Portable Full Channel Sounder for Industrial Wireless Applications With Mobility by Using Sub-Nanosecond Wireless Time Synchronization

Wireless communications have attracted great interest from the industry due to its lower costs and the possibility of enabling new use cases. The new use cases are commonly related to mobile robotics, such as Unmanned Aerial Vehicles or terrestrial robots. The design of wireless systems for these use cases requires deep knowledge of the channel behavior and therefore the use of channel sounders that are able to measure the phase and gain of the channel is mandatory. However, channel sounders require very precise synchronization, which is typically implemented through a wired connection between the nodes. As a result, the mobility of the nodes is constrained to the length of the synchronization wire. In this paper, we present the design and implementation of a portable 802.11-based channel sounder that exploits a sub-nanosecond wireless time synchronization scheme. Thanks to the wireless synchronization, the channel sounder can operate as a channel sounder with wired synchronization, being able to measure synchronized channel impulse response samples. From these samples, relevant channel parameters can be extracted, including the Power Delay Profile, Doppler spectrum, and channel delay. The channel sounder presents several advantages compared to a conventional channel sounder with wire synchronization, such as smaller size and weight, simpler and more flexible operation, and it does not constraint the movement of the environment or nodes. The verification of the channel sounder through a wireless channel emulator and the measurement carried out in an industrial facility confirm its feasibility for industrial wireless and other applications.