R

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Radio

A device that either makes, or responds to, radio waves, which are part of a larger group of electromagnetic waves.

Radio Access Network (RAN)

The portion of a mobile network that handles subscriber access, including radio base stations and control and concentration nodes.

Radio Frequency (RF)

Alternating current having characteristics such that, if the current is input to an antenna, an electromagnetic field is generated that is suitable for wireless broadcasting and/or communications. Radio frequencies cover a significant portion of the electromagnetic spectrum, extending from nine kilohertz (9 kHz) to thousands of gigahertz (GHz).

Radio Receiver

A device for converting radio waves into perceptible signals; a radio receiver may be a component of a complete radio set consisting of a combined transmitter-receiver, i.e., a transceiver.

Radio Spectrum

Another term for "radio frequency."

See also Radio Frequency (RF).

Radio Transmitter

A device that can take some kind of information (in this book it is data) and convert it into radio waves that can be transmitted through the air via an antenna attached to the radio transmitter. A radio receiver then intercepts the radio waves (via its antenna) and changes the radio waves back into usable data.

RADIUS

See Remote Authentication in Dial-in User Service (RADIUS).

Receive Sensitivity (Rx Sensitivity)

The minimum level signal a radio can demodulate. Transmit power and receive sensitivity together constitute what is know as "link budget." The link budget is the total amount of signal attenuation you can have between the transmitter and receiver and still have communication occur.

See also Transmit Power (Tx Power).

Remote Authentication in Dial-in User Service (RADIUS)

This term refers to a client/server protocol and software that enables remote access servers to communicate with a central server to authenticate dial-in users and authorize their access to the requested system or service.

Return on Investment (ROI)

A business process that measures the profit or cost savings that an organization realizes from an investment.

RF

See Radio Frequency (RF).

RF Tag

An identification label capable of transmitting data via RF. Some tags also receive and store data.

RIPE Network Coordination Centre (RIPE NCC)

This is one of three Regional Internet Registries that provide allocation and registration services supporting the operation of the global Internet. The RIPE NCC performs activities primarily for the benefit of the membership in Europe and the surrounding areas; mainly activities that its members need to organize as a cohesive group, even though they may compete in other areas.

Roaming

A service offered by both mobile communications network operators and HotSpot operators to enable subscribers to use telephone or computing device while in the service area of another operator. Roaming requires an agreement between operators of technologically compatible systems in individual markets to permit customers of either operator to access the other's systems.

Robust Header Compression (ROHC)

This is an Internet Engineering Task Force standard that takes advantage of the fact that consecutive data packets often have identical headers. ROHC is a robust and efficient header compression scheme for RTP/UDP/IP (Real-Time Transport Protocol, User Datagram Protocol, Internet Protocol), UDP/IP, and ESP/IP (Encapsulating Security Payload) headers. ROHC can reduce header size by around 95 percent.

Router

A device that is responsible for making decisions about which of several paths network (or Internet) traffic will follow. To do this, the device uses a routing protocol to gain information about the network and algorithms to choose the best route based on several criteria known as "routing metrics." In OSI terminology, a router is a Network Layer intermediate system. Compare with Bridge and Gateway.

Rx

Receive/receiver.

Rx Sensitivity

See Receive Sensitivity (Rx Sensitivity).



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Going Wi-Fi. A Practical Guide to Planning and Building an 802.11 Network
Going Wi-Fi: A Practical Guide to Planning and Building an 802.11 Network
ISBN: 1578203015
EAN: 2147483647
Year: 2003
Pages: 273

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