1: Introduction
APCD-WM001-1.0
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1.3.3 MMT9000 Nomadic Operation
A key feature of the MMT9000 is its Nomadic Operations. This feature allows the MMT9000 to
quickly search for the best Base Station. Should the signal from theBase Station become too
poor, the MMT9000 re-searches for the next Base Station. In this way, the MMT9000 is never
out of touch with a Base Station for more than a few seconds, provided that it is moving
around within the coverage areas of several base stations.
To implement Nomadic Operations, the MMT9000 constantly monitors the signal from the
Base Station. When the packet error rate goes above 15% for 15 seconds, the MMT9000
searches through a list of frequencies and registers with the “best” Base Station that will allow
it to register.
The factory default is for the MMT9000 to search all 101 frequencies. To speed up the search,
a list of frequencies to be used can be configured to force the MMT9000 to search only the
relevant frequencies.
Care must be taken when designing an LMS network that will support nomadic units. If an
MMT9000 moves between two Base Station that support the same IP subnet (i.e. are in
switched mode on the same Ethernet broadcast domain) then service will continue nearly
uninterrupted. However, if an MMT9000 moves between two Base Station supporting
separate IP subnets (routed mode or separate domains), then the end-user’s PC(s) will have
to have new IP addresses, by DHCP or mobile IP protocols.
The “break-on-line” feature can assist in triggering the end-user PC to get a new IP address.
This feature disables the Ethernet port on the MMT9000 for a configurable period of time when
a search for a new base station frequency is started. Disabling the Ethernet port for long
enough forces most current operating systems on the user's computer to request a new IP
address, gateway and DNS servers via DHCP. For computers running Windows XP,
WaveRider recommends a 7 second break time. Use the command “rad freq nomadic 7” to set
the MMT9000 to nomadic mode with a 7 second break time.
The “break-on-line” feature only works if the PC is directly connected to the MMT9000
Ethernet port. If a hub or switch is placed between the PC and the MMT9000, the PC will not
lose its Ethernet link, since that is provided by the hub or switch.
If the MMT9000 itself has its DHCP client enabled, then it will use DHCP to get a new IP
address for the modem when it changes Base Stations.
