## 3 Equipment and Scenario Description
### Scenario of Interest  
The scenario for evaluating the LHO scheme is presented in Figure 3 where a typical office setting is employed to mimic an industrial environment. The corridor, where the test was held is \(3\times 2.5\) m wide/high. The offices are separated from the corridor with \(10\) cm wide partition walls. Inside the office, the WiFi AP is installed on a \(1.5\) m height (see Figure 3). Along the office walls there are installed  
\begin{table}
\begin{tabular}{c c} \hline \hline Framework & **Dagu Wild Thumper Chassis with 6 Wheels and 2 Motors** \\ \hline Computing unit & UDOO \(\times 86\) \\ Operating system & Debian Jessie \\ Radio access technologies & MikroTik wAP 60G (mmWave) and 802.11n Wi-Fi transceiver \\ Battery & \(2\times 8000\) mAh LiPo \\ Camera & Logitech C270 HD \\ Sensors & SEN-13959 distance meters and \(2\times\) quadrature wheel encoders and BMI160 six-axis sensor \\ \hline \hline \end{tabular}
\end{table}
Table 2: Technical specifications and features of multi-RAT robotic platform.  
Figure 2: Prototype photo (disassembled) with notes.  
three wooden tables, four metal chairs and two cupboards, which do not obstruct the LoS condition between robot and WiFi nor robot trajectory during the test.  
In terms of the robot trajectory, the starting location was 15 m away from the mmWave AP that is attached to the ceiling and tilted 15 degrees down, to provide stable coverage to the robot in the LoS conditions. The LoS coverage of the mmWave AP is modeled in Blender, as is discussed in Section 4.1 and shown in Figure 2(a) with the viewing angles corresponding to the location of the AP and its antenna array configuration span. The WiFi is located inside the office, in the NLoS state w.r.t. the initial location of the robot. It is noteworthy that there exists only one mmWave AP (WiGig) and one cmWave AP (WiFi) within the considered environment, and we tried to minimize the existing interference from other WiFi APs operating in the same area by choosing the least used frequency channel. The overall robot trajectory is as follows. After the first 10 s of initialization (when the vehicle remains stationary), the robot starts moving along the corridor with the constant velocity of approximately 0.5 m/s, until it reaches the entrance to the office, in which the WiFi is located, see Figure 2(b). Further, it turns left and moves into the office (entering the mmWave NLoS area). In the end, the robot drives one meter inside the office and stops. All in all, the core objective of this work is to maximize the radio connection with the mmWave AP for an augmented throughput, while switching to the WiFi in the non-ideal condition for enhanced link robustness in the industrial environment.  
Last but not least, we emphasize that the proposed handover scheme works the best in static environments, where the scenario layout either changes rarely, or changes are periodic and predictable. If there is a need to consider dynamic scenario reconfiguration, the LoS map of the environment should be modified accordingly, which certainly increases the overall complexity. An example of an environment with predictable geometry dynamics could be a fully automated factory or storage/production hall.  
Figure 3: Test scenario 3D model and layout. (**a**) The 3D model of the corridor. (**b**) Test scenario layout combined with LoS map.