User's Manual

138 BreezeMAX CPEs Product Manual
Glossary
PER Packet Error Rate. In a digital transmission, PER is the percentage of
packets with errors divided by the total number of packets that have
been transmitted, received or processed over a given time period.
PHY PHYsical Layer. The physical, or lowest, layer of the OSI Network
Model. In a wireless network, the PHY defines parameters such as data
rates, modulation method, signaling parameters, transmitter/receiver
synchronization, etc. Within an actual radio implementation, the PHY
corresponds to the radio front end and baseband signal processing
sections.
POTS Plain Old Telephone System. A basic analog telephone equipment.
PPPoE Point-to-Point Protocol over Ethernet. PPPoE relies on two widely
accepted standards: PPP and Ethernet. PPPoE is a specification for
connecting the users on an Ethernet to the Internet through a
common broadband medium, such as a single DSL line, wireless
device or cable modem. All the users over the Ethernet share a
common connection, so the Ethernet principles supporting multiple
users in a LAN combines with the principles of PPP, which apply to
serial connections.
QAM Quadrature Amplitude Modulation. A technique used in wireless
applications to double the available bandwidth by combining two
amplitude-modulated signals. The two combined signals differ in
phase by 90 degrees; this technique doubles the bandwidth by
combining the two signals at the source before transmission,
transmitting digital data at a rate of 4 bits per signal change.
QoS Quality of Service. Measure of performance for a transmission system
that reflects its transmission quality and service availability.
QPSK Quadrature Phase Shift Keying. A data transfer technique used in
coaxial cable networks that sends data using modulating signals. Four
different phases represent data, with each signal's information
determined by the signal before it. For example, if a phase stays the
same from one signal to the other, the information has not changed.
RADIUS Remote Authentication Dial-In User Service, an authentication and
accounting system used by many Internet Service Providers (ISPs).
When you connect to the system you must enter your username and
password. This information is passed to a RADIUS server, which
checks that the information is correct, and then authorizes access to
the system.
RF Radio frequency. An AC signal of high enough frequency to be used for
wireless communications.