Massively Distributed Database Systems In-Network Query Processing (Ad-Hoc Sensor Network) Fall 2015 Ki-Joune Li Pusan National University

Basic Concepts – in-network query processing 2 each node has - a local & tiny DB and - sensors a query "find the nodes where temperature is higher than 35 o C" How to process it?

Why in-network query processing ? scalable No need to store the entire DB Interact with neighbor nodes A node failure is not critical Issue Query processing time  determined by # of hops Energy consumption Battery is normally limited Energy consumption for communication is relatively high SQL-like query 3

Energy Consumption 4 in S. Banerjee, A. Misra,

Multi-hop instead of infrastructure network No global network topology like TCP/IP Network topology with its neighbors  local stateless routing algorithm 5

Unit-Disk Graph UDG: Graph G(N,E) where N is the set of nodes (sensors) and E is set of edges whose length is less than 1 (unit) Types if UDG RNG Gabriel Graph Delaunay Graph Each node in V maintains the node IDs connected via edges in E 6

Gabriel Graph Graph GG(V,E) V is a set of nodes n (id, p) where p is a point in Euclidean space E is a set of edge (a, b) that there is no other node within the closed disk of (a, b) 7

RNG – Relatively Neighborhood Graph Graph RNG(V,E) V is a set of nodes n (id, p) where p is a point in Euclidean space E is a set of edge (a, b) that two points a and b by an edge whenever there is no third point c that is closer to both a and b than they are to each other (there is no other point within the intersection of the circles centered at a and b with radius the distance d(a, b)) 8

Delaunay Triangulation Graph Graph DTG(V,E) V is a set of nodes n (id, p) where p is a point in Euclidean space E is a set of edge e (a, b) where e is a side of triangle constructed by Delaunay Triangulation. Delaunay Triangulation: for a set P of points in a plane is a triangulation DT(P) such that no point in P is inside the circumcircle of any triangle in DT(P) 9

Routing - GPSR in Brad Karp and H.T. Kung in MobiCom 2000, pp GPSR (Greedy Perimeter Stateless Routing) A node x broadcasts a query message with destination point D the closest node y receives and forwards the message. 10

Example 11 full UDG with 200 nodesGG with 200 nodes (subset of full UDG) RNG with 200 nodes (subset of GG) GG with 200 nodes over 2Km X 2Km where radio range is 250 m

Routing - GPSR Problem both of node x are farther from the destination D Right-Hand Rule: Perimeter Combination of UNG and Perimeter routing 12 circle(xD)