Performance Evaluation of LoRa Networks for Confirmed Messages

In the LoRaWAN protocol, the confirmed message is used for the reliable transmission service. Once a server received a confirmed message from an end device, it responds with an acknowledgement message to make sure that the uplink message was successfully delivered. For doing this, the protocol reserves two receive windows that follows uplink message transmission in the specified intervals. However, when GW responds with an acknowledgement message in one of the receive windows, it fails to receive messages from other end devices since it operates in half-duplex mode. This can cause high data loss as the number of confirmed messages increases. In this paper, we study how the increase of confirmed messages and message traffic affects packet delivery ratio. The simulation results shown that up to 24% number of uplink messages is lost or collided when 1000 end devices transmit data with 0.1% duty cycle and the confirmed message ratio is 0.2.