# Insights into the Issue of Deploying a Private LoRaWAN
## 2 Background and State of the Art  
The essence of LPWAN dates back to the 1980s-1990s, when technologies and networks with similar architectures were introduced, i.e., AlarmNet from ADEMCO [14], followed by 2G (second generation mobile network) technologies, and many others. However, the modern technological concept recognized as LPWAN started with SigFox in 2009 and continued with many new technologies such as Weightless, LoRaWAN, Ingenu, Waiot, NB-IoT, and others. Moreover, the first relevant scientific papers about LPWAN were published a few years ago, in 2015; since then, interest in LPWAN has grown steadily (see Figure 1). LPWAN technologies differ from their precursors as well as from other conventional technologies, i.e., cellular technologies (2G+), mesh technologies (IQRF, Wirepas PINO(tm)), and short-to-middle range radio access technologies (Wi-Fi, ZigBee, Bluetooth, RFID). The main difference is the combination of the long range with a long battery life, which, however, results in the low throughput and limited transmission frequency. This paper focuses on the most widely adopted LPWAN technology, namely LoRaWAN. The LoRaWAN is an open standard technology based on the proprietary modulation known as the long-range (LoRa) derivative of the chirp spread spectrum (CSS) modulation. The LoRa modulation was introduced in 2007 by the Cycleo company and was taken over by the Semtech company in 2012. Nowadays, it is protected by patents EP2763321 [15] and US7791415 [16]. On the OSI (open systems interconnection) model layer structure, LoRa can be attributed to the physical layer of LoRaWAN, while LoRaWAN defines the MAC (medium access control) layer. Nowadays, the standard defines two main modulations for terrestrial LoRaWAN (long-range-LoRa; frequency-shift keying--FSK), and the network is deployed in the star topology, similar to cellular networks (see Figure 2). The gateways connect the end-devices (sensors, indicators, meters, and others) via the radio channel, covering selected areas. Subsequently, the data are transmitted via the transport technology (i.e., metallic Ethernet or cellular network) through the LoRaWAN server to the end-user application (e.g., remote monitoring or quality management). The LoRaWAN server is a combination of several different sub-servers--network server (NS), join server (JS), and application server (AS), which are handling different layers and processes (services) [17]. The NS terminates the LoRaWAN MAC layer for end-devices connected to the network. JS manages the over-the-air activation (OTAA) and activation-by-personalization (ABP) processes for end-devices. AS handles all the application layer payloads of the associated end-devices, provides the application-level service to the end-user, and generates all the application layer downlink payloads towards the connected end-devices. However, we will consider the LoRaWAN server as a complex co-located solution for hosting these servers [10]. Many theoretical works and surveys have already been published, focusing on the main parameters of LoRaWAN as well as providing comparison of LoRaWAN and the other LPWAN technologies [9; 18; 19; 20; 21; 22; 23; 24]. To give an example, Table 1 illustrates the data rate and the maximum communication range for LoRaWAN as defined by selected papers. The data rate negligibly differs, while the estimated communication range significantly changes through the different papers. The data rate varies mostly because of formal issues, such as not considering the frequency-shift keying modulation or packet overheads of different layers, rounding the values, estimating only the maximal value, and others. On the other hand, the estimates of the maximum communication range differ significantly-from 10 to 50 km; this shows that the experience of various scientists of the LoRaWAN technology differs across the field. Figure 1: Results of keyword search of the term “LPWAN” in Google Scholar for selected years. Figure 2: Architecture of the LoRaWAN from the end-device to end-application.