The Cable Center

This glossary of cable and telecommunications terms is intended to enhance your understanding of this dynamic industry. We are able to present this information with the generous help of CableLabs - consult their website for the most up-to-date information about cable technology.

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QoS Parameter Set
The set of Service Flow Encodings that describe the Quality of Service attributes of a Service Flow or a Service Class.

Quality-of-Service (QoS)
Guarantees network bandwidth and availability for applications. Any real time media stream that crosses a DOCSIS access link needs to be given prioritized traffic management treatment in order to assure the best user-perceived quality end-to-end. DOCSIS 1.1 and PacketCable provide several potential methods for classifying traffic (ranging from DIFFSERV to flow-classification) and several access-link traffic management functions, which can be applied to such classified traffic (priority, CBR real-time polling, header compression, stream specific modulation methods). PacketCable enables on-demand, real-time bandwidth management of DOCSIS QoS sessions.

Quadrature Amplitude Modulation (QAM)
A method of modulating digital signals onto a radio-frequency carrier signal involving both amplitude and phase coding. A modulation scheme used by telecommunications providers. More advanced modulation offers increased capacity (for example, 256 QAM offers greater capacity/transmission speeds than 64 QAM).

Quadrature Phase-Shift Keying (QPSK)
A method of modulating digital signals onto a radio-frequency carrier signal using four phase states to code two digital bits.