But the Internet of Things shares only a need of wide
connectivity with "the cloud". In most other important ways, it’s
completely different: crowds of billions of end devices that connect
intermittently at very low speeds to other machines, not to humans. In my
developing picture of the IoT, this makes traditional protocol stacks
irrelevant – or at the very least, overkill.
While the traditional protocols may make sense for
connecting Propagator nodes and Integrator functions (see the previous blog
post), the vast numerical majority of
connections will be to relatively low-data-need devices such as HVAC units, air
quality sensors, and street lights. This is the segment of the communications
architecture that must be re-thought from the ground up, in my opinion.
Rather than treat intermittent connections, data loss, and
low data rates as problems (as they would be in IP), we must embrace these as
facts of life in the Internet of Things. It’s a lossy world on the IoT
frontier, and that's OK – if we
engineer the architecture with that in mind. Most of these end devices won't
need constant check-ins with a central site to function. They'll simply keep
running, functioning with or without network updates. If an update comes, fine,
but there's no immediate response required.
Turning to nature, birdsong and pollen give us another
picture of how the IoT devices will treat communications. Many birds sing
without expecting (or waiting for) an answer. They sing "blindly" to
mark territory, advertise mating availability, or signal danger – and trust in
the universe to deliver the message to hearers who may act upon the message. Similarly, trees and other flowering
plants broadcast pollen extremely broadly (hence, allergy season) without any
feedback on whether the "message" is received. Propagated by winds,
pollen may be carried hundreds or thousands of miles away from the originating
source.
All of this leads to my heretical view of the very edge of
the Internet of Things: it just isn't reliable
when viewed from the perspective of a single
message. The devices may be switched off at various times, propagation paths
may be lost, etc. Yet by sending the same small data chirps over and over,
eventually there is a good chance that some or a few will get through. This
will mean over-transmitting on a massive scale. But because each data chirp is
so small, there is virtually no net cost involved in this over-provisioning.
I believe that this is one of the key things about the
Internet of Things that is completely different from the "Big I"
Internet: the very small amount of data in each transmission and the lack of
criticality of any single
transmission. As the traditional Internet becomes clogged with ever larger
real-time data streams such as those generated by video and multiplayer gaming,
the IoT's growth will be at the fringes of the network with billions of
low-duty-cycle, low-data-rate devices.
I believe we'll need a new
architecture at the edges of the Internet of Things. In place of the
traditional IP protocol stack with hierarchical layers of routing topologies,
there will instead be a gigantic crowd
of devices speaking and listening – each unconcerned with what's happening
anywhere else in the network. Instead of rigid routing paths there will be
transient clumps and aggregations of unrelated devices sharing propagation
facilities. It's a truly best-effort world, and as I have said before – that will be good enough.
Conceptually, I am breaking this new
architecture into the elements of Naming,
Communication, and Propagation. Next blog, we'll start
with the most challenging aspect of this architecture: naming those billions of
IoT end points in the crowd.
