Self-Adaptive, Decentralised Data Publication over Wireless Networks Richard Cooksey Supervisor: Prof. A. Taleb-Bendiab

Introduction Many wireless communication technologies to enable short-range communications between devices such as WiFi, Bluetooth, and UWB Interest in extending these by nodes co- operatively message passing. Many possible applications of this concept/algorithm with varying requirements and placing different demands on a 'would be' solution.

Wireless data capabilities

Current Ideas for ad-hoc wireless Reactive protocols have no real idea where they are until they have a need to pass a message to another node Proactive protocols regularly announce their presence to each other, and tell other nodes about their surroundings, so that a node has a ‘picture’ of where it is in the network that is refreshed at intervals. Hybrid approaches Hardware assisted protocols – such as requiring GPS

Problems Lack of Scalability Dynamic Network Topology Large protocol bandwidth overhead

Limitations of Wireless Power Constraints Bandwidth Scalability Adaptability to situations/scenarios Non differential of node types

Example Usage Scenarios Sensor Network Static network topology All devices ‘equal’ Fairly evenly spaced Small amounts of data at regular intervals

Example Usage Scenarios Group working Build node familiarity Networking with irrelevant devices is wasteful

Example Usage Scenarios Clustered Groups of Devices Mobile team-working situation Different device types with different constraints (power, range, etc) Use of ‘gateways’

Adaptability to different usage scenarios Automatically attempt to maximise efficiency despite conflicting goals ‘Generic’ algorithm/protocol with sufficient adaptability to be relatively efficient regardless of appliance

Desirable Attributes Node/Service awareness Integration with other longer-range wireless technologies such as 3G and use of fixed infrastructure where available Information boundaries - restricting message propagation within a structure, or within a certain distance from source Location awareness

Service-based Services ‘published’ by their service description propagating outwards from source to desired audience Easy to send to host, and path constructed en route for reply

Measured Approach Possible use of ‘coincidental’ data to aid routing through concept of location, distance, and movement rate? Signal strength an aid in tracking node movement for routing path repair? Use of different radio frequencies to determine physical boundaries?

Adaptability Taking advantage of periods of stability to reduce communication overhead (such as polling interval) Change parameters such as power output (transmission distance) based on surroundings (node density, level of interference) Modes of operation? Work differently when user is ‘sleeping’, ‘working’, ‘stationary’, ‘in motion’ etc. Form ‘relationships’, group together, and elect leaders

Summary Great deal of interest in this area No ‘perfect’ solution, ideas require simulating and testing. Many possible uses Gaps in current ideas have been identified and solutions proposed

References [Epidemic-style Protocls] Gupta, I.;Kermarrec, AM.;Ganesh, A.; “Efficient Epidemic-style Protocols for Reliable and Scalable Multicast”, Dept. of Computer Science, Cornell University, Ithaca, NY USA, April 2002 [Associativity-Based Routing for Ad-Hoc Mobile Networks] Toh, CK.; “Associativity-Based Routing For Ad-Hoc Mobile Networks”, University of Cambridge Computer Laboratory, Cambridge, 1996 [Broadcasting for Mobile Ad Hoc Networks] Willaims, B.; “Network Wide Broadcasting Protocols for Mobile Ad Hoc Networks”, Colorado School of Mines, 2002 [Broadcast Storm] Tseng, YC.; Ni, SY.; Chen, YS.; Sheu, JP.; “The Broadcast Storm Problem in a Mobile Ad Hoc Network”, Department of Computer Science and Information Engineering, National Chiao-Tung University, Feb 2001 [Wireless Networking Roundup] “Wireless Networking Roundup: Ricochet, Bluetooth and IEEE b”, January 2003http:// [Ultra-wideband] Kelland, B.; “Ultra-wideband wireless technology”, University of Southampton: Department of Electronics and Computer Science, December 2002

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