Typically, LoRaWAN utilizes an adaptive data rate (ADR) for resource assignment (e.g., spreading factor and transmit power) to a large number of end devices (EDs). However, the slow adaptation of the spreading factor and transmitting power strategy makes the ADR vulnerable to destructive concurrent transmissions, resulting in massive packet collision. Therefore, this paper analyzes the impact of massive concurrent transmissions and proposes a novel "nondestructive adaptive data rate (ND-ADR)" approach to address the packet collision problem. The proposed ND-ADR aims to monitor the destructive concurrent transmissions proactively and mitigate them by allocating nondestructive transmission time to EDs. The proposed ND-ADR ensures high robustness and reliability by reducing the chances of destructive transmissions and retransmissions. Results show that the proposed ND-ADR outperforms the existing state-of-the-art ADRs in packet success ratio and energy consumption.adaptive data rate, Internet of Things (IoT), Long Range (LoRA), LoRaWAN, spreading factor
| INTRODUCTIONMassive sensor networks are the main engine to driving the Internet of Things (IoT) from environmental, home, military, health, and other commercial areas. 1 Battery-operated sensors are used across all industries 2 to gather a massive amount of critical data. There is always a big challenge in wireless communication related to power consumption and communication. There are short-range technologies like WiFi, Zigbee, and Bluetooth in the pool of wireless technologies. Cellular networks (e.g., 3G, 4G, and 5G) are available to meet the market requirements based on the bandwidth and long-range. However, these short-range (e.g., WiFi, Zigbee, and Bluetooth) and cellular technologies cannot fulfill the need for lower power consumption over a long distance. 3 Low power wide area network (LPWAN) is a new type of wireless technology designed to transmit small data over long-range using low power, low bandwidth, and low bit rate (e.g., 0.3 to 50 kbit/s) needed for robust IoT networks.There are numbers of competing technologies in the LPWAN, such as narrowband-IoT (NB-IoT), 4 Long Range (LoRa), 5 RPMA, 6 Sigfox, 7 and weightless. 8 Therefore, the following listed unique features of LPWAN technologies make it suitable for machine-to-machine and IoT needs.(i) Long-range: LPWAN covers the long area over 2 km in an indoor area, and up to 10 km in a line of sight (LoS). 9