Original URL: http://www.theregister.co.uk/2013/08/12/cut_wifi_power_consumption_using_bigger_frames_boffins/

Bigger frames make Wi-Fi a power miser: boffins

How many networks do you want to run to enable the internet of bits?

By Richard Chirgwin

Posted in Data Networking, 12th August 2013 03:34 GMT

A group of researchers from Greece's University of Thessaly and the Centre for Research and Technology Hellas believe there's scope for energy consumption reductions of as much as 75 percent if 802.11n's energy saving extensions are combined with frame aggregation techniques.

The reason this is important? Because, as wireless devices outrun fixed connections for existing users, new users, and the default connection type for the much-touted Internet of Bits (which Vulture South hopes becomes known as the iNoB), power consumption out at the edge of the Internet is going to be a shocker.

For example, earlier this year the University of Melbourne's Centre for Energy Efficient Telecommunications (CEET) stated that the network edge is responsible for around ten times the energy consumption attributable to data centres. As the number of end user devices skyrockets, so will the amount of energy consumed in the access network to serve them.

CEET also predicts that the “wireless cloud” will demand more than 4.5 times as much electricity in 2015 than it did in 2012.

While 802.11n includes a variety of power saving modes, these focus on sleep and idle modes – they don't save power if the interface is active. Getting transmit/receive power consumption down is much harder.

Which brings us back to the Thessaly/CRTH benchmarking work published at Arxiv, here. Among other things, the researchers demonstrate that frame aggregation can have a big impact on power consumption in the 802.11n world.

With A-MPDU aggregation active, the researchers found, the energy consumption per transmitted bit is 75 percent lower than without aggregation.

A last word: we all know that 802.11n can in theory hum along at up to 600Mbps. The current favorite for internet of things wireless connections, over short distances at least, is Bluetooth SMART (aka Bluetooth Low-Energy or BLE) which operates at up to 24 Mbps. Few remote sensors will need 802.11n's speed, but few organisations like the idea of running multiple networks. If frame aggregation helps to get 802.11n power consumption competitive with Bluetooth, it could make single-network sensor strategies sensible. ®