LINKSYS WUSB11-V28 Wireless-B USB Network Adapter User Manual WUSB11v2 8 ug Rev A

LINKSYS LLC Wireless-B USB Network Adapter WUSB11v2 8 ug Rev A

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Part 4

27264. The Network Mode screen shows a choice of two network modes. Click theInfrastructure Mode radio button if you want your wireless computers tocommunicate with computers on your wired network via a wireless accesspoint. Click the Ad-Hoc Mode radio button if you want multiple wirelesscomputers to communicate directly with each other. Then complete the SSID field. Click the Next button to continue or theBack button to return to the previous screen.Infrastructure Mode - This mode allows wireless and wired networks tocommunicate through an access point.Ad-Hoc Mode - This mode allows wireless-equipped computers to com-municate directly with each other. No access point is used.SSID - The SSID is the unique name shared by all devices in a wireless net-work. The SSID must be identical for all devices in the wireless network. Itis case-sensitive and must not exceed 32 characters (use any of the charac-ters on the keyboard). Make sure this setting is the same for all devices inyour wireless network.Figure 7-133. The Network Setting screen will appear next. If your network has a DHCPserver, click the radio button next to Obtain an IP address automatically(DHCP). Click the Next button to continue, or click the Cancel button toreturn to the Profiles screen.If your network does not have a DHCP server, click the radio button next toSpecify the IP Address. Enter an IP Address, Subnet Mask, DefaultGateway, and DNS appropriate for your network. You must specify the IPAddress and Subnet Mask on this screen. If you are unsure about theDefault Gateway and DNS address, then leave these fields alone. Click theNext button to continue, or click the Cancel button to return to the Profilesscreen. IP Address - This IP Address must be unique to your network.Subnet Mask - The Adapter’s Subnet Mask must be the same as your wirednetwork’s Subnet Mask.Default Gateway - Enter the IP address of your network’s Gateway here. DNS 1 and DNS 2 - Enter the DNS address of your Ethernet (wired) net-work here.Figure 7-12

2928Passphrase - Instead of manually entering a WEP key, you can enter apassphrase in the Passphrase field, so a WEP key is automatically generat-ed. It is case-sensitive and should not be longer than 16 alphanumeric char-acters. This passphrase must match the passphrase of your other wirelessnetwork devices and is compatible with Linksys wireless products only. (Ifyou have any non-Linksys wireless products, enter the WEP key manuallyon those products.)WEP Key - The WEP key you enter must match the WEP key of your wire-less network. If you are using 64-bit WEP encryption, then the key mustconsist of exactly 10 hexadecimal characters. If you are using 128-bit WEPencryption, then the key must consist of exactly 26 hexadecimal characters.Valid hexadecimal characters are “0” to “9” and “A” to “F”.Tx Key - The default transmit key number is 1. If your network’s accesspoint or wireless router uses transmit key number 2, 3, or 4, then select theappropriate number in the Tx Key drop-down box.Figure 7-155. If you chose Infrastructure Mode, then proceed to step 6. If you chose Ad-Hoc Mode, then the Wireless Channels screen will now appear. Select thechannel at which the network broadcasts its wireless signal. Then click theNext button to continue or the Back button to return to the previous screen.Channel - From the drop-down box, select the appropriate channel that cor-responds with your network settings. All devices in your wireless networkmust use the same channel in order to communicate.6. The Security Settings screen will appear (see Figure 7-15). Choose theWired Equivalent Privacy (WEP) encryption settings for your wireless net-work. If you enable WEP, enter a passphrase or WEP key. Then click theNext button to continue or the Back button to return to the previous screen. WEP - If you do not want to use WEP encryption, keep the default setting,Disable. To use WEP encryption (recommended to increase wireless net-work security), select 64-bit / 10 hex. characters or 128-bit / 26 hex. char-acters from the drop-down menu, and enter a passphrase or WEP key.Figure 7-14

3332that links access points and nodes. In such a system, the user’s end node under-takes a search for the best possible access to the system. First, it evaluates suchfactors as signal strength and quality, as well as the message load currentlybeing carried by each access point and the distance of each access point to thewired backbone. Based on that information, the node next selects the rightaccess point and registers its address. Communications between end node andhost computer can then be transmitted up and down the backbone.As the user moves on, the end node’s RF transmitter regularly checks the sys-tem to determine whether it is in touch with the original access point or whetherit should seek a new one. When a node no longer receives acknowledgmentfrom its original access point, it undertakes a new search. Upon finding a newaccess point, it then re-registers, and the communication process continues.What is ISM band?The FCC and their counterparts outside of the U.S. have set aside bandwidthfor unlicensed use in the ISM (Industrial, Scientific and Medical) band.Spectrum in the vicinity of 2.4 GHz, in particular, is being made availableworldwide. This presents a truly revolutionary opportunity to place convenienthigh-speed wireless capabilities in the hands of users around the globe. What is Spread Spectrum?Spread Spectrum technology is a wideband radio frequency technique devel-oped by the military for use in reliable, secure, mission-critical communica-tions systems. It is designed to trade off bandwidth efficiency for reliability,integrity, and security. In other words, more bandwidth is consumed than in thecase of narrowband transmission, but the trade-off produces a signal that is, ineffect, louder and thus easier to detect, provided that the receiver knows theparameters of the spread-spectrum signal being broadcast. If a receiver is nottuned to the right frequency, a spread-spectrum signal looks like backgroundnoise. There are two main alternatives, Direct Sequence Spread Spectrum(DSSS) and Frequency Hopping Spread Spectrum (FHSS).What is DSSS? What is FHSS? And what are their differences?Frequency-Hopping Spread-Spectrum (FHSS) uses a narrowband carrier thatchanges frequency in a pattern that is known to both transmitter and receiver.Properly synchronized, the net effect is to maintain a single logical channel. Toan unintended receiver, FHSS appears to be short-duration impulse noise.Direct-Sequence Spread-Spectrum (DSSS) generates a redundant bit patternfor each bit to be transmitted. This bit pattern is called a chip (or chippingcode). The longer the chip, the greater the probability that the original data canbe recovered. Even if one or more bits in the chip are damaged during trans-Can I play computer games with other members of the wireless network?Yes, as long as the game supports multiple players over a LAN (local area net-work). Refer to the game’s user guide for more information.What is the IEEE 802.11b standard?It is one of the IEEE standards for wireless networks. The 802.11b standardallows wireless networking hardware from different manufacturers to commu-nicate, provided that the hardware complies with the 802.11b standard. The802.11b standard states a maximum data transfer rate of 11Mbps and an oper-ating frequency of 2.4GHz.What IEEE 802.11b features are supported?The product supports the following IEEE 802.11b functions: • CSMA/CA plus Acknowledge protocol • Multi-Channel Roaming • Automatic Rate Selection • RTS/CTS feature • Fragmentation • Power Management What is ad-hoc mode?When a wireless network is set to ad-hoc mode, the wireless-equipped com-puters are configured to communicate directly with each other. The ad-hocwireless network will not communicate with any wired network. What is infrastructure mode?When a wireless network is set to infrastructure mode, the wireless network isconfigured to communicate with a wired network through a wireless accesspoint.What is roaming?Roaming is the ability of a portable computer user to communicate continu-ously while moving freely throughout an area greater than that covered by a sin-gle access point. Before using the roaming function, the workstation must makesure that it is the same channel number with the access point of dedicated cov-erage area. To achieve true seamless connectivity, the wireless LAN must incorporate anumber of different functions. Each node and access point, for example, mustalways acknowledge receipt of each message. Each node must maintain contactwith the wireless network even when not actually transmitting data. Achievingthese functions simultaneously requires a dynamic RF networking technology

35mission, statistical techniques embedded in the radio can recover the originaldata without the need for retransmission. To an unintended receiver, DSSSappears as low power wideband noise and is rejected (ignored) by most nar-rowband receivers. Would the information be intercepted while transmitting on air?WLAN features two-fold protection in security. On the hardware side, as withDirect Sequence Spread Spectrum technology, it has the inherent security fea-ture of scrambling. On the software side, WLAN offers the encryption function(WEP) to enhance security and access control.What is WEP?WEP is Wired Equivalent Privacy, a data privacy mechanism based on a 40/64bit shared key algorithm, as described in the IEEE 802.11 standard. 34Appendix B: Glossary802.11b - One of the IEEE standards for wireless networking hardware.Products that adhere to a specific IEEE standard will work with each other,even if they are manufactured by different companies. The 802.11b standardspecifies a maximum data transfer rate of 11Mbps, an operating frequency of2.4GHz, and WEP encryption for security. 802.11b networks are also referredto as Wi-Fi networks.Ad-hoc Network - An ad-hoc network is a group of computers, each with awireless adapter, connected as an independent 802.11 wireless LAN. Ad-hocwireless computers operate on a peer-to-peer basis, communicating directlywith each other without the use of an access point. Ad-hoc mode is alsoreferred to as an Independent Basic Service Set (IBSS) or as peer-to-peermode, and is useful at a departmental scale or SOHO operation.CTS (Clear To Send) - An RS-232 signal sent from the receiving station to thetransmitting station that indicates it is ready to accept data.Default Gateway - The router used to forward all traffic that is not addressedto a station within the local subnet.DHCP (Dynamic Host Configuration Protocol) - A protocol that lets networkadministrators manage centrally and automate the assignment of InternetProtocol (IP) addresses in an organization’s network. Using the Internet’s set ofprotocol (TCP/IP), each machine that can connect to the Internet needs aunique IP address. When an organization sets up its computer users with a con-nection to the Internet, an IP address must be assigned to each machine.Without DHCP, the IP address must be entered manually at each computer and,if computers move to another location in another part of the network, a new IPaddress must be entered. DHCP lets a network administrator supervise and dis-tribute IP addresses from a central point and automatically sends a new IPaddress when a computer is plugged into a different place in the network. DHCP uses the concept of a “lease” or amount of time that a given IP addresswill be valid for a computer. The lease time can vary depending on how long auser is likely to require the Internet connection at a particular location. It’s espe-cially useful in education and other environments where users change fre-quently. Using very short leases, DHCP can dynamically reconfigure networksin which there are more computers than there are available IP addresses.

3736LAN. In infrastructure mode, the wireless devices communicate with eachother and to a wired network by first going through an access point. An infra-structure wireless network connected to a wired network is referred to as aBasic Service Set (BSS). A set of two or more BSS in a single network isreferred to as an Extended Service Set (ESS). Infrastructure mode is useful ata corporation scale, or when it is necessary to connect the wired and wirelessnetworks.IP Address - In the most widely installed level of the Internet Protocol (IP)today, an IP address is a 32-binary digit number that identifies each sender orreceiver of information that is sent in packet across the Internet. When yourequest an HTML page or send e-mail, the Internet Protocol part of TCP/IPincludes your IP address in the message (actually, in each of the packets if morethan one is required) and sends it to the IP address that is obtained by lookingup the domain name in the Uniform Resource Locator you requested or in thee-mail address you're sending a note to. At the other end, the recipient can seethe IP address of the Web page requester or the e-mail sender and can respondby sending another message using the IP address it received. IPCONFIG - A utility that provides for querying, defining and managing IPaddresses within a network. A commonly used utility, under Windows NT and2000, for configuring networks with static IP addresses.ISP - An ISP (Internet service provider) is a company that provides individualsand companies access to the Internet and other related services such as Web sitebuilding and virtual hosting. LAN - A local area network (LAN) is a group of computers and associateddevices that share a common communications line and typically share theresources of a single processor or server within a small geographic area (forexample, within an office building). MAC Address - The MAC (Media Access Control) address is your computer’sunique hardware number. mIRC - mIRC runs under Windows and provides a graphical interface for log-ging onto IRC servers and listing, joining and leaving channels.Network Mask - also known as the “Subnet Mask.”Plug-and-Play - The ability of a computer system to configure expansionboards and other devices automatically without requiring the user to turn offthe system during installation.DHCP supports static addresses for computers containing Web servers thatneed a permanent IP address. DNS - The domain name system (DNS) is the way that Internet domain nameare located and translated into Internet Protocol (IP) addresses. A domain nameis a meaningful and easy-to-remember “handle” for an Internet address. DSSS (Direct-Sequence Spread Spectrum) - DSSS generates a redundant bitpattern for all transmitted data. This bit pattern is called a chip (or chippingcode). Even if one or more bits in the chip are damaged during transmission,statistical techniques embedded in the receiver can recover the original datawithout the need for retransmission. To an unintended receiver, DSSS appearsas low power wideband noise and is rejected (ignored) by most narrowbandreceivers. However, to an intended receiver (i.e. another wireless LAN end-point), the DSSS signal is recognized as the only valid signal, and interferenceis inherently rejected (ignored).Dynamic IP Address - An IP address that is automatically assigned to a clientstation in a TCP/IP network, typically by a DHCP server. Network devices thatserve multiple users, such as servers and printers, are usually assigned static IPaddresses. ESS (Extended Service Set) - A set of more than two or more BSSs (multipleaccess points) forming a single network.Firmware - Code that is written onto read-only memory (ROM) or program-mable read-only memory (PROM). Once firmware has been written onto theROM or PROM, it is retained even when the device is turned off.IEEE - The Institute of Electrical and Electronics Engineers. The IEEEdescribes itself as “the world’s largest technical professional society—promot-ing the development and application of electrotechnology and allied sciencesfor the benefit of humanity, the advancement of the profession, and the well-being of our members.” The IEEE fosters the development of standards that often become national andinternational standards. The organization publishes a number of journals, hasmany local chapters, and several large societies in special areas, such as theIEEE Computer Society. Infrastructure Network - An infrastructure network is a group of computersor other devices, each with a wireless adapter, connected as an 802.11 wireless

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