I'm exploring using Xbee's and DigiMesh for an outdoor solution. There would be one always on node and the rest would be solar powered with batteries. 14 to 22 nodes would be spread over a lightly wooded area about 300 by 600 feet. The furthest distance from one node to another is about 200 feet with most about 150 feet apart. Generally each node would be within those ranges of two or more other nodes. I'm thinking the 900mhz nodes are best for the ranges and being outdoor with scrubs and trees over most of the area.
The system would be idle most of the week and only used for a couple of hours each day of the weekend. When it is active the nodes would need to stay on 100% of the time until command to return to the sleep cycle would happen. The main powered node would have a button to wake up the network or tell it to go back to the sleep cycle. It is fine if the network might take 10 minutes before all nodes are back on line.
How easy or not would this be to make work? The remote nodes would only be using their I/O pins and not have anything on the local serial port. The main powered node would have a Raspberry Pi talking to its serial port for passing messages and managing the sleep cycles.