User's Manual

Glossary
4Motion 921 System Manual
RS-232 A serial interface published by the EIA (Electronic Industries Association) for
asynchronous data communication over distances up to a few hundred feet.
Characterized by a single-ended (not differential) physical layer, it uses one signal
wire for transmission, another for reception, and a common wire (ground), plus some
timing and control signals.
RS-422 RS-422 is a serial interface standard in which data is sent in a differential pair (two
wires, or twisted pair cable), which allows greater distances and higher data rates
than non-differential serial schemes such as RS-232.
RSSI Received Signal Strength Indicator. A signal or circuit that indicates the strength of
the incoming (received) signal in a receiver.
R&TTE Radio & Telecommunications Terminal Equipment. The R&TTE Directive 1999/5/EC
governs the marketing and use of R&TTE equipment. With the exception of a few
categories of equipment, the Directive covers all equipment, which uses the radio
frequency spectrum. It also covers all terminal equipment attached to public
telecommunication networks.
RTC Real Time Clock.
RTD Round Trip Delay.
RTP Real Time Protocol. An Internet protocol for transmitting real-time data such as audio
and video. RTP itself does not guarantee real-time delivery of data, but it does
provide mechanisms for the sending and receiving applications to support streaming
data. Typically, RTP runs on top of the UDP protocol, although the specification is
general enough to support other transport protocols.
RT-VR Real Time - Variable Rate. Service supporting real-time applications with variable bit
rates that require guaranteed data rate and delay such as streaming video.
Rx Receive
SBS Serving Base Station
SDU Service Data Unit. A set of data that is sent by a user of services of a given layer,
and is transmitted to a peer service user semantically unchanged. The SDU is the
data that a certain layer will pass to the layer below.
SFA Service Flow Authorization.
SFM The Service Flow Manager (SFM) located in the BS is responsible for the creation,
admission, activation, modification, and deletion of IEEE 802.16e-2005 service
flows. It consists of an Admission Control (AC) function, data path function and the
associated local resource information. AC decides whether a new service flow can
be admitted to the system.