Clock synchronization in IEEE 802.11 wireless LANs using physical layer timestamps

Packet-based clock synchronization protocols, such as IEEE 1588, depend on the quality of the timestamps taken at the reception and transmission of packets. As software-based timestamping generates large non-deterministic delays, Ethernet synchronization implementations have moved the timestamping closer to the physical layer. However, most wireless synchronization approaches are restricted to software timestamping due to the lack of hardware timestamping features. This paper presents a physical layer timestamping approach for IEEE 802.11b, which is able to generate timestamps with sub-100 picosecond accuracy. When synchronizing the clocks of two WLAN devices with the proposed approach, the measurements show that the system can reach synchronization accuracies below 1 ns even with standard crystal oscillators.