With 802.11n ratification finally upon us, you may wonder what impact it could have on the channel.
A draft 802.11n standard has been available for two years. The draft satisfied many customers, but encouraged others to wait until the final standard, to avoid potential problems caused by any changes.
The international Institute of Electrical and Electronics Engineers (IEEE) has finally completed its task. The good news is that the ratified standard is fundamentally compatible 802.11n.
The Wi-Fi Alliance has announced that the certificates for draft 2.0 products will automatically convert to ones for the 802.11n standard. Draft 2.0 hardware does not need to be replaced.
However, this is even better news for those who waited for the final standard. The pent-up demand is expected to result in sales.
IT organisations evaluating 802.11n are likely to have a number of business-critical applications they could migrate to wireless. And because of how 802.11n provides its high throughput, assured application delivery can be a challenge.
It marks a departure from the radio frequency (RF) techniques used by previous 802.11a, 802.11g, and 802.11b-based technologies.
By requiring multiple antennas and using each one simultaneously to double or quadruple throughput, 802.11n takes advantage of the multipath that previously hindered wireless networks.
Multipath techniques increase throughput over legacy networks, but in less predictable ways. Installers previously found network performance collapsing as the client moved further away from the access point.
Surprisingly, performance with 802.11n can improve over distance. So what were once weak spots in a deployment may become the strongest locations for 802.11n.
Customers who want to displace Ethernet for business-critical applications, however, will need predictability.
Whereas draft-N adopters may have been driven by a need for speed, this new, larger group of customers will want predictability first and foremost and are likely to take performance as a given.
Predictability in performance over 802.11n-compliant wireless networks will only be achieved by combining the right products, installation practices and service offerings.
Notions of predicting RF coverage and network throughput based on planning tools and automated radio management do not reliably work with multipath.
Whether one gets 140Mbps or 300Mbps in any one location depends on how the radio waves travel around and through the location. Radio waves bounce off every service and can vary by time of day and user orientation.
You cannot tune what you cannot predict. Dynamically transmitted power control only exaggerates the unpredictability. Constantly adjusting coverage does nothing to help troubleshooting. Problems are difficult to recreate or understand if the network keeps changing.
Client selection for 802.11n has also become trickier. The past two years of 802.11n development has led to multiple chipsets, all with differing features and capabilities. Recent 802.11n-compliant chipsets, such as Intel 4965, 5100, and 5300, are all quite different in performance capability and behaviour.
Examine mobile device features prior to purchase and you will understand how network infrastructure may address differences and issues, using tactics such as wireless client port isolation.
The 802.11n ratification will drive adoption of wireless in ways not previously seen with 802.11. Organisations hesitant to consider draft-based devices will consider 802.11n now. They will naturally assume, with 802.11n having throughput greater than edge Ethernet, that it will be an easy replacement for cabled networking.
And they will be right, so long as everyone involved in the deal is aware of the new challenges and higher expectations for 802.11n and tackles network predictability head on.
Joe Epstein is senior technology director for Meru Networks
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