Spectrum Sharing Exploiting Spectrum Database for LPWA

Abstract

In the most of current low power wide area (LPWA), packet collisions of uplink communication are controlled by setting duty cycle (DC), which controls the transmission cycle not to exceed the predefined fixed threshold. However, as the number of LPWA nodes increases, the fixed DC fatally increases the number of packet collisions and degrades the communication quality. Therefore, in this paper, we propose an adaptive DC decision algorithm. The proposed algorithm aims at adapting the period that the system interferes with others and reducing the packet loss rate of uplink communication of the whole system to below the required value by adapting DC with the help of measurement-based spectrum database (MSD). In the proposed method, MSD knows the number of LoRa nodes that interfere with the nodes of other systems. The DC is calculated for keeping the period of interference to less than a certain duration. In addition, the DC is also adapted based on the required packet loss rate to improve communication efficiency. Computer simulation results show that the allowable interference time ratio and the required packet loss rate can be accurately guaranteed compared to the conventional method with the fixed DC even if the number of nodes increases.