Mitac Digital Technology LBU02 Wireless USB Adapter User Manual Manual

Mitac International Corporation Wireless USB Adapter Manual

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LBU02 User Manual

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LBU02User’s ManualRevision: R00(December 2001)

10 Table of ContentsRegulations Information.........................................................iiiSafety Precautions................................................................. 31 Introduction ..........................................................................51.1 Product Description................................................................. 11.2 Product View........................................................................... 32 Setting Up .............................................................................52.1 System Requirements............................................................. 52.2 Installing the Driver and Utility................................................. 5For Windows 98/2000/Me/XP ................................................ 5For Linux................................................................................ 82.3 Connecting the WLAN USB Dongle ........................................ 82.4 Site Selection .......................................................................... 93 Using Configuration & Monitor Application Utility..........113.1 Getting Started...................................................................... 113.2 Monitor.................................................................................. 123.3 Statistics................................................................................ 143.4 Site Survey............................................................................ 153.5 Encryption............................................................................. 163.6 Advanced.............................................................................. 174 Troubleshooting.................................................................194.1 Preliminary Checklist............................................................. 194.2 Installation Problem............................................................... 194.3 Configuration Problem........................................................... 204.4 Access Point Problem (Infrastructure Mode) ......................... 204.5 Communication Problem....................................................... 204.6 LAN Problem......................................................................... 21

4.7 Software Problem..................................................................21A Appendix............................................................................. 23A.1 Specifications ........................................................................23A.2 Uninstalling the Utility and Driver ...........................................24Configuration & Monitor Application Utility............................24WLAN USB Dongle..............................................................24Glossary.................................................................................... 25

3Regulations InformationFederal Communications Commission Interference StatementThis equipment has been tested and found to comply with the limits for a Class B digital devicepursuant to Part 15 of the FCC Rules. These limits are designed to provide reasonable protectionagainst harmful interference in a residential installation. This equipment generates, uses, and canradiate radio frequency energy and, if not installed and used in accordance with the instructions,may cause harmful interference to radio communications. However, there is no guarantee thatinterference will not occur in a particular installation. If this equipment does cause harmfulinterference to radio or television reception, which can be determined by turning the equipmentoff and on, the user is encouraged to try to correct the interference by one or more of the followingmeasures: Reorient or relocate the receiving antenna. Increase the separation between the equipment and receiver. Connect the equipment into an outlet on a circuit different from that to which the receiver isconnected. Consult the dealer or an experienced radio/TV technician for help.FCC Caution:To ensure continued compliance, use only shielded interface cables when connecting to thecomputer or peripheral devices. Any changes or modifications not expressly approved by theparty responsible for compliance could void the user’s authority to operate this equipment.This device complies with Part 15 of the FCC Rules. Operation is subject to the following twoconditions:1. This device may not cause harmful interference, and2. This device must accept any interference received, including interference that may causeundesired operation.FCC Radiation Exposure Statement: This equipment complies with FCC radiation exposure limits set forth for an uncontrolledenvironment. This equipment should be installed and operated with a minimum distance of20 cm between the radiator and your body. This transmitter must not be co-located or operated in conjunction with any other antenna ortransmitter.

Safety Precautions Be sure to read and follow all warning notices and instructions. In order to extend the life of the device it is advised to store it in a protectivecasing whenever carrying the computing device on travel and not operatingthe device. Never use abrasive materials or rinse the device with liquids. At all times, it will be the responsibility of the end-user to ensure that anoutdoor antenna installation complies with local radio regulations. Do not service the product by yourself. Refer all servicing to qualifiedservice personnel.Exposure to Radio Frequency SignalYour wireless device is a low power radio transmitter and receiver. When it isON, it receives and also sends out Radio Frequency (RF) signals. Internationalagencies have set standards and recommendations for the protection of publicexposure to RF electromagnetic energy. The design of your wireless devicecomplies with these standards when used normally. In order to limit RadioFrequency (RF) exposure, the following rules should be applied: While installing the antenna in the location, please do not turn on power ofthe device. While the device is working (linking), please do not touch or move theantenna. Contact with the antenna affects link quality and may cause thewireless device to operate at a higher power level than otherwise needed. Do not operate a portable transmitter near unshielded blasting caps or in anexplosive environment unless it is a type especially qualified for such use.

51 IntroductionThis chapter introduces the features and functions of the product.1.1 Product DescriptionCongratulations on purchasing this USB (Universal Serial Bus) DongleWireless Local Area Network (WLAN) device.Your WLAN USB Dongle’s 11 Mbps data rate provides an equivalent Ethernetspeed to access corporate networks or the Internet in a wireless environment.When installed, the WLAN USB Dongle is able to communicate with any802.11b-compliant product, allowing you to work anywhere in the coveragearea, enjoying its convenience and mobility.Your WLAN USB Dongle features: IEEE 802.11b and Wi-Fi-compliant 11 Mbps WLAN access solution Direct Sequence Spread Spectrum (DSSS) standard Wired Equivalent Privacy (WEP) 128-bit data encryption Frequency range at 2.4 GHz ISM band Automatic data rate selection at 11 Mbps, 5.5 Mbps, 2 Mbps, and 1 Mbps(automatic data rate fallback under noisy environment) USB interface Plug-and-Play High sensitivity and output power

Typical applications include: IEEE 802.11b-compliant WLAN radio Notebook computer wireless modem Point-to-Point data Wireless home networking Small Office Home Office (SOHO) wireless application

71.2 Product ViewRef Component DescriptionWireless ConnectionIndicator Glows green when the WLAN USB Dongle hassuccessfully linked with an Access Point(Infrastructure mode) or with another wireless station(Ad-Hoc mode).Power Indicator Glows red when the WLAN USB Dongle is connectedto your computer and is deriving power from it.Integrated Antenna Allows the WLAN USB Dongle to receive andtransmit wireless data.USB Port Use a USB cord to connect the WLAN USB Dongle toa computer.

92 Setting UpThis chapter tells you how to setup the device for use.2.1 System RequirementsTo use the device, you need: Operating system: Windows 98, Windows Me, Windows 2000, WindowsXP, or Linux 2.2.x Available USB port on your computing device CD-ROM Drive2.2 Installing the Driver and UtilityFor Windows 98/2000/Me/XPCAUTION: Do not connect your WLAN USB Dongle to the computer at this stage until youare required to do so.NOTE: When using Windows 2000 and before proceeding, make sure you have logged onas “Administrator.”1. Insert the driver CD into the CD-ROM drive and double-click the fileSETUP.EXE under the Windows/Setup directory.2. Follow the onscreen instructions to continue.3. When the next screen appears, select the option “Application & USBDrivers” to install the utility (Configuration and Monitor Application) andthe WLAN USB Dongle driver.

NOTE: If the WLAN USB Dongle driver have been previously installed and have not beenuninstalled prior to this latest installation, the new driver will overwrite the old one withoutprompting you.4. After you have confirmed the driver’s “Destination Location” as well as the“Program Folders,” choose the mode of operation whether Ad-Hoc orInfrastructure on the Operating Mode Dialog window.

11 Ad-Hoc ModeIn Ad-Hoc mode the wireless stations can communicate directly witheach other.When selecting the Ad-Hoc mode you need to specify the ESSID andthe Channel parameters.– ESSID: All stations participating in the Ad-Hoc network shouldhave the same ESSID.– Channel: Select the 14 channels available for use. Infrastructure ModeIn Infrastructure mode the use of an Access Point (AP) is necessary forwireless stations to communicate with each other.When selecting the Infrastructure mode you need to specify theESSID.– ESSID: Specify the ESSID of the AP to which the wireless stationwill be associated with.NOTE: You can still change the Operating Mode afterwards using the Configuration &Monitor Application utility.

5. After you have made your selection, click Next and a window listing yourinstallation setting appears. If the settings are correct, click Next tocontinue. In case you made a mistake, click Back to make the correction andfollow the onscreen instructions to exit the installation.NOTE: For Windows 2000, select Yes when the “Digital Signature Not Found” windowappears.6. Re-boot your system after completing the installation.NOTE: To uninstall the driver and utility, refer to the section “Uninstalling the Driver andUtility” on the Appendix.7. Upon re-booting your system, the Configuration & Monitor Applicationutility icon should appear on your Window’s system tray.For LinuxModule ParametersIn order to reconfigure the WLAN USB Dongle, use one of the applications thatcomes with the driver: fvnet (command line utility) or xvnet (graphical interface for the X windows)For more information on using the fvnet and xvnet applications, refer to therelevant Linux system manual pages (man xvnet or man fvnet).NOTE: If nothing happens the first time you plug in your WLAN USB Dongle,then run # insmod vnetusba.2.3 Connecting the WLAN USB DongleNOTE: Make sure that the WLAN USB Dongle’s driver as well as the Configuration &Monitor Application utility has been properly installed (see previous section).Connect one end of the included USB cord to the WLAN USB Dongle’s USBport and the other end to the USB port of your computer.

13NOTE: If you have never installed the driver of the USB port of your system, then Windowswould automatically detect the new hardware and may prompt you to install it. Have theWindows installation CD ready (in case you are prompted for it) and follow the onscreeninstructions to install the driver.Your WLAN USB Dongle should start searching for wireless signals from anAP (Infrastructure mode) or another wireless station (Ad-Hoc mode).2.4 Site SelectionThe following are the tested typical outdoor operating range: 250 M at 11 Mbps (high speed) 350 M at 5.5 Mbps (medium speed) 400 M at 2 Mbps (standard speed) 500 M at 1 Mbps (low speed)The range of the wireless signal is related to the Transmit Rate of the wirelesscommunication (Tx Rate on the Monitor utility of the Configuration &Monitor Application utility). Communications at lower transmit range maytravel larger distances.

NOTE: The range values listed above are typical distances measured. These values mayprovide a rule of thumb and may vary according to the actual radio conditions at thelocation where the WLAN USB Dongle will be installed. The range of your wireless devices can be affected when the antennas are placed nearmetal surfaces and solid high-density materials. Range is also impacted due to “obstacles” in the signal path of the radio that may eitherabsorb or reflect the radio signal.If you intend to use the WLAN USB Dongle as part of an outdoor antennainstallation, the range of the outdoor antenna installation will be related toclearance of the radio signal path.The typical conditions when used indoors in “office environments” can bedescribed as follows: In Open Office environments, antennas can “see” each other, i.e., there areno physical obstructions between them. This describes the ideal indoorantenna installation. In Semi-open Office environments, workspace is divided by shoulder-height, hollow wall elements; antenna are at desktop level. This describesthe typical indoor antenna installation. In Closed Office environments, workspace is separated by floor-to-floorceiling brick walls. This type of indoor antenna installation is not applicableto your WLAN USB Dongle.

153 Using the Configuration &Monitor Application Utility3.1 Getting StartedIn special circumstances, you may need to change configuration settingsdepending on how you would like to manage your wireless network. TheConfiguration & Monitor Application utility enables you to make configurationchanges and perform user-level diagnostics on your WLAN USB Dongle aswell as monitor the status of communication.To use the Configuration & Monitor Application utility:1. Make sure that the Configuration & Monitor Application utility has beeninstalled properly (see Chapter 2).2. The Configuration & Monitor Application utility appears as an icon on theWindows’ system tray. Double-click on this icon.NOTES: When the station is in Infrastructure mode and not associated with an AP, color of theicon is red. When the station is in Infrastructure mode and associated with an AP, color of icon isblue. When the station is in Ad-Hoc mode, color of icon is always blue. When the station is in Ad-Hoc mode and the WLAN USB Dongle is resetting andinitializing, color of icon is red.3. When the Configuration & Monitor Application utility appears onscreen,make sure that “USB Dongle” is selected on the very top of the window.

3.2 MonitorThe following configuration parameters are shown: Operating ModeAllows you to choose between Ad-Hoc or Infrastructure mode. In Ad-Hocmode the wireless stations can communicate directly with each other. InInfrastructure mode the use of an Access Point (AP) is necessary forwireless stations to communicate with each other. ChannelThis item is available only if Ad-Hoc mode was selected in the previousfield. Select the 14 channels available for use.

17 SSIDWhen using the wireless station in an Ad-Hoc mode then all participatingstations should have the same SSID. When using the wireless station in anInfrastructure mode the SSID must be the same as the SSID of the AP it isassociated with. TxRateYour WLAN USB Dongle provides various transmission (data) rate optionsfor you to select. In most networking scenarios, the option Auto will provethe most efficient. This setting allows your WLAN USB Dongle to operateat the maximum transmission rate. When the communication quality dropsbelow a certain level, the WLAN USB Dongle will automatically switch toa lower transmission rate. Transmission at lower data speeds are usuallymore reliable. However, when the communication quality improves again,the WLAN USB Dongle will gradually increase the transmission rate againuntil it reaches the highest available transmission rate. If you wish tobalance speed versus reliability, you can select any of the available options. Power Mgmt ModeAllows you to minimize power consumption and conserve the battery life ofyour computer. MAC AddressOn a Local Area Network (LAN) or other network, the MAC (MediaAccess Control) address is your computer’s unique hardware number. Onan Ethernet LAN, it is the same as your Ethernet address.The communication status is also shown: BSSIDBasic Service Set IDentifier of the AP to which the WLAN USB Dongle isassociated. Signal StrengthSignal level when receiving the last responding packet. Signal strength iscalculated as the percentage of its signal level measurement relative to thefull signal level.

 Link QualityShows the point-to-point data transmission quality between your WLANUSB Dongle and another WLAN station (Ad-Hoc mode) or thetransmission quality between your WLAN USB Dongle and the AP it isassociated with (Infrastructure mode).To change the configuration parameters press Change, make your changes thenclick Submit to save your changes.3.3 StatisticsThe Statistics utility allows you to view the statistic (Packets) information(Data Packets, Mgmt Packets, and Rejected Packets). To renew or update thelist of statistics, press Clear.

193.4 Site SurveyThe Site Survey utility allows you to scan all the channels to locate all the APs(Access Points) within range of your WLAN USB Dongle. When an/variousAP(s) are located, information regarding the BSSID and SSID, signal strengthand channel where the AP operates, whether or not WEP encryption is used, andthe operating mode is shown. Click Re-Scan to update the list.To associate with any of the APs listed, double-click on your choice (on theBSSID field) and the utility will take you back to the Monitor utility showingyou the parameters of the newly established connection.

3.5 EncryptionTo prevent unauthorized wireless stations from accessing data transmitted overthe network, the Encryption utility offers highly secure data encryption byallowing you to set four different WEP keys and specify which one to use. Toset encryption:1. Choose Enabled on the Encryption window.2. Select any of the available WEP keys (Key #1 to #4) on the WEP Key touse window. The WEP keys must be in HEX (hexadecimal) format in therange of a to f, A to F, and 0 to 9.

213. Select the WEP Mode (Mandatory or Optional). If Mandatory is selected, then not only must you use WEP encryptionbut also any other station you are communicating with must also useWEP encryption for a link to be established. This requirement is part ofthe IEEE 802.11b standard. If Optional is selected, then your station can communicate with everyother station regardless if they use WEP encryption or not.4. Select the Authentication Type (Open System or Shared Key).5. Press Submit for any changes to take effect.3.6 Advanced

The Advanced utility allows you to change the following advancedconfiguration settings: Preamble TypeBefore selecting Short, make sure that the other station(s) and AP supportsthis feature. The WLAN USB Dongle has an auto-detect feature that allowsit to select the Preamble Type depending on the Preamble Type of the APit is associated with. Fragmentation ThresholdAllows you to set the Fragmentation Threshold (threshold for the activationof the fragmentation mechanism). The Fragmentation function is used forimproving the efficiency when high traffic flows along in the wirelessnetwork. If you often transmit large files in the wireless network, move theslide bar with your mouse and then use the right and left arrow keyboardkeys to select an exact number. The figure shows the recommendedconfiguration setting. RTS/CTS ThresholdAllows you to set the RTS Threshold (threshold for the activation of theRTS/CTS mechanism). Transmitter contending for the medium may nothear each other. RTS/CTS (Request-To-Send/Clear-To-Send) mechanismcan solve this “Hidden Node Problem.” If the packet size is smaller than thepreset RTS Threshold size, the RTS/CTS mechanism will not be enabled.To enable RTS/CTS Threshold, move the slide bar with your mouse andthen use the right and left arrow keyboard keys to select an exact number.The figure shows the recommended configuration setting.

234 TroubleshootingThis chapter covers potential problems you may run into and the possibleremedies. After each problem description, some instructions are provided tohelp you to diagnose and solve the problem.4.1 Preliminary ChecklistHere are helpful hints to follow before you take further actions when youencounter problems: Try to isolate which part of the computer’s network connection is causingthe problem. Make sure that the cable connections are correct and secure (from WLANUSB Dongle’s USB port to the computer’s USB port). Absence of, or conflict of the WLAN USB Dongle driver. Make sure that alldevice drivers are correctly installed (refer to chapter 2).If a problem persists after you follow the instructions in this chapter, contact anauthorized dealer for help.4.2 Installation ProblemProblems encountered during installation. Reconnect one end of the USB cable to the WLAN USB Dongle and theother end to the computer again. The Power LED indicator on the WLANUSB Dongle should be ON (red) if the USB cable is properly connected. Check if the I/O and IRQ for the WLAN USB Dongle have conflictproblems with other devices connected to your computer.

 For Windows 98 / 2000 / Me / XP operating system, make sure that the USBdevice driver is installed on your computer.4.3 Configuration ProblemProblems encountered with the configuration. Use the Monitor utility of your Configuration & Monitor Applicationutility to check the Link Quality of your WLAN USB Dongle with the AP itis associated with (Infrastructure mode) or with other wireless station(s)(Ad-Hoc mode). Use the Site Survey utility of your Configuration & Monitor Applicationutility to check if there is high interference around the environment.4.4 Access Point Problem (Infrastructure Mode)Problems with settings for the Access Point. Make sure that the Access Point that your WLAN USB Dongle is associatedwith is powered on and all the LEDs are working properly. Reconfigure and reset the Access Point. Use the Web Manager / Telnet of the Access Point to check whether it isconnected to the network.4.5 Communication ProblemThe WLAN USB Dongle cannot communicate with the computer in theEthernet when Infrastructure mode is configured. Make sure that the Access Point your WLAN USB Dongle is associatedwith is powered on. Use the Site Survey utility of the Configuration & Monitor Applicationutility to verify if the operating radio channel is in good quality. Or, changethe Access Point and all the wireless station(s) within the BSSID to anotherradio channel.

25 Out-of-range situation, which prevents the WLAN USB Dongle fromestablishing a wireless connection with the network. Move the WLAN USBDongle closer to the Access Point it is associated with. Make sure that your WLAN USB Dongle is configured with the samesecurity option (encryption) to the Access Point. Make sure that the BSSID is the same as the Access Point for a roaming-disabled wireless station, or the ESSID is the same as the Access Point for aroaming-enabled wireless station.4.6 LAN ProblemI cannot access the network. Make sure that the necessary driver(s) is correctly installed. Make sure that the network configuration is appropriate. Make sure that the user name or password is correct. You have moved out of range of the network. Turn off power management.4.7 Software ProblemThe Configuration & Monitor Application utility does not work correctly. Make sure that the Configuration & Monitor Application utility iscorrectly installed (refer to chapter 2). If you are sure the operation has stop, reset the computer.

27A AppendixA.1 SpecificationsNOTE: Specifications are subject to change without notice.Parts SpecificationsFrequency Band ISM Band2400 to 2483.5 MHz (for USA and Canada)2400 to 2483.5 MHz (for Europe)2400 to 2497 MHz (for Japan)Operating Channel IEEE 802.11b, Direct Sequence Spread Spectrum (DSSS)11 Channels (for USA and Canada)13 Channels (for Europe)14 Channels (for Japan)Modulation Technique BPSK (low transmit rate) / QPSK (standard transmit rate) /CCK (high and medium transmit rate)Data Rate Up to 11 Mbit/sAntenna SingleAntenna Gain 1 dBi maximumRadiation Power 16 dBm typicalReceiver Sensitivity –80 dBm at 11 Mbps–82 dBm at 5.5 Mbps–87 dBm at 2 Mbps–90 dBm at 1 MbpsPower Consumption 5 V, 320 mA TX, 230 mA RXDimension (W×H×D) 84×20×92 mmWeight 48 gEnvironmentTemperature Operating: 0°C (32°F) to 55°C (131°F)Storage: –20°C (–3.91°F) to 70°C (158.02°F)Environment Humidity Operating: 0% to 70%Storage: 0% to 95% (non-condensing)

Parts SpecificationsRegulation (compliant) Wi-Fi compliant, FCC/CA, CE (Europe), DGT/BSMIOS Support Windows 98 / Me / 2000 / XP / Linux 2.2.xA.2 Uninstalling the Utility and DriverConfiguration & Monitor Application Utility1. Exit the Configuration & Monitor Application utility if it is currently active.2. Select the “Uninstall Configuration & Monitor Application” option byclicking on Start, then Programs, then 802.11 Wireless LAN.NOTE: If during the uninstall process you receive an error message, insert the driver CDand try to uninstall again.WLAN USB DongleFor Windows 98 / Me / XP –1. Select the “Network” icon by clicking on Start, then Settings, then ControlPanel.2. Select the “WLAN USB Dongle” from the list and click on Remove.3. When the system prompts you to re-boot, select “Yes.”For Windows 2000 –1. Make sure that the WLAN USB Dongle is plugged into the USB port.2. Select the WLAN USB Dongle under Device Manager.3. Click on Uninstall.

29G lossary802.11 The IEEE standard that specifies WLAN MAC and PHY (PhysicalLayer) specifications.802.11b The IEEE standard that specifies Higher-Speed Physical LayerExtension in the 2.4 GHz band for 5.5 and 11 Mbps WLANs.802.3 The IEEE standard that specifies carrier sense media access control andphysical layer specifications for Ethernet LANs.Access Control The prevention of unauthorized usage of network resources bydemanding that users supply a login name and password.Access Point(AP) Any entity that has station functionality and provides access to thedistribution services, via the Wireless Medium (WM) for associatedstations.Ad-Hoc An Ad-Hoc WLAN is a group of computers each with wireless adaptersconnected as an independent WLAN.Authentication In a multi-user or network operating system, the process by which thesystem validates a user's logon information. A user's name and passwordare compared against an authorized list, and if the system detects amatch, access is granted to the extent specified in the permission list forthat user.Authenticity Proof that the information came from the person or location thatreportedly sent it. One example of authenticating software is throughdigital signatures.Bandwidth A frequency measurement, expressed in cycles per second (hertz) or bitsper second (bps), of the amount of information that can flow through achannel. The higher the frequency, the higher the bandwidth.Base Station In mobile telecommunications, a base station is the central radiotransmitter/receiver that maintains communication with the mobile radiotelephone sets within its range. In cellular and personal communicationsapplications, each cell or micro-cell has its own base station, each basestation in turn is interconnected with other cell’s base stations.Bit (Binary Digit) – A single digit number in base-2, in other words, either aone or a zero. The smallest unit of computerized data.

Broadband Of or relating to communications systems in which the medium oftransmission (such as a wire or fiber-optic cable) carries multiplemessages at a time, each message modulated on its own carrier frequencyby means of modems. Broadband communication is found in wide areanetworks.BSS Basic Service Set. An AP associated with several wireless stations.Byte Abbreviated B. Short for binary term. A unit of data, today almostalways consisting of 8 bits. A byte can represent a single character, suchas a letter, a digit, or a punctuation mark. Because a byte represents onlya small amount of information, amounts of computer memory andstorage are usually given in kilobytes (1,024 bytes), megabytes(1,048,576 bytes), or gigabytes (1,073,741,824 bytes).Cryptoanalysis The act of analyzing (or breaking into) secure documents or systems thatare protected with encryption.Decryption The act of restoring an encrypted file to its original state.DirectionalAntenna An antenna that concentrates transmission power into a direction therebyincreasing coverage distance at the expense of coverage angle.Directional antenna types include yagi, patch and parabolic dish.Direct SequenceSpread Spectrum Abbreviated DSSS. A type of spread spectrum radio transmission thatspreads its signal continuously over a wide frequency band.EMI ElectroMagnetic Interference. The interference by electromagneticsignals that can cause reduced data integrity and increased error rates ontransmission channels.Encryption The act of substituting numbers and characters in a file so that the file isunreadable until it is decrypted. Encryption is usually done using amathematical formula that determines how the file is decrypted.ESSID (Extended Service Set IDentification) The ESSID identifies the ServiceSet the station is to connect to. Wireless clients associating to the APmust have the same ESSID.Ethernet A very common method of networking computers in a LAN. There are anumber of adaptations to the IEEE 802.3 Ethernet standard, includingadaptations with data rates of 10 Mbits/sec and 100 Mbits/sec overcoaxial cable, twisted-pair cable and fiber-optic cable. The latest versionof Ethernet, Gigabit Ethernet, has a data rate of 1 Gbit/sec.Gateway A device that connects networks using different communicationsprotocols so that information can be passed from one to the other. Agateway both transfers information and converts it to a form compatiblewith the protocols used by the receiving network.Gigahertz (GHz) One billion cycles per second. A unit of measure for frequency.Hertz (Hz) The unit of frequency measurement; one cycle (of a periodic event suchas a waveform) per second. Frequencies of interest in computers andelectronic devices are often measured in kilohertz (kHz = 1,000 Hz = 103Hz), megahertz (MHz = 1,000 kHz = 106 Hz), gigahertz (GHz = 1,000MHz = 109 Hz), or terahertz (THz = 1,000 GHz = 1012 Hz).

31Host Any computer on a network that is a repository for services available toother computers on the network. It is quite common to have one hostmachine provide several services, such as WWW and USENET.HTTP Acronym for HyperText Transfer Protocol. The client/server protocolused to access information on the World Wide Web.IEEE 802Standards A set of standards developed by the IEEE to define methods of accessand control on LANs. The IEEE 802 standards correspond to thephysical and data-link layers of the ISO Open Systems Interconnectionmodel, but they divide the data-link layer into two sublayers. The logicallink control (LLC) sublayer applies to all IEEE 802 standards and coversstation-to-station connections, generation of message frames, and errorcontrol. The MAC sublayer, dealing with network access and collisiondetection, differs from one IEEE 802 standard to another: IEEE 802.3 isused for bus networks that use CSMA/CD, both broadband andbaseband, and the baseband version is based on the Ethernet standard.IEEE 802.4 is used for bus networks that use token passing, and IEEE802.5 is used for ring networks that use token passing (token ringnetworks). In addition, IEEE 802.6 is an emerging standard formetropolitan area networks, which transmit data, voice, and video overdistances of more than five kilometers.internet (Lower case I) Any time you connect two or more networks together,you have an internet.Internet (Upper case I) The worldwide collection of networks and gateways thatuse the TCP/IP suite of protocols to communicate with one another. Atthe heart of the Internet is a backbone of high-speed data communicationlines between major nodes or host computers, consisting of thousands ofcommercial, government, educational, and other computer systems, thatroute data and messages. One or more Internet nodes can go off linewithout endangering the Internet as a whole or causing communicationson the Internet to stop, because no single computer or network controls it.Currently, the Internet offers a range of services to users, such as FTP,email, the World Wide Web, Usenet news, Gopher, IRC, telnet, andothers. Also called Net.Intranet A private network inside a company or organization that uses the samekinds of software that you would find on the public Internet, but that isonly for internal use.ISP (InternetServiceProviders)ISPs provide connections into the Internet for home users andbusinesses. There are local, regional, national and global ISPs. You canthink of local ISPs as the gatekeepers into the Internet.

LAN (Local AreaNetwork) Personal and other computers within a limited area that are linked byhigh-performance cables so that users can exchange information, shareperipherals, and draw on programs and data stored in a dedicatedcomputer called a file server.Ranging tremendously in size and complexity, LANs may link only afew personal computers to an expensive, shared peripheral, such as laserprinter. More complex systems use central computers (file servers) andallow users to communicate with each other via electronic mail to sharemulti-user programs and to access shared databases.Linux A version of the UNIX System V Release 3.0 kernel developed for PCswith 80386 and higher-level microprocessors. Linux is distributed freewith source code through BBSs and the Internet, although somecompanies distribute it as part of a commercial package with Linux-compatible utilities. The Linux kernel works with the GNU utilities.MAC (MediaAccess Control) On a LAN or other network, the MAC address is your computer’s uniquehardware number. (On an Ethernet LAN, it is the same as your Ethernetaddress.) The MAC layer frames data for transmission over the network,then passes the frame to the physical layer interface where it istransmitted as a stream of bits.Megahertz (MHz) A measure of frequency equivalent to 1 million cycles per second.Modulation The conversion of a digital signal to its analog equivalent, especially forthe purposes of transmitting signals using telephone lines and modems.Network Any time you connect two or more computers together so that they canshare resources, you have a computer network. Connect two or morenetworks together and you have an internet.NIC (NetworkInterface Card) A board that provides network communication capabilities to and from acomputer system. Also called an adapter.Node In LAN, a connection point that can create, receive, or repeat a message.Nodes include repeaters, file servers, and shared peripherals. In commonusage, however, the term node is synonymous with workstation.Packet A basic message unit for communication across a network. A packetusually includes routing information, data and (sometimes) error detectioninformation.PCMCIA(PersonalComputerMemory CardInternationalAssociation)Develops standards for PC Cards, formerly known as PCMCIA Cards.They are available in three types that are about the same length and widthas credit cards but range in thickness from 3.3 mm (Type I) to 5.0 mm(Type II) to 10.5 mm (Type III). These cards provide many functions,including memory storage and acting as landline modems and as WLAN.POP (Post OfficeProtocol) This is a common protocol used for sending, receiving and delivering mailmessages.

33Port (H/W) An interface on a computer for connecting peripherals or devices to thecomputer. A printer port, for example, is an interface that is designed tohave a printer connected to it. Ports can be defined by specific hardware(such as a keyboard port) or through software.Port An Internet port refers to a number that is part of a URL, appearing after acolon (:) right after the domain name. Every service on an Internet serverlistens on a particular port number on that server. Most services havestandard port numbers, e.g., web servers normally listen on port 80.Privacy The concept that a user's data, such as stored files and email, is not to beexamined by anyone else without that user's permission. A right to privacyis not generally recognized on the Internet. Federal law protects onlyemail in transit or in temporary storage, and only against access by Federalagencies. Employers often claim a right to inspect any data on theirsystems. To obtain privacy, the user must take active measures such asencryption.Protocol A “language” for communicating on a network. Protocols are sets ofstandards or rules used to define, format and transmit data across anetwork. There are many different protocols used on networks. Forexample, most web pages are transmitted using the HTTP protocol.Proxy Server A server that performs network operations in lieu of other systems on thenetwork. Proxy servers are most often used as part of a firewall to maskthe identity of users inside a corporate network yet still provide access tothe Internet. When a user connects to a proxy server via a web browser orother networked application, he submits commands to the proxy server.The server then submits those same commands to the Internet, yet withoutrevealing any information about the system that originally requested theinformation. Proxy servers are an ideal way to also have all users on acorporate network channel through one point for all externalcommunications. Proxy servers can be configured to block certain kindsof connections and stop some hacks.Public KeyEncryption An asymmetric scheme that uses a pair of keys for encryption: the publickey encrypts data, and a corresponding secret key decrypts it. For digitalsignatures, the process is reversed: the sender uses the secret key to createa unique electronic number that can be read by anyone possessing thecorresponding public key, which verifies that the message is truly from thesender.Radio Frequency(RF) The portion of the electromagnetic spectrum with frequencies between 3kilohertz and 300 gigahertz. This corresponds to wavelengths between 30kilometers and 0.3 millimeter.Range A linear measure of the distance that a transmitter can send a signal.RFC (Request forComments) An RFC is an Internet formal document or standard that is the result ofcommittee drafting and subsequent review by interested parties. SomeRFCs are informational in nature. Of those that are intended to becomeInternet standards, the final version of the RFC becomes the standard andno further comments or changes are permitted. Change can occur,however, through subsequent RFCs.

Roaming A function that enables one to travel with his mobile end system (e.g.,WLAN mobile station) throughout a domain (e.g., an ESS) while beingcontinuously connected to the infrastructure.Router An intermediary device on a communications network that expeditesmessage delivery. On a single network linking many computers through amesh of possible connections, a router receives transmitted messages andforwards them to their correct destinations over the most efficientavailable route. On an interconnected set of LANs using the samecommunications protocols, a router serves the somewhat differentfunction of acting as a link between LANs, enabling messages to be sentfrom one to another.RTS (Request-To-Send)ThresholdA signal sent, as from a computer to its modem, to request permission totransmit. Transmitter contending for the medium may not hear each other.RTS/CTS mechanism can solve this “Hidden Node Problem.” If thepacket size is smaller than the preset RTS Threshold size, the RTS/CTSmechanism will not be enabled.Server 1. On a LAN, a computer running administrative software that controlsaccess to the network and its resources, such as printers and disk drives,and provides resources to computers functioning as workstations on thenetwork.2. On the Internet or other network, a computer or program that respondsto commands from a client. For example, a file server may contain anarchive of data or program files; when a client submits a request for a file,the server transfers a copy of the file to the client.SSL (SecureSockets Layer) Technology that allows you to send information that only the server canread. SSL allows servers and browsers to encrypt data as theycommunicate with each other. This makes it very difficult for third partiesto understand the communications.Station (STA) Any device that contains an IEEE 802.11 conformant Medium AccessControl (MAC) and physical layer (PHY) interface to the WirelessMedium (WM).Telnet An Internet protocol that enables Internet users to log on to anothercomputer linked to the Internet, including those that cannot directlycommunicate with the Internet’s TCP/IP protocols. Telnet establishes a“plain vanilla” computer terminal called a network virtual terminal. Thiscapability is frequently used to enable communications with bulletinboard systems (BBSs) and mainframe computers. For example, you willoften see hyperlinks to Telnet sessions while browsing the WWW. If youclick such a hyperlink, your browser starts a Telnet helper program, andyou see a text-only command window. In this window, you typecommands and see the remote system’s responses.

35URL (UniformResourceLocator)An address for a resource on the Internet. URLs are used by Web browsersto locate Internet resources. A URL specifies the protocol to be used inaccessing the resource (such as http: for a World Wide Web page or ftp:for an FTP site), the name of the server on which the resource resides(such as //www.whitehouse.gov), and, optionally, the path to a resource(such as an HTML document or a file on that server).VPN (VirtualPrivate Network) 1. A set of nodes on a public network such as the Internet thatcommunicate among themselves using encryption technology so that theirmessages are as safe from being intercepted and understood byunauthorized users as if the nodes were connected by private lines.2. A WAN formed of permanent virtual circuits (PVCs) on anothernetwork, especially a network using technologies such as ATM or framerelay.WAN (Wide AreaNetwork) A network that uses high-speed, long-distance communications networksor satellites to connect computers over distances greater than thosetraversed by LANs – about 2 miles (3.22 km).Wired EquivalentPrivacy (WEP) The optional cryptographic confidentiality algorithm specified by IEEE802.11 used to provide data confidentiality that is subjectively equivalentto the confidentiality of a wired LAN medium that does not employcryptographic techniques to enhance privacy.Wireless LocalArea Network(WLAN)A flexible data communications system implemented as an extension to,or an alternative for a wired LAN. Using radio frequency (RF)technology, WLANs transmit and receive data over the air, minimizingthe need for wired connections.Wireless Medium(WM) The medium used to implement the transfer of protocol data units (PDUs)between peer physical layer (PHY) entities of a WLAN.WWW (WorldWide Web) The total set of interlinked hypertext documents residing on HTTP serversall around the world. Documents on the World Wide Web, called pages orWeb pages, are written in HTML (Hypertext Markup Language),identified by URLs (Uniform Resource Locators) that specify theparticular machine and pathname by which a file can be accessed, andtransmitted from node to node to the end user under HTTP (HypertextTransfer Protocol). Codes, called tags, embedded in an HTML documentassociate particular words and images in the document with URLs so thata user can access another file, which may be halfway around the world, atthe press of a key or the click of a mouse. These files may contain text (ina variety of fonts and styles), graphics images, movie files, and sounds aswell as Java applets, ActiveX controls, or other small embedded softwareprograms that execute when the user activates them by clicking on a link.A user visiting a Web page also may be able to download files from anFTP site and send messages to other users via email by using links on theWeb page. Also called w3, W3, Web.

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