In addition to faster data speeds, the latest wireless standard 802.11n adopts a new radio technology, enables new applications and requires a change in wireless and wired network architecture. In a previous article we looked at how 802.11n offers resellers opportunities for equipment sales far beyond the normal cycle of periodic upgrades. In this article we look at the opportunities 802.11n affords systems integrators.
The WiFi Alliance has begun testing 802.11n Draft 2.0 compliant products, and the final standard is expected to be complete by 2009 at the latest. The new standard promises a maximum data rate of 540 Mbps with typical rates in the 100 to 200 Mbps range. It achieves this improvement primarily through the use of Multiple Input Multiple Output (MIMO) technology. It also uses a wider radio frequency channel. 802.11n operates on either the 2.4 GHz or the five GHz band.
MIMO: A new radio technology
MIMO uses multiple antennas at both the sending and receiving stations to increase data rate and range. Signals from the individual antennas take different paths from the sender to the receiver. Signals bounce off obstacles along the way and arrive at slightly different times. Unlike current wireless technology where bounced signals can prevent correct reception, with MIMO, the receiver uses the multiple signals to reconstruct the original data stream.
802.11n equipment can opera...
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te over much larger distances and with fewer dead spots than current technology, because obstacles in the path actually contribute to the ability of the receiver to reconstruct the signal.
Because MIMO signals travel through an area differently than current wireless signals, systems integrators must perform a new analysis to determine where to place access points (APs). It may be advantageous to place APs in cluttered areas instead of the wide open areas favored by 802.11g since 802.11n's high data rates depend to some extent on bouncing off of obstacles.
MIMO data rate increases with the number of antennas at both the sending and receiving end, and different antenna shapes affect the shape and size of the coverage area. Selecting the optimal number and type of antennas requires knowledge of radio propagation characteristics. Integrators experienced in radio technology will be able to achieve much higher performance than network support staff without this specific knowledge.
Since 802.11n promises a much higher data rate and improved range, it is easy to think that fewer APs are required. However, it is important to factor in the impact of the new applications enabled by 802.11n before reducing the number of APs.
Enable new applications: Opportunities for VAR expertise
Where voice over WLAN may not have been feasible in the past, 802.11n's higher data rate plus MIMO signals' ability to reach previously unreachable building spaces now make it a possibility.
Customers will require the help of an experienced value-added reseller (VAR) or integrator to undertake a project with the complexity of voice. Specialized knowledge and test equipment is required to match available products to customer needs, install and configure equipment, provide training and finally to test the completed installation.
The increased data rate also enables other previously unfeasible applications such as streaming video. While perhaps requiring less analysis than voice, streaming video adds opportunities to assist the customer in selecting equipment and testing the network to make sure it can provide the necessary data rate and quality of service required.
Although MIMO signals benefit from bouncing off obstacles, they also achieve greater range in uncluttered environments such as outdoor areas. Designing and installing an outdoor wireless network requires additional attention to security. Expertise in choosing components designed to survive the elements is also required.
Careful analysis of compatibility with existing networks will be required. The 802.11n standard specifies that it can operate in either the 2.4 GHz band used by 802.11g or in the five GHz band used by 802.11a.
Most 802.11n products will provide compatibility with 802.11g equipment operating on the same channel by reducing speed to the level of 802.11g. The speed reduction will affect the entire wireless network, not just the 802.11g equipment. Some 802.11n APs may include two radios, one supporting existing 802.11g networks at 2.4 GHz and another operating at five GHz with full 802.11n speed.
The advent of 802.1n requires adding a scan at five GHz even for customers with no interest in an upgrade. It has been customary to periodically scan for rogue APs installed by employees who want their own private wireless access. In the past, all APs available at retail were 802.11g and operated at 2.4 GHz. Now 802.11n APs are widely available. Remind customers to add the additional band to their scans. Some may need to upgrade test equipment to cover the five GHz band.
WLAN redesign requirements for 802.11n
Higher data rates and new applications have implications throughout the entire network. Existing wireless switches will require replacement. In many cases, the switch-based architecture will also need replacement to eliminate the requirement that all wireless data flow through the switch.
Wired network components will also require upgrading. A 100 Mbit Ethernet link was sufficient to connect an 802.11g AP to the switch. Gbit Ethernet will be required for 802.11n. The extent of required changes offers VARs and integrators an opportunity to perform an extensive network analysis and redesign.
Wireless vendors are now developing new architectures to support the increased data rate. Analyzing vendor offerings, selecting components, designing, installing and testing the modified network will offer many opportunities for VARs and integrators.
802.11n will offer a multitude of opportunities to assist customers in leveraging the new radio technology and new applications it enables. Now is the time to begin discussions with customers while you monitor vendor offerings and the results of Wi-Fi Alliance testing.
About the author
David B. Jacobs of The Jacobs Group has more than twenty years of networking industry experience. He has managed leading-edge software development projects and consulted to Fortune 500 companies as well as software start-ups.
