Method and system of determining and preventing relay attack for passive entry system

A method of preventing relay attack of a passive entry system (PES) used within a vehicle to provide passive access to one or more vehicle systems, the method comprising:nupon detecting a PES triggering event, transmitting a query message from one or more PES antennas included within the vehicle, each of the query messages including a continuous wave (CW) portion having an amplitude that decreases as the query message travels farther from the transmitting PES antenna;receiving a first response of a fob receiving one or more of the query messages, the response indicating the amplitude of each CW portion included within the one or more query messages being responded to by the fob;determining whether the fob is one of near field and far field from the vehicle based on the amplitude included in the response indicating a distance of the fob from the vehicle to correspond with one of the near field and the far field;transmitting a challenge query to the fob that is dependent on whether the fob is near field or far field, the challenge query providing a first test if the fob is near field and a second test if the fob is far field; andgranting access to the one or more vehicle systems to be passively controlled according to the PES triggering event depending at least in part on a second response of the fob to the one of the first test and the second test provided by the challenge query.

A method of preventing relay attack of a passive entry system (PES) used within a vehicle to provide passive access to one or more vehicle systems, the method comprising:nexecuting an amplitude differentiation test, a perpendicularity test, and a saturation test in response to detection of a passive entry event, each of the tests evaluating a response of a fob to one or more messages wirelessly issued from a controller within the vehicle; andgranting passive control of one or more vehicle systems upon successful completion of each of the amplitude differentiation test, the perpendicularity test and the saturation test.

A method of preventing relay attack of a passive system (PS) used within a vehicle to provide passive access to one or more vehicle systems, the method comprising:nupon detecting a PS triggering event, transmitting a PS query message from one or more PS antennas included within the vehicle;receiving a first response of a fob receiving one or more of the PS query messages, the response indicating a strength of signals used to convey the one or more query messages;determining whether the fob is one of near field and far field from the vehicle based on the strength of the signals;creating a challenge query for the fob that is dependent on whether the fob is near field or far field, the challenge query requesting the fob to differentiate between signals having a first amplitude and signal having second amplitude;transmitting a challenge query message to the fob to request to fob to differentiation between signals wherein the second amplitude is greater than the first amplitude in the event the fob is far field and wherein the second amplitude is less than the first amplitude in the event the fob is near field; andgranting access to the one or more vehicle systems to be passively controlled according to the PS triggering event depending at least in part on a second response indicting the fob differentiated between the signal having the first and second amplitudes.