THE PROTOCOL
Network Discovery and Maintainence
The network is supposed to be deployed inside a home which is one of the most challenging environments with respect to security, privacy and intrusiveness. We have developed a robust, self healing system secured with a private 128 bit key (AES).
Network Topology
We are implementing a basic layered tree topology. It consists of three layers, Edge nodes, Router nodes and the Gateway.
The Edge nodes are responsible for sensing and actuation and used as anchors to localize the user.
The Router nodes are used for forwarding of packets from gateway to edge nodes and vice versa.
The Gateway node is the main node which controls the whole system by pinging the nodes .
Multi Hop Communication
In the interests of power saving as well limited memory on each node, we have developed a multihop communication scheme. The Gateway node is responsible to poll each edge node for it's sensor readings, act on it and instruct an appropriate node to actuate.
The Routers act a level of abstraction provided for a space roughly equal to a room. These Routers also act as a single point of contact for the Context Aware subsystem.
The Edge nodes are merely used to sense and actuate.
Robustness
The Smart Home System (Santosh) is designed to be robust to all the typical faults occuring in a wireless network. Packet drop is reduced by appending a long preamble(2048 bytes)Â to each packet. Furthermore, each packet sent in the network is repeated once if a packet drop is noticed.
In the event of an edge node failing, the concerned router is asked to rediscover it's neighbours and report to the Gateway.
If a Router fails, the user is informed with an alert and temporarily, the Gateway shifts the load to another active Router.
