# LoRa, Zigbee and 5G Propagation and Transmission Performance in an Indoor Environment at 868 MHz
## 1 Introduction
### Related Works  
Research work has been carried out in indoor corridors at 868 MHz [15; 16], where a channel attenuation model has been proposed from radio frequency (RF) measurements. Further, papers [17; 18] describe measurements in the same corridor used for this work. Other researchers have conducted their work on path loss in a LoRa transmission in various environments such as forests [19], buildings [20], long-range urban communications [21], urban areas [22], mountains (Bletterbach canyon) [23] and a block cave gold mine [24]. In [25; 26; 27], the empirical propagation of LoRa in indoor environments is described. Paper [28] models and discusses the behavior of different loss models of a LoRa transmission under LOS and NLOS conditions in a harsh environment. In [29], a similar procedure is performed, but in an environment with a high presence of vegetation and foliage. On the other hand, research has been performed on: the possibility of making Zigbee-based underground miner locators that make use of the measured RSSI and a path loss model to extrapolate the distance [30]; transmission distance estimation for 2.4 GHz Zigbee applications [31]; Zigbee propagation analysis for health-care applications in hospitals [32]; ZigBee and LoRa propagation on a snowy hill area [33]; and the propagation of a Zigbee signal in an indoor environment [34]. Several studies have been proposed in the literature about the behavior of the slope, \(n\), in path loss models at high frequency in indoor environments. In [35], the propagation of a millimeter-wave at 26 and 38 GHz in an indoor corridor and stairwell was studied and modeled. In the work [36], the authors studied a path loss model in an indoor commercial area at a frequency of 28 GHz and in LOS and NLOS situations. Moreover, the path loss behavior in an indoor corridor at frequencies of 14, 18 and 22 GHz has been investigated using the CI and FI model in [37]. Similarly, in [38], the impact of the antenna height on the measured path loss in an indoor corridor using the CI and FI models was analyzed. In the work [39], the design of a path loss model using CI and FI fitting at a frequency of 40 GHz in an indoor environment was studied. In the study [40], the authors present the propagation characteristics of indoor radio channels at the frequencies of 3.5, 6, 14, 23, 26 and 28 GHz, in LOS and NLOS situations; it should be noted that they perform the FI fitting of the path loss model. In paper [41], [PERSON] et al. conducted an extensive study on the propagation of millimeter-waves, 28 and 73.5 GHz, in an indoor office, presenting the results of different path loss model fitting methods (CI, FI, CIX, CIF, CIFX, ABG and ABGX models), for vertical and horizontal polarizations in LOS and NLOS situations. [PERSON] et al. conducted, in their work [42], a brief analysis of the behavior of path loss in urban NLOS environments, basing their measurements on a vehicle-to-vehicle (V2V) scenario using commercial vehicle-to-X (V2X) platforms. Since the early 1990s, the behavior of UHF radio waves in different environments has been investigated. [PERSON] et al. conducted research on propagation and modeling for indoor and outdoor wireless communication channels [43], characterization and fading in factory buildings [44; 45], path loss prediction models for indoor multifloored buildings [46] and propagation for personal-communication systems [47], based on the use of the CI path loss model in all investigations. Other researchers worked on the modeling of an Ultra-Wide Bandwidth Indoor Channel [48], delay spread and signal level within office buildings [49], and receiver spatial diversity propagation path-loss model in an indoor environment at 2.4 GHz [50]. [PERSON] et al. [51] present in their paper an extensive investigation of the accuracy of three propagation models (ABG, CI and CIF models) in their use over the entire microwave and millimeter-wave (mmWave) radio spectrum in LOS and NLOS conditions.