Increasing LPWAN Scalability by Means of Concurrent Multiband IoT Technologies: An Industry 4.0 Use Case

Abstract

One of the most important challenges of the Internet of Things (IoT) in the next years will be the smooth incorporation of millions of smart devices into its communications paradigm. The greater coverage area of sub-1-GHz low-power wide area networks (LPWANs) makes them a suitable technology to easily encompass hundreds of end devices under a single base station. However, LPWAN inherent simplicity affects negatively on scalability, as these networks are not flexible enough to deal with a high number of nodes unless their traffic load is really low, which limits many potential use-cases. This paper analyzes the scalability issue in LPWAN and proposes the INTER-HARE protocol: a solution based on the use of concurrent multiband IoT technologies, where an 868-MHz LPWAN acts as transparent backhaul for a set of subnetworks working at 2.4 GHz. The implementation of the INTER-HARE protocol on a real IoT platform was assessed both in several laboratory testbeds and in a pilot developed in the premises of an industrial company, proving its suitability in non-delay sensitive monitoring applications with end devices scattered throughout the targeted area.

LoRaWAN Mesh Networks: A Review and Classification of Multihop Communication

“…Scalability and multihop optimization: The scalability of single-hop LoRaWAN has been extensively studied, and it is one of the main challenges of the technology. When the traffic load or the node density increases, the network performance can be severely affected [ 12 , 13 , 15 ]. Some works propose to improve scalability at the MAC layer level of LPWAN, using techniques such as scheduled MAC protocols, station grouping algorithms, adaptive transmission mode, and adaptive power control [ 14 , 58 ], or even using concurrent multiband technologies [ 15 ].…”

“…Several works have shown that dense networks with many devices may degrade the overall network performance with longer delays and low reliability [12][13][14]. LoRaWAN uses ALOHA as the Medium Access Control (MAC) protocol, which does not perform well when traffic load or node density increases, due to interference and packet collisions [15,16]. Multihop strategies may also contribute to improve scalability, capacity, and reliability, as pointed in [12,15].…”

“…LoRaWAN uses ALOHA as the Medium Access Control (MAC) protocol, which does not perform well when traffic load or node density increases, due to interference and packet collisions [15,16]. Multihop strategies may also contribute to improve scalability, capacity, and reliability, as pointed in [12,15].…”

“…The ALOHA protocol controls the medium access since it is suitable for energy-constrained applications. However, the ALOHA protocol is well known to provide low network throughput in dense networks because of a high number of packet collisions [15,16]. The ALOHA limitation in LoRaWAN was already discussed in terms of scalability and reliability in several works [12,48] LoRaWAN end-devices implement a mechanism called Adaptive Data Rate (ADR) to improve the use of network resources.…”

“…When the traffic load or the node density increases, the network performance can be severely affected [12,13,15]. Some works propose to improve scalability at the MAC layer level of LPWAN, using techniques such as scheduled MAC protocols, station grouping algorithms, adaptive transmission mode, and adaptive power control [14,58], or even using concurrent multiband technologies [15]. [17,24], beacon flooding [27], TSCH scheme [29], or using synchronization by flooding with concurrent transmission [18].…”