Succinctly, use the purloined letter technique -- hide it in plain sight. There are RF bands set aside for unlicensed low-power operation; some new phones use spread-spectrum techniques in these bands. Build and sell wireless ethernet nodes that talk using these techniques. Customers will demand strong encryption to prevent their data leaking out and outsiders sneaking in, so you have a good reason for adding this to the product. Develop a robust set of protocols that automatically manage the net, which is logically dynamic (movement of nodes and episodes of interference are logically equivalent to dynamic modification of the topology of the net. You can consider each node to be on N ethernets, where N is the number of nodes it is currently able to talk to, each ethernet having only two members.) Now the kicker; the nodes can be programmed to only talk to other nodes known to them (ie: the office work-group, building, etc), or to freely accept and route messages from "alien" nodes. Given a population of "liberal" message passing nodes, one can then add a new layer of routing protocols that do regional networking, with dynamic re-routing as needed. Purchasers of the wireless nodes should be encouraged to enable the "pass-through" option, and the protocols should guarantee that assisting in the passing on of messages does not affect local net performance. If you do it this way, you'll succeed much faster because people will be paying you to do it. You'll have more money for R&D, and you'll have a lot more people bitching if someone tries to take your toys away. The protocol design is, as they say, left as an exercise to the reader. It isn't all that difficult.