wireless communication that use the 920 MHz frequency band must observe the
transmission time limit (10% duty limit: radio transmission time must be no longer than 360
seconds for every hour) defined by ARIB STD-T108.
As such, wireless communication modules have a “monitoring unit time of radio
transmission” function for measuring the radio usage rate. However, because the
transmission time within a given 1-hour time frame must be kept no longer than 360
seconds, the transmittable time varies depending on each “monitoring unit time of radio
transmission.”
The examples shown in the following figure are for when the monitoring unit time is set to
60 minutes and 30 minutes, respectively. If the monitoring unit time is set to 60 seconds,
to keep the radio transmission time within 360 seconds in a given hour, the possible radio
transmission time is 3 minutes because radio signals can be transmitted in the first and last
3 minutes of two consecutive monitoring unit times. Likewise, if the monitoring unit time is
set to 30 minutes, the possible radio transmission time in 60 minutes is 4 minutes.
Note that in reality, communication is possible for a time period shorter than 360 seconds.
The default monitoring unit time in the maintenance console is 10 minutes (600 seconds),
but the default value in the hardware is 60 seconds.
If the monitoring unit time is reduced, the ratio of the possible transmission time relative to
that time period increases, but if numerous packets or large packets are transmitted in a
short time period, the transmission time limit may be exceeded. On the other hand, if the
monitoring unit time is increased, the ratio of the possible transmission time relative to that
time period decreases, but the size of packets that can be transmitted within the monitoring
unit time increases.
If a repeater wireless module violates the 10% duty limit, routers connected under the
repeater will also no longer be able to communicate. However, if such routers have detour
routes through a different repeater when communication failure is detected, communication
continues through the detour route. Wireless communication modules that exceed the 10%
duty transmission time limit will not be able to transmit radio signals for a given time period.
3 minutes3 min
No communication
No communication
2 minutes2 min
2 min
No communication
No communication
No communication
Transmittable time in a 1-hour radio usage
rate unit is 3 minutes.
A given hour
Transmittable = 6 min
A given hour
Transmittable = 6 min
Radio usage
rate unit
1 hr
Radio usage
rate unit
30 min
Radio usage
rate unit
30 min
Radio usage
rate unit
30 min
Radio usage
rate unit
1 hr
Radio usage
rate unit
1 hr
Transmittable time in a 30-minute radio usage rate unit
is 2 minutes (= 4 minutes in 1 hour).
3.4 Multi-hop Communication
