Low-Power Low-VHF Ad-Hoc Networking in Complex Environments.

A low-power, low-frequency, ad hoc networking paradigm is considered for robust communications among mobile agents in complex non-line-of-sight (NLOS) indoor and urban-type scenarios. Compared with higher frequency, the lower portion of the very high frequency (VHF) band offers improved penetration and reduced multipath in such scenarios. Low VHF is underutilized for mobile ad hoc networking due to the lack of compact low-power systems and efficient miniature antennas. We investigate the proposed approach through experiments in realistic scenarios. In order to carry out the experiments, we leverage a compact, low-power ZigBee radio operating seamlessly in the low-VHF band by introducing a bi-directional frequency converter, which translates ZigBee signals into low-VHF carriers, along with a recently developed highly miniaturized efficient antenna. The experimental low-VHF radio system and a conventional ZigBee operating at 2.4 GHz are both integrated on a compact ground robotic platform for autonomous experimentation and comparison in NLOS indoor and outdoor settings. Measurements quantify the significant advantages of the low-VHF radio system in terms of packet error rate, fading, radio signal strength, and extended spatial coverage, in a number of complex communication environments.