Links and Reference

Glossary of wireless terminology

Sources: www.wlana.com, www.itcom.itd.umich.edu, and www.geckobeach.com

AMPS: Advanced Mobile Phone Service, commonly known as analog cellular. AMPS offers limited battery life, poor sound quality, and has a much higher power output rate than the newer digital phones. Available only in the 800 MHz frequency band.

Access Point: A device that transports data between a wireless network and a wired network infrastructure. Also referred as base station.

Bluetooth: a technology specification for small form factor, low-cost, short-range wireless links between mobile PCs, mobile phones, and other portable handheld devices, and connectivity to the Internet. The Bluetooth Special Interest Group (SIG) is comprised of over 1,800 Adopter/Associate member companies. Bluetooth technology and products are not expected until the end of 2000.

Broadband: Also called wideband. Transmission facility whose bandwidth is greater than that available on voice-grade facilities.

CDPD: Cellular Digital Packet Data. Wide area data network which takes advantage of exciting AMPS cellular network by transmitting data packets on unused voice channels.

CDMA: Code Division Multiple Access. CDMA differs from GSM and TDMA by its use of spread spectrum techniques for transmitting voice or data over the air. Available in either 800 or 1900 MHz frequencies.

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DSL: Digital Subscriber Line. A data distribution service that utilizes POTS-Plain Old Telephone Service. Provides Mbps throughput rates.

DSSS: Direct Sequence Spread Spectrum. A spread spectrum modulation that divides the 2.4 GHz band (83 MHz wide) into three 24 MHz channels. One wireless LAN uses one channel. Each bit of data fills the channel with multiple frequencies. More complex than Frequency Hopping, but semiconductor improvements have reduced the cost.

DNS: Domain Name Server. The Domain Name Service is simply a two-way translation between IP name and IP address (e.g. the IP name www.utk.edu corresponds to the IP address 128.169.76.38). Dynamic DNS is a more complex service and it is usually updated regularly by DHCP servers.

DHCP: Dynamic Host Configuration Protocol. A protocol for assigning dynamic IP addresses to devices on a network.

Electromagnetic (EM) waves: Commonly characterized by their frequency (radio waves, infrared, ultra-violet, visible light, microwaves, etc.)

FCC: Federal Communications Commission. The Government agency responsible for regulating telecommunications in the United States. The agency is located in Washington, D.C.

FHSS: Frequency Hopping Spread Spectrum. A spread spectrum modulation that divides the 2.4 GHz band (83 MHz wide) into 79 hops, each 1 MHz wide. Every 0.4 seconds the transmitter hops to the next frequency determined by a pseudo-random sequence. Multiple channels, each creating a separate wireless LAN, are created with up to 15 different hopping sequences.

GSM: Global System for Mobile Communications. The most common digital cellular system in the world.

IEEE: Institute for Electrical and Electronics Engineers. A membership organization that includes engineers, scientists and students in electronics and allied fields.

IP: Internet Protocol. A method or protocol by which data is sent from one computer to another on a network, i.e. the Internet. Each computer has to have a unique assigned 32-bit IP address.

LDAP: Light Weight Directory Access Protocol. A protocol designed for accessing online directory services.

LMDS: Local Multi-point Distribution Service. This service can provide two way digital communication. Applications of LMDS include voice, video, and high speed data communication. The bandwidth of LMDS is more than twice the total bandwidth of AM/FM radio, VHF/UHF TV, and cellular telephone combined.

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MAC address: Media Access Control address. A unique hardware identifier. On Ethernet, it is the same as Ethernet address.

MMDS: Multi-channel multi-point distribution service. It operates at lower frequencies, in the 2 GHz licensed frequency bands. MMDS has wider coverage than LMDS, up to 35 miles, but has lower throughput rates. Companies such as Sprint and WorldCom own MMDS licenses in the majority of U.S. metropolitan areas.

PCS: Personal Communication Services. PCS and cellular are sometimes interchanged.

POTS: Plain Old Telephone Service Standard. Plain wired, telephone service.

RADIUS: Remote Authentication Dial-In User Service is both a software program and a detailed communications protocol. Its primary function is to allow front-end authentication and then authorize access based on multiple criteria.

Roaming: Movement of a wireless client between two access points or cells. Roaming usually occurs in infrastructure networks built around multiple access points.

Spread Spectrum: Radio frequency modulation that spreads the radio energy across a wide frequency spectrum, reducing the power at any one frequency. This is used to reduce interference and make eavesdropping difficult. Spread spectrum is a required modulation in the 2.4 GHz band, by FCC rules.

Subnet: A part of the network. Computers on the same subnet have a specific number of leading bits in their IP address that are fixed (same). Geographically distinct locations usually belong to different subnets.

TDMA: Time Division Multiple Access. Divides frequency bands available to the network into time slots, with each user having access to one time slot at regular intervals. Available in either 800 or 1900 MHz frequencies.

WAP: Wireless Access Protocol.

WEP: Wireless Equivalency Privacy. A standard that defines encryption mechanisms for data transmitted in WLANs.

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