Asynchronous ad-hoc network discovery for low-power systems

Unattended ground sensor systems (UGS) have become an important part of a covert monitoring arsenal in operations throughout the world. With the increased use of unattended ground sensor systems, there is a need to develop communication architectures that allow the systems to have simple emplacement procedures, have a long mission life, and be difficult to detect. Cur-rent ad-hoc networking schemes use either a network beacon, extensive preambles, or guaranteed time synchronization to achieve reliable communications. When used in wireless sensor systems many of these schemes waste power through unnecessary transmissions. These schemes compromise the covert nature of UGS through excess transmissions for a non-beaconed network or the periodic beaconing in a beaconed network. These factors are detrimental to sensor systems, which chiefly rely on being covert and low-power. This paper discusses a nonarbitrated, non-GPS synchronized, beaconless approach to discovering, joining, and reliably transmitting and receiving in a low-power ad-hoc wireless sensor network. This solution is capable of performing network discovery upon demand to get an initial aligninent with other nodes in the network. Once aligned, end points maintain alignment and can predict when other nodes will be available to listen.