I was keyed into the concept of the “proximal network” by the AllJoyn network, conceived by Qualcomm and managed by the AllSeen Alliance. I started poking around to learn more about proximal networks and to see which other ones might exist.

What I found was that there are two different senses of proximal network, although they share a conceptual basis.

Once concept is what you might call a mesh network for cellular. That concept notes that, if you make a cell call or send a text to a person 20 feet away from you (hey, it could happen…), then that call might travel a mile to a tower and then a mile ±20 ft back. This works up until the point where the tower gets overloaded.

What if a phone-to-phone network could be set up where the call simply went the 20 feet? Calls or data could hop from phone to phone to their destination, bypassing the towers.

There are some obvious issues to be worked for this to happen, not the least of which is the fact that the cell providers lose some control and visibility – unless, perhaps, the phones themselves radio back to HQ to report every call that passed through. My sense when reading up on this was that this might be the biggest barrier to deployment.

Traffic would also have to be managed somehow to figure out which phones would carry a given call. Would it be limited to phones that aren’t in use? Or would streams be multiplexed so that, even if you’re on a call, another call could silently pass through? And would there be enough processing power?

There’s also the security issue: a phone owner should have access only to his or her own call/data stream. Any other streams passing through the phone would have to be inaccessible to the phone owner. And… I guess there would need to be a hand-off mechanism in case someone shuts down their phone or goes out of range while someone else’s stream is moving through it.

Such a network, however, has nothing to do with AllJoyn. AllJoyn is a home network – think Internet of Things (IoT) – where Things can discover and communicate with other Things in their proximity. In particular, it’s transport-agnostic, and can bind together Things using different transport protocols as long as there is one Thing in the network that supports both protocols, and can therefore act as the bridge. At present, it’s been implemented over WiFi, WiFi-Direct, Ethernet, and Powerline. Others, like Bluetooth LE, are open for implementation.

The focus with AllJoyn is on interoperability – being able to take diverse Things with diverse transports and get them all talking to each other in a manner that’s accessible to your average person.

Note that AllJoyn typically can’t penetrate a firewall simply because of the network address translation (NAT) issue. Inside the home, you’re using private IP addresses; at the gateway, it all gets translated to your single public IP address. The private addresses for Things aren’t public, and they get lost when they cross the firewall.

I started to speculate on ways that such a protocol could bridge across firewalls, although it would only apply to Things that ran over IP. But I decided that this was speculation of a not-particularly-useful kind. As AllJoyn is defined, it doesn’t do this, and communication can’t pass through the firewall. Which, critically, means that someone shouldn’t be able to penetrate your firewall and fish around for your Things.

The common thread between these two different concepts is that networks should be defined by what’s in the neighborhood, not by what protocol is running. In the cellular mesh idea, you might use some other transport mechanism to get to a neighboring phone in the same manner that Things running over IP and Bluetooth could interact over AllJoyn.

You can find out more about AllJoyn here; you can’t find out more about any real-world cell-style proximal network, since, as far as I could tell, there isn’t one: it’s only an idea at present.