## 3 Research Methodology and Procedures
### Technical Specifications and Core Concepts of LoRa Technology  
Setting a number of PHY variables, including Bandwidth (BW), Spreading Factor (SF), Coding Rate (CR), Transmit Power (TP), and Carrier Frequency (CF) are the primary specifications for configuring a LoRa device. Table 2 shows the LoRa configuration parameters. SF is the number of symbols per payload bit, ranging from 7 to 12. In exchange for superior sensitivity and range, a higher applied SF results in a lower data rate, longer propagation time, and higher power consumption. As a result, devices further away from the gateway require a larger SF due to the increased link budget requirement, which increases the processing gain but reduces the data rate. In addition, since SFs are orthogonal (basically quasi-orthogonal [31]), different SFs can be used to modulate different signals in the same channel. The BW is usually 125, 250, and 500 kHz in frequency. A higher number provides more security at the cost of longer transmission times, while the CR, which represents the rate of the Forward Error Correction (FEC) code, can be set to 4/5, 4/6, 4/7, or 4/8. The LoRa modulation bit rate \(R_{b}\) can then be set using Equation (1). \[R_{b}=SF\times\frac{BW}{2^{SF}}\times CR \tag{1}\]  
In addition, different parts of the LoRa spectrum have different multi-frequency channels, with CF being the center frequency of these channels. The hardware of a LoRa radio imposes limits on its Transmit Power (TP), which is typically in the range of 2 to 20 dBm [32]. Figure 2: Implementing the LoRa connectivity in urban environments. The CF is also adjustable and programmable from 137 MHz to 1020 MHz in steps of 61 Hz. This range may be limited between 860 MHz and 1020 MHz depending on the LoRa chip. A higher CR provides more protection, but the time on air is longer, including an explicit header that allows radios with different CRs (but the same CF, SF, and BW) to still interact with each other. This is possible because the packet header, which is always encoded at CR 4/8, contains information about the CR of the payload. Chirp, which stands for \"Compressed High-Intensity Radar Pulse\", is a technology used in both sonar and radar systems. Chirp signals are characterized by their changing frequency at a constant amplitude. They are referred to as \"up-chirps\", when the frequency increases from the lowest to the highest point, and \"down-chirps', when the frequency decreases from the highest to the lowest point. This unique spectral characteristic allows the Chirp Spread Spectrum (CSS) to transmit information efficiently. The reduced spectral efficiency inherently provides resistance to frequency-selective noise and interference from other devices. In addition, with appropriate precautions, CSS can be more resilient to multipath and Doppler effects than other conventional modulation techniques. In the context of LoRa modulation, the initial frequency of a chirp serves as the symbol. SF is a critical parameter that determines the number of bits encoded in a symbol. Essentially, a chirp using SF represents 2 SF bits per symbol, where a symbol is represented by multiple chips in a spread spectrum code pulse, often using a Pseudo-Noise (PN) code sequence. SF is defined in Equation (2). \[SF=ChipRate/SymbolRate \tag{2}\]  
CSS spreads the energy of the signal over a wider band and the symbol time (Ts) is determined by the spreading factor of the transmission, as described by Equation (3). \[T_{s}=\frac{2^{SF}}{BW} \tag{3}\]  
BW stands for the signal bandwidth. An increase in the spreading factor lengthens the symbol duration, enhancing resistance to noise and interference. However, this effect can be offset by the higher likelihood of symbol errors with greater spreading factors, emphasizing the importance of receiver-to-signal synchronization, especially for small data bits. Additionally, longer message transmission increases the risk of collisions. SF also impacts the receiver's Sensitivity (S), defined in Equation (4):  
\[S_{Rx}=-174+10\log_{10}(BW)+NF+SNR \tag{4}\]