# LoRa 2.4 GHz Communication Link and Range
## 2 Related Work  
With the aim of providing a low power, long-range wireless communication protocol, Semtech acquired the startup company Cycleo, which developed LoRa in 2009. The authors in [7] provided an in-depth analysis of the functional components of both the physical (LoRa) and data link (LoRaWAN) layer of the popular LPWAN protocol operating in unlicensed bands.  
Sub-GHz LoRa-based communication has been studied thoroughly in the past decade. Acting as a layer above LoRa, LoRaWAN is widely used to communicate small messages over large areas. A LoRaWAN network can fully cover a city-scale environment with only a few gateways. The mobility of LoRaWAN has been addressed in [8]. The forwarding of an uplink message by multiple gateways ensures that a handover can take place without any loss of data. In another study, a robust frame detection algorithm was proposed in order to detect LoRa-modulated frames with minimal complexity implementations [9]. Furthermore, a frame relay strategy was found to be a feasible way to improve the link quality of poorly connected nodes and successfully extend the range of LoRaWAN [10].  
In addition to the communication aspect of LPWAN, a significant amount of research, both from academic and industrial perspectives, has involved the location objects with of sub-GHz LPWAN. We conducted extensive research on localization with different LPWAN technologies. We evaluated the accuracy of received signal strength (RSS)-based localization algorithms for Sigfox [11], LoRaWAN [12] and NB-IoT [13]. We also provided an angle of arrival (AoA) estimation solution that is suitable for use in sub-GHz bands [14; 15]. Furthermore, we devised a probabilistic localization model that combines time difference of arrival (TDOA) and AoA estimations in a sub-GHz LoRa network [6].  
Recently, Semtech released the SX1280 chipset, which operates at 2.4 GHz [5]. In an application note, the company provides an introduction to time-of-flight (ToF) ranging possibilities with the radio chip [16]. A proof-of-concept implementation for coherent multi-channel ranging with this LoRa radio chip is provided in [17].  
A few concerns are raised by the move from sub-GHz frequencies to the widely used unlicensed 2.4 GHz ISM band. The interference properties of wireless local area networks (WLAN, also denoted as Wi-Fi) devices operating in this band were characterized in [18]. In another study, coexistence issues with Wi-Fi and LoRa 2.4 GHz were addressed [19]. The theoretical assumptions about the high robustness of the system against interference are confirmed. However, it was found that the robustness highly depends on both the configuration of LoRa and the properties of interfering technologies. Moreover, [PERSON] et al. used different bandwidths in their evaluation and compared them to the bandwidths that are currently available for LoRa at 2.4 GHz.  
The maximum communication range in the 2.4 GHz band strongly depends on the technology and its respective transmission power. For the latest Bluetooth Low Energy (BLE 5) standard, the maximum communication ranges in different scenarios are summarized in [20]. Typical ranges are 50 m in an indoor scenario, 165 m in an outdoor non-line-of-sight (NLoS) scenario and 780 m in a LoS scenario. In this research, we will investigate the range of 2.4 GHz LoRa in a free space and in indoor and outdoor scenarios.