Enhanced TPMS security through acceleration timed transmissions

Tire Pressure Monitoring Systems (TPMS) offer real-time diagnostics of the status of a vehicle's tires via a wireless communications link back to the vehicle. These links, which provide data, mandated by the NHTSA, generally possess low security/low privacy, leading to a demonstrated potential for spoofing attacks or tracking a person/vehicle through the unencrypted emission of the tire's unique identifier. Due to the radiation pattern of the valve stem (used as the TPMS antenna), much of the signal is directed away from the vehicle. This paper investigates the possibility of decreasing the required signal strength by using the already existing accelerometer on the TPMS to detect the angle of the wheel and to transmit data at an optimal wheel orientation. This paper shows that the received signal strength at the vehicle receiver can differ by up to 20 dB between the best and worst orientations and provides a low computation option for estimating the angle of the wheel. Implementation of this algorithm or a similar algorithm would provide better battery life and better security for the TPMS while keeping cost the same.