With smartphone motion sensors, improving wireless connectivity

If you've ever used a smartphone and traveled around a large city, you've probably experienced a dropped call or a frozen download.

The reason: the cell towers that provide the wireless network on which your phone operates are limited and scattered, requiring your service provider to "hand-off" your connection between towers as you roam around a large area.

It's the complete opposite of receiving a radio signal.

It takes an enormous amount of technology -- in the form of software infrastructure -- to make that hand-off happen, and it doesn't always work seamlessly.

But researchers at the Massachusetts Institute of Technology are working on a way to improve the exchange, using the built-in motion sensors -- GPS, accelerometers, gyroscopes -- found in modern smartphones.

MIT researchers say they have developed new communications protocols that use information about a mobile device's movement to improve handoffs, improving network throughout -- the amount of data sent and received by a device in a given time period -- by 50 percent.

The researchers -- Lenin Ravindranath, Hari Balakrishnan, Sam Madden and Calvin Newport -- used motion detection to improve four distinct protocols:

• The phone's selection of the nearest transmitter. Currently, phones choose the strongest signal -- but if you're moving around, that choice quickly becomes less effective. The new protocol incorporates the user's inferred trajectory, improving throughput and decreasing hand-offs.
• The phone's selection of bit rate. Your phone is constantly matching its information exchange rate with the size of the bandwidth available. But mobile phones are often in motion, and available bandwidth fluctuates. The new protocol takes that into account, improving bit rate by about 50 percent.
• The behavior of wireless base stations. A base station only knows when a device has lost contract after repeated failures to transmit information. With the incorporation of motion prediction, it can make an educated guess when a device will lose contact.
• Routing procedures for networks of wirelessly connected cars. Connected cars are usually in rapid motion when active; the researchers' new protocol makes this process more efficient.

Some of these protocols requires network infrastructure modifications, but the researchers' goal is clear: with sensors, we can make wireless connectivity smarter.

This post was originally published on Smartplanet.com