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To access the contents, click the chapter and section titles.
Wireless Networking Handbook
To ensure interoperability with existing standards, the 802.11 Working Group is developing a standard that will be compatible with other existing 802 standards, such as:
Infrared Light LAN StandardsThe Infrared Data Association (IrDA) is a group of more than 80 computer and telecommunications hardware and software firms including Hewlett-Packard, AMP, Apple Computer, AST, Compaq, Dell, IBM, Intel, Lexmark, Motorola, National Semiconductor, Northern Telecom, Novell, Photonics, and Sharp. IrDA has adopted a standard covering three levels of a networks architecture: Serial Infrared Physical Layer Link (IrDASIR), Ir Link Access Protocol (IrLAP), and Ir Link Management and Transport Protocols (IrLMP). This standard specifies a 115.2 Kbps point-to-point infrared transmission between computers, laptops, printers, and fax machines. Other higher speed standards of 1.15 Mbps and 4 Mbps that will be more suitable for backups and offline storage are currently being considered by IrDA. Migrating Existing Wireless LAN Products to 802.11A common question that people ask is, Will my existing wireless LAN hardware be able to interface with the upcoming 802.11 standard? Most wireless LAN vendors, especially those that have been active in the development of 802.11, are planning to migrate their products to the new standard. These companies have been laying the seeds for 802.11 compatibility. Proxim, for example, has been heavily involved with the development of 802.11, shaping many aspects of the standard while developing RANGELAN2. Many of the ideas implemented in RANGELAN2 have been included in the proposed 802.11 standard and vice versa. RANGELAN2 and 802.11, for example, share a common contention-based media access scheme called Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA). Also, 802.11 utilizes a dual data rate approach sponsored by Proxim, called 4FSK/2FSK, that maximizes both range and throughput. This mechanism allows networks to run at high speeds at short and medium range and fall back to a lower speed at long range. The point is that some vendors, such as Proxim, will have an easy time modifying their product to match 802.11 specifications. Owners of existing wireless LAN products, however, will probably have to interface these devices to 802.11 components through access points, as shown in figure 2.16.
Wireless LAN Case StudiesMany companies implement wireless LANs to support needs for wireless connectivity to computing resources. The following sections cover some of these examples. TGI Fridays, Inc.2
Restaurant employees must juggle a great deal of information, such as lists of waiting customers, sizes of each party, seating preferences, table availability, orders, activity at each table, service requests, and bill payments. In addition, employees in this environment are always on the go, seating patrons, taking orders, and delivering drinks and food. If you multiply this information by the 40 to 80 tables in an average restaurant, plus the random elements of patron walk-ins and party size, you will have a good idea of the problems restaurant employees face in tracking information. Some restaurant chains are trying to accommodate these employees with computer technology. Rock Systems, a Dallas-based hardware and software firm specializing in restaurant systems, assisted TGI Fridays, Inc. with implementing a system that reduces customer wait times. Rock Systems produces a table management software package called ProHost, which coordinates information from a variety of locations in the restaurant. This system works best if the employees carry a handheld computer that can communicate via a wireless network. Rock Systems recently implemented such a system using ProHost and Proxims RangeLAN2/PCMCIA at a TGI Fridays in Tallahassee, Florida. When guests arrive at the door, they give their name to the person working the wait list on a Fujitsu handheld computer. Their name is recorded and transmitted to the main ProHost terminal, which keeps track of the dining room and lets the host know what tables are available and the capacity of each. When a table of the appropriate size becomes available, the patrons name is automatically highlighted and the hostess walks the party to their seats. This function, as well as others, significantly reduces customer wait times. American Red Cross3
When disaster strikes, the American Red Cross Disaster Service operates like a huge mobile warehouseon a moments notice, setting up locations for receiving and storing thousands of pallets of food, supplies, and equipment, and efficiently distributing those supplies to disaster victims. Often, these operations take place under extreme conditions, such as heavy storms, power and telephone outages, and floods. When relief needs have been met, they must be shut down quickly and the equipment made ready for immediate deployment to a new disaster site. Most Americans are unaware of the fundamental logistical problems these activities present. Space suitable for warehousing must be quickly obtained from the often small pool of structurally safe buildings available for donation or leasing. After the Los Angeles Northridge earthquake of 1993, for example, Sears Roebuck donated the use of a one million square foot warehouse that served as the central Red Cross facility for the entire L.A. basin. By contrast, the relief operation deployed in response to the midwestern floods of 1993 and 1994 required numerous warehouses in several states due to the large geographical area affected.
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