Glossary

Hutchison 3G (Three), 3UK

A system in which signals may be sent in two directions, but not at the same time. In a half-duplex system, one end of the link must finish transmitting before the other end may begin.

Data transmission over a circuit capable of transmitting in either direction. Transmission can be bidirectional but not simultaneously.

One of the following elements: chlorine, fluorine, bromine, astatine, or iodine.

May be referred to as curly cord or curly handset lead.

An optical fiber with a hard plastic cladding surrounding a step index silica core.

The address is represented by six sections of two hexadecimal addresses; for example, 00-03-fe-e7-18-54. This number is hard-coded into networking hardware by manufacturers. Also called the physical address; see also MAC address.

Connects the transmission pins directly to the receiving pins, allowing diagnostic software to test whether a device can successfully transmit and receive.

High Density also known as HDC or HD

High Density also known as HDC or HD

(1) The central facility where signals are combined and distributed in a cable television system or a public telephone system. See central office.

The section of a packet (usually the first part of the packet) where the layer-specific information resides.

The number of decibels by which a system exceeds the minimum defined requirements. The benefit of more headroom is that it reduces the bit-error rate (BER) and provides a performance safety net to help ensure that current and future high-speed applications will run at peak accuracy, efficiency, and throughput. Also called overhead or margin.

A measurement of frequency defined as cycles per second.

An LED design in which the pn (P-type and N-type semiconductor) junction is formed from similar materials that have different refractive indices. This design is used to guide the light for directional output.