Methods and performance aspects for wireless clock synchronization in IEEE 802.11 for the IoT

IEEE 802.11 Wireless Local Area Networks are an appealing complement, if not an alternative, to Ethernet-based industrial solutions because it not only can match Ethernet's high throughput but also leads to reduced costs and more system-design flexibility. However, like in Ethernet, clock synchronization service for applications has not been inherently present in IEEE 802.11. This paper analyzes the clock synchronization mechanisms of IEEE 802.11, which has become a major communication technology to establish the Internet of Things in industries, and how they can be used to provide high precision clock synchronization. In doing so, this work discusses the different parameters which can affect the performance of clock synchronization over the wireless channel, such as timestamping quality, clock adjustment, and synchronization overhead. An outlook to the future includes the new trends for synchronization for wired-wireless hybrid and fully wireless mesh networks where the IEEE 802.1AS audio video bridging networks and IEEE 802.11s mesh networks are leading the line, respectively.