# Indoor Signal Strength Evaluation of the Orbcomm Low Earth Orbit Satellite Constellation +
## 2 Related Work  
A limited amount of studies have been conducted on the topic of the indoor signal strength of LEO satellites. A few experiments have already been conducted using the Iridium constellation, which utilizes the L-band frequency (1610 MHz up to 1626.5 MHz) to transmit downlink packets [6; 7]. However, higher frequencies experience significantly more wall attenuation than lower frequencies [5].  
A first study simulated the differences in the Carrier-to-Noise Density Ratio (\(C/N_{0}\)) between LEO constellations and Medium Earth Orbit (MEO) constellations in an indoor environment. [PERSON] et al. have shown that in simulation, the indoor \(C/N_{0}\) of LEO satellites is similar to the outdoor \(C/N_{0}\) of Medium Earth Orbit satellites [8]. More specifically Starlink, OneWeb, and Kuiper, which are all situated in LEO, showed a similar indoor \(C/N_{0}\) to the outdoor \(C/N_{0}\) of the Galileo constellation which is situated in MEO. In the simulation the outdoor \(C/N_{0}\) of Galileo is 24.9 dB-Hz, similar results were observed for Starlink, OneWeb and Kuiper in an indoor setting. More specifically, the Starlink constellation had an indoor \(C/N_{0}\) of 23.1 dB-Hz, the OneWeb Constellation had a \(C/N_{0}\) of 23.7 dB-Hz and Kuiper had a \(C/N_{0}\) of 22.3 dB-Hz. To conduct this simulation, the QUAsi Deterministic Radlo channel GenerAtor (QuaDRiGa) framework was used in addition to MATLAB [9]. Furthermore, the frequencies used in the simulation matched with the real constellation frequencies as well as the antenna parameters [8]. The values put forward in this paper do deviate from what is commonly found in other papers. Specifically, the outdoor \(C/N_{0}\) of GPS typically ranges between 30 dB-Hz and 50 dB-Hz which was not the case in this paper [7; 10].  
Second, a study by [PERSON] et al. conducted real-life measurements of the \(C/N_{0}\) of LEO satellites [6]. These experiments were performed in a 13-story office building. The experiment consisted of measuring the \(C/N_{0}\) of Iridium Satellite Time and Location (STL) signals. Additionally, a GPS receiver was used to evaluate if the Ground Receiving Station (GRS) could use this MEO constellation to locate itself. The results of this study showed that even on the 13 th floor the GPS signals could not penetrate inside well enough to determine the location. A minimum of four satellite signals are necessary to determine the location of the receiver and in this study, only one to two satellite signals arrived strong enough to decode. In contrast to the Iridium STL signals, which were received with high \(C/N_{0}\) on the 13 th floor. Moreover, the Iridium STL signals even arrived with high \(C/N_{0}\) inside on the second floor. More specifically, these signals arrived with a \(C/N_{0}\) between 45-55 dB-Hz [6].  
A third and last study, similar to that of [PERSON] et al., was conducted by [PERSON] et al. They measured \(C/N_{0}\) inside a metal container [7]. These measurements showed that the of the Iridium STL signals inside of the container were similar to that of GPS in an outdoor environment (\(\pm 45\,\mathrm{dB}\)-Hz).  
The above studies have shown the potential of indoor satellite communication from LEO. However, a more complete picture in terms of environments is needed to judge the feasibility. Hence, this work aims to analyze the received signal strength in different indoor rooms and floor levels.