Specifications

144 Network Design and Engineering Guide 2010-10-26
Appendix C - Glossary
Modem A piece of network equipment containing a modulator and de-
modulator for receiving or transmitting satellite signals. See
SkyWAN
®
IDU.
Modulation The encoding of a carrier wave by amplitude or frequency or
phase.
Multicast Multicast is a subset of broadcast whereby the signal can be
sent to many sites within a defined group, but not necessarily
to all sites in that group.
Multicast Aggregate Group of multicast-microflows logically grouped together. It de-
scribes a certain multicast routing behavior. This multicast ag-
gregate abstraction depends on the current scope. If the scope
is the sat-access subnet a multicast aggregate is a group of
multicast microflows belonging to one MF-TDMA channel. See
also Multicast Microflow.
Multicast Microflow A microflow which is destined to one of the multicast IP ad-
dresses (224.0.1.0 to 239.255.255.255).
Multiplexing Sending multiple signals or streams of information on a carrier
simultaneously transmitting on a single signal.
Network Operations Cent-
er (NOC)
Centralized location where control over operation of a network
is managed and monitored remotely.
Network Management
System (NMS)
Hardware and software used for monitoring and controlling a
satellite network. See also SKYNMS.
Node From a networking perspective a SkyWAN
®
IDU acts as a net-
work node. Hence, in the context of communication services
the term node for aSkyWAN
®
IDU is preferred.
Outbound In a VSAT network it is typically referred to as the transmission
from the network hub to a remote station.
Outdoor Unit (ODU) Equipment located outside of a building close to the satellite
dish or antenna. It typically includes a low noise block convert-
er (LNB) and a block up converter (BUC).
Packet Basic unit of encapsulation which is passed across the inter-
face between the network layer and the data link layer. A pack-
et is usually mapped to a frame.
Polarization A technique used by satellite operators to reuse the satellite
transponder frequencies when transmitting these signals to
earth (linear or circular). To successfully receive and decode
these signals on earth, the antenna must be outfitted with a
properly polarized feedhorn to select the signals as desired.
Linear or Circular Polarization is used on satellite transpond-
ers.
Term Definition