  The precision of synchronization algorithms based on the theory of
pulse-coupled oscillators is evaluated on FPGA-based radios for the first time.
Measurements show that such algorithms can reach precision in the low
microsecond range when being implemented in the physical layer. Furthermore, we
propose an algorithm extension accounting for phase rate deviations of the
hardware and show that an improved precision below one microsecond is possible
with this extension in the given setup. The resulting algorithm can thus be
applied in ad hoc wireless systems for fully distributed synchronization of
transmission slots or sleep cycles, in particular, if centralized
synchronization is impossible.
