Glossary of Wireless Terms
Glossary of Wireless Terms
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
A
AMPS (advanced mobile phone service): The term used by AT&T’s Bell Laboratories (prior to the break-up of the Bell System in 1984) to refer to its cellular technology. The AMPS standard has been the foundation for the industry in the United States, although it has been modified in recent years. “AMPS-compatible” means equipment designed to work with most cellular telephones.
Analog: The traditional method of modulating radio signals so that they can carry information. AM (amplitude modulation) and FM (frequency modulation) are the two most common methods of analog modulation. An analog signal can be represented as a series of sine waves. The term originated because the modulation of the carrier wave is analogous to the fluctuations of the human voice or other sound that is being transmitted.
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B
Base Station: The central radio transmitter/receiver that maintains communications with mobile radiotelephone sets within a given range (typically a cell site).
Bluetooth: A wireless technology specification for linking portable computers, personal digital assistants (PDAs), and mobile phones for short-range transmission of voice and data across a global radio frequency band without the need for cables or wires. Bluetooth is a frequency-hopping technology in the 2.4 GHz frequency spectrum, with a range of 30 feet.
BREW: QUALCOMM’s Binary Runtime Environment for Wireless™ is an open source application development platform for wireless devices equipped for code division multiple access (CDMA) technology. BREW makes it possible for developers to create portable applications that will work on any handsets equipped with CDMA chipsets. Because BREW runs in between the application and the chip operating system software, the application can use the device’s functionality without the developer needing to code to the system interface or even having to understand wireless applications. Users can download applications – such as text chat, enhanced e-mail, location positioning, games (both online and offline), and Internet radio – from carrier networks to any BREW-enabled phone.
BREW is competing for wireless software market share with J2ME (Java 2 Micro Edition), a similar platform from Sun Microsystems. The initial version of BREW is solely for CDMA networks; later versions could be enabled for time division multiple access (TDMA) and Global System for Mobile Communication (GSM) networks. (see Java)
Broadband: Using a wide-bandwidth channel for voice, data and/or video services.
Broadband PCS: Synonymous with personal communications services created in the A- through F-Block auctions and used for voice and data.
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C
CDMA (code division multiple access): Any of several protocols used in so-called second-generation (2G) and third-generation (3G) wireless communications. As the term implies, CDMA is a form of multiplexing, which allows numerous signals to occupy a single transmission channel, optimizing the use of available bandwidth. The technology is used in ultra-high-frequency (UHF) cellular telephone systems in the 800-MHz and 1.9-GHz bands.
CDMA employs analog-to-digital conversion in combination with spread spectrum technology. Audio input is first digitized into binary elements. The frequency of the transmitted signal is then made to vary according to a defined pattern (code), so it can be intercepted only by a receiver whose frequency response is programmed with the same code, so it follows exactly along with the transmitter frequency. There are trillions of possible frequency-sequencing codes; this enhances privacy and makes cloning difficult.
The CDMA channel is nominally 1.23 MHz wide. CDMA networks use a scheme called soft handoff, which minimizes signal breakup as a handset passes from one cell to another. The combination of digital and spread-spectrum modes supports several times as many signals per unit bandwidth as analog modes. CDMA is compatible with other cellular technologies; this allows for nationwide Roaming.
The original CDMA standard, also known as CDMA One and still common in cellular telephones in the U.S., offers a transmission speed of only up to 14.4 Kbps in its single channel form and up to 115 Kbps in an eight-channel form. CDMA2000 and wideband CDMA deliver data many times faster. With CDMA, each conversation is digitized and then tagged with a code. The mobile phone is then instructed to decipher only a particular code to pluck the right conversation off the air. The process can be compared in some ways to an English-speaking person picking out in a crowded room of French speakers the only other person who is speaking English.
Cell: The basic geographic unit of a cellular system. Also, the basis for the generic industry term “cellular.” A city or county is divided into smaller “cells,” each of which is equipped with a low-powered radio transmitter/receiver. The cells can vary in size depending upon terrain, capacity demands, etc. By controlling the transmission power, the radio frequencies assigned to one cell can be limited to the boundaries of that cell. When a wireless phone moves from one cell toward another, a computer at the Mobile Telephone Switching Office (MTSO) monitors the movement and at the proper time, transfers or hands off the phone call to the new cell and another radio frequency. The handoff is performed so quickly that it’s not noticeable to the callers.
Cell Site: The location where the wireless antenna and network communications equipment is placed.
Cell Splitting: A means of increasing the capacity of a cellular system by subdividing or splitting cells into two or more small cells.
Channel: A path along which a communications signal is transmitted.
Churn: A measure of the number of subscribers who leave or switch to another carrier’s service.
Circuit-Switched: A type of network in which a physical path is obtained for and dedicated to a single connection between two end-points in the network for the duration of the connection. Ordinary voice phone service is circuit-switched. The telephone company reserves a specific physical path to the number you are calling for the duration of your call. During that time, no one else can use the physical lines involved.
Circuit-switched is often contrasted with packet-switched. Some packet-switched networks such as the X.25 network are able to have virtual circuit switching. A virtual circuit-switched connection is a dedicated logical connection that allows sharing of the physical path among multiple virtual circuit connections. (See packet-switched.)
Cloning: A wireless phone programmed with stolen or duplicated electronic serial and mobile identification numbers. At the urging of the Cellular Telecommunications Industry Association, President Clinton signed into law in April of 1998 the Wireless Telephone Protection Act (PL 105-172). The legislation amends the Federal criminal code to prohibit knowingly using, producing, trafficking in, having control or custody of, or possessing hardware or software knowing that it has been configured to insert or modify telecommunication identifying information associated with or contained in a telecommunications instrument so that such instrument may be used to obtain telecommunications service without authorization.
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D
Digital: Electronic technology that generates, stores, and processes data in terms of two states: positive and non-positive. Positive is expressed or represented by the number 1 and non-positive by the number 0. Thus, data transmitted or stored with digital technology is expressed as a string of 0′s and 1′s. Each of these state digits is referred to as a bit (and a string of bits that a computer can address individually as a group is a byte).
Prior to digital technology, electronic transmission was limited to analog technology, which conveys data as electronic signals of varying frequency or amplitude that are added to carrier waves of a given frequency. Broadcast and phone transmission has conventionally used analog technology.
Digital technology is primarily used with new physical communications media, such as satellite and fiber optic transmission. A modem is used to convert the digital information in your computer to analog signals for your phone line and to convert analog phone signals to digital information for your computer.
Dual Band Handset: Describes a handset that works on 800MHz cellular and 1900MHz PCS frequencies.
Dual Mode Handset: Describes a handset that works on both analog and digital networks.
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E
Encryption: The process of “scrambling” a message such as a digital phone signal to prevent it from being read by unauthorized parties.
ESMR (enhanced specialized mobile radio): Digital SMR networks, usually referring to Nextel Communications Inc., which provides dispatch, voice, messaging and data services.
ESN (electronic serial number): The unique identification number (like a “fingerprint”) embedded in a wireless phone by the manufacturer. Each time a call is placed, the ESN is automatically transmitted to the base station so the wireless carrier’s mobile switching office can check the call’s validity. The ESN cannot be altered in the field. The ESN differs from the mobile identification number, which is the wireless carrier’s identifier for a phone in the network. MINs and ESNs can be electronically checked to help prevent fraud.
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F
FCC (Federal Communications Commission): The government agency responsible for regulating telecommunications in the United States.
Fourth-Generation (4G): Future wireless tech could enable the use of hologram generating virtual reality programs to give users an artificial presence just about anywhere. Industry experts are predicting that such technologies are about 10 years out.
Frequency: A measure of the energy, as one or more waves per second, in an electrical or light wave information signal. A signal’s frequency is stated in either cycles-per-second or Hertz (Hz).
Frequency Reuse: The ability of specific channels assigned to a single cell to be used again in another cell, when there is enough distance between the two cells to prevent co-channel interference from affecting service quality. The technique enables a cellular system to increase capacity with a limited number of channels.
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G
GHz: gigaHertz. Billions of Hertz.
GPRS (general packet radio service): A GSM data transmission technique that enables networks to offer ‘always-on’ higher capacity access to the Internet. This enables services such as color Internet browsing, e-mail on the move, powerful visual communications, multimedia messages, and location-based services.
GPRS service promises data rates from 56 Kbps up to 114 Kbps and continuous connection to the Internet for mobile phone and computer users. The higher data rates will allow users to take part in videoconferences and interact with multimedia Web sites and similar applications using mobile handheld devices as well as notebook computers. GPRS will complement existing services such circuit-switched cellular phone connections and the Short Message Service (SMS).
In theory, GPRS packet-based service should cost users less than circuit-switched services since communication channels are being used on a shared-use, as-packets-are-needed basis rather than dedicated only to one user at a time. It should also be easier to make applications available to mobile users because the faster data rate means that middleware currently needed to adapt applications to the slower speed of wireless systems will no longer be needed. As GPRS becomes available, mobile users of a virtual private network (VPN) will be able to access the private network continuously rather than through a dial-up connection.
GPRS will also complement Bluetooth, a standard for replacing wired connections between devices with wireless radio connections.
GPS (global positioning system): A series of 24 geosynchronous satellites that continuously transmit their position. Used in personal tracking, navigation and automatic vehicle location technologies. Some wireless carriers have chosen to use GPS for tracking.
GSM (global system for mobile communications): A digital mobile telephone system that is widely used in Europe and other parts of the world. GSM uses a variation of time division multiple access (TDMA) and is the most widely used of the three digital wireless telephone technologies (TDMA, GSM, and CDMA). GSM digitizes and compresses data, then sends it down a channel with two other streams of user data, each in its own time slot. It operates at either the 900MHz or 1800MHz frequency band.
GSM is the de facto wireless telephone standard in Europe. GSM has over 747 million users worldwide and is available in 120 countries. Since many GSM network operators have roaming agreements with foreign operators, users can often continue to use their mobile phones when they travel to other countries.
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H
Handoff: The process occurring when a wireless network automatically switches a mobile call to an adjacent cell site.
Hands-Free: A feature for mobile phones that allows drivers to use their car phone without lifting or holding the handset to their ear. An important safety feature.
Hertz or HZ: The international unit for measuring frequency, equivalent to the older unit of cycles per second. One megaHertz (MHz) is one-million Hertz. One gigaHertz (GHz) is one-billion Hertz. The standard U.S. electrical power frequency is 60Hz, the AM broadcast radio frequency band is 535—1605kHz, the FM broadcast radio frequency band is 88—108 MHz, and wireless 802.11b LANs operate at 2.4GHz.
HotSpot: A place where you can access Wi-Fi service. This can be for free or for a fee. HotSpots can be inside a coffee shop, airport lounge, train station, convention center, hotel or any other public meeting area. Corporations and campuses are also implementing HotSpots to provide wireless Internet access to their visitors and guests. In some parts of the world, HotSpots are known as CoolSpots.
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I
iDEN (integrated digital enhanced network): Nextel’s technology platform. A Motorola Inc. enhanced specialized mobile radio network technology that combines two-way radio, telephone, text messaging, and data transmission into one network.
Interconnection: The connecting of one network with another; e.g., a cellular carrier’s wireless network with the local exchange.
Interoperability: The ability of a network to operate with other networks, such as two systems based on different protocols or technologies.
IS (interim standard): A designation of the American National Standards Institute – usually followed by a number – that refers to an accepted industry protocol; e.g,, IS-95, IS-136, IS-54.
IS-41: The network standard that allows all switches to exchange information about subscribers.
IS-54: The first generation of the digital standard time division multiple access technology.
IS-95: The standard for code division multiple access.
IS-136: The latest generation of the digital standard time division multiple access technology.
IS-661: North American standard for 1.9GHz wireless spread spectrum radio-frequency access technology developed by Omnipoint Corp. IS-661, for which Omnipoint was awarded a pioneer’s preference license for the New York City market, is based on a composite of code division multiple access and time division multiple access technologies. The company says IS-661 reduces infrastructure costs and allows higher data speeds than mainstream GSM or TDMA platforms.
ISDN (integrated services digital network): An advanced high-capacity wireline technology used for high-speed data transfer. Also referred to as DSL.
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J
Java or J2ME: Java 2 Micro Edition (J2ME) is a mobile platform enabling carriers to offer subscribers downloadable applications on wireless phones. Developed by Sun Microsystems, J2ME enables developers to write a single application program that is compatible with several types of devices. The platform directly competes with BREW — Binary Runtime Environment for Wireless — backed by Qualcomm.
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K
L
LEO (low-earth orbit): A mobile communications satellite between 700 and 2,000 kilometers above the earth.
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M
Message Alert (also called a “call-in-absence” indicator): A light or other indicator on a wireless phone that notifies a user that a call has come in. It’s a useful feature especially if the wireless subscriber has voice mail.
MIN (mobile identification number): Uniquely identifies a mobile unit within a wireless carrier’s network. The MIN often can be dialed from other wireless or wireline networks. The number differs from the electronic serial number, which is the unit number assigned by a phone manufacturer. MINs and ESNs can be electronically checked to help prevent fraud.
MMS (multimedia messaging service): A new standard that is being defined for use in advanced wireless terminals. The service allows for non-real-time transmission of various kinds of multimedia contents like images, audio, video clips, etc.
MTSO (mobile telephone switching office): The central computer that connects a wireless phone call to the public telephone network. The MTSO controls the entire system’s operations, including monitoring calls, billing, and handoffs.
MVNO (mobile virtual network operator): Companies that can vary from those companies that are re-branding the services of a mobile operator to those that deploy their own infrastructure and provide their own billing and services platform.
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N
NAM (number assignment module): The NAM is the electronic memory in the wireless phone that stores the telephone number and an electronic serial number.
NAMPS (narrowband advanced mobile phone system): NAMPS combines cellular voice processing with digital signaling, increasing the capacity of AMPS systems and adding functionality.
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O
Off-Peak Airtime: The periods of time after the business day has ended during which carriers offer discounted airtime charges.
Overlay Area Code: A solution to the scarcity of new phone numbers, overlays involve issuance of new 10-digit phone numbers for use alongside an area’s existing seven-digit numbers, which have a different area code.
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P
Packet-Switched: Describes the type of network in which relatively small units of data called packets are routed through a network based on the destination address contained within each packet. Breaking communication down into packets allows the same data path to be shared among many users in the network. This type of communication between sender and receiver is known as connectionless (rather than dedicated). Most traffic over the Internet uses packet switching and the Internet is basically a connectionless network.
Contrasted with packet-switched is circuit-switched, a type of network such as the regular voice telephone network, in which the communication circuit (path) for the call is set up and dedicated to the participants in that call. For the duration of the connection, all resources on that circuit are unavailable for other users. Voice calls using the Internet’s packet-switched system are possible. Each end of the conversation is broken down into packets that are reassembled at the other end.
Another type of digital network that uses packet switching is the X.25 network, a widely installed commercial wide-area-network protocol. Internet protocol packets can be carried on an X.25 network. The X.25 network can also support a virtual circuit in which a logical connection is established for two parties on a dedicated basis for some duration. A permanent virtual circuit (PVC) reserves the path on an ongoing basis and is an alternative for corporations to a system of leased lines. A permanent virtual circuit is a dedicated logical connection but the actual physical resources can be shared among multiple logical connections or users. (See circuit-switched.)
PCS (personal communications services): A two-way 1900MHz digital voice, messaging, and data service designed as the second generation of cellular.
PDA (personal digital assistant): A portable computing device capable of transmitting data. These devices make possible services such as paging, data messaging, electronic mail, computing, facsimile, date book, and other information handling capabilities.
PIN (personal identification number): A code used by a mobile telephone number in conjunction with a SIM card to complete a call.
Peak Airtime: That part of the business day in which cellular customers can expect to pay full service rates.
Prepaid Cellular: A system allowing subscribers to pay in advanced for wireless service. Prepaid is generally used for credit-impaired customers or those who want to adhere to a budget.
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Q
R
Roaming: Traveling outside a carrier’s local area.
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S
Service Charge: The amount you pay each month to receive wireless service. This amount is fixed, and paid monthly regardless of how much or how little you use your wireless phone.
SIM Card/Smart Card: A plastic card or chip containing subscriber information, often inserted into GSM phones for roaming to different countries.
SMS (short messaging service): A service for sending messages of up to 160 characters (224 characters if using a 5-bit mode) to mobile phones. SMS is similar to paging.
However, SMS messages do not require the mobile phone to be active and within range and will be held for a number of days until the phone is active and within range. SMS messages are transmitted within the same cell or to anyone with roaming service capability. They can also be sent to digital phones from a Web site equipped with PC Link or from one digital phone to another. Typical uses of SMS include:
Notifying a mobile phone owner of a voice-mail message
Notifying a salesperson of an inquiry and contact to call
Notifying a doctor of a patient with an emergency problem
Notifying a service person of the time and place of their next call
Notifying a driver of the address of the next pickup
An SMS gateway is a Web site that lets you enter an SMS message to someone within the cell served by that gateway or that acts as an international gateway for users with roaming capability.
Slamming: The unauthorized switching of a customer’s phone service to another carrier.
Smart Phone: A class of wireless phones typically used to describe handsets with many features and often a keyboard. What makes the phone “smart” is its ability to handle data, not only voice calls.
Soft Handoff: Procedure in which two base stations – one in the cell site where the phone is located and the other in the cell site to which the conversation is being passed – both hold onto the call until the handoff is completed. The first cell site does not cut off the conversation until it receives information that the second is maintaining the call.
Subscriber Fraud: A deception deliberately practiced by an impostor to secure wireless service with intent to avoid payment. This is in contrast to bad debt, which occurs when a known person or company has a payment obligation overdue and the debt cannot be collected.
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T
TDM (Time-division multiplexing ): A method of putting multiple data streams in a single signal by separating the signal into many segments, each having a very short duration. Each individual data stream is reassembled at the receiving end based on the timing.
The circuit that combines signals at the source (transmitting) end of a communications link is known as a multiplexer. It accepts the input from each individual end user, breaks each signal into segments, and assigns the segments to the composite signal in a rotating, repeating sequence. The composite signal thus contains data from multiple senders. At the other end of the long-distance cable, the individual signals are separated out by means of a circuit called a demultiplexer, and routed to the proper end users. A two-way communications circuit requires multiplexer/demultiplexer at each end of the long-distance, high-bandwidth cable.
If many signals must be sent along a single long-distance line, careful engineering is required to ensure that the system will perform properly. An asset of TDM is its flexibility. The scheme allows for variation in the number of signals being sent along the line, and constantly adjusts the time intervals to make optimum use of the available bandwidth.
Telecommunications Act of 1996: Legislation designed to spur competition among wireless and wireline carriers. Signed into law by President Clinton Feb. 8, 1996.
Telematics: The integration of wireless communications, vehicle monitoring systems, and location devices for personal automobiles and trucks.
Termination Charges: Fees that wireless telephone companies pay to complete calls on wireline phone networks or vice versa.
3G: A short term for third-generation wireless, and refers to near-future developments in personal and business wireless technology, especially mobile communications. The third generation, as its name suggests, follows the first generation (1G) and second generation (2G) in wireless communications. The 1G period began in the late 1970s and lasted through the 1980s. These systems featured the first true mobile phone systems, known at first as “cellular mobile radio telephone.” These networks used analog voice signaling, and were little more sophisticated than repeater networks used by amateur radio operators. The 2G phase began in the 1990s, and much of this technology is still in use. The 2G cell phone features digital voice encoding. Examples include CDMA, TDMA, and GSM. Since its inception, 2G technology has steadily improved, with increased bandwidth, packet routing, and the introduction of multimedia. The present state of mobile wireless communications is often called 2.5G.
Ultimately, 3G will include capabilities and features such as:
Enhanced multimedia (voice, data, video, and remote control)
Usability on all popular modes (cellular telephone, e-mail, paging, fax, videoconferencing, and Web browsing)
Broad bandwidth and high speed (upwards of 2Mbps)
Routing flexibility (repeater, satellite, LAN)
Operation at approximately 2GHz transmit and receive frequencies
Roaming capability throughout Europe, Japan, and North America
While 3G is generally considered applicable mainly to mobile wireless, it is also relevant to fixed wireless and portable wireless. The ultimate 3G system might be operational from any location on, or over, the earth’s surface, including use in homes, businesses, government offices, medical establishments, the military, personal and commercial land vehicles, private and commercial watercraft and marine craft, private and commercial aircraft (except where passenger use restrictions apply), portable (pedestrians, hikers, cyclists, campers), and space stations and spacecraft.
Triangulation: The lengthy process of pinning down a caller’s location using radio receivers, a compass and a map.
Tri-Mode Handset: Phones that work on three frequencies, typically using 1900MHz or 800MHz digital or reverting to 800MHz analog cellular when digital is not available.
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U
UMTS (universal mobile telecommunications system): Europe’s approach to standardization for third-generation cellular systems. (Universal Mobile Telecommunications Service) is a so-called “third-generation (3G),” broadband, packet-based transmission of text, digitized voice, video, and multimedia at data rates up to 2 megabits per second (Mbps) that will offer a consistent set of services to mobile computer and phone users no matter where they are located in the world. Based on the GSM (global system for mobile communications) communication standard, UMTS, endorsed by major standards bodies and manufacturers, is the planned standard for mobile users around the world by 2002. Once UTMS is fully implemented, computer and phone users can be constantly attached to the Internet as they travel and, as they roam service, have the same set of capabilities no matter where they travel. Users will have access through a combination of terrestrial wireless and satellite transmissions. Until UMTS is fully implemented, users can have multi-mode devices that switch to the currently available technology (such as GSM 900MHz and 1800MHz) where UMTS is not yet available. Today’s cellular telephone systems are mainly circuit-switched, with connections always dependent on circuit availability. Packet-switched connection, using the Internet protocol, means that a virtual connection is always available to any other end point in the network. It will also make it possible to provide new services, such as alternative billing methods (pay-per-bit, pay-per-session, flat rate, asymmetric bandwidth, and others). The higher bandwidth of UMTS also promises new services, such as video conferencing. UMTS promises to realize the virtual home environment in which a roaming user can have the same services to which the user is accustomed when at home or in the office through a combination of transparent terrestrial and satellite connections.
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V
Voice Activation: A feature that allows a subscriber to dial a phone by spoken commands instead of punching the numbers in physically. The feature contributes to convenience as well as safe driving.
Voice Recognition: The capability for cellular phones, PCs, and other communications devices to be activated or controlled by voice commands.
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W
WAP (wireless application protocol): The Wireless Application Protocol (microbrowser) provides a standardized way of linking the Internet to mobile phones, thereby linking two of the hottest industries anywhere.
Wi-Fi: Also known as 802.11b, is a leading wireless networking standard and operates in the unlicensed spectrum at 2.4GHz, which is the same frequency band used by cordless phones, microwave ovens and Bluetooth. It uses a direct sequence spread spectrum modulation scheme.
Wi-Fi is capable of transmitting data at distances up to about 300 feet and at a rate of 11 megabits per second. Because the spectrum is shared with other users, the rates fall as more users log on.
Wireless LAN (local area network): Using radio frequency (RF) technology, wireless LANs or WLANs transmit and receive data over the air, minimizing the need for wired connections. Thus, wireless LANs combine data connectivity with user mobility. WLANs are essentially networks that allow the transmission of data and the ability to share resources, such as printers, without the need to physically connect each node, or computer, with wires. Wireless LANs offer productivity, convenience, and cost advantages over traditional wired networks.
Wireless PBX: Equipment that allows employees or customers within a building or limited area to use wireless handsets connected to an office’s private branch exchange system. WPBX systems, for example, include a wireless handset that is programmed to ring simultaneously with the desk phone.
X
Y
Z
- 48 A central computer that connects a cellular phone call to the public telephone network It controls the entire system’s operation including monitoring calls billing and handoffs