Positioning based on inter-packet arrival time

A method of operating a radio frequency identification (RFID) tag, the method comprising:

• transmitting a first packet to an RFID station at a first transmission time, an energy level of an energy storage device of the RFID tag being reset as a result of the first packet being transmitted;
• harvesting energy at least based on radio frequency waves from the RFID station after the first packet being transmitted, and storing the harvested energy in the energy storage device;
• and
• transmitting, based on the energy level of the energy storage device reaching a configured level, a second packet to the RFID station at a second transmission time after the first transmission time to enable the RFID station to determine an inter-packet arrival time between the first packet and the second packet.

A radio frequency identification (RFID) station, comprising:

• at least one memory;
• at least one transceiver;
• and
• at least one processor communicatively coupled to the at least one memory and the at least one transceiver, the at least one processor configured to:
• receive, via the at least one transceiver, a first packet from an RFID tag at a first arrival time;
• receive, via the at least one transceiver, a second packet from the RFID tag at a second arrival time after the first arrival time;
• and
• estimate a distance between the RFID station and the RFID tag based on an inter-packet arrival time between the first packet and the second packet, the inter-packet arrival time being based on a time difference between the first arrival time and the second arrival time.

A radio frequency identification (RFID) tag, comprising:

• at least one memory;
• at least one transceiver;
• and
• at least one processor communicatively coupled to the at least one memory and the at least one transceiver, the at least one processor configured to:
• transmit, via the at least one transceiver, a first packet to an RFID station at a first transmission time, an energy level of an energy storage device of the RFID tag being reset as a result of the first packet being transmitted;
• harvest energy at least based on radio frequency waves from the RFID station after the first packet being transmitted, and storing the harvested energy in the energy storage device;
• and
• transmit, via the at least one transceiver and based on the energy level of the energy storage device reaching a configured level, a second packet to the RFID station at a second transmission time after the first transmission time to enable the RFID station to determine an inter-packet arrival time between the first packet and the second packet.