## 2 Related Work  
In the literature, there has been a vast amount of research on long range (LoRa) networks. Some of the conducted research has mainly focused on comparing LoRa with other LPWA technologies such as NB-IoT and Sigfox [7]. The authors [8] explored and discussed the wide variation of performance in a specific paradigm and focused on the limitations and capabilities. The analytical and simulation-based approaches are used in these studies for experiments and performance analysis. There are many issues with the deployment of LoRa in a practical scenario. For example, LoRa does not work for digital communication: the low power promise is violated when the LoRa network transmits images, audio, video, and large size file from source to destination. Another problem that LoRa uses the radiofrequency range 300 MHz to 3 GH, which is more harmful to the human body and causes cancer. Moreover, many IoT cloud platforms have been proposed to manage and process IoT data [9]. The authors have proposed on-off keying (OOK), pulse-position modulation (PPM), digital pulse interval modulation (DPIM), pulse amplitude and position modulation (PAPM) and differential amplitude pulse modulation (DAPIM) to calculate power spectrum densities for free-space digital communication [10]. The bandwidth of these techniques has been calculated based on the occurrence of null in the PSDs. During the analysis, it was observed that the bandwidth requirement is very high in certain cases. The PSD curves are very important to design the link as these will give information on how the signal poser changes with the bandwidth. The results are helpful in the selection of modulation schemes for free-space optical links and to determine how the power content of the signals is affected by filters and other devices in the link. OOK is more spectrally efficient than frequency-shift keying but is more sensitive to noise when using a regenerative receiver or a poorly implemented superheterodyne receiver [7]. For a given data rate, the bandwidth of a BPSK (binary phase-shift keying) signal and the bandwidth of the OOK signal are equal. The authors proposed a novel approach to realize photonic analog-to-digital conversion in a system using phase modular (PM) and delay-line interferometer (DLI) [11]. The phase modulation and interferometric demodulation techniques are used to calculate quantization and encoding. In the design system, the multiwavelength pulsed source and phase-shifted transfer function are used for signal sampling in phase modulation. Besides, the influence of amplitude and timing jitter is alleviated through a balance-detection technique. The proposed technique is not suitable when the double phase of frequency modulation occurs at the same time in the communication. In [12], the authors proposed 5G-enabled IoT gateways to communicate with remote radio heads (RRhs) of 5G C-RAN. The 5G C-RAN is endowed with compression schemes to improve uplink utilization. The experimentsand results show that the C-CARN makes it possible to support a massive number of IoT devices in terms of uplink utilization through the development of a C-RAN gateway. In Centralized Radio Access Network (C-RAN), downlink communication is not considered, which is equally essential for IoT communication. The unipolar method is a simple line-code method. It represents only one polarity format, which may be data bit 1 s or 0 s. In the case of high-polarity data bit 1 s, the waveform jumps to a positive level. The absence of waveform or low polarity represents 0 data bits. This technique is also known as ON-OFF modulation. The ON-OFF modulation technique has the drawbacks of synchronization and a DC component [12]. The unipolar method is designed for short-range communication and it is not suitable for long-range communication. The polar method is another digital line coding method, which is further categorized into Non-Return to Zero (NRZ), Return to Zero (RZ), and bi-phase. The polar digitizing scheme uses two voltage levels, positive and negative.