User's Manual

APCD-LM043-4.0 257
GOS (Grade of Service) A level of service associated with an EUM, which determines
how often, and when, an EUM will be polled. Since an EUM
can only send one packet each time it is polled, the data rate is
related to the polling rate.
IP (Internet Protocol) The network-layer protocol in the TCP/IP stack (defined by
RFC 791).
Line of Sight The radio link between a transmitter and receiver is said to be
line of sight if the direct path between the two is relatively free
from physical obstruction.
MAC (Medium Access
Control)
The mechanism of managing access, by multiple users, to a
common transmission medium.
Multicast (Message) A message sent by a network device to a limited set of network
devices.
Orthogonal Channels Communications channels that can operate over a common
transmission medium without significantly interfering with each
other. In the context of LMS, radio frequencies on
appropriately spaced frequencies are considered to be
orthogonal.
OSPF (Open Shortest
Path First)
A link-state, hierarchical interior gateway routing protocol that
can provide least-cost routing, multipath routing, and load
balancing.
NAT (Network Address
Translation)
An Internet standard that enables a local area network to use
one set of IP addresses for internal traffic and another set of
addresses for external traffic.
PAT (Port Address
Translation)
A feature that lets you number a LAN with inside local
addresses and filter them through one globally routable IP
address.
Point-to-Multipoint A communications architecture in which a central station
(CAP, for example) communicates with multiple remote
stations (EUMs).
POTS (Plain Old
Telephone Service)
The basic telephone service provided by the public switched
telephone network (PSTN).
Radio Module The device in the EUM (or CCU) that provides the wireless
interface to the LMS network. The radio module performs
signal spreading and modulation, channelization, up-
conversion and amplification in the transmit direction, and
signal amplification, down-conversion, channel selection,
demodulation, de-spreading and data recovery in the receive
direction.
Range The maximum distance that a signal can be reliably
transmitted between a CCU and EUM.
Term Definition