Build a Super-Fast 802.11n Wireless Network

The emerging 802.11n wireless networking standard is certain to change the landscape for businesses of all types. It promises as much as 10 times the speed, and four times the range, of today's 802.11g wireless devices. For the system builder, that translates into lower hardware expenditures for both internal wiring and access points. And if your customers have heard about the new standard, or have seen "n" devices for sale, they're likely to be looking for both information and guidance.

But here's the rub: The 802.11n standard is still in draft form. A final standard isn't likely to be released by the IEEE until 2007 at the earliest. Even the second draft of the standard, which will incorporate hundreds of pieces of feedback from the first draft, isn't expected before the end of this year.

Such details haven't stopped wireless-equipment manufacturers from releasing a range of pre-802.11n wireless networking devices. They haven't stopped early adopters from trying them out, either.

In this Recipe, I'll give an overview of the emerging 802.11n standard and describe some of the devices that claim to deliver improvements in range and speed over 802.11g devices. Then I'll list the components you'll need to build a pre-802.11n network from scratch—as well as to integrate the hardware components into an existing 802.11g network. Finally, I will cover some best practices for implementing these standards. I'll also warn you about a few wireless-networking pitfalls that are best avoided.

Overview of 802.11n

The 802.11n wireless networking standard achieves its enhanced speed and range by building on existing technology with some clever engineering. More specifically, the 802.11n standard can run on two frequencies at the same time: the 2.4 GHz frequency band used by 802.11g/b, as well as the 5 GHz frequency band used by 802.11a. In fact, 802.11n routers and cards generally have multiple antennas to allow for simultaneous data streams at different speeds; this feature is known as MIMO (short for Multiple Input/Multiple Output).

The first draft of 802.11n specifies support of speeds up to 270 megabits per second (Mbps), or five times that of a typical 802.11g network, which runs at 54 Mbps. Longer term, the speed of 802.11n devices is expected to double, reaching 540 Mbps.

Range gets trickier. While many manufacturers claim their 802.11n devices can deliver four times the range of 802.11g/b devices, these companies tend to use graphical representations of the range rather than specific feet or meters. By contrast, the IEEE's draft 802.11n specification clearly calls for an indoor range of 50 meters (roughly 164 feet), compared with 802.11g's 30 meters (or just under 100 feet). Of course, even these are only rough estimates. A number of variables can come into play, such as the density of building materials, the location of access points, and the position of the wireless card. Outdoor range is even trickier, particularly because data speed tends to drop off precipitously with greater ranges, regardless of the standard.

Ingredients

To get started with 802.11n, you'll need the following gear:

• A pre-802.11n router or access point. I used a Linksys WRT300N router because the 802.11g equipment I tested was also manufactured by Linksys. The Linksys WRT300N router has street price of about $150.
• A pre-802.11n network card. I used a Linksys WPC300N wireless adapter, which has a street price of about $120.

To reach the potential speed of 802.11n's 270 Mbps, each device in the path to an end user's computer will also need to be upgraded to a gigabit Ethernet infrastructure. Any device or wiring supporting only 100 Mbps would create a bottleneck. At a minimum, you'll need: Gigabit ethernet router/switches/hubs; and Gigabit ethernet network cards.

Hardware

The first MIMO pre-802.11n routers and cards were released earlier this year. The suppliers are the same manufacturers that dominate the existing consumer and commercial wireless market, including Belkin, Buffalo Technology, D-Link, Linksys, and Netgear.

If uncertainty over the implementation of a draft standard wasn't enough, there are three main camps of chipset manufacturers: Broadcom's Intensi-fi, Marvell's TopDog, and Airgo's Gen 3. Both Broadcom and Marvell's chipsets are based on the 802.11n draft specification. Airgo's Gen 3 chipset uses MIMO technology for similar performance, but doesn't adhere to the 802.11n draft.

A quick survey of the manufacturers seems to show a more-or-less even split among vendors. Linksys and Buffalo use Intensi-fi. D-Link and one of Netgear's devices use TopDog. And Belkin and a second Netgear device use Gen 3.

Each company offers the standard assortment of wireless adaptor cards, as well as a few options for routers and access points. Most manufacturers marketing pre-802.11n equipment offer both lower-end "consumer" routers and higher-end "commercial" routers. The consumer-oriented devices generally come with an integrated four-port 10/100 Ethernet switch, which seems a bit off target on a device claiming speeds up to 270 Mbps. The higher-end commercial routers command their higher price point by including additional networking and security features, such as VPN capability and support for gigabit Ethernet.

Also, several manufacturers offer access points without integrated switches. Linksys even offers a power-over-Ethernet option for its access point, a good candidate for placement in tough-to-reach places.