Cluster discovery in phase-shift beamformed ad-hoc and sensor networks

Interference in ad-hoc networks had been seen as the “black sheep” of radio communications - this is generally true because interference causes collisions on the channel, resulting in damaged data frames, retransmissions and inefficiency. There are two main directions to cope with interference: to ignore it (and let packets to be repeated) or to avoid it (to establish precise moments when transmissions can take place and interference will not occur). There is however one more direction: to use it. Interference is in essence the combination of electromagnetic waves and, if harnessed in a proper manner, it will generate signals with amplitude higher than the amplitude of any constituent signal; higher amplitude translates into higher power in given directions and higher power means greater coverage distances. In conclusion, the good side of interference is that it can be used to extend communication ranges of transmitters in cases when installing a relay is not possible. The area of interfering radio waves has been studied thoroughly when the antennas are powered by the same radio chip (smart antennas, MIMO, antenna arrays, etc.), however the science of achieving good results in a distributed manner (one antenna per device) and over multiple layers in the communication stack (e. g. routing tables based on radio wave interference) is still in its infancy. The work of the authors is exactly to explore this realm of phase-shift interfering waves and this paper brings into attention the possibility of cluster discovery that will proceed communication between two clusters through phase-shift distributed beamforming.