| CPC G07C 9/00309 (2013.01) [B60R 25/209 (2013.01); G01S 5/0284 (2013.01); G01S 13/0209 (2013.01); G07C 2209/63 (2013.01)] | 10 Claims |

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1. A method for activating a vehicle function via ultra-wide band communication using an item of portable user equipment communicating via ultra-wide band with an activation device on board the vehicle, the activation of the vehicle function being carried out as a function of a position of the item of portable user equipment relative to a boundary between an internal zone and an external zone of the vehicle, the activation method comprising:
a) previously equipping the vehicle with an internal antenna and an external antenna;
b) determining a presence of the item of portable user equipment in an authorization zone around the vehicle;
c) storing a power delay of multi-path ultra-wide band signals received by each of the internal antenna and the external antenna according to time;
d) determining an attenuation delay of received power for at least one power threshold value for each of the internal antenna and the external antenna;
e) comparing said attenuation delay with at least one reference delay;
f) determining, as a function of the result of said comparison, whether the item of portable user equipment is located in the internal zone or in the external zone; and
g) activating the vehicle function corresponding to the position of the item of portable user equipment.
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