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Wireless LANs are governed by the IEEE Wireless Local Area Networks Standard Working Group Project 802.11. The 802.11 standard establishes the components and interface requirements for a wireless LAN. The basic architecture established by the 802.11 committee organizes wireless LANs into basic service areas (BSAs) and access points (APs). Multiple BSAs can be interconnected at the APs into an extended service area (ESA). The protocols for this model are divided into two groups: the media access control (MAC) specification and physical specifications (PHY). There are different specifications for each radio frequency supported: 915MHz, 2.4GHz, and 5.2GHz.
Traditional fixed-media systems are based on coaxial cable, twisted-pair wiring, fiber optics, or a combination of all three. Over time, the documentation for fixed networks can become lost or rendered inaccurate because of unrecorded equipment moves and changes. As new functions are established or offices rearranged, segments with undocumented cables are often installed to support added network nodes. Some companies that experience a high degree of internal moves and changes find it necessary to abandon at least 30% of their original network media. For these companies, a wireless network strategy superimposed over a base network provides the flexibility to support many permanent and temporary moves. Under this plan, the user is only required to establish a base radio, transmitters for each terminal to be moved, and a series of line-of-sight antennas. Thereafter, relocating network users only requires that the new location has line-of-sight to a network antennae.
A wireless LAN solution at $750 to $1500 per node may be expensive when compared with a traditional wired solution (approximately $350 to $550). However, when the costs of lost productivity and rewiring are added, a wireless solution may be more cost- effective for organizations that move or change equipment frequently. Wireless solutions find their best fit where there are large unwired manufacturing areas to support, campus buildings that must be interconnected, open office areas without access to wire facilities, or older buildings with concrete partitions and no wire access.
There are several different vendor approaches for supporting wireless LANs. For example, Motorolas Altair systems use the 18-19GHz frequency range to support a microcellular approach. A series of intelligent antennae is used to establish microcells within the users building. These microcells are supported with low-powered, high frequency radios designed to support frequency reuse. This process results in a very efficient network.
Other manufacturers often use two basic components: the radio hub and the transceivers. In some systems, a single hub can support up to 62 transceivers. The transceivers are attached to the terminals and communicate with the hub using a line-of-sight arrangement.
Wireless LAN bridges are used to connect LANs in neighboring buildings. These devices establish a point-to-point connection and may not be a complete system. Examples of wireless bridges can be seen in the Motorolas Altair VistaPoint and the Cylink Airlink,
Infrared and laser technology can also be used to interconnect LANs in different buildings. This technique places information on a beam of light and can support very wide bandwidth over a short distance. In addition, this technology is immune to electric interference and is much more secure than radio transmission. Although infrared and laser techniques do not require an FCC license, users are responsible for any radio interference that develops while they are operating in a densely occupied area. LCI (Lancaster PA) has been developing laser systems for several years and has well over 750 mature systems installed.
Projections for wireless applications vary depending on the user and the interpretation of the technology. There is no doubt that there will be a tremendous penetration in the basic telephone service market. Wireless local loop access will allow more users in developing nations to enjoy telephone service faster and at an affordable level.
The continued decline in the cost of PCMCIA cards for mobile radio will result in the continued rise in the number of laptops and PDAs used for basic communications functions such as E-mail and information access.
Satellite and radio-based service will continue to support vehicle management and tracking. Services like Qualcomms OmniTracs provide a cost-efficient method for tracking and establishing a data communications connections with truck assets in the field.
Global positioning systems (GPS) will allow users to track vehicles and provision driver information. Avis rental car agency is testing a system that tracks Avis cars and sends driver information to fleets of specially equipped rental cars.
Hertz, Alamo, and other rental car agencies are using RAM Mobile Data to allow their service personnel to directly process returned vehicles as they are driven onto the company ramps. Using a handheld data entry terminal, the service person is able to enter the vehicle ID code and rental status. This process allows the rental car location to more efficiently manage their available pool of cars.
Considering that many of the current wireless applications have come into being in only the last few years, new applications are certain to proliferate as users gain confidence in the available services. Mobile workers such as field sales representatives can spend more time with customers. New levels of productivity will emerge as telecommuting employees freed from expensive office space are able to focus more on the delivery of an end product.
Paradynes Enhance Throughput Cellular (ETC) can greatly improve the process for sending data over the cellular network. This technology makes the cellular data user transparent to all other cellular traffic. Advancements such as this one will allow wireless users to resolve many of their data transmission requirements that were previously difficult to resolve. There is no question that users are adopting wireless solutions. The important issue to consider is the rate at which this technology is absorbed by mobile workers and the extent to which the penetration of services exceeds the available capacity of the network to support these users needs.
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