Algorithms for Communication in Wireless multi-hop ad hoc Networks using Broadcasts in Opportunistic Large Arrays (OLA)

A new physical layer technique in Hong, Y-W abd Scaglione, A., (2003) for broadcasting in multi-hop wireless ad hoc networks makes broadcast a much more efficient building block than traditional flooding broadcast. This broadcasting technique requires that all nodes that receive a message retransmit it at the same time. Because the messages are identical, interference can be constructive rather than destructive, and the multiple transmitters act as an antenna array - an Opportunistic Large Array, or OLA -to transmit the message farther and ultimately with fewer hops than it could have been transmitted by conventional means. This paper presents several networking algorithms for utilizing such physical layer broadcast to solve problems that are common within distributed systems, including wireless ad hoc sensor networks, mesh networks, and mobile ad hoc networks. In such an environment, broadcasting may be more efficient than conventional algorithms and protocols that employ unicast or multicast communications, including routed communications. This paper uses broadcasting in wireless ad-hoc networks to addresses issues and requirements common to different applications of wireless ad hoc networks. Some of these requirements, such as broadcasting, multicasting, polling, geocasting, and synchronization, are straightforward given an efficient broadcasting mechanism. This paper considers some of the specific benefits available for these cases when employing broadcasting using OLAs. Other common requirements can also be satisfied by implementations using this building block. As well as considering the challenge of assigning unique identifiers, these include associative access to the data in the network as well as selecting a unique leader among all the nodes.