Method and system for relay attack prevention using subzones

A system for detecting if a relay is present in a Passive Entry Passive Start (PEPS) system for a vehicle, the PEPS system including a plurality of predefined subzones within one or more vehicle inclusion zones, the plurality of predefined subzones being sized based on a relationship between a total number of subzones used and an allowable Received Signal Strength Indicator (RSSI) variation value within each subzone, the system comprising:

• two or more antennas associated with the vehicle for transmitting a challenge signal from the two or more antennas to a key fob and one or more controllers configured to:
• (a) transmit a challenge signal including a Low Frequency (LF) telegram transmitted from at least one antenna and Continuous Wave (CW) signals from two or more antennas associated with a vehicle to a key fob, the CW signals being measured by the key fob;
• (b) determine if the CW signals measured by the key fob meet predetermined RSSI magnetic field strength values associated with one or more subzones from the plurality of predefined subzones, the predefined subzones being derived to accept the allowable RSSI variation values of magnetic field distributions at localised positions within a valid inclusion zone and reject magnetic field distributions outside the allowable RSSI variation values generated by a relay at a relay transmitter.

A method of detecting if a relay is present in a Passive Entry Passive Start (PEPS) system for a vehicle, the PEPS system including a plurality of predefined relay subzones for one or more vehicle inclusion zones, the relay subzones being sized based on a relationship between a total number of subzones used and an allowable Received Signal Strength Indicator (RSSI) variation value within each relay subzone, the method comprising the steps of:

• (a) transmitting a challenge signal including a Low Frequency (LF) telegram transmitted from at least one antenna and Continuous Wave (CW) signals from two or more antennas associated with the vehicle to the key fob, the CW signals being measured by the key fob;
• and
• (b) determining if the CW signals measured by the key fob meet predetermined RSSI magnetic field strength values associated with one or more predefined relay subzones from the plurality of predefined relay subzones, the predefined relay subzones being derived to accept the allowable RSSI variation values of magnetic field distributions at the relay transmitter and reject magnetic field distributions outside the allowable RSSI variation values generated at the vehicle inclusion zone.

A system for detecting if a relay is present in a Passive Entry Passive Start (PEPS) system for a vehicle, the PEPS system including a plurality of predefined relay subzones for one or more vehicle inclusion zones, the relay subzones being sized based on a relationship between a total number of subzones used and an allowable Received Signal Strength Indicator (RSSI) variation value within each relay subzone, the system comprising:

• two or more antennas associated with the vehicle for transmitting a challenge signal from the two or more antennas to a key fob and one or more controllers configured to:
• (a) transmit a challenge signal including a Low Frequency (LF) telegram transmitted from at least one antenna and Continuous Wave (CW) signals from two or more antennas associated with a vehicle to a key fob, the CW signals being measured by the key fob;
• (b) determine if the CW signals measured by the key fob meet predetermined RSSI magnetic field strength values associated with one or more predefined relay subzones from the plurality of predefined relay subzones, the predefined relay subzones being derived to accept the allowable RSSI variation values of magnetic field distributions at the relay transmitter and reject magnetic field distributions outside the allowable RSSI variation values generated at the vehicle inclusion zone.