What is a wireless LAN?

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Introduction

A wireless local area network (WLAN) is a local area network (LAN) that doesn't rely on wired Ethernet connections. A WLAN can be either an extension to a current wired network or an alternative to it. Use of a WLAN adds flexibility to networking. A WLAN allows users to move around while keeping their computers connected, without having to depend on Ethernet cables.

WLANs have data transfer speeds ranging from 1 to 54Mbps, with some manufacturers offering proprietary 108Mbps solutions. The 802.11n standard can reach 300 to 600 Mbps.

Because the wireless signal is broadcast so everybody nearby can share it, several security precautions are necessary to ensure only authorized users can access your WLAN.

A WLAN signal can be broadcast to cover an area ranging in size from a small office to a large campus. Most commonly, a WLAN access point provides access within a radius of 65 to 300 feet.

WLAN types

The private home or small business WLAN

Commonly, a home or business WLAN employs one or two access points to broadcast a signal around a 100- to 200-foot radius. You can find equipment for installing a home WLAN in retail stores like Office Max, Radio Shack, Target, and Wal-Mart, among others.

With few exceptions, hardware in this category subscribes to the 802.11a, b, or g standards (also known as Wi-Fi). Home and office WLANs adhering to the new 802.11n standard are appearing. Also, because of security concerns, many home and office WLANs adhere to the WiFi Protected Access 2 (WPA2) standard.

The enterprise class WLAN

This type employs a large number of individual access points to broadcast the signal to a wide area. The access points have more features than equipment for home or small office WLANs, such as better security, authentication, remote management, and tools to help integrate with existing networks. These access points have a larger coverage area than home or small office equipment, and are designed to work together to cover a much larger area. Such equipment adheres to the 802.11a, b, g, or n standard, though it's becoming common that equipment subscribes to security-refining standards, such as 802.1x and WPA2.

The Wireless Metropolitan Area Network (WMAN)

The most common type of WMAN is composed of individual enterprise class wireless networks that collectively allow users to access all of them. A WMAN can cover a large area, such as an entire city.

City-wide WMANs are commonly composed of wireless networks belonging to several businesses or Internet service providers.

The Indiana University wireless network is an example of a WMAN. It is a collection of individual building and departmental WLANs working together as a whole. Additionally, IU Bloomington users can use the Kiva Everywhere network to access a Bloomington-area WMAN.

The most common WMANs, including IU's, use 802.11a, b, g, or n technologies. Another standard, WiMAX (802.16) is in use as well, and has branched off into two newer standards:

802.16-2004: Also called 802.16d or "fixed WiMAX", this standard does not address some issues with mobile connectivity and use, thus it is best for connections from relatively stationary computers.
802.16e-2005: Also called 802.16e or "mobile WiMAX", this standard addresses issues with mobile data connections, so devices like PDAs, laptops, and smartphones can connect while roaming.

Note: A Metropolitan Area Network (MAN) is not the same as a Wireless Metropolitan Area Network (WMAN). MANs tend to be wired networks, and normally provide backbone connectivity to local ISPs, or business and enterprise class LANs. WMANs provide connectivity directly to the end user's computer.

Wireless WAN (Wide Area Network)

Although a WAN by definition is the exact opposite of a LAN, Wireless WANs (WWANs) deserve brief mention here, especially because the distinction is becoming less and less obvious to end users.

WANs used to exist in order to connect LANs that are not in the same geographical area (see What is the difference between a LAN, a MAN, and a WAN, and what is a LAN connection?). Until recently, this was also the case for WWANs. Now, cellular phone companies, such as Sprint (BroadBand Direct), Verizon (Broadband Access), and AT&T (Broadband Connect), have begun offering WWAN technology that the end user can access directly.

The cellular WWANs use cellular data technology to cover extremely wide areas. Cellular WWAN data transfer rates are considerably slower than wireless LANs, with most advertising between 50Kbps to 2Mbps (compare this to dial-up speeds, which are around 56Kbps). Cellular WWANs rely on coverage by the cellular network provider, so coverage areas for wireless Internet access are more or less the same as they are for cellular phones. There are many different standards for this type of network. Most of them are mobile data standards that previously were used only on cell phones, but are increasingly offered for computing. Some manufacturers offer "mobile broadband" add-ons to their portable computers using the Sprint Broadband Direct, Verizon Broadband Access, and AT&T Broadband Connect networks.

WLAN standards

Several standards for WLAN hardware exist:

802.11a, b, and g

The 802.11a, b, and g standards are the most common for home wireless access points and large business wireless systems. The differences are:

802.11a: With data transfer rates up to 54Mbps, it is faster than 802.11b and can support more simultaneous connections. Because it operates in a more regulated frequency, it gets less signal interference from other devices and is considered to be better at maintaining connections. In areas with major radio interference (e.g., airports, business call centers), 802.11a will outperform 802.11b. It has the shortest range of the three standards (generally around 60 to 100 feet), broadcasts in the 5GHz frequency, and is less able to penetrate physical barriers, such as walls.
802.11b: It supports data transfer speeds up to 11Mbps. It's better than 802.11a at penetrating physical barriers, but doesn't support as many simultaneous connections. It has better range than 802.11a (up to 300 feet in ideal circumstances; tests by independent reviewers commonly achieve between 70 and 150 feet), uses hardware that tends to be less expensive. It's more susceptible to interference, because it operates on the same frequency (2.4GHz) as many cordless phones and other appliances. Therefore, it's not considered a good technology for applications that require absolutely reliable connections, such as live video streaming.
802.11g: It's faster than 802.11b, supporting data transfer rates up to 54Mbps. It has a slightly shorter range than 802.11b, but still better than 802.11a. Most independent reviews report around 65 to 120 feet in real-world situations. It is backward compatible with 802.11b products, but will run only at 802.11b speeds when operating with them. It uses the 2.4GHz frequency, so it has the same problems with interference as 802.11b.

802.11n

The Institute of Electrical and Electronics Engineers (IEEE) has not yet ratified the 802.11.n standard. Because of this, some manufacturers advertise their 802.11n equipment as "draft" devices.

Though specifications may change once the standard is finalized, it is expected to allow data transfer rates up to 600Mbps. Product manufacturers are advertising ranges twice as large as those of as 802.11b/g devices, but as with any wireless devices, range ultimately depends more on the manufacturer and the environment than the standard.

Security standards

The 802.11x standards provide some basic security, but becoming less adequate as use of wireless networking spreads. Security standards exist that extend or replace the basic standard:

WEP (Wired Equivalent Privacy)

One of the earliest security schemas, WEP was originally created for 802.11b, but migrated to 802.11a as well. It encrypts data traffic between the wireless access point and the client computer, but doesn't actually secure either end of the transmission. Also, WEP's encryption level is relatively weak (only 40 to 128 bits). Many analysts consider WEP security to be weak and easy to crack.

WPA (Wi-Fi Protected Access)

WPA implements higher security and addresses the flaws in WEP, but is intended to be only an intermediate measure until further 802.11i security measures are developed.

802.1x

This standard is part of a full WPA security standard. WPA consists of a pair of smaller standards that address different aspects of security:

TKIP (Temporal Key Integrity Protocol encryption), which encrypts the wireless signal
802.1x, which handles the authentication of users to the network

Commonly, wireless systems have you log into individual wireless access points or let you access the wireless network, but then keep you from accessing network data until you provide further authentication (e.g., VPN).

802.1x makes you authenticate to the wireless network itself, not an individual access point, and not to some other level, such as VPN. This boosts security, because unauthorized traffic can be denied right at the wireless access point.

WPA2/802.11i

The WiFi Alliance has coined the term "WPA2", for easy use by manufacturers, technicians, and end users. However, the IEEE name of the standard itself is 802.11i. The encryption level is so high that it requires dedicated chips on the hardware to handle it.

In practical use, WPA2 devices have interoperability with WPA devices. When not interfacing with older WPA hardware, WPA2 devices will run strictly by the 802.11i specifications.

WPA2 consists of a pair of smaller standards that address different aspects of security:

WPA2-Personal, which uses a pre-shared key (similar to a single password available to groups of users, instead of a single individual); the pre-shared key is stored on the access point and the end user's computer
WPA2-Enterprise, which authenticates users against a centralized authentication service

IU Secure, the new IU wireless network for students, faculty, and staff, uses WPA2 Enterprise for authentication.

The information in this document was adapted from the Wireless LAN Association web page.

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Last modified on July 16, 2008.

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