User's Manual

pulsAR radio Operator’s Manual
2-2
2.1.1 Point to point
In a point-to-point topology, when the two sites are fixed we recommend using directional antennas at
both ends, pointing at each other. This increases the signal strength in the desired direction and
shields the radios against unwanted interference from other sources. When you use directional
antennas make sure you install both antennas with the same polarization (vertical or horizontal). Most
often interfering sources are vertically polarized so you may want to install your link with horizontal
polarization to get some additional isolation against those interference sources.
The point-to-point topology operates like a point-to-multipoint network where the hub has a single
remote. You still need to configure one of the two radios to be the hub but configure it with the max
number of children set to one. This optimizes the radio performance for point-to-point operation. See
the node command in section 4.
2.1.2 Point to Multipoint
In a Point to Multipoint topology one radio is designated as the hub and all other radios are
designated as remotes. You can have up to 32 remote nodes. You typically deploy the hub radio
with an omni-directional or sectorial antenna so that it can cover all the remotes. If the remote sites
are fixed deploy them with directional antennas pointing at the hub. If the remotes are mobile use
omni-directional antennas everywhere.
Remote radios connect to the network automatically without need to change the configuration of the
hub radio. All you need is to point an antenna at the hub and ensure that the following parameters are
configured correctly:
1. The RF receive channel of the remote must match the transmit channel of the hub (see rf-1-
setup).
2. The network-id parameter of the remote must match the network-id of the hub (see node
command).
3. The max-children parameter at the hub must be large enough to give access to all the planned
remotes (see node command).
There are situations when you may want to deploy multiple hub radios at the central site. These
situations include:
• You need to increase total throughput of the central site.
• The number of remotes increases beyond 32.
• Provide hub redundancy.
In these situations configure each co-located hub to operate in non-overlapping channels. Refer to
section 2.4 for additional guidelines on how to synchronize the transmissions from the multiple hubs.
For hub redundancy you need to configure the remote nodes to roam between the two channels used
by the two hubs. You can split the remotes into two groups with one hub servicing each group. If one
hub fails or there is strong interference in that channel, then the remotes will reattach to the other hub
keeping the connection to the central site intact. Refer to section 2.2 for the roaming options.