Predicting the Lifetime of Lora Based Wireless Sensor Networks Using a Probabilistic Model of Markov Chains

Abstract

Real-time monitoring systems and sensors are not complete without wireless data transmission modules. Improving energy efficiency requires examining various system parameters that affect the power consumption of transmitting and receiving devices. The most important parameter of any autonomous wireless network is its uptime. In this work, we used LoRa wireless modules on the SX1278 chip manufactured by Semtech to determine their power consumption in various operating modes. The obtained data were used to build a consumption model of the device when connected to a receiver. Three operating modes are considered: transmit mode, receive mode and sleep mode. In an ideal communication channel, all transmitted data reaches the receiver with 100% probability. In a real situation, data reaches the receiver with a certain probability, depending on the communication channel, transmission power, distance to the addressee, and network parameters. In this work, the occurrence of an error is random. In this case, the occurrence of an error during reception entails a lack of confirmation of receipt or a request for re-sending data. Sending data again increases the power consumption of the device and, consequently, decreases the operating time of the wireless device. This paper shows the dependences of the operating time on various initial monitored parameters of the device, such as: confirmation timeout, packet length, time of one transmission cycle and the maximum number of retransmissions in one cycle. The developed model for predicting the consumption of the device can be used in the design of autonomous wireless sensor monitoring networks.

Understanding the impact of packet size on the energy efficiency of LoRaWAN

“…Several papers have modeled the energy performance of LoRaWAN by means of mathematical analysis [6]- [10], [12]- [20], whereas a few others have studied it by using simulation [11], [18]. Impact of packet size on energy performance has only been considered in some of the analytical studies [10], [12]- [14], [17], [19]. The latter works are briefly reviewed next.…”

“…However, collisions and duty cycle restrictions were neglected. In [17], a similar analytical approach was followed, also overlooking collisions and duty cycle restrictions, and furthermore, only the LoRa layer of the LoRaWAN protocol stack (without specifying the coding and data rate) was considered. The work reports a monotonically decreasing lifetime as a function of packet size.…”