wireless networking - what is it, how it works, benefits, etc

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Wireless Networking

What Is It, How It Works, Benefits, Etc.

Decisive Business Systems, Inc.


What Is Wireless Local-area Networking?

In the simplest of terms, a wireless local-area network (WLAN) does exactly what the name implies: it provides all the features and benefits of traditional LAN technologies such as Ethernet and token ring without the limitations of wires or cables. But to view a WLAN just in terms of the cables it does not have is to miss the point: WLANs redefine the way we view LANs. Connectivity no longer implies attachment. Local areas are measured not in feet or meters, but miles or kilometers. An infrastructure need not be buried in the ground or hidden behind the walls—an "infrastructure" can move and change at the speed of the organization. This technology has several immediate applications.


The Wireless LAN Standard

• Defined by the institute of electrical and electronics engineers (IEEE).

• The first wireless LAN technologies were low-speed (1-2 mbps) proprietary offerings.

• In June 1997, the IEEE released the 802.11 standard for wireless local-area networking.

• Data rates have increased from 1 to 11 mbps, interoperability became reality.


Wireless Ethernet Compatibility Alliance

The wireless Ethernet compatibility alliance (www.wi-fi.Org) is a non-profit organization formed in 1999 to certify interoperability of Wi-Fi (IEEE 802.11b high rate) products and to promote Wi-Fi as the global wireless LAN standard across all market segments. WECA has defined a test suite that defines how member products are tested to certify that they are interoperable with other vendor products. An independent test lab, the silicon valley networking lab, inc., (Www.svnl.Com) conducts the testing. When a product successfully passes the test, the company will be granted the Wi-Fi seal of interoperability and may display the Wi-Fi logo on that product and its corresponding collateral material. Consumers are assured that any product bearing the Wi-Fi logo will work with other Wi-Fi products. Membership in WECA is open to all companies who support Wi-Fi; The standard for 2.4 GHz wireless LAN products, including any manufacturer that would like to submit its Wi-Fi based product for interoperability testing.

http://www.compaq.com/products/wireless/wlan/wifi.html


Performance

• Unlicensed frequency• 802.11b

– 2.4-GHz 11 mbps - now– 5-GHz 22 mbps on the road map 2001

• 802.11a– 54-mbps data rate – 2001/2002– 5.7-GHz band = 100mbps – 20??

• 802.15 (Bluetooth) & 802.16 (Broadband)• http://www.ieee.org/wireless


Security

• 802.11 standard is only the first step in addressing customer security concerns

• RC4 algorithm with a 40 or 128 bit key• Keys are used to encrypt the data before it is transmitted

through the airwaves


Management

• Wireless access points share the functions of both hubs and switches

• Telnet or SNMP (I or II) services or a web browser interface

• Mapping of wireless access points • WLAN network policy


Price

• As volumes continue to increase, manufacturing efficiencies and cost-reduction engineering will allow for even further price reductions.

• Although it is unlikely that the price of a wireless client adapter will ever match that of a wired one when cabling cost and labor are accounted for, the difference will become increasingly insignificant.


How Does It Work?

• PC card works in a notebook computer and receives and transmits digital information over a radio frequency of 2.4 GHz. The PC card converts the radio signal into digital data (actually small packets of information) the PC can understand and process.

• PCI card fits into a desktop PC and operates like the PC card.

• Software access point allows a PC connected to the Ethernet (a common type of local area network or LAN) to act as a hardware access point.


How Does It Work? (Cont.)

Hardware access point receives and transmits information similar to the PC card. The hardware access point connects via a RJ-45 wire to the Ethernet and handles the ingoing and outgoing traffic from and to wireless LAN users or "clients" - thereby acting as a wireless hub. Said another way, the hardware access point acts as the gateway (or on-ramp) for wireless users to access a wired LAN. It is important to note that similar to a freeway at rush hour, the more users on that access point, the slower traffic goes.


How the Products InteractThere Are 2 Basic Modes on the Client End (Where Wireless LAN Users Are the "Client"):

• Infrastructure -when infrastructure mode is selected (on the PC via a configuration utility) the user will send/receive radio signals (i.E. Information) to/from an access point (please note that this can either be a either hardware or software access point. The access point, which is connect to a wired network through a cable, receives the radio signal from the client and converts it to digital format that the network (and server) can understand and process. If the user called up information (like a web page), the access point would send a radio signal to the WLAN users' PC. Access points are located at network connections where any networked PC, printer, etc. Would attach to the network through a RJ-45 cable (looks like a phone plug, but slightly larger).


1. Peer to peer - when peer to peer mode is selected, users connect to other PCs (either portable or desktop) that have IEEE 802.11b high rate (HR) wireless products. This mode is used when there is no wired network or when a group of users want to set up their own network to collaborate and share files.

On the server/network side, the IT manager is required to install a software package that the IT department needs to install on the appropriate server. This software package will configure, manage, and track wireless traffic across the network.

How the Products InteractThere Are 2 Basic Modes on the Client End (Where Wireless LAN Users Are the "Client"):


Capacity

• Each hardware access point has up to 11 mbps throughput. This capacity is adequate for the following:– 50 nominal users who are mostly idle and check an occasional text

based e-mail.– 25 mainstream users who use a lot of e-mail and down/up load

moderately sized files.– 10-20 power users who are constantly on the network and deal

with large files.– To increase capacity, more access points may be added - allowing

users more opportunity to enter a network. It is important to note, that networks are optimized when the access points are set to different channels.


Capacity

• Ex. A company may place 3 access points (with a range of up to 100 meters each) in 3 adjacent offices - each set to a different channel. In theory, this would allow many users to "share" a total of up to 33 mbps total capacity (although no single user would ever have throughput speeds greater than up to 11 mbps). In reality, since clients associate with the access point with which it shares the strongest signal, the bandwidth may not be dispersed evenly among users.


The Connection Process"SSID" & "Channels" & "Overlapping" & "Cross-talk"

• SSID: to have a client and an access point communicate, they both require the same SSID. "SSID" is the name of the network that the PCs will share. This "name" - (which could be "EngineeringNet") is entered in a field that comes up when the configuration software is launched. The client's SSID is entered locally on the client PC. The access point SSID is entered through the network software utility.

• Channels: A channel represents a specific frequency (ex. Channel 2 is 2.402 GHz, channel 3 is 2.403 GHz, etc.) At which a client and access point communicate with each other. An access point it set to a specific channel (in addition to a specific SSID), but a client however has only a set SSID - that channel it associates with is variable.


The Connection Process How It Works

• Channels (cont.).– A client searches for and associates with the access point that has

the strongest signal. The client then scans all the channels and sets itself to the channel of that access point.

– There are 80 total channels, but different countries allow only certain channels to be utilized. In north America, for example, only channels 1-11 channels may be utilized. See the white paper for more details.

• Overlapping: it is recommended that if the user is going to roam, the cells (access point ranges) should overlap slightly to guarantee seamless wireless connectivity. When roaming all the access points and clients will share the same SSID, but should not share the same channel (see cross-talk below). In fact, there should be a 25 MHz difference (or about 5 channel separation) between overlapping cells.


• Overlapping (cont.).– Example: in north America, channel 1, 6, & 11 are recommended

by the FCC since these channel frequencies are isolated from each other. Channels 2-5, 7-10 in NA have the possibility to develop cross-talk and interfere with data transmission.

• Cross-talk: when access points are set to the same channel (i.E.. Frequency) and are in close proximity (i.E.. Their "cells" or ranges overlap), the possibility of "cross-talk" occurs. Cross-talk occurs because access points pick up the signals of the adjacent access point and visa versa. The information traffic from the various clients collide at the access points creating a jumble of information. It takes the access points time to sort out the combined information and the result is a significant dampening of performance.



• The inverse relationship between data transmission and distance from access points

• Data transmission rates decrease as users get farther from the access point. Refer to the table for details:

Distance from Access Point

Data Transmission Rate

Up to 100' Up to 11 Mbps

Up to 150' Up to 5.5 Mbps

Up to 300' Up to 2 Mbps



It is important to note that actual data transmission rates may vary considerably depending on number of users, type of usage (i.e.. File sizes & frequency of down/up loading), speed of network, and so on. On ALL networks (wired and wireless) some of the data being transmitted is "overhead" which controls and manages data flow. This overhead means that file transfer rate (for example downloading a file from a shared drive) will not reach 11 mbps. These issues are accepted and understood by IT professionals and network managers.



Education Benefits

• Works with existing infrastructure • Availability of network - speed • Old buildings – less cabling • Room restrictions - mobility • Cost – long term decrease • Standard – 802.11• Scalable secure


Resources

WebSites• http://www.microsoft.com/ISN/ind_solutions/wireless_data.asp• http://www.compaq.com/products/wireless/index.html• http://www.cisco.com/warp/public/779/edu/build/solutions• http://www.techweb.com/encyclopedia/defineterm?

exact=1&term=wireless%20glossary• http://www.bluetooth.org/• http://www.ieee.org/wireless


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– Vice President – Peter Busam– Major Account Manger – Mr. Jamie Hawkes– Inside Sales Representative – Mr. Kevin Klein

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wireless networking - what is it, how it works, benefits, etc

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