Abstract:
Internet of Things (IoT) deployments are on the rise globally with Low Power Wide Area
Networks (LPWAN) providing the wireless networks needed for this expansion. One of these technologies
namely Long Range Wide Area Network (LoRaWAN) has proven to be a very popular choice. The
LoRaWAN protocol allows for confirmed traffic from the end device to the gateway (uplink) and the
reverse (downlink), increasing the number of IoT use cases that it can support. However, this comes at a
cost as downlink traffic severely impacts scalability due to in part a gateway's duty cycle restrictions. This
paper highlights some of the use cases that require confirmed traffic, examines the recent works focused
on LoRaWAN confirmed traffic and discusses the mechanism with which is implemented. It was found
that confirmed traffic is viable in small networks, especially when data transfer is infrequent. Additionally,
the following aspects negatively impact the viability of confirmed traffic in large networks: the duty cycle
restrictions placed on gateways, the use of spreading factor 12 for receive window 2 transmissions, a high
maximum number of transmissions (NbTrans) and the ACK_TIMEOUT transmission backoff interval. The
paper also raises and suggests solutions to open research challenges that must be overcome to increase the
viability of confirmed traffic.
