Filter
Top Products
Q-S
QOS
Quality of Service. QoS indicates user perception of a particular service and is
defined in terms of a range of technical parameters including delay, jitter,
reliability, etc. Under the OSI reference model stipulated by ISO, QoS is
considered to be controlled at the network layer (third layer). Although
definition varies depending on the type of network service, the following
service classes apply in the case of ATM (asynchronous transfer mode).
(1) CBR (constant bit rate): Transfer at a set bit rate. For real-time transmission
of voice and video data, etc. (2) VBR (variable bit rate): Transmission quality is
enhanced by altering the transfer band depending on data volume. For
variable bit rate voice and video. (3) ABR (available bit rate): Dynamic altering
of data bit rate without band reservation. (4) UBR (unspecified bit rate):
Attempts the best transmission possible without guaranteeing any specific
throughput level.
RNC
Radio Network Controller under the UMTS system.
ROAMING
A service which enables the user to utilised his or her mobile phone via the
network facilities of another provider outside the service area of the
communication service operator to which he or she actually subscribes.
RRM
Radio Resource Management. One of the RNC functions.
SGSN
Service GPRS Support Node. Gateway between the RNC and the core
network.
22