The term “pedestrian-to-vehicle communication network” or “PVCN” refers to a scheme for detecting pedestrians by vehicles. It has many advantages over vision-based or radar-based systems, since pedestrians obstructed by vehicles can still be detected (observed). Each pedestrian is expected to have a small pedestrian communication unit associated therewith. The PU will interact with vehicles having integrated vehicle communication units.
The biggest challenges facing implementation of a PVCN are cost, power and positioning accuracy: the PU must be extremely low cost, even at the expense of limiting functionality. For example, a GPS (or similar) receiver may be too costly, and placing the GPS antenna in a position with a clear view to the sky may be too challenging. However, if a GPS receiver is not included, a PU may not have no location/positioning capability. Even if a GPS receiver is included, the processing power and memory size need to be kept very low, severely limiting the ability of the PU to have an accurate map of all roads and vehicles in its surroundings.
Power reduction may be achieved by limiting PU receive and transmit operations (referred to herein generally as “activity”). In Pus which include a GPS receiver, the “activity” may also refer to GPS receive activity. Achieving these without compromising the safety goals requires understanding of the road topology and assessment of risk from approaching vehicles. Road topology storage requires significant memory, while risk assessment requires extensive processing. Implementing these features will increase the PU cost beyond acceptability.
Transmission from a PU of a person sitting inside a vehicle may confuse processing of proximal vehicles, which might trigger a false alert for pedestrian safety risk. The conditions for pedestrian safety risk are different than those for vehicle risk. The sensitivity to raising pedestrian alerts will be likely higher than that to raising vehicle alerts. Therefore, there is a difference in risk analysis between pedestrians and vehicles and the two must not be confused. Another reason to reduce activity in a PVCN is to reduce network load and to increase battery life of a PU belonging to a pedestrian who is not posing a threat, such as a person sitting inside a vehicle.
There is therefore a need for, and it would be advantageous to have activity reduction in pedestrian-to-vehicle communication network without implementing understanding of surroundings in a pedestrian unit. It would also be advantageous to have such activity reduction even if the PU includes a GPS receiver.