Networking resellers and their customers can look forward to the benefits the latest WiFi standard, IEEE 802.11n, will bring. Faster data speeds will make additional applications possible
The IEEE began work on 802.11n in 2004. Work has proceeded slowly with Draft 1 of the standard released in 2006. Pre-standard equipment based on it became available shortly after. Draft 2.0 was approved in January, 2007; and products based on it are expected to be released within the next few months. The WiFi Alliance plans to begin testing Draft 2.0 compliant equipment for interoperability and adherence to the draft late this spring or summer. The final standard is not expected to be released until sometime in 2008, but any changes between Draft 2.0 and the standard are expected to be minor, and vendors expect to address them with software only upgrades.
802.11n promises a data rate potentially as high as 540 Mbps with typical rates expected to be between 100 and 200 Mbps. Pre-standard equipment now available has reached rates in this range. Data rates are expected to increase as experience with the standard grows.
The increased data rate is achieved primarily through use of Multiple Input Multiple Output (MIMO) radio technology. MIMO uses multiple antennas at the sending and receiving stations to achieve increases in both data rate and range. 802.11n also utilizes a wider radio frequency channel and introduces a method to decrease the time between transmissions.
Opportunities for equipment sales result both from replacement of current wireless components but also from the additional applications made possible by the increased data rate. Applications such as wireless VoIP and streaming video that are not practical with 802.11g are possible with 802.11n.
802.11n requires equipment replacements
The upgrade to 802.11n will require a far more extensive set of equipment replacements than the earlier move from 802.11b to 802.11g. The previous upgrade required simply replacing the access points (APs) and laptop wireless interfaces. 802.11n will require not only new APs and interfaces, but in many cases a change in the entire wireless architecture due to the magnitude of the increase in data rate.
Most current APs are described as "thin AP's" and consist of little more than a radio. Intelligence is concentrated in a wireless switch. The switch is responsible for authenticating users, encrypting and decrypting data, and coordinating roaming among APs. All wireless data flows from the APs to the wireless switch and then on to its ultimate destination. A typical switch in an 802.11g network is capable of supporting approximately 50 APs, each generating a 20 Mbps data rate.
The current architecture will be sufficient until added applications begin to take advantage of 802.11n's increased performance. Then, if each 802.11n AP generates just 100 Mbps, a switch that could support 50 APs will be capable of supporting only 10 802.11n APs.
Increasing the number of switches would not be a solution even if it were economically feasible. The mechanism most vendors use for coordinating roaming among APs works on the assumption that a single switch communicates with all APs. Wireless vendors recognize the problem and are working on solutions. But any vendor architecture now relying on a switch will require either that the switch be replaced by a higher capacity unit or that a new architecture eliminates or reduces traffic through the switch. Either alternative is a major change.
Upgrades and replacement of the wireless components are only part of the opportunity for new equipment sales. 802.11n will require upgrades throughout the wired network. 100 Mb Ethernet links connecting APs to the wireless switch are sufficient today but will need to be upgraded to 1 Gb. This means that routers and switches along the path will need to be upgraded or replaced. In some cases network cabling will also need to be upgraded.
Laptop wireless interfaces will need to be upgraded. 802.11n APs will continue to support 802.11g, but without any increase in data rate. Laptops are now available with pre-standard support built in, but most existing laptops will not be able to benefit from the increased speed without adding an 802.11n compliant wireless card.
The increased wireless capacity that 802.11n brings makes possible applications such as wireless VoIP and streaming video. Addition of these applications opens up many opportunities for server and software and sales.
Begin planning now
However, the standard is not yet complete. Products currently available are based on Draft 1 and are available only from vendors such as Linksys, D-Link and NetGear that concentrate on the consumer market. Vendors supplying the enterprise market are expected to release Draft 2.0-compliant products later this year.
Begin discussing 802.11n with customers now, but hold off purchase decisions at least until the WiFi Alliance completes testing of Draft 2.0 products. Review vendor announcements to see how each intends to address the required architectural changes. Then work with customers as they plan the initial upgrade to the new standard followed by the addition of new applications.
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.
This was first published in May 2007