Dirk Kutscher

We just published our IEEE Communications Magazine article on Rethinking LoRa for the IoT with an Open Access license.

LoraWAN and the Internet

Internet of Things (IoT) interconnects numerous sensors and actuators either locally or across the global Internet. From an application perspective, IoT systems are inherently data-oriented, their purpose is often to provide access to named sensor data and control interfaces. From a device and communication perspective, things in the IoT are resource-constrained devices that are commonly powered by a small battery and communicate wirelessly.

LoRaWAN systems today integrate the LoRa physical layer with the LoRaWAN MAC layer and corresponding infrastructure support. Among the IoT radio technologies, LoRa is a versatile and popular candidate since it provides a physical layer that allows for data transmission over multiple kilometers with minimal energy consumption. At the same time, the high LoRa receiver sensitivity enables packet reception in noisy environments, which makes it attractive for industrial deployments. On the downside, LoRa achieves only low data rates requiring long on-air times, and significantly higher latencies compared to radios that are typically used for Internet access.

LoraWAN MAC Layer

The LoRaWAN MAC layer and network architecture that is often used in LoRa deployments, thus provide a vertically integrated sensor data delivery service on top of the LoRa PHY that implements media access and end-to-end network connectivity. Unfortunately, LoRaWAN cannot utilize the LoRa PHY to its best potential with respect to throughput and robustness and is mostly used for upstream-only communication. It is not intended to directly interconnect with the Internet, but relies on a bespoke middlebox architecture consisting of gateways and network servers. Overall LoRaWAN has the following main problems, as depicted in the figure below.

1. Centralization around a network server prevents data sharing between users, across distributed applications, and requires permanent infrastructure backhaul of the wireless access network.
2. Uplink-oriented and uncoordinated communication leads to wireless interference. Downlink traffic is rarely available in practice and suffers from scalability issues.

Data-centric Delay-tolerant End-to-End Communication over the Internet

This paper presents an overview about recent advancements to enable data-centric, long-range IoT communication based on LoRa. The proposed network system aims for delay-tolerant, bi-directional communication in the presence of vastly longer latencies and lower bandwidth compared to regular Internet systems – without relying on vertically integrated middlebox-based architectures. The resulting system resolves current LoRaWAN performance issues using two main building blocks: a new network layer based on Information-centric Networking (ICN) and a new MAC layer.

Originally designed for non-constrained wired networks to abandon the end-to-end paradigm and access data only by names instead of IP endpoints, ICN migrated to the constrained wireless IoT over the past years. ICN still lacks a lower layer definition but provides mechanisms that are beneficial for the challenging LoRa domain: Decoupling of content from endpoints separates data access from physical infrastructure. Inherent content caching and replication potentially reduce link load, thus, wireless interference, and it preserves battery resources. The ICN-LoRa system presented in this paper bases its design on IEEE 802.15.4 DSME which was originally designed for low-power personal area networks. This MAC handles media access reliably using time- and frequency multiplexing, and enables reliable bi-directional communication.

Synergizing the advantages of LoRa, DSME, and ICN enables delay-tolerant, bi-directional LoRa communication, wich enhances many existing IoT applications. Wide area data retrieval and control as for solar power stations or smart street lighting systems are facilitated by the new MAC and its ICN integration. High voltage overhead line monitoring connecting voltage sensors and transformers relies on high data reliability, even under intermittent connectivity or loss. ICN achieves this, employing content caching and replication. Traveling container monitoring (RFC 7744) is challenging due to mobility and interference from metallic surfaces, where LoRa surpasses other radio systems. Decoupling content from its location for mobile containers and an adaptation to long producer delays are naturally contributed by LoRa-ICN.

Results

In our paper, we provide the essential technical background and challenges to design a LoRa-ICN system. We identify the key performance potentials of five protocol variants based on an implementation in RIOT OS and experiments on off-the-shelf IoT devices.

LoRa is an attractive radio technology for the IoT, providing a long wireless transmission range for battery-driven devices. Its versatility is hindered, though, by common deployments with LoRaWAN. We re-visited LoRa in the IoT to provide a serverless, data-oriented communication service. We presented the design of a new media access and network layer that leverages 802.15.4 DSME and Information-centric Networking to allow for reliable LoRa transmissions. To scale to a global Internet (of Things), LoRa-ICN facilitates ubiquitous connectivity of constrained nodes and robust bi-directional communication in the presence of power-saving regimes and high loss rates.

We showed that vastly higher latencies in low-power wireless domains can be addressed by extending the default ICN node behavior at the network edge. Two protocol extensions enable ICN-style data transport between resource-constrained LoRa nodes and a domain-agnostic application on the ICN Internet. The core idea is not limited to LoRa but caters to various delay-prone scenarios. Our experiments based on common IoT hardware and software showed significant performance improvements and further optimization potential compared to Vanilla ICN.

The new LoRa-ICN system paves the way for more versatile LoRa deployments in the IoT that serve additional use cases, mixed sensor-actor topologies, or firmware updates utilizing beacon overloading.

References

This article

• P. Kietzmann, J. Alamos, D. Kutscher, T. C. Schmidt and M. Wählisch, Rethinking LoRa for the IoT: An Information-centric Approach in IEEE Communications Magazine, doi: 10.1109/MCOM.001.2300379.

Reflexive forwarding

The ICN communication mechanisms this work is based on.

• Reflexive Forwarding in NDN
• Oran, D. R. and D. Kutscher; Reflexive Forwarding for CCNx and NDN Protocols; Work in Progress; Internet-Draft draft-oran-icnrg-reflexive-forwarding-05; 26 March 2023

In-depth publications this work is based on

• Peter Kietzmann, José Alamos, Dirk Kutscher, Thomas C. Schmidt, and Matthias Wählisch. 2022. Delay-tolerant ICN and its application to LoRa. In Proceedings of the 9th ACM Conference on Information-Centric Networking (ICN '22). Association for Computing Machinery, New York, NY, USA, 125–136. https://doi.org/10.1145/3517212.3558081
• P. Kietzmann, J. Alamos, D. Kutscher, T. C. Schmidt and M. Wählisch, Long-Range ICN for the IoT: Exploring a LoRa System Design, 2022 IFIP Networking Conference (IFIP Networking), Catania, Italy, 2022, pp. 1-9, doi: 10.23919/IFIPNetworking55013.2022.9829792. https://ieeexplore.ieee.org/document/9829792
• José Álamos, Peter Kietzmann, Thomas C. Schmidt, and Matthias Wählisch. 2022. DSME-LoRa: Seamless Long-range Communication between Arbitrary Nodes in the Constrained IoT. ACM Trans. Sen. Netw. 18, 4, Article 69 (November 2022), 43 pages. https://doi.org/10.1145/3552432