The Internet of Things (IoT) is one of the most important emerging technologies, spanning a myriad of possible applications, especially with the increasing number and variety of connected devices. Several network simulation tools have been developed with widely varying focuses and used in many research fields. Thus, it is critical to simulate the work of such systems and applications before actual deployment. This paper explores the landscape of available IoT and wireless sensor networks (WSNs) simulators and compares their performance using the Low Power Wide Area Network (LPWAN) communication technology called LoRa (Long Range), which has recently gained a lot of interest. Using a systematic approach, we present a chronological survey of available IoT and WSNs simulation tools. With this, we categorized and content-analyzed published scientific papers in the IoT and WSNs simulation tools research domain by highlighting the simulation tools, study type, scope of study and performance measures of the studies. Next, we present an overview of LoRa/LoRaWAN technology by considering its architecture, transmission parameters, device classes and available simulation tools. Furthermore, we discussed three popular open-source simulation tools/frameworks, namely, NS-3, OMNeT++ (FLoRa) and LoRaSim, for the simulation of LoRa/LoRaWAN networks. Finally, we evaluate their performance in terms of Packet Delivery Ratio (PDR), CPU utilization, memory usage, execution time and the number of collisions.

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A hybrid multiple pulse amplitude and position modulation (H-MPAPM) scheme based on gradual multi-pulse pulse-position modulation (G-MPPM) and multi-level pulse amplitude modulation (M-PAM) schemes is proposed for deep-space optical communication. In this scheme, transmitted information is conveyed by different combinations of the positions and amplitudes of multiple optical pulses. The performance of the proposed scheme with multi-pulse pulse-position modulation (MPPM), G-MPPM and multiple pulse amplitude and position modulation (M-PAPM) schemes in terms of the number of transmitted symbols, data rate, symbol error rate (SER), bit error rate (BER), bandwidth utilization efficiency and power requirements are studied in this work. Our results reveal that, at the same frame size, the proposed scheme allows much more symbols per frame transmission, achieves higher transmission energy and further enhance the bandwidth utilization efficiency of MPPM, G-MPPM and M-PAPM schemes. Moreover, compared to the MPPM and G-MPPM, the proposed scheme achieves lower levels of SERs but at the expense of peak power levels. Furthermore, the proposed scheme outperforms G-MPPM and MPPM schemes by approximately 1 and 2 dB at a BER of 10 −6 , respectively. In addition, the analytical expressions for the BER and SER of the proposed scheme are validated using Monte Carlo (MC) simulations.

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