Uplink throughput optimization for multiple gateway systems in LoRaWAN Class A

Abstract

LoRaWAN (long range wide area network) is widely considered as a promising wireless communication technology that can meet the requirements for thousands or millions of IoT (internet of things) end devices to be able to connected to the Internet. In this paper, a scheme is proposed for end devices to select a spreading factor for uplink transmissions in LoRaWANs. In our proposed scheme, connectivity between end devices and gateways is first constructed, which depends on the received signal strength. As an end device may be able to be connected to multiple gateways at the same time, the reliability of uplink transmissions improves. Nonetheless, the traffic load seen at each gateway increases, thereby leading to more packet collisions during uplink transmissions. In order to deal with this tradeoff situation, a systematic probability-based approach is employed in the selection of a spreading factor for each end device, and a water-filling algorithm is utilized to balance traffic loads between spreading factors, from which the proabability distribution for the spreading factor selection of each end deivce can then be determined. Numerical results show that our proposed scheme significantly outperforms ADR (adaptive data rate), which is a scheme recommended by the standard.