I wonder if the new light-based communication networks recently proposed could make applications like these more reliable - there were suspicions that radio frequency interference was a factor in this failure.<p>Light, while having directional and occlusion risks, would appear to be more readily directed and filtered. Stray sources of light modulated at the frequency selected for communication would also likely be less of an issue.<p>However, some method would have to be devised to allow hundreds of nodes to share the network - though with the bandwidth of light based communication, simple TDMA or even broadcast could work.