# In Situ Assessment of Uplink Duty Cycles for 4G and 5G Wireless Communications
## 2 Materials and Methods  
The uplink duty cycle of a smartphone under realistic exposure conditions was measured using the setup shown in Figure 1. This setup consisted of a smartphone with the drive test tool QualiPoc (Rohde & Schwarz, Munich, Germany), a tripod, and a laptop that was connected to the smartphone using a USB cable. To avoid interference from the operator, the smartphone was connected to the laptop with a 5 m USB cable, allowing the operator to remotely control it using the Vysor app. The drive test tool QualiPoc logged the relevant parameters of the smartphone chipset to determine the uplink duty cycle. We measured the duty cycle for different smartphone applications at ten positions using a 4G/5G base-station antenna. During the measurements, the smartphone was placed in a plastic holder on a tripod at a height of 1.5 m (Figure 1). This in situ measurement campaign was performed in the vicinity of a collocated 4G LTE and 5G NR base station in Leuven, Belgium (Figure 2). Measurements were conducted at ten positions covering Line-of-Sight (LOS) and Non-Line-of-Sight (NLOS) paths between the smartphone and the base-station antenna (Figure 2). The distance between the base-station antenna and the measurement positions together with the corresponding path types are listed in Table 1.  
Figure 1: Measurement setup consisting of a smartphone with QualiPoc on a plastic tripod. The smartphone was connected via a USB cable to the laptop for remote control with the Vysor app. At each measurement position, six use cases (UCs) were assessed for 4G LTE and five UCs were assessed for 5G NR. The use cases together with brief descriptions of each case are listed in Table 2. The voice call in UC1 was only performed for LTE [Voice over LTE (VoLTE)] because Voice over NR (VoNR) was not available. In total, 110 experiments were performed. 5G NR used the time division duplexing (TDD) band n78 at 3.7 GHz. 4G LTE used the frequency division duplexing bands n3, n7, and n20 at 1800 MHz, 2100 MHz, and 800 MHz. We used a Samsung S20+ 5G (SM-G986) smartphone with the drive test tool QualiPoc (Android Ver. 21.03 SP2, Rohde & Schwarz, Germany). The smartphone only allowed us to lock onto 4G LTE technology and not onto 5G NR since the 5G NR network was non-standalone (NSA). \begin{table}
\begin{tabular}{c c c} \hline \hline
**Measurement** & **Distance to Base-Station** & \\
**Position** & **Antenna (m)** & **Path Type** \\ \hline Pos 1 & 169.7 & LOS \\ Pos 2 & 235.8 & LOS \\ Pos 3 & 310.2 & LOS \\ Pos 4 & 377.0 & LOS \\ Pos 5 & 476.4 & NLOS (vegetation) \\ Pos 6 & 594.1 & NLOS (vegetation/buildings) \\ Pos 7 & 670.0 & NLOS (vegetation/buildings) \\ Pos 8 & 1066.9 & LOS \\ Pos 9 & 136.1 & NLOS (buildings) \\ Pos 10 & 95.5 & LOS \\ \hline \hline \end{tabular}
\end{table} 
Table 1: List of measurement positions with their distance from the base station and the visually perceived path type between the smartphone and the base-station antenna. \begin{table}
\begin{tabular}{c c} \hline \hline
**Use Case** & **Description** \\ \hline UC1 & Voice call (VoLTE) 1  \\ UC2 & Voice call via WhatsApp (VoIP) \\ UC3 & Twitch video upload stream \\ UC4 & Ping \\ UC5 & Internet Performance Working Group (iPerf) (maximum traffic) \\ UC6 & File Transfer Protocol (FTP) upload of a large file (10 GB) \\ \hline \hline \end{tabular}
\end{table} 
Table 2: List of use cases (UCs) and their descriptions. Figure 2: The measurement positions (colored dots). The positions were in Line-of-Sight (LOS) or Non-Line-of-Sight (NLOS) paths in relation to the base-station antenna (black circle). In the NLOS path, there was no 5G connection. Table 3 shows a non-exhaustive list of parameters reported by QualiPoc Android Ver. 21.03 SP 2 [11] relevant for this study. The interval during which results are reported in QualiPoc, also called the observation period, depends on the chipset of the used phone and on the technology used. The phone used during our in situ measurements was a Samsung S20 with an Exynos chipset.