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WLAN FAQ

What is a wireless LAN?
How is a WLAN different from my regular wired LAN?
Why is a WLAN better than a regular LAN?
What do I need to make a WLAN work?
What is WEP?
Is a WLAN secure?
Do I need some sort of broadcast license for a WLAN?
What is 802.11?
What are DSSS and FHSS?
What is an access point?
Do I need an access point to connect my two wireless computers?
Are WLAN's compatible with cellular and PCS?

 


 

 

What is a wireless LAN?

A wireless LAN (WLAN) is simply a local area network where data (Internet, e-mail, etc.) is transferred via radio waves instead of the traditional wire.

 

How is a WLAN different from my regular wired LAN?

A WLAN allows the users to move around with their laptop, PDA, etc. without being confined by a wire, AND while maintaining access to the Internet. Other than that, it can be considered the same, only much more convenient!

 

Why is a WLAN better than a regular LAN?

A WLAN is cheaper to install and maintain.

There is no costly cabling to be pulled through the walls. Also as faster data rates become available the current-cabling specifications will become obsolete (just ask all those places that had to replace their CAT5 cabling with CAT5+). This means you won't have to rip out the old cabling and pay for more to be installed only to become obsolete again

A WLAN can make many tasks easier and make your time much more efficient.

Being able to move around with a laptop allows for direct data entry rather than taking notes only to have to re-enter the data once back at the computer.

Time spent disconnected from the Internet is often un-productive time. For example, waiting at the airport for a plane. It is possible to work from a laptop, but what if you need a file from your corporate drive at work, or want to check your e-mail? With a WLAN it's as if you're still at the office connected to the Internet.

A WLAN is also much more flexible.

Say you get that big promotion and move from your tiny cube to that big corner office with a window. With a LAN you have to call the IT department and wait for someone to change the addresses of the cables or even install a new cable in the wall! With a WLAN, you simply pick up your computer and move.

 

What do I need to make a WLAN work?

Basically all that is needed is a transmitting device, which connects to the Internet and operates in one of the unlicensed frequency bands, and a receiver (typically a PCMCIA card), which connects to your computer. But it's not that easy...

There are many current products that have been designed with specific uses in mind. Some are very simple, and others very sophisticated. It's sort of like asking what kind of computer does someone need? Well it really depends on what it's being used for. Is it processing large amounts of data, maybe just used for surfing the web, possibly holding top-secret information! It's obvious that the type of job dictates the type of equipment needed. Are you confused yet? Don't worry! LBA has the expertise to help you decide what is the right system for your business application. The LBA network engineering capability supports all "flavors" of medium to large scale WLAN deployments!

 

What is WEP?

WEP stands for Wired Equivalent Privacy. WEP is a security feature built into the 802.11 standard. The intention was to make a WLAN as secure as a traditional wired LAN. It achieves this by encrypting the data that each user sends across the radio link. This is accomplished with the use of an encryption "key". Each user on the WLAN has a unique key, which identifies them as authorized users of the WLAN. Any "intruder" without a key is denied access. The 802.11 specification permits the use of 40/64-bit and 128-bit encryption key lengths.

 

Is a WLAN secure?

YES! WLANs use much of the same technology (and even more in cases) that makes digital PCS phones secure. Spread spectrum and frequency hopping was originally developed for military use. The technology was designed to keep prying enemy ears from intercepting highly sensitive data. Both of these technologies are used in virtually all WLAN applications.

Besides making the radio link secure, the data is also encrypted for even more security if the radio link were ever "tapped". Different equipment manufacturers have implemented 40 bit, 64bit and 128 bit encryption. This initial attempt at security had some weaknesses, which were quickly identified.

New enhancements known as "Wi-Fi Protected Access" (WPA) greatly improve the security of WLAN links. The two primary areas of improvements are in the areas of data encryption and user authentication.

The new encryption technique TKIP (Temporal Key Integrity Protocol) addresses all the known vulnerabilities of the previous WEP encryption technique by "wrapping" a very secure protective layer over the existing WEP packets.

WEP had virtually no user authentication mechanism in it's initial deployment. WPA coupled with another authentication technique EAP (Extensible Authentication Protocol) provides the mechanism for true authentication services. This not only authenticates the user at login, but also protects the user from accidentally joining an un-wanted rogue network, which may steal network credentials.

Additional layers of security can be supported through virtual private networks (VPN), radius servers, and other techniques.

 

 

Do I need some sort of broadcast license for a WLAN?

NO! WLANs operate in portions of the frequency band that are deemed open by the FCC. This means that all the devices that would make up a WLAN are exempt from licensing in the same way that your cordless phone at home is exempt.

 

What is 802.11?

802.11 and its variants are a technical standard, which governs the internal workings of the WLAN hardware. The standard specifies things such as frequency, transmit power, data encoding and decoding. These standards ensure that you can mix and match any vendors' products and they will work with everyone else's as long as it's the same standard. A similar standard exists in mobile phones. That's why a Nokia, Motorola, and Ericsson phone can all work on CDMA networks.

802.11 devices specifically operate in the 2.4 GHz frequency range and provide a data capacity of 1 to 2 Mbps. The radio link uses either frequency hopping spread spectrum (FHSS) or direct sequence spread spectrum (DSSS) as their modulation schemes.

802.11a is an extension of the 802.11 standard with improvements for higher data rates and use a different frequency band. 802.11a devices use a different modulation scheme known as Orthogonal Frequency Division Multiplexing (OFDM). This is the primary reason that improved data rates can be achieved. 802.11a devices operate in the 5GHz band and can provide up to 54 Mbps.

802.11b (also known as Wi-Fi) is an extension of the 802.11 standard with improvements for higher data rates. 802.11b devices also operate in the 2.4 GHz band and have a maximum data capacity of up to 11 Mbps. Depending on connection quality data rates can also drop back to 5.5, 2 and 1 Mbps.

802.11g is a proposed standard that will operate in the 2.4 GHz band and support up to 20 Mbps.

 

What are DSSS and FHSS?

DSSS (Direct-Sequence Spread Spectrum) is a technology that spreads a signal over a wide frequency band. DSSS maps the incoming bit-pattern into a higher data rate bit sequence using a "chipping" code. The new coded bit-stream is much more robust due to redundancy which is added after processing. This allows for data, which may have been lost during transmission to be recovered by processing.

FHSS (Frequency Hopping Spread Spectrum) is a technology that uses multiple narrow frequency bands in a pre-determined pattern. A portion of the data will be transmitted on one frequency, then the transmitter (and receiver) will re-tune to the next frequency for more data exchange. Typically the devices will stay on one frequency for a few milli-seconds then transition to the next. This makes eavesdropping nearly impossible.

 

What is an access point?

An access point is the device or software that connects a wireless device (laptop, PDA) to the wired Ethernet. Some of the more common access points are wireless routers made by companies such as Proxim, Linksys, etc.

 

Do I need an access point to connect my two wireless computers?

No. Two wireless computers are capable of communicating without an access point. The wireless cards can be put into an "ad hoc" mode, which will let them communicate.

 

Are WLAN's compatible with cellular and PCS?

Yes. With the right "in-building" system, both WLAN and cellular/PCS services can be extended to any area. New applications are also developing to permit "roaming" between WLAN and cellular/PCS data networks. LBA offers the enterprise user a full set of in building wireless capabilities.

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About LBA

LBA Group companies serve technical infrastructure needs related to the broadcast, wireless, electromagnetic compatibility and safety sectors worldwide. We provide consulting, training and other telecommunications industry services. We also produce and market hardware for radio transmission, RF shielding, safety and testing.

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