June 25, 2007 Modern warfare is increasingly urban - when you're fighting small groups of anonymous guerrilla insurgents there's no pitched battlefields and American forces are finding that their radio communications are suffering in these Non-Line-Of-Sight environments. The solution? Squadrons of smart communications robots, or LANdroids, each the size of a deck of cards, that can be scattered through an urban environment to create a self-organizing mesh radio network. Each unit constantly repositions itself for maximal signal strength, and if a LANdroid is destroyed, the rest of the units will reposition themselves to restore communications.

While radio communications work well in Line-Of-Sight environments, the U.S. Army is finding itself fighting more commonly in built-up areas where walls and other obstacles reflect, diffract, refract and absorb radio signals. Tight communications being a key factor in troop safety and strategy, the Defense Advanced Research Projects Agency (DARPA) has called for tenders to develop and test the LANdroid program.

The goal is to create small, inexpensive, smart robotic relay nodes that autonomously establish and manage mesh networks when deployed in a scattered formation through an urban environment, securing a temporary communications network for the soldiers. As signal strength is paramount, the LANdroids will have the ability to move to constantly adjust their positioning and find the best signal as the other droids in the network do the same; movements as small as half a wavelength can make huge differences to signal quality and the LANdroid units will be expected to independently optimize their positions in this regard.

The units will be expendable, as they will be deployed in dangerous areas and troops will not be expected to endanger themselves to retrieve them. Still, they will be expected to have a 7-14 day battery lifespan, no small feat considering the units will be roughly the size of a deck of cards and the battery will be expected to manage not only constant signal transmission but the movement of the robotic platform. Thus, the units will need to make intelligent choices about how power is spent - perhaps expending energy moving the droid to a clearer signal spot which allows it to turn down its transmission power, spending energy to save it in the longer term.

Should a LANdroid unit be destroyed or disabled, the rest of the network will be able to reposition to cover up the resulting black spot - thus, the temporary radio network should be "self healing" in combat situations. And as the network is intended to be multi-path and multi-hop, the loss of individual nodes should not stop data finding its way to its endpoint via alternative node paths. As they will be numerous and expendable, DARPA hopes to keep the LANdroids under a US$100 per unit cost ceiling.

Such a clever, self-organizing communications network would clearly have applications in peacetime as well - the system could be used to establish communications throughout disaster-stricken urban areas to co-ordinate rescue and emergency operations.

View gallery - 8 images