Peer-To-Peer With Repeater Assistance - Microwave Data Systems MDS 9810 Installation And Operation Manual

Antennas
Data "Collision"
Avoidance
Repeater Setup
20 MDS 9810 Installation and Operation Guide
applied to all remote radios as soon as they become synchronized
with the master radio.
Omnidirectional antennas are normally required at all stations in a
simplex system. The transmission range may be significantly
reduced as compared with stations using directional antennas, so it
is especially important that sites be chosen to allow sufficient signal
strength between all units. A discussion of site selection is provided
in Section 3.2.
One drawback with peer-to-peer systems is the risk of data "colli-
sions" that can occur through self-interference. This problem can be
alleviated with data protocols (such as Harris DNP3) which use
Carrier Sense Multiple Access (CSMA) to detect a busy channel. In
these systems, Pin 10 (Receiver Unsquelched-RUS) on the trans-
ceiver should be connected to the RTU's Data Carrier Detect
(DCD) pin.

Peer-to-Peer with Repeater Assistance

A shortcoming of a simplex peer-to-peer network is that communication
range is often reduced because of the need for all stations to use omni-
directional antennas. An alternative peer-to-peer network can be estab-
lished using a repeater station to re-transmit the signals of all stations in
the network. (See Figure 16.) Because directional antennas (aimed at the
repeater site) can be used at all remote sites, the communication range
of the system is greatly increased. Like a simplex peer-to-peer system,
each remote station can "hear" the transmissions of the others so that
data collisions can be avoided.
REMOTE
HOST
COMPUTER
Figure 16. Peer-to-Peer Network with Repeater Assistance
Here are some specific requirements for peer-to-peer systems with
repeater assistance:
The repeater station in a peer-to peer network consists of two
co-located transceivers—one programmed as a remote using master
Invisible place holder
REPEA TER
STATION
REMOTE-MASTER
Pin 3 Pin 2
REMOTE
RTU
REMOTE
RTU
MASTER
REMOTE
RTU
MDS 05-3301A01, Rev. C