A Slotted Transmission with Collision Avoidance for LoRa Networks

Despite that the LoRa technology has its salient features such as long transmission range and low power consumption, it suffers from data collision and signal suppression. The signal suppression problem not only degrades reliability in data transmission, but also tends to incur the unfairness such that a receiver demodulates only the strongest one of multiple received signals. To tackle this problem, the proposed approach tries to avoid the situation that multiple nodes send data simultaneously. It allows every node to transmit data only at the boundary of transmission slots and uses both random delay slots and the listen-before-talk (LBT) mechanism for collision avoidance. It is proven by experiments that the proposed approach, named ST/CA, achieves high reliability and fairness against the variation of traffic loads compared with LoRaWAN.