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Q: What is a Wireless LAN (WLAN)?
A: A WLAN is a type of Local Area Network (LAN) that uses high frequency radio waves rather than wires to communicate and transmit data among nodes. It is a flexible data communication system implemented as an extension to, or as an alternative for, a wired LAN within a building or campus.
Q: What are the benefits of using a WLAN instead of a wired network connection?
A: Increased Productivity - WLAN provides "untethered", campus-wide network and Internet access. WLAN offers the freedom to roam and stay connected. - Fast and Simple Network Set-up - There are no cables to install.
- Installation Flexibility - WLANs can be installed in places where wires can't, and they facilitate temporary set-up and relocation.
- Reduced Cost-of-Ownership - Wireless LANS reduce installation costs because there is no cabling; as a result, savings are greatest in frequently changing environments.
- Scalability - Network expansion and reconfiguration is uncomplicated, and users can be added to the network simply by installing a wireless LAN adapter to the client device.
- Interoperability - Customers can rest assured that other brands of compatible client and network-sided products will work with superior HP solutions.
Q: Are HP WLAN products interoperable with other product brands?
A: Yes. HP WLAN products are compatible with products from different vendors employing the same technology (i.e., Direct Sequence Spread Spectrum); this will allow users to use client adapters from multiple vendors. The goal of industry standards, including the IEEE 802.11 specifications, is to allow compliant products to interoperate without explicit collaboration between vendors. WECA (Wireless Ethernet Compatibility Alliance) is an industry organization that certifies WLAN product interoperability. The 802.11b specification provides the guidelines for WLAN interoperability, and the Wireless Ethernet Compatibility Alliance (WECA) ensures that products interoperate in real-world applications. Systems will interoperate as long as the PC client card and access point are 802.11b compliant and WECA certified.
Q: Is the installation and administration of a WLAN difficult?
A: No. A wireless LAN is simpler to install than a wired LAN, and the administration of the two network types is very similar. The client-side WLAN solution offers Plug-and-Play simplicity to connect to the network or other computers (peer-to-peer).
Q: What is IEEE 802.11b?
A: IEEE 802.11b is a technical specification issued by the Institute of Electrical and Electronic Engineers (IEEE) that defines the operation of 2.4 GHz, 11 Mbps, Direct Sequence Spread Spectrum Wireless Local Area Networks (WLANs).
Q: Are WLANs secure?
A: Yes, WLANs are highly secure. Because wireless technology has roots in military applications, security provisions have long been designed into wireless devices and wireless LANs are typically more secure than most wired LANs. WLANs use Direct Sequence Spread Spectrum (DSSS) technology, which is extremely resistant to corruption, interference, jamming, and detection. In addition, all wireless users on your network can identify themselves with a system ID that prevents unauthorized users from gaining access. Users with particularly sensitive data can enable Wired Equivalent Privacy (WEP), which further encrypts the signal and verifies the data with an electronic "security key". In general, individual nodes must be security-enabled before participating in network traffic. 802.11b WLANs may use 40-bit and 128-bit encryption along with user authentication to provide a high degree of network security. It is virtually impossible for unintended receivers and eavesdroppers to listen in on wireless LAN traffic.
Q: What is the transmission range of WLAN products?
A: Radio Frequency (RF) range, especially in indoor environments, is a function of product design, including transmitted power and receiver design, interference, and propagation path. Interactions with typical building objects, including walls, metal, and even people, can affect how energy propagates, and thus what range and coverage a particular system achieves. Wireless LAN systems use RF because radio waves can penetrate many indoor walls and surfaces. The range or radius of coverage for typical WLAN systems varies up to 500 feet (164 meters) depending on the number and types of obstacles encountered. Coverage can be extended, and freedom of true mobility and roaming can be provided for a greater area through the use of multiple access points.
Q: What is WECA?
A: The Wireless Ethernet Compatibility Alliance (WECA) is a non-profit organization formed in 1999 and was officially and publicly launched on August 23, 1999 in Santa Clara, CA. WECA's mission is to certify interoperability of Wi-Fi (IEEE 802.11b High Rate) WLAN products and to promote Wi-Fi as the standard for wireless LAN deployments across all market segments.
Q: What is Wi-Fi?
A: Wi-Fi is the trademarked name that WECA uses to signify WLAN product interoperability. The name stands for "wireless fidelity." WECA performs elaborate tests on WLAN products; those that meet the interoperability standard are awarded the Wi-Fi logo.
Q: What is the data throughput speed of an 802.11b WLAN network connection?
A: 802.11b WLANs operate up to speeds of 11 Mbps. WLAN users experience speed comparable to that offered by the wired network, and similar to the wired network, WLAN throughput speed depends on network topology, load, distance from the access point, etc. There is typically no perceived difference in performance compared to a wired connection.
Q: What is an Access Point?
A: An Access Point connects wired and wireless networks together and enables the sending and receiving of data between wireless clients and the wired network. Each Access point also increases total system capacity and range. Users can "roam" between access points without losing their connection similar to a cellular phone. A hardware device or software used in conjunction with a computer serves as a communications hub for wireless clients and provides a connection to a wired LAN.
Q: When do I need an Access Point?
A: Access points are required for network access but not for peer-to-peer connections. A wireless network only requires an access point when connecting notebook or desktop computers to a wired network. Some important advantages make access points a valuable addition to your wireless network, with or without a wired network. First, a single access point can nearly double the range of your wireless LAN compared to a simple peer-to-peer (ad-hoc) network. Second, the wireless access point acts as a traffic controller, directing all data on the network, allowing wireless clients to run at maximum speed. Finally, an access point can be your central connection to the outside world, providing Internet sharing.
Q: What is the difference between an Access Point and a bridge product?
A: Bridges allow wired LANs to wirelessly interconnect with other wired LANs. You can use a bridge to connect one segment on the LAN to another segment in the same building or in another building across town. Access Points are used to connect wireless clients to wired LANs.
Q: How many users can a WLAN system support?
A: The number of users is virtually unlimited. The number of users can be expanded simply by adding network access points. By introducing overlapping access points, set at different frequencies (channels), the wireless network can expand to accommodate additional simultaneous users in the same area. Up to three overlapping channels can be used concurrently without interference, which effectively triples the number of supported network users. Similarly, the WLAN can support more users by installing additional access points in various locations in the building. This increases the total number of users and allows roaming throughout the building or across the campus.
Q: How many simultaneous users can a single access point support?
A: The number of simultaneous users that an access point can support depends primarily on the amount of data traffic encountered (heavy downloads and uploads vs. light). Bandwidth is shared among users on a WLAN as with wired network connections. Network performance, as gauged by the number of simultaneous users, is contingent upon the type of activity engaged in by users.
Q: How can I increase the number of users supported on the WLAN?
A: You can increase the range of your network simply by adding access points. Adding access points in the same location (overlapping coverage) will support more simultaneous users in that area, and adding access points throughout the building will enable system users to roam among access points while maintaining their network connection.
Q: Why do WLANs operate on the 2.4 GHz Frequency range?
A: This frequency range has been set aside by the FCC, and is generally labeled the ISM (Industrial, Scientific and Medical) band. A few years ago Apple and several other large corporations requested that the FCC allow the development of wireless networks within this frequency range. What we have today is a protocol and system that allows for unlicensed use of radios within a prescribed power level. The ISM band is populated by Industrial, Scientific and Medical devices that are all low power devices.
Q: What is WEP?
A: WEP (Wired Equivalent Privacy) is an optional IEEE 802.11 feature used to provide data security that is equivalent to that of a wired LAN without privacy-enhancing encryption techniques. WEP will ensure the wireless LAN link is as secure as a wired link. According to the 802.11 standard WEP data encryption is used to prevent (i) access to the network by "intruders" using similar wireless LAN equipment and (ii) capture of wireless LAN traffic through eavesdropping. WEP allows the administrator to define a set of respective "Keys" for each wireless network user based on a "Key String" passed through the WEP encryption algorithm. Access is denied by anyone who does not have the required key. As specified in the standard, WEP uses the RC4 algorithm with a 40-bit or 128-bit key. When WEP is enabled, each station (clients and Access Points) has a key. The key is used to encrypt the data before it is transmitted through the airwaves. If a station receives a packet that is not encrypted with the appropriate key, the packet will be discarded and not be delivered to the host; this prevents unauthorized network access and eavesdropping.
Q: What is Frequency-Hopping Spread Spectrum (FHSS)?
A: Frequency-Hopping Spread-Spectrum (FHSS) is a spread spectrum modulation scheme that uses a narrowband carrier that changes frequency in a pattern known to both the transmitter and receiver. Properly synchronized, they maintain a single logical channel. To an unintended receiver, FHSS appears as short-duration impulse noise. FHSS technology uses bandwidth inefficiently in order to assure high security; therefore, FHSS systems typically have lower throughput speeds than Direct Sequence Spread Spectrum (DSSS) systems. Slower performing WLAN devices (1 Mbps) use FHSS.
Q: What is Direct Sequence Spread Spectrum (DSSS)?
A: Direct-Sequence Spread-Spectrum (DSSS) is a spread spectrum modulation scheme that generates a redundant bit pattern for each transmitted bit. The bit pattern, called a chip or chipping code, enables receivers to filter out signals that don't use the same bit pattern, including noise or interference. The chipping code serves two primary functions: 1) It identifies the data so that the receiver can recognize it as belonging to a certain transmitter. The transmitter generates the chipping code and only receivers that know the chipping code can decipher the data. 2) The chipping code spreads the data across the available bandwidth. Longer chips require more bandwidth but allow a greater probability that the original data can be recovered. Even if one or more bits in the chip are damaged during transmission, technology embedded in the radio can recover the original data using statistical techniques without the need for retransmission. Unintended narrowband receivers ignore DSSS signals as low-power, wideband noise. 802.11b WLANs use DSSS and have higher data throughput than their FHSS counterparts because of the lower overhead of the DSSS protocol.
Q: Will Bluetooth and Wireless LAN (WLAN) interfere with each other?
A: No, both Bluetooth and WLAN can co-exist. Since Bluetooth devices use Frequency Hopping and most WLANs use Direct Sequence Spreading techniques they each appear as background noise to the other and should not cause any perceivable performance issues.
Q: Is WLAN technology only for notebook computers?
A: No. While WLAN systems are ideal for networking mobile computers they are equally useful for connecting desktop computers and a variety of emerging mobile platforms. WLAN solutions are designed to eliminate cables to networked devices thereby eliminating cabling costs and increasing connection flexibility and mobility.
Q: Will I need to replace my computer to use HP's WLAN solutions?
A: No. HP WLAN products can be used with your existing notebook or Desktop PC.
Q: Are there any adverse health effects caused by WLAN products?
A: The output power of wireless LAN systems is much less than that of hand-held cellular phones. Since radio waves fade rapidly over distance, those in the area of a wireless LAN system are exposed to very little RF energy. Wireless LANs must meet stringent government and industry regulations for safety. No adverse health effects have ever been attributed to wireless LANs.
Q: Will WLANs receive interference from other wireless devices? From other WLANs?
A: The unlicensed nature of radio-based wireless LANs means that other products (cordless phones, microwave ovens, garage door openers) that transmit energy in the same frequency spectrum can potentially interfere with a WLAN system. Microwave ovens are a concern, but most WLAN manufacturers design their products to account for microwave interference. Another concern is the close proximity of more than one WLAN system. However, there are network management techniques that can minimize or eliminate the interference of overlapping WLANs.
Q: Are all WLAN products (802.11 and 802.11b) interoperable?
A: No. 802.11b WLANs will certainly interoperate with other 802.11b WLAN products, but 802.11b WLANs will not operate with WLANs that use other modulation techniques (i.e., Frequency-Hopping Spread Spectrum). HP WLAN products are WECA certified to assure their interoperability with all other 802.11b WLAN products.
Q: What are the comparisons between 802.11b and 802.11a technology?
A:- Provides fast response time for those more "bandwidth hungry" applications.
- When compared to 802.11b requires less bandwidth sharing, less device interference resulting in higher throughput.
- As well with more non-overlapping radio channels, can support more simultaneous users at higher throughput than 802.11b.
Q: In which markets and target segments will WLAN products be sold?
A: Vertical markets first adopted the use of WLANs, but WLAN usefulness has spread into horizontal, mainstream applications. IEEE 802.11b High Rate standard products are being developed for use across all market segments-enterprise, small business, warehousing, retail, education, home, public access, education, etc.-virtually all network users will benefit from using wireless LANs.
Q: Is a WLAN suitable for home use?
A: Absolutely! With no wires to run and no networking knowledge required, WLAN is one of the easiest ways to install a home network. Unlike wired networking solutions WLANs allow you to roam freely with your portable computer. Use your notebook computer to pay bills, read or send email, or access the Internet-anywhere-without wires. And since WLANs meet the demanding standards of networking professionals, they provide more reliable performance and better range than "home only" wireless devices.
Q: Where can I find more information on WLANs?
A: The following web sites contain additional WLAN information:
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