Key Product Features; Media Access Control (Mac); Coordination Of Channel Access - GE MDS SD Series Technical Manual

Coordination of
Channel Access
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2.2 Key Product Features

The transceiver is designed to meet the demanding needs of today's
wireless networks in a compact, and rugged package. It offers an array
of features in a single hardware platform:
• Software-configurable via a built-in Device Manager—no man-
ual controls or adjustments.
• Media Access Control (MAC) to prevent data collisions when two
or more radios try to use the radio channel at the same time.
• Available encryption of payload data (AES 128-bit)
• Supports a wide variety of modem speeds and bandwidths for reg-
ulatory compliance in virtually all regions of the world
• Ethernet & serial interfaces—ideal for migration to IP networks
• Dual serial functionality (RS-232 and RS-485)
• Over-the-air reprogramming of remote units—no unnecessary
trips to radio sites
• Licensed 5-watt design, maximizes communications range with
low interference risk from other users
• Configurable via software as a Remote or a Master unit
• Low power "sleep mode"—ideal for battery-powered solar sites
• Virtual Radio Channels (VRC) support multiple polling applica-
tions on one radio
NOTE:
Some features may not be available on all units, depending on the
options purchased and regulatory constraints for the region in which
the radio will operate

Media Access Control (MAC)

An important feature of the SD Transceiver is Media Access Control
(MAC). The SD's MAC is specifically designed for use with narrow
bandwidth, half duplex radio networks such as those commonly used in
licensed telemetry systems. A central unit is designated an Access Point
(AP) and other units are designated as remotes. When enabled, the MAC
provides efficient support of multiple data traffic models including mul-
tiple hosts, synchronous and asynchronous polls, and report-by-excep-
tion (push traffic).
The main objective of the MAC is to coordinate channel access for all
radios in the network, preventing interference or data "collisions" that
can occur from simultaneous transmissions of radios on the same RF
frequency. With MAC operation a single radio is configured as an
Access Point. This AP serves as the controller of the RF network. All
other radios are configured as remotes. Remote's request permission
from the AP to use the RF channel before sending payload data, thus
avoiding collisions of data, and creating a highly reliable wireless net-
work. The MAC is responsible for allocating which unit gets access to
the broadcast medium (the RF channel), when, and for how long.
SD Series Technical Manual
.
MDS 05-4846A01, Rev. D