We consider a network of nodes distributed in physical space without physical links communicating through message broadcasting over specified distances. Typically, communication using smaller distances is desirable due to savings in energy or other resources. We introduce a network formation mechanism to enable reducing the distances while retaining connectivity. Nodes, which initially transmit signals at a prespecified maximum distance, sub ject links to preferential detachment by autonomously decreasing their transmission radii while satisfying conditions of zero communication loss and fixed maximum node-hopping distance for signaling. Applied to networks with various spatial topologies, we find cost reductions as high as 90% over networks that are restricted to have all nodes with equal transmission distance.
Cambridge, MA - In an article in the current issue of Europhysics Letters, scientists at The New England Complex Institute examine broadcast networks with nodes distributed in physical space, but without physical links between them. One use of such networks might be multi-hop communication networks. Today cell phones wirelessly send signals to cell towers that are themselves connected by wires. However, in the future cell phones might form a network with calls hopping between phones to reach their destination.
"To save energy, the smaller the distance of transmission between the nodes of a network the better," said Dr. May Lim, NECSI researcher. "In a network like a cell phone system, energy is an especially key commodity because the nodes are not normally connected to a power supply. As a result, each phone should transmit no further than it absolutely has to. Our study introduces a network formation mechanism that reduces the distance between nodes while maintaining maximum communication."
The mechanism for minimizing energy cost works by subjecting links to "preferential detachment," decreasing their transmission distance as much as possible without sacrificing connectivity.
"The ideas of removing links when they are not needed is also how many other networks work," said Dr. Yaneer Bar-Yam, NECSI President. "An important process of learning in the brain is pruning unnecessary neural connections."
Applying their approach resulted in energy cost reductions as high as 90%. "If we all had cell phones that worked by sending messages to one another, an incredible amount of energy could be saved," said NECSI researcher Dr. Dan Braha. "This distributed strategy is very, very different from the use of centralized base stations, which is how cell phones work today."
Preferential Detachment in Broadcast Signaling Networks: Connectivity and Cost Trade-off appears the September issue of Europhysics Letters.
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