Today’s mobile networks support a wide range of machine to machine (M2M) applications but are ill-suited to many emerging IoT applications that require low bandwidth communication with static devices that are expected to operate for a decade or more on a AA battery.
The cellular industry is evolving LTE to better meet the requirements of IoT with LTE-M and is building the requirements of IoT into 5G from the outset. It’s also taking a hand in the evolution of quite separate technology: low powered wire area radio networks, with the GSMA announcing plans to set up a ‘Mobile IoT Initiative’ aimed at standardising, in licenced spectrum, low power wide area wireless technologies designed specifically for connecting the Internet of Things.
Now the cellular industry, or at least Ericsson, is going after the IoT market with another networking paradigm: capillary networks – the integration of short range wireless technologies like ZigBee and bluetooth with cellular in service of IoT.
Ericsson pushing capillary networks
Ericsson had a demo of the idea at Mobile World Congress back in 2014, and was very bullish about the prospects for capillary networks. “The feedback that we got was very positive and encouraging. It was seen as the key to the future, that we look at the system as whole; in order to meet the expectations of the future that we predict will include billions of devices connecting to networks.”
Ericsson gave a much more comprehensive expose of capillary networks in an article in the September 2014 edition of the Ericsson Review. It asserts that “By leveraging the key capabilities of cellular networks – ubiquity, integrated security, network management and advanced backhaul connectivity – capillary networks will become a key enabler of the Networked Society.”
This was followed by a much more comprehensive demonstration at MWC 2015 with over 50 sensors attached to a model railway installation.
The architecture of a capillary network raises some interesting questions about the practicalities, especially commercial, of its implementation. Ericsson breaks it down into three domains: the local and capillary domains and a data domain that spans the end to end network. It makes the point that all three could have one owner, or three separate owners.
The architecture also lends itself to edge or fog computing: the gateways that interface the local capillary network are ideally placed to perform local processing either to filter out redundant data or make decisions and control the connected ‘things’ when low latencies are important.
From what I can see Ericsson seems to be the only company really pushing the concept in an IoT context, although perhaps others use a different name. And the concept of capillary networks in an IoT context seems to have originated in an academic paper published in 2012, Capillary Networks: A Novel Networking Paradigm for Urban Environments, presented at the 8th International Conference on emerging Networking EXperiments and Technologies (CoNEXT), in Nice. The authors “identify the emerging needs of smart cities, focus on the capillary networks paradigm which unifies the wealth of wireless connectivity available in urban environment, and present the research issues it yields.”
Add in mesh networks
However, their focus seems to be on mesh networks integrated with cellular rather than short range wireless. “Beyond cellular networks, multi hop wireless mobile networks are now mature technologies and provide a wealth of connectivity surrounding mobile devices. These manifold networking interfaces define a new class of networks, denoted capillary networks, which could provide a flexible link between the access network and the devices.”
Either way, there seems little doubt that the concept is gathering momentum. The IEEE Wireless Communications magazine has issued a call for papers for an edition looking at enabling wireless communication and networking technologies for internet of things. Among the topics listed is “IoT access network technologies and capillary networks.” Manuscripts are due on 15 October.