Benefits of WLAN
The widespread strategic reliance on networking among competitive businesses and the meteoric growth of the Internet and online services are strong testimonies to the benefits of shared data and shared resources. With wireless LANs, users can access shared information without looking for a place to plug in, and network managers can set up or augment networks without installing or moving wires. Wireless LANs offer the following productivity, service, convenience, and cost advantages over traditional wired networks:
The distance over which RF waves can communicate is a function of product design (including transmitted power and receiver design) and the propagation path, especially in indoor environments. 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. Most 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 from under 100 feet to more than 500 feet. Coverage can be extended, and true freedom of mobility via roaming, provided through microcells.
As with wired LAN systems, actual throughput in wireless LANs is dependent upon the product and how it is configured. Factors that affect throughput include airwave congestion (number of users), propagation factors such as range and multipath, the type of WLAN system used, as well as the latency and bottlenecks on the wired portions of the WLAN. Typical data rates range from 1 to 11 Mbps.
As Figure 9 shows, a radio signal can take multiple paths from a transmitter to a receiver, an attribute called multipath. Reflections of the signals can cause them to become stronger or weaker, which can affect data throughput. Affects of multipath depend on the number of reflective surfaces in the environment, the distance from the transmitter to the receiver, the product design and the radio technology.
Figure 9. Radio Signals Traveling over Multiple Paths
Wireless data technologies have been proven through more than fifty years of wireless application in both commercial and military systems. While radio interference can cause degradation in throughput, such interference is rare in the workplace. Robust designs of proven WLAN technology and the limited distance over which signals travel result in connections that are far more robust than cellular phone connections and provide data integrity performance equal to or better than wired networking.
Interoperability with Wired Infrastructure
Most wireless LAN systems provide industry standard interconnection with wired systems including Ethernet (802.3) and Token Ring (802.5). Standards based interoperability makes the wireless portion of the network completely transparent to the rest of the network. Wireless LAN nodes are supported by network operating systems(NOS) in the same way any other LAN node via network device drivers. Once installed, the NOS treats the wireless nodes like any other component of the network.
Interoperability with Wireless Infrastructure
There are several types of interoperability that are possible between wireless LANs. This will depend both on technology choice and on the specific vendor's implementation. Products from different vendors employing the same technology and the same implementation typically allow for the interchange of adapters and access points. An eventual goal of the IEEE 802.11 specification, currently being drafted by a committee of WLAN vendors and users, is to allow compliant products to interoperate without explicit collaboration between vendors.
Interference and Coexistence
The unlicensed nature of radio-based wireless LANs means that other products that transmit energy in the same frequency spectrum can potentially provide some measure of interference to a WLAN system. Micro-wave ovens are a potential concern, but most WLAN manufacturers design their products to account for microwave interference. Another concern is the co-location of multiple WLAN systems. While co-located WLANs from different vendors may interfere with each other, others coexist without interference. This issue is best addressed directly with the appropriate vendors.
Simplicity/Ease of Use
Users need very little new information to take advantage of wireless LANs. Because the wireless nature of a WLAN is transparent to a user&#acirc;s NOS, applications work the same as they do on tethered LANs. WLAN products incorporate a variety of diagnostic tools to address issues associated with the wireless elements of the system; however, products are designed so that most users rarely need these tools.
WLANs simplify many of the installation and configuration issues that plague network managers. Since only the access points of WLANs require cabling, network managers are freed from pulling cables for WLAN end users. Lack of cabling also makes moves, adds, and changes trivial operations on WLANs. Finally, the portable nature of WLANs lets network managers pre-configure and troubleshoot entire networks before installing them at remote locations. Once configured, WLANs can be moved from place to place with little or no modification.
Because wireless technology has roots in military applications, security has long been a design criterion for wireless devices. Security provisions are typically built into wireless LANs, making them more secure than most wired LANs. It is extremely difficult for unintended receivers (eavesdroppers) to listen in on wireless LAN traffic. Complex encryption techniques make it impossible for all but the most sophisticated to gain unauthorized access to network traffic. In general, individual nodes must be security-enabled before they are allowed to participate in network traffic.
A wireless LAN implementation includes both infrastructure costs for the wireless access points and user costs for the wireless LAN adapters. Infrastructure costs depend primarily on the number of access points deployed; access points range in price from $800.00 to $2,000.00. The number of access points typically depends on the required coverage region and/or the number and types of users to be serviced. The coverage area is proportional to the square of the product range.
Wireless LAN adapters are required for standard computer platforms, and range in price from $200.00 to $700.00. The cost of installing and maintaining a wireless LAN is generally lower than the cost of installing and maintaining a wired LAN for two reasons. First, a WLAN eliminates the direct costs of cabling and the labor associated with installing and repairing it. Second, because WLANs simplify moves, adds, and changes, they reduce the indirect costs of user downtime and administrative overhead.
Wireless networks can be designed to be extremely simple or quite complex. Wireless networks can support large numbers of nodes and/or large physical areas by adding access points to boost or extend coverage.
Battery Life for Mobile Platforms
End-user wireless products are capable of being completely untethered, and run off the battery power from their host notebook or hand-held computer. WLAN vendors typically employ special design techniques to maximize the host computer&#acirc;s energy usage and battery life.
The output power of wireless LAN systems is very low, much less than that of a hand-held cellular phone. Since radio waves fade rapidly over distance, very little exposure to RF energy is provided to those in the area of a wireless LAN system. Wireless LANs must meet stringent government and industry regulations for safety. No adverse health affects have ever been attributed to wireless LANs.
<p><b>Table of Contents</b>
<li><a href="/learn/educate1.htm">Executive Summary</a>
<li><a href="/learn/educate1.htm#app">Overview: Applications for WLANs</a>
<li><a href="/learn/educate2.htm#benef">Overview: Benefits of WLANs</a>
<li><a href="/learn/educate2.htm#tech">Technology Options</a>
<li><a href="/learn/educate3.htm">How WLANs Work: WLANs and Other Wireless Technologies</a>
<li><a href="/learn/educate5.htm">WLAN Customer Considerations</a>
<li> <a href="/learn/educate4.htm">WLAN Configurations</a>
<li><a href="/learn/glossary.htm">WLAN Glossary</a>
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