Constant connection
For most of the 20th century, the paradigm of wireless communication was a radio station with a single high-power transmitter. As long as you were within 20 miles or so of the transmitter, you could pick up the station.With the advent of cell phones, however, and even more so with Wi-Fi, the paradigm became a large number of scattered transmitters with limited range. When a user moves out of one transmitter’s range and into another’s, the network has to perform a “handoff.” And as anyone who’s lost a cell-phone call in a moving car or lost a Wi-Fi connection while walking to the bus stop can attest, handoffs don’t always happen as they should.Most new phones, however, have built-in motion sensors — GPS receivers, accelerometers and, increasingly, gyros. At the Eighth Usenix Symposium on Networked Systems Design and Implementation, which took place in Boston in March, MIT researchers presented a...