METHOD FOR ACTIVATING A FUNCTION OF A VEHICLE VIA AN ULTRAWIDE BAND WITH AN ITEM OF PORTABLE USER EQUIPMENT, ASSOCIATED SYSTEM AND DEVICE FOR ACTIVATING A FUNCTION

A method for activating a vehicle function using portable user equipment communicating via ultra-wide band with an activation device on the vehicle. The activation of the vehicle function is carried out as a function of a position of the portable equipment relative to a boundary between an internal zone and an external zone of the vehicle. The activation method including: previously equipping the vehicle with an internal and external antennas; determining the presence of the portable equipment in an authorization zone around the vehicle; storing a power delay of the multi-path ultra-wide band signals received by each antenna according to time; determining an attenuation delay of the received power; comparing the attenuation delay with at least one reference delay; determining whether the portable equipment is located in the internal zone or in the external zone; activating the vehicle function corresponding to the position of the portable equipment.