Ruckus tackles channel-changing in Wi-Fi
- — 29 November, 2011 10:29
Ruckus Wireless has taken another shot at optimising Wi-Fi capacity, introducing a technology called ChannelFly that is designed to place network clients on the best possible channel based on the actual capacity of that channel.
Because Wi-Fi uses unlicensed radio spectrum, Wi-Fi networks are susceptible to interference from Bluetooth devices, microwave ovens and other spectrum users, as well as from other Wi-Fi systems. The two bands where it works, in the 2.4GHz and 5GHz ranges, can be divided into several channels. But the growing number of Wi-Fi devices and networks all have to contend for the use of those channels.
Intelligently assigning clients to the various channels is one way of making the best use of a network's capacity, and other vendors have targeted this solution. For example, in 2008, Aruba Networks introduced its Adaptive Radio Management 2.0 network management software, one purpose of which was making better channel assignments. Ruckus, which pioneered beamforming, another Wi-Fi optimization technique, said it has taken a new approach to picking channels with ChannelFly.
The software, which is available free for all Ruckus access points, determines how long it takes each packet to traverse the network in order to gauge the performance offered by each channel. It uses both current and cumulative results to predict which channel will be the best for a client to use. The access point communicates a change of channel to the client via the IEEE 802.11h standard.
By contrast, most other channel selection systems involve an access point passively listening for evidence of interference or congestion in adjacent bands, said David Stiff, director of product management at Ruckus. ChannelFly directly measures the impact of interference or congestion on actual packets.
In addition, ChannelFly performs this real-time monitoring without forcing the access point to briefly switch over to the adjacent channel to gauge its performance, Stiff said. This also improves performance, he said. Ruckus claims its new software can deliver capacity improvement between 25 percent and 100 percent in congested environments.
Ruckus uses the same real-time packet monitoring concept in its BeamFlex technology, which selects among different signal paths created by Ruckus's adaptive antennas. The company decided to adapt the software to channel selection after seeing demand for better channel management from customers that operate Wi-Fi in public areas, including service providers and hotels, Stiff said. Ruckus said ChannelFly was invented by Bill Kish, the company's co-founder and chief technology officer.
The more devices there are on a wireless network, the smarter that network has to be about assigning channels, Farpoint Group analyst Craig Mathias [cq] said. The problem is getting worse even though all major Wi-Fi vendors are addressing it, because Wi-Fi has become the default network of choice for a widening array of devices including tablets, smartphones and traditional PCs, he said.
"Demands for capacity are increasing quite dramatically," Mathias said. "Efficient management of wireless channels is going to continue to be a challenge for the foreseeable future."
As companies allow employees to use their own devices at work, it's not uncommon for authorized individuals in an enterprise facility to use three or four Wi-Fi devices at once, he said. That means more clients contending for a given number of channels. The problem can be even worse for service providers that roll out Wi-Fi networks in public places, because they have no control over what other Wi-Fi networks are active in the area, Mathias added.
For a network that uses typical 20MHz channels on IEEE 802.11n, which uses both the 2.4GHz and 5GHz bands, there are 23 possible channels for clients to share, Mathias said. But making more channels available in a given space can force the company to buy and manage more access points. Most enterprises today use no more than five or six channels, he said. Any technology that can assign the best possible channel to each device helps to make the most of existing infrastructure to deliver network capacity.
"What we're really optimising for is the time of users, the productivity of people," by providing enough network speed that they can work instead of wait, Mathias said.
ChannelFly is available immediately. It works only on Ruckus access points but is compatible with all Wi-Fi clients, the company said.