Time-Slotted ALOHA-based LoRaWAN Scheduling with Aggregated Acknowledgement Approach

Long range (LoRa) wide-area network (LoRaWAN) protocol is a promising candidate for Internet of Things devices that operate on Low Power Wide Area Networks (LPWAN). Recent studies on this protocol are mostly focused on uplink (UL) communication. In particular, the performance of the pure ALOHA type MAC protocol used in this protocol is not fully observed. Investigations have revealed that the pure ALOHA type MAC protocol and downlink (DL) traffic may cause significant negative impacts in terms of the scalability and the reliability of the network. For this respect, in this paper, we propose an extension to LoRaWAN MAC layer, called Aggregated Acknowledgment Slotted Scheduling LoRaWAN (A2S2-LoRaWAN), to improve the scalability and reliability of LoRaWAN. A2S2-LoRaWAN contains time-slotted ALOHA-based periodic frame structure, which is supported by aggregated acknowledgment methods, for scheduling transmissions. A2S2-LoRaWAN reduces UL-DL traffic and increases the scalability of LoRaWAN. For instance, while A2S2-LoRaWAN decreases UL-DL traffic five times compared to LoRaWAN, its success rate with 10,000 End-Devices (EDs) transmitting 10-byte payload is twice better than the success rate of LoRaWAN with a single gateway (GW).