Researchers from Germany's Technische Universitaet Muenchen developed the Ko-TAG system, in which pedestrians and cyclists carry a transponder - this could be a small wearable device, or it could simply be built into their smartphone.
Cars then transmit a coded radio signal. As a vehicle gets within range of a pedestrian, that person's transponder picks up the signal and responds by altering the code, then transmitting it back to the vehicle "in a very precise temporal pattern."
By analysing that pattern, the vehicle's onboard positioning system is able to determine the speed and trajectory of the pedestrian, 'Gizmag' reported.
If it determines that the car and the person are about to collide, it can alert the driver or even automatically apply the brakes.
Unlike radar-based technology, it can detect pedestrians even when they are hidden from view, researchers said.