A fundamental challenge facing information technology (IT) decision makers is identifying and implementing architectures, technologies, and processes that reduce the total cost of ownership (TCO) of corporate networks - one way is the wireless LAN (WLAN).
WLAN is not a replacement for the wired infrastructure, but it is a significant complement to it. Schools, manufacturing companies, hospitals, and government offices purchase WLAN systems for two predominant reasons: increase in user and IT team productivity.
WLANs consist of Network Interface Cards (NICs) and access points/bridges (end-user-to-LAN and LAN-to-LAN) for communications. NICs provide an interface between the end-user device (desktop PC, portable PC, or handheld computing device) and the airwaves via an antenna on the access point/bridge.
To obtain a more thorough understanding of how wireless LANs are being implemented, corroborating and enhancing previous qualitative research conducted by several leading technology corporations
To provide in-depth insight into the costs and benefits of wireless LAN implementation, as well as offering input into the challenges experienced by organizations who have deployed wireless LANs
To show how cost savings and/or benefit associated with the deployment of wireless LAN technologies can be obtained and presented for organizations aspiring to justify expenditure for the deployment of wireless LANs
Wireless Networking is an exciting technology that enables computer users to access files stored on a network while moving around or working in a temporary office space—or enable one to access a network in other locations
A variety of applications have benefited from the WLAN implementation. Among these are:
Home Usage - Wireless networks can save time and money
Small business - entrepreneurs focus on growing their businesses and WLAN can grow with them Enterprise - Many larger corporations and manufacturing facilities found that significant benefits of their WLANs. In most instances, only a portion of the network is wireless
LAN to LAN Bridging - Installing buried cable between buildings to provide connectivity may be difficult at times, but with wireless many companies are finding a quick and reliable solution.
Wireless LANs use electromagnetic airwaves (radio and infrared) to communicate information from one point to another without relying on any physical connection.
In a typical WLAN configuration, a transmitter/receiver transceiver) device, called an access point, connects to the wired network from a fixed location using standard Ethernet cable.
At a minimum, the access point receives, buffers, and transmits data between the WLAN and the wired network infrastructure. A single access point can support a small group of users and can function within a range of less than one hundred to several hundred feet.
End users access the WLAN through wireless LAN adapters, which are implemented as PC cards in note-book computers, or use ISA or PCI adapters in desktop computers, or fully integrated devices within hand-held computers. WLAN adapters provide an interface between the client network operating system (NOS) and the airwaves (via an antenna). The wireless connection is transparent to the NOS.
Most wireless LAN systems use spread-spectrum technology, a wideband radio frequency technique originally developed by the military for use in reliable, secure, mission-critical communications systems.
Spread-spectrum is designed to trade off bandwidth efficiency for reliability, integrity, and security. There are two types of spread spectrum radio: frequency hopping and direct sequence.
A narrowband technology -- radio system transmits and receives user information on a specific radio frequency. Narrowband radio keeps the radio signal frequency as narrow as possible just to pass the information. Undesirable cross talk between communications channels is avoided by carefully coordinating different users on different channel frequencies.
THROUGHPUT -- Factors that affect throughput include airwave congestion (number of users), range, the type of WLAN system used, as well as bottlenecks on the wired portions of the WLAN. Typical data rates range from (1 to 11 Mbps).
COVERAGE -- Function of product design including transmitted power and receiver design and the propagation path, especially in indoor environments. Coverage for typical WLAN systems varies from under 100 feet to more than 500 feet.
INTEROPERABILITY -- Industry-standard interconnection with wired systems, including Ethernet (802.3) and Token Ring (802.5). Wireless LAN nodes are supported by network operating systems in the same way as any other LAN node-via drivers.
RELIABILITY -- Wireless data technologies have been proven in both commercial and military systems. While radio interference can cause degradation in throughput, such interference is rare. WLANs provide data integrity performance equal to or better than wired networking.
Many WLAN devices today do not have adequate security. The optional 40-bit RC4 ciphers in the original IEEE WLAN standard has been shown to be breakable*.
Ciphers implemented in software are not certifiable (by the DIA and the NSA) as militarily secure.
Most ciphers today encrypt the data, they do not encrypt the headers
*The RC4 40-bit cipher can be broken in just a few seconds working with an expensive machine. (RSA Burt Kalinski 6/22/2002 ) ORiNOCO, which is a subsidiary of Lucent Technologies (now called Avaya Corporation). Their “Gold PC Card” can use a 128-bit RC4 cipher, which is considered essentially unbreakable.
Selected Major WLAN Manufacturers* *As of Dec. 2001. Figures represent vendor published quotes and may not correspond to individual situations Vendor Product Technolog y Rate(s) of Communication Nos. of Users Security List Price Avaya (formerly Lucent) Silver PC Card DSSS 802.11b 11, 5.5, 2, or 1 Mbps 64-bit RC4 $179 Gold PC Card DSSS 802.11b 11, 5.5, 2, or 1 Mbps 128-bit RC4 $199 ISA/PCI Adapter PC Card PC Card PC Card $69 Ethernet Adapter PC Card PC Card PC Card $229 RS-232 Adapter PC Card PC Card PC Card $329 WavePOINT-II AP 32 users per PC Card PC Card PC Card PC Card $995 Cisco (Aironet) 340 PC Card DSSS 802.11b 11, 5.5, 2, or 1 Mbps 40/128-bit RC4 $369 ISA/PCI Adapter PC Card PC Card PC Card $369 340 Access Point 2048 users PC Card PC Card PC Card $1,299 3Com AirConnect PC Card DSSS 802.11b 11, 5.5, 2, or 1 Mbps 40/128-bit RC4 $219 PCI Adapter PC Card PC Card PC Card $329 AirConnect AP 63 users per AP PC Card PC Card PC Card $1295
Cost Element Structure (CES) for WLAN Implementation
Network Interface Cards
WLAN Management SW
Test and Evaluation Costs
License Fees (HW & SW)
Typical WLAN ROIs* *Based on data published by the WLAN Association
ROI = (Present Value of Net Savings) / (Present Value of Net Investments)
On an annualized basis, the ROI is that discount rate at which the present value of the savings is equal to the present value of the investment cost through the life cycle of the project being evaluated.
Retail Manufacturing Health care Office Automation Education Benefits per company(TY$M) 5.6 2.2 . 94 2.5 . 5 Costs per company(TY$M) 4.2 1.3 .90 1.3 .3 Payback(# of months) 9.7 7.2 11.4 6.3 7.1
Multi-Site Consistency -- IT staff need to ensure WLAN setup, settings and configurations are similar and thus transparent to the worker and remain consistent throughout offices
users will be able to seamlessly connect to enterprise-wide resources with little to no re-configuration
mobile workers experience less down time
IT staff will be relieved of technical support requirements
APs and Client Management -- partner with a company that can support the entire wireless infrastructure, including services such as a 24/7 help desk, remote administration capabilities and RF diagnostics
Wireless Card Interoperability -- 802.11b cards from various vendors can provide very different range limits. This is the result of the basic radio frequency (RF) performance of the radio’s transmitter/receiver.
Best Practices for Deploying WLANS
Best Practices for Deploying WLANS - concluded
Security – 802.11 based products have experienced a great deal of criticism due to their vulnerabilities; security features may not be interoperable among various vendors. Security solutions differ depending on control over client card deployment.
Site Survey (SS) – SS can provide details about coverage and bandwidth performance at different locations
Indicates where access points should be located
Access point density will increase if an all time 11Mbps coverage area is required
Clearly indicate where the fall back data rate of 5.5, 2 and 1Mbps areas are
Antenna Selection – select antenna for flexibility and robustness to optimize your applications
Wireless LAN ROI/Cost-Benefit Study , Sponsored by The Wireless LAN Association, October 1998
Wireless LAN Benefit Study , NOP Worldwide, Fall 2001, Conducted on Behalf of CISCO Systems, Inc.
Bing, Benny, 2000, High-Speed Wireless ATM and LANs , Artech House Publishers.
Van Nee, Richard, Geert Awater, Masahiro Morikura, Hitoshi Takanashi, Mark Webster, and Karen Halford, December 1999, “New High-Rate Wireless LAN Standards,” IEEE Communications Magazine, pp. 82-88.
Bugala,, Paul, April 2001, “ Wireless LANs Management: Forecast and Analysis ,” IDC.
IEEE 802.11-1997, November 18, 1997, “ Information Technology—Telecommunications and Information Exchange between Systems, Local and Metropolitan Area Networks, Specific Requirements—Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications .”
IEEE 802.11a & b-1999, January 20, 2000, “ Supplement to IEEE Standard for Information Technology—Telecommunications and Information Exchange between Systems, Local and Metropolitan Area Networks, Specific Requirements —Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications, High-Speed Physical Layer in the 5-GHz Band.”
W LAN Glossary Access Point — A device that transports data between a wireless network and a wired network (infrastructure). IEEE 802.X — A set of specifications for Local Area Networks (LAN) from The Institute of Electrical and Electronic Engineers (IEEE). Most wired networks conform to 802.3, the specification for Ethernet networks. The 802.11 committee completed a standard for 1 and 2 Mbps wireless LANs in 1997 that has a single MAC layer for the following physical-layer technologies: Frequency Hopping Spread Spectrum, Direct Sequence Spread Spectrum, and Infrared. IEEE 802.11 HR, an 11 Mbps version of the standard. Independent network — A network that provides (usually temporarily) peer-to-peer connectivity without relying on a complete network infrastructure. Infrastructure network — A wireless network centered around an access point. In this environment, the access point not only pro-vides communication with the wired network but also mediates wireless network traffic in the immediate neighborhood. Microcell — A bounded physical space in which a number of wireless devices can communicate. Because it is possible to have overlap-ping cells as well as isolated cells, the boundaries of the cell are established by some rule or convention. Roaming — Movement of a wireless node between two microcells. Roaming usually occurs in infrastructure networks built around multiple access points. Wireless Node — A user computer with a wireless network interface card (adapter).