Phones can be set to discover each other at ease, based on various features and capabilities packed inside them.
Based on that, four members of Microsoft Research came up with a system that allows handsets to locate one another based on sound.
The idea is pretty simple: each handset makes specific sounds and, based on the time that the sound needs to travel to the other device, it can be pinpointed in space.
Zengbin Zhang, David Chu, Xiaomeng Chen, and Thomas Moscibroda from Microsoft Research came up with FAR, a ranging scheme that can localize at 12Hz with 2cm median error, and which also withstands up to 0dB noise, multipath and Doppler effect issues.
They even demoed the new system on two Windows Phones, through a game called SwordFight, in which handsets are used as swords, but without the needs of a blade, since the aforementioned system can do all the work in this area.
“Our implementation runs on commodity smartphones and does not require any external infrastructure,” the project’s description on Microsoft Research reads.
“Moreover, distance measurement accuracy is comparable to that of Kinect, a fixed-infrastructure motion capture system. Evaluation on users playing two prototype games indicate that FAR can fully support dynamic game motion in real-time.”
To ensure that the game works successfully, they needed to make sure that it could rely on continuous, accurate distance ranging, thus creating FAR, which can deliver all that.
“With phone in hand, the users' thrusts and blocks translate to attacks and counterattacks in the game,” said description continues.
“Such Phone-to-Phone Mobile Motion Games (MMG) represent interesting and novel gameplay for ad hoc users in the same location. One enabler for an MMG game like sword fight is continuous, accurate distance ranging.”
You can have a look at the manner in which things work in the video embedded below. Unfortunately, the system is not perfected, and the game is intended only for testing purposes, which means that we won’t see it arriving on Windows Phone devices that soon.