Towards high accuracy in IEEE 802.11 based clock synchronization using PTP

The introduction of the precision time protocol has brought forth the possibility to have a standardised synchronization mechanism in networks, independent from the actual communication technology. However, it can be observed, for example in the annexes of the standard, that many implementations focus only on Ethernet based communication. The logical next step is to investigate how this protocol will fare when used for synchronizing clocks in a distributed manner over IEEE 802.11 based devices. The availability of features like roaming, the broadcast nature of the wireless medium and different hardware platform architectures require an investigation on how clock synchronization can be realized in wireless environments. This paper proposes an approach to import the precision time protocol to IEEE 802.11. Furthermore, standard nodes are enhanced with software timestamping, leading to a synchronization accuracy of a few microseconds.