| CPC G01S 13/84 (2013.01) [B60R 25/209 (2013.01); B60R 25/24 (2013.01); B60R 25/241 (2013.01); B60R 25/248 (2013.01); G07C 9/00309 (2013.01); B60R 2325/101 (2013.01); B60R 2325/108 (2013.01); B60R 2325/205 (2013.01); G01S 13/79 (2013.01); G07C 2209/63 (2013.01)] | 20 Claims |

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1. An access system for a vehicle, the access system comprising:
a transmitter configured to transmit a first wireless signal from the vehicle to a portable access device via one or more antennas;
a receiver configured to receive a second wireless signal transmitted from the portable access device to the vehicle via the one or more antennas; and
a control module configured to determine a phase based on the first wireless signal and the second wireless signal, and to determine a location of the portable access device relative to the vehicle based on the phase,
wherein
the second wireless signal indicates a phase delay of the first wireless signal, and
the control module is configured to determine the location of the portable access device based on the phase delay.
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