QAM (Quadrature Amplitude Modulation)
A single-carrier scheme that modulates both the amplitude and phase to yield higher spectral efficiency. Various levels of QAM exist, and they are referred to as QAM nn, where nn indicates the number of states per Hertz. The number of bits per symbol time is k, where 2k = nn. So, 4 bits/Hz is equivalent to QAM 16, 6 bits/Hz is equivalent to QAM 64, and 8 bits/Hz is equivalent to QAM 256.
QoS (Quality of Service)
In networking, a concept by which applications may indicate their specific requirements to the network, before they actually start transmitting information data. Implicit QoS means that the application chooses the required levels of QoS. Explicit QoS means that the network manager controls that decision.
QPSK (Quadrature Phase Shift Keying)
A single-carrier modulation scheme that supports 2 bits per symbol time. Equivalent to QAM 4.
The ECMA standard for common-channel signaling between PBXs.
Signal errors caused by the process of digitizing a continuously variable slope.
A request for information entered while the computer system is processing.
An ordered accumulation of data or transactions stored for later processing.
The process whereby communications calls, processing requests, processes, and so on are stacked or held so that they can be worked with in sequence.