Zone Sharing: A Hot-Spots Decomposition Scheme for Data-Centric Storage in Sensor Networks Mohamed Aly, Nicholas Morsillo, Panos K. Chrysanthis, and Kirk Pruhs ACM International Workshop on Data Management for Sensor Networks(DMSN), August 29, 2005, Trondheim, Norway.

Outline Introduction Related Work Zone Sharing –Distributed Migration Criterion (DMC) –Single-Hop Zone Sharing (SHZS) –Multiple-Hop Zone sharing (MHZS) Simulation Conclusion

Introduction Event –One or more sensor compose –A set of attributes In order to improve the lifetime of nodes –Propose data centric storage Event to sensor mapping –Based on the attributes values of an event

Introduction The problem is the storage hot-spot –Due to irregular data distribution –A high percentage of load assigns to small potion of the nodes Propose Zone Sharing (ZS) –Hot-spot –Energy saving –Network lifetime

Related Work – Multi-dimensional Range Queries in Sensor networks [0.5, 1) [0, 0.25) [0, 0.5) [0.5, 1) [0, 0.5) [0.25, 0.5)[0.5, 0.75) [0.75, 1) [0.5, 0.75) [0.25, 0.5) [0, 0.25) E 1 = Store E 1 light temperature

Related Work – Multi-dimensional Range Queries in Sensor networks Routing an event to its owner Compare event code with node own zone code Hand to GPSR E 1 = Store E 1

Related Work – Multi-dimensional Range Queries in Sensor networks Range queries Query initially routed –corresponding to the entire range Split a large query into smaller subqueries [0.5, 1) [0, 0.25) [0, 0.5) [0.5, 1) [0, 0.5) [0.25, 0.5)[0.5, 0.75) [0.75, 1) [0.5, 0.75 [0.25, 0.5) [0, 0.25) Q 10 = Q 1 = Q 12 = Q 11 =

Zone sharing – Basic Idea Z = 0Z = 11 Z = 10 S1 S2 S3 70% 5% 25% Z = 01Z = 1 Z = 00 S1 S2 S3 35% 30% (migrator) (donor) (receiver)

Zone sharing – Distributed Migration Criterion (DMC) l migrator : the original load of the migrator l donor : the total load of the donor T : the mount of load that the donor passes to the migrator Applied by the donor and the receiver donor 70% migrator receiver 5% 25% Applied by the migrator C1 should be greater than or equal to 2 to make sure that the donor is really falling in a hot-spot C2 should be greater than or equal to 2 to avoid cyclic migrations donor 35% migrator receiver 35% 30%

Zone sharing – Distributed Migration Criterion (DMC) Applied by the donor Applied by the migrator Applied by the receiver donor migrator receiver E1 、 E2 and E3 must be less than or equal to donor migrator receiver donor migrator receiver To make sure in the migration process will not cause the death

Goal: Overall minimal changes to the original DIM Single Hop Zone Sharing: –A zone can be traded at most once –Periodic exchange of neighbors information –DMC applied locally by nodes –No changes needed to GPSR Applicability: Small Hot Spots Zone sharing – Single-Hop Zone Sharing (SHZS)

Z = 0Z = 11 Z = 10 S1 S2 S3 70% 5% 25% Z = 01Z = 1 Z = 00 S1 S2 S3 35% 30% Request to Migrate message Inform migration decision Accept to Migrate message

Problems: –Large hot-spots: overloaded neighbors DMC hard to be satisfied –Zone traded only once nodes still in hot-spots after migration process –Messages pass by donor before going to migrator energy consumption overhead Solution: –Allow a zone to be traded more than once Zone sharing – Single-Hop Zone Sharing (SHZS)

Zone sharing – Multiple-Hop Zone Sharing (MHZS) Zone addressOriginal donorFinal migrator A Shared Zones List (each node) hot-spots migrator

Zone sharing – Multiple-Hop Zone Sharing (MHZS) Multiple sharing of the same zone migrator

Zone sharing – Multiple-Hop Zone Sharing (MHZS) Multiple sharing of the same zone Zone addressOriginal donorFinal migrator A Shared Zones List (each node)

Simulation Network of sizes ranging 50~300 Initial energy50 units Radio range40m Storage capacity15 units DMC parameter C 1 C 2 2 DMC parameter E 1 E 2 E 3 0.3

Simulation — Data persistence Networks with a 30% hot-spot

Simulation — Quality of Data Query size of a 50% query for networks with a 50% hot-spot

Simulation — Load balancing Networks with a 40% hot-spot

Simulation — Energy consumption Networks with a 50% hot-spot

Conclusion A novel scheme –Decomposing storage load of hot-spots –The hot-spots nodes toward their neighbor In the future –Incremental load balancing throughout the network time