Wireless LANs

Wireless networking products have become more popular in the last few years due to an increase in competition among manufacturers and the emergence of a more dominant wireless technology standard. This report looks at the benefits and drawbacks of wireless networking and provides further resources for research into wireless products.

Definition: Wireless Networking

Wireless networking refers to hardware and software combinations that enable two or more appliances to share data with each other without direct cable connections. Thus, in its widest sense, wireless networking includes cell and satellite phones, pagers, two-way radios, wireless LANs and modems, and Global Positioning Systems (GPS).

Definition: Wireless LAN

Wireless LANs enable client computers and the server to communicate with one another without direct cable connections. Generally, a wireless LAN is connected to an existing wired LAN, although they can exist without a wired LAN (in this case, users will only be able to communicate with other users on the same subnet).

Components of a Wireless LAN

Necessary components include an access point, Client LAN adaptors and the wired LAN. The access point is a device that translates between the wired LAN and the wireless LAN. The Client LAN Adaptors are PC cards, PCI or ISA boards with radio transceivers to communicate with the Access point and can plug into laptop or desktop computers. Other components to a wireless LAN can include Extension Points and Directional Antennas. Extension Points are devices similar to the access point, but not connected to the wired LAN. Extension points serve to extend the range of the wireless network by relaying signals from client computers to the Access point. Directional Antennas serve to connect wireless networks located at a greater distance from one another. Each network would have an antenna targeted at each other (known as a "line of site" connection).

Technology Standards

Manufacturers have adopted many competing standards for implementing wireless communication. Interoperability between different communications standards is currently not available. It is important to evaluate, with any wireless LAN networking system, the technology it uses, the features it provides and the industry support it has. Below are common standards available:

Standard	Coverage	Speed	Access Point	Network Card
802.11b	150 feet	11Mbps	less than $100	$50-$100
802.11a	50 feet	54Mbps	$150	$70-$100
802.11g	150 feet	54Mbps	$120	$70-$100
Dual Band 802.11a/b/g	150 feet	11-54Mbps	$300	$90-$125
Bluetooth	30 feet	1Mbps	N/A	$50-$150
UWB (no consumer products yet)	100 feet	40-1000Mbps	$100	$100
HomeRF	150 feet	1.6-10Mbps	$200	$100

IEEE 802.11b:

is sometimes referred to as "Wi-Fi". Currently this open standard, developed by the Wireless Local Area Networks Standards Working Group, is the most widely used wireless LAN system. Large technology companies such as Linksys, Apple, SMC, and 3Com have adopted it for their product lines. This technology uses radio waves in the 2.4- GHz frequency band (same as many other appliances such as cordless phones and microwaves) and has the potential for interference. Speed ranges from 1-11Mbps (newer products are most often specified at 11Mbps).

IEEE 802.11a:

is the standard that many believed would replace 802.11b. It was released in late 2001, with speeds reaching 54 Mbps. 802.11a travels on the less congested 5GHz band, reducing the potential for interference. Range however is limited to 50 feet, making it mainly useful for one-room installations. 802.11a never really caught on as most people went with the tried and true b solution. It is difficult now to even purchase just 802.11a solutions, as most vendors went with dual band access points and cards that will adapt to both the 11b and 11a standards.

IEEE 802.11g or 54g:

is the successor to 802.11b. This technology allows for the speeds of 802.11a, while maintaining compatibility with the market-leading 802.11b standard by using the same 2.4GHz band. The distance is the same as 802.11b, and the product costs are lower than a 802.11a/b solution. Some vendors are producing products designed to work with a, b and g. These “universal” devices might be an option for you, though they are almost double the price.

Bluetooth:

is an inexpensive, very low-powered and short-range frequency-hopping radio system that would link your pagers, personal access devices, cell phones, and laptops (designed for small, mobile devices). The potential for interference (shares 2.4 GHz frequency), particularly to the low-powered Bluetooth, remains an open problem. Range is only 30 feet but line of sight is not necessary -- the distance limitation is a problem for serious LAN implementation, and not many Bluetooth LAN systems have been developed as a result. Named after the 10 century Danish King Harald, "Bluetooth" is the English translation of his last name "Blatand." King Harald was famous for uniting the kingdoms of Denmark and Norway and for his extensive travels; like King Harald, Bluetooth unites separate entities (peripherals, laptops, PDAs, Cellphones, cameras, etc..

Ultra Wide Bandwidth:

is an emerging technology that promises much higher bandwidth speeds at low costs. Inventor Larry Fullerton created UWB transmission as a radically different approach to data transmission in the 1960s. Instead of trasnferring data within a given frequency (such as radio stations, who have one frequency on which to broadcast), UWB broadcasts its signal across the spectrum, using different patterns and combinations, avoiding the whole signal switching process that confines signals to certain frequencies.

So what about all those radio stations: will UWB interfere? Fortunately, the UWB signal is detected as noise by most radio receivers and is easily filtered out, although groups that rely on low-powered radio signals have been discussing UWB's potential for interference.

The speed of the transmission depends on the center of the spectrum on which the signal is transmitted. Plans were initially to roll out products at speeds of 40Mbps in 2002 (the PulseON chip developed by Time Domain of Alabama), then as the hardware size could be reduced in manufacturing, increasing this to 1GHz or more. Look for cheaper and faster wireless networking products over the next year or two (or three).

HomeRF:

provides four high-quality voice transmission channels as well as a 1- to 5-Mbps data transmission channel. Designed more for the home network as it includes support for telephony together with data, lower costs and supports shorter range signals. Pushed by Intel but not an open standard, and speed is less than 802.11b (1.6 Mbps). Just released as of this writing is the new improved HomeRF that promises up to 10 Mbps. Visit the HomeRF Resource Center for more details.

How a Wireless LAN works

In a typical wireless LAN configuration, the access point connects to the wired network from a fixed location using standard cabling. The access point receives and transmits data between the wireless LAN 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 wireless LAN through the wireless-LAN adapters installed in their computers.

Benefits of Wireless LANs

Cost:

Wireless LANs can cost less to implement than wired LANs, especially in situations where implementing a wired LAN requires extensive labor and materials to install the wiring and drops. For environments that are difficult to wire (such as schools or temporary spaces) a wireless network can be more cost-effective in the long run than a wired one.

Simple/flexible to Install:

Wireless LANs eliminate the time needed with wired LANs for laying and pulling wires, and can reach places that cannot be reached by wires.

Portability:

Wireless LAN systems can move physical locations much easier than wired LANs, reducing total cost of ownership for organizations that are on the move.

Mobility:

Wireless LAN systems can provide LAN users with access to network information anywhere in their organization.

Scalability:

Wireless LAN systems can be configured for small offices and large, with peer-to-peer systems or large established LANs, specific to the localized need of a workgroup or across the whole enterprise. Wireless LAN systems grow easily with the need by adding more access points, client LAN adaptors and extension points. Wireless can be a good solution if you need to connect several buildings without installing a wired connection. Wireless LAN bridges can extend LANs that are typically one to five miles apart. These wireless bridges span multiple-building LANs without incurring the monthly costs of a T1 or higher speed lines.

Drawbacks of Wireless LANs

Cost:

In environments with installed wiring or less demanding wiring needs, the up front costs of adopting a wireless LAN system can be more expensive than with wired LANs.

Interoperability:

There are several competing technologies used by wireless LAN vendors to communicate data between hardware, with no ability for communication directly between systems using these different standards.

Interference:

Most of the wireless devices today operate on 2.4-GHz radio bands, which are also used by cordless phones and most microwave ovens. The potential for interference when used near other devices sharing the same frequency band.

Speed:

Most commonly used wireless LAN products are rated for a maximum 11Mbps throughput, and in practice see speeds about 80% less than this - some wireless LAN products are rated for speeds much less than this (HomeRF systems for example). Still quite speedy for most network needs and for broadband Internet sharing, but for larger offices with high network traffic and demands for speed, this should be taken into consideration.

Wireless LAN Products

Simple wireless LAN systems provide an access point that is plug-and-play when connected to an existing wired network. They may or may not include client LAN adaptors. More advanced solutions function as stand-alone networking systems that often provide cable/ DSL router, switch, DHCP and firewall technology together with an access point. As of this report, prices for access points have plummeted over the last two years. Currently you can purchase an access point that includes all the advanced features above for $75-$200 and client LAN adaptors cost from $50-$150 each. When networking Macintosh systems, it is important to consider whether the product comes with macintosh drivers for the access point and the client LAN adaptors, and if there is a Macintosh version of the supporting administration software. If you've decided that a wireless LAN is the right networking solution for your organization, here are a few products that we recommend:

For the small office, I would recommend going with an 802.11g solution. The speed, distance and compatibility with the mainstream 802.11b are key. This will be obsolete as I type it, but currently you can get an 802.11g access point for around $130. I personally like the dual-antennas of the Linksys devices however D-Link and NetGear have excellent (and comparably cheap) products as well.

For larger systems, Orinoco AP-2000 offers a wireless access point with an array of features, including the ability to upgrade radio technology by swapping in new PC cards -- so if you want to add 802.11g support, the access point can still be used. Also has load balancing, support for voice transmission, uses 802.11b standard, supports wired and fully wireless setups and more. access point costs around $400 and each client LAN adaptor costs around $100. Mac and PC.

If you have mainly Macs, Apple Airport offers a wireless solution geared primarily toward Macintosh networks. The 802.11g standard is supported via Airport Extreme. Airport Extreme costs about $200 for each access point, and another $100 for each network adaptor. This device even has built-in support for wireless USB printer sharing. Check out http://www.apple.com/airportexpress/ for information.