Vehicle safety system, distance determination method, and vehicle

A distance determination method, comprising:

• detecting, at a second electronic device, a first received signal strength indicator (RSSI) of a wireless signal sent from a first electronic device;
• detecting, at the first electronic device, a second RSSI of a wireless signal sent from the second electronic device;
• obtaining, at the first electronic device, the first RSSI from the second electronic device;
• and
• calculating, at the first electronic device, a distance of the second electronic device relative to the first electronic device according to the first RSSI and the second RSSI;
• and
• starting a process of certification between the first electronic device and the second electronic device when the distance continues to decrease.