  The IEEE 802.1 time-sensitive networking (TSN) standards aim at improving the
real-time capabilities of standard Ethernet. TSN is widely recognized as the
long-term replacement of proprietary technologies for industrial control
systems. However, wired connectivity alone is not sufficient to meet the
requirements of future industrial systems. The fifth-generation (5G)
mobile/cellular technology has been designed with native support for
ultra-reliable low-latency communication (uRLLC). 5G is promising to meet the
stringent requirements of industrial systems in the wireless domain. Converged
operation of 5G and TSN systems is crucial for achieving end-to-end
deterministic connectivity in industrial networks. Accurate time
synchronization is key to integrated operation of 5G and TSN systems. To this
end, this paper evaluates the performance of over-the-air time synchronization
mechanism which has been proposed in 3GPP Release 16. We analyze the accuracy
of time synchronization through the boundary clock approach in the presence of
clock drift and different air-interface timing errors related to reference time
indication. We also investigate frequency and scalability aspects of
over-the-air time synchronization. Our performance evaluation reveals the
conditions under which 1 \(\mu\)s or below requirement for TSN time
synchronization can be achieved.
