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

Example Usage ScenariosSensor Network

• Static network topology• All devices ‘equal’• Fairly evenly spaced• Small amounts of data at

regular intervals

Example Usage ScenariosGroup working

• Build node familiarity• Networking with

irrelevant devices is wasteful

Example Usage ScenariosClustered 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 802.11b”, http://www.dansdata.com/wireless.htm, January 2003

• [Ultra-wideband] Kelland, B.; “Ultra-wideband wireless technology”, University of Southampton: Department of Electronics and Computer Science, December 2002

Questions and Answers