Enabling the IP and IoT worlds to converge through an innovative interconnection protocol: a solution for compressing and fragmenting messages exchanged on LPWAN networks.
In the “Internet of Things”, there is of course the Internet. However, dedicated networks for device communications do not use the IP protocols that are used by the networks making up the Internet today. IP protocols are too resource-hungry for IoT networks. And this technological gap is one of the factors holding back or adding to the complexity of the development and deployment of IoT services on an industrial scale.
Bringing the IoT into the Internet arena
The unique features of the communication protocols used on dedicated LPWAN networks for small devices, with cost, energy and bandwidth constraints, mean that developers need to be familiar with specific interfaces and models. Similarly, network managers require specialised skills for designing, operating and maintaining specific management tools for IoT networks.
Laurent Toutain, associate professor at IMT Atlantique, a pioneer of LoRa technology and the co-founder of Acklio, explains: “We have seen all the potential offered by LoRa, which was in a non-IP world. IP opens up possibilities for interoperability, making it simpler to create services. However, IP protocols are incompatible with bandwidth-constrained LPWAN networks because they are too resource-hungry in terms of energy and data. The solution proposed by Acklio, a spin-off from the IMT Atlantique engineering school, involves making these two worlds converge through an interconnection protocol with a solution for compressing and fragmenting messages exchanged on LPWAN networks”.
This solution is called SCHC, which stands for Static Context Header Compression. While Acklio is leading the way forward for its development and the resulting product deployments, the design and implementation of this technology are likely to be of interest to many different stakeholders from the IoT and telecommunications ecosystem. And the project is part of a standardisation drive, with the IETF’s LPWAN working group set up in 2016, notably bringing together academics and experts from SigFox, LoRaWAN®, the IEEE and Orange. This will enable the benefits of the SCHC technology to be shared as widely as possible. “The IETF stands out from other standardisation bodies by drawing on the expertise and contributions of individual specialists in their fields, rather than entities”, explains Marianne Laurent, Head of Marketing at Acklio. “We are focused on pure engineering and expertise, and not lobbying considerations, we want to standardise solutions in order to bring them to the IoT market”. And in this way maximise the interest and potential of IoT networks – which were relatively isolated up until now due to this incompatibility with the IP world – in line with Metcalfe’s Law, which states that the value of a network is proportional to the square of the number of its users. And SCHC is making it possible to attract large numbers of users and communities to LPWAN networks.
Generic architecture to extract entropy
But how is this innovation being made possible? How can the SCHC technology compress and fragment the IPv6/UDP/CoAP Internet protocols so they can be transported by constrained networks? Dominique Barthel, IoT networks research engineer with Orange, explains: “The more constrained and basic the device, the greater the predictability and similarities between the messages that it exchanges, which reduces their entropy. Headers contain information that is already known, which we do not need to transmit. Our technology is based on an algorithm that extracts the data bits, i.e. the “surprise elements”, and a protocol that transmits only this information, while enabling recipients to reconstitute the original message. In other words, this is a generic machine to extract entropy, which we have designed to be as flexible as possible, and which can be adapted to many types of messages, networks and use cases”.
With SCHC, a typical 80 byte IPv6/UDP/CoAP packet can be compressed to 3 to 5 bytes for transmission.
RFC coming up
As an operator of LPWAN networks, such as LoRaWAN®, Orange is very interested in this technology and right from the outset has been part of the work carried out by IMT-Atlantique, Acklio and the IETF’s LPWAN working group in particular. This work will make it possible to both harmonise and accelerate the development of applications, while promoting the reuse of existing network management tools and skills, and delivering optimum end-to-end security. Basically, it will thus enable the IoT to benefit from the best properties of the IP world, which have been proven and mastered for decades.
Orange and the startup have worked together on many different aspects, from defining the generic compression-fragmentation mechanism with the IETF to carrying out demonstrations of this. Today, the standardisation of the generic mechanism has moved into its final phase, with a Request For Comments (RFC) expected before the end of the year. A major milestone, which will mark the starting point for the technology’s adoption by other key communities within the IoT ecosystem, such as the LoRa Alliance TM, and the industrialisation of solutions deploying SCHC on networks for many different use cases.
With SCHC, the “Internet” side of the Internet of Things is really coming to the fore.