KUASAR An efficient and light-weight protocol for routing and data dissemination in ad hoc wireless sensor networks David Andrews Aditya Mandapaka Joe Evans Venu Mangipudi ITTC, The University of Kansas An efficient and light-weight protocol for routing and data dissemination in ad hoc wireless sensor networks David Andrews Aditya Mandapaka Joe Evans Venu Mangipudi ITTC, The University of Kansas

KUASAR KU A d hoc S ensor web A ctive R outing KUASAR KU A d hoc S ensor web A ctive R outing

Design goals Leverage the many-to-one nature of communication in sensor webs Minimize control information Minimize complexity of routing decisions Maximize number of paths to base station from each node Maximize reliability of message delivery Eliminate route loops

The Algorithm Dissemination phase –routes between nodes calculated –requests for sensor information dissipated Collection phase –Sensor information transmitted back reliably over the shortest possible route –Multiple paths to fall back on, in case of node failure

Dissemination If a command broadcast message is received: –Increment distance to reflect distance from base –If the packet is from a node that does not have this node as next-hop insert the new node in neighbor table; calculate new next hop –If the command has not been flooded flood the new route request packet after a wait period ( to avoid collisions)

Dissemination – Data Structures Neighbor table, next-hop Neighbor table is a list of the form: –Ntab{} = {[N 1,d 1 ], [N 2,d 2 ],……. [N n,d n ]} where N 1 indicates a neighbor and d 1 is the distance from the sink. –If min(Ntab{d}) = d k, then next-hop = N k

Collection When sensor data is ready –Transmit data packet to next-hop node –Wait for ACK When packet to be relayed arrives –Transmit to next-hop node if It is not the same node as where the packet just came from It does not exceed its time-to-live –Else Discard the packet Upon ACK timeout –mark current node in the neighbor table as dead –Calculate new next-hop node

The good Each node generates only one broadcast message per routing phase Routing algorithm converges in very quick time Constant number of routing packets No routing messages need to be exchanged when the topology changes

The good (contd) Routing loops are pre-empted to a large extent and can be detected if any occur Reliable delivery of data packets Simulations have shown that average packet loss in a healthy sensor web is negligible

The bad No mechanisms for energy conservation…. ….yet Simulations being run on IEEE b Mac layer, which is very hard to implement for small platforms like the Mica boards.

And The ugly Dealing with concurrent message reception, collisions and the effect of such scenarios on the stored state of the network without Mac layer support

An example sensor web scenario Examples of how KUASAR builds shortest multi-hop paths and successfully routes around failed nodes avoiding loops

Simulation of the KUASAR protocol ns2 Simulator Simulations run for a 35 node network over 5000 seconds. KUASAR successfully creates shortest path routes Nodes are successfully able to switch to new next-hop nodes when faced with failed nodes

Future work KUASAR port on TinyOS 1.0 Further research of power conservation techniques Further testing of route loop avoidance and detection mechanisms