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The superior robustness of the Shoal platform comes from the merging of two main design concepts:
Mesh networks utilise peer nodes to propagate the signal in a series of small hops. Each node is a transmitter, receiver and intelligent routing device. The routing section understands its links with neighbouring nodes and the optimum route to propagate the signal from source to destination. If this optimum route blocks the signal for whatever reason, the system will re-route the signal via a different set of nodes without any human intervention. This ensures that the signal reaches its final destination. The ability to bypass interference and obstructions at a system level is known as self-healing. At the level of the individual nodes, there is a need to harden the radio links to make them tolerant of their electromagnetic and physical environment. Spread spectrum transmission is one such method. By converting a traditional narrow band transmission into a wide band alternative we can make the signal less susceptible to air borne interference. Spreading the narrow band signal over a greater frequency range also reduces the effects of multi-path reflections form the building fabric and installed services. Combine mesh architecture with spread spectrum techniques and you have an extremely robust RF platform. Shoal improves on this by employing a very efficient network algorithm that minimises the management software overhead and ensures efficient signal propagation. |
