# Insights into the Issue of Deploying a Private LoRaWAN
## 2 Background and State of the Art
One of the reasons for this is the fact that the main parameters of LoRaWAN strongly depend on many variables, which we discuss below [10; 31; 32; 33; 34]:  
* **Selected channel (CH) or sub-band (f)** determines the maximum transmit power (10 mW, 25 mW, or 500 mW), which impacts, for example, the communication range, material penetration capability, signal propagation, and the duty-cycle (0.1%, 1%, 10%, or 100%), which impacts the allowed transmission frequency and thus the maximum data rate. * **Bandwidth (BW)** established for Europe is either 125 kHz or 250 kHz. * **Modulation (MOD)**; LoRaWAN specifies two types of modulation: (i) FSK, and (ii) LoRa modulation. The FSK demands higher signal-to-noise ratio (SNR) and thus is typically used when the communication channel is good and communication range is relatively short. Compared to FSK, the LoRa modulation offers a 13 dB better channel budget and Doppler resistance and approx. 10-20 dB increased interference immunity. * **Spreading factor (SF)** is defined as \(SF\in\{7;\ldots;12\}\) and determines the symbol duration \(T_{s}=2^{SF}T_{c}\), where the chirp interval is defined by BW as \(T_{c}=1/BW\). Moreover, the SF together with BW define the physical layer bit-rate: \[R_{b}=SF\frac{CR}{\frac{2^{SF}}{BW}}.\] (1)
* **Code rate (CR)** is defined as \(CR=\frac{4}{4+R}\), where the rate \(R\in\{0,\ldots,4\}\) and determines redundant bits used for forward error correction--FEC (impacts the ability to correct damaged messages and error-rates). LoRaWAN prescribes use of \(R=1\) for packet payload, and \(R=4\) for the packet header. * **Device class**, which defines the type of media access for downlink traffic, which also affects the end-device's power consumption (class A--downlink only after uplink and the minimum consumed power; class B--periodic downlink slots with slightly higher device consumption; class C--highest consumption for devices, but downlink can be sent any time). * **Device settings** provide a number of other configuration capabilities, including activation (over-the-air activation--OTAA or activation by personalization--ABP), key-generation, firmware updates, data rate (adaptive data rate--ADR, or fixed data rate--FDR), and others). A lot has been written about the general LoRaWAN parameters. Specifically, a number of the scientific papers provide a general overview of LoRaWAN parameters, met \begin{table}
\begin{tabular}{c c c} \hline \hline
**Paper** & **Data Rate (kb/s)** & **Communication Range (km)** \\ \hline
[25] & 0.29–50 & 15 \\ \hline
[13] & 0.29–50 & less than 35 \\ \hline
[5] & max. 50 & 5 (U), 20 (R) \\ \hline
[6] & 0.3–37.5 & 3–10 (U), 30–50 (R) \\ \hline
[26] & 0.3–37.5 (L), 50 (F) & 10 (U), 50 (R) \\ \hline
[27] & 27 (L), 50 (F) & 2–5 (U), 15 (R) \\ \hline
[7] & 0.25/5.5/11/50 & 2–15 \\ \hline
[9] & max.50 & 5 (U), 20 (R) \\ \hline
[28] & 0.3–50 & up to 10 \\ \hline
[29] & 0.3–50 & 2–5 (U) \\ \hline
[30] & 0.29–50 & 2–5 (U) 45 (R) \\ \hline \hline \end{tabular} Note: L —LoRa; F—FSK; U—Urban; R—Rural.  
\end{table} 
Table 1: Comparison of different parameter estimations based on the physical level in selected papers. rics, and performance indicators, i.e., capacity [35], coverage [36], maximal range [37], free-space behavior [38], usage [39], energy-efficiency [40], technology comparison [41], performance [42], mobility [43], and other parameters [44]. The authors of [45] compare analytically-obtained parameters of the well-known LPWAN technologies. There are also articles offering datasets from the already functional LoRaWAN network, for the possibility of in-depth research, to mention a few [46; 47]. Authors in [19; 48] propose routing schemes to create multi-hop communication and routing protocols or decentralized architecture [49] in order to improve LoRaWAN performance. Still, it requires special devices in the network or the end-device modification. The authors in [50] are experimenting with multi-RAT (multiple radio access technology) devices, combining LoRaWAN and NB-IoT to improve mainly energy consumption.