H. Fathi, J. Figueiras, F. Fitzek, T. Madsen, R. Olsen, P. Popovski, HP Schwefel

1. Wireless Networking Trends –Architectures, Protocols & optimizations for future networking scenarios H. Fathi, J. Figueiras, F. Fitzek, T. Madsen, R. Olsen, P. Popovski, HP Schwefel • Session 1 Network Evolution & Mobility Support (HPS) • Session 2 Ad-hoc networking (TKM/FF) • Session 3 Enabling technologies for ad-hoc NWs (TKM/FF) • Session 4 Wireless Sensor Networks (PP) • Session 5 Performance aspects & optimizations (HF/TKM) • Session 6 Context-sensitive Networking (RLO/JF)

2. Content • Part I – Context management • Context awareness and definitions • Context Management • Context discovery • Context Maintenance • Part II - Context aware service discovery • Introduction to Personal Networks • Scenarios, components and building blocks • Service discovery in Personal Networks • Requirements • Approach specific for Personal Networks • The principle behind context aware service discovery • Ranking and service/context evaluation • Summary

3. Content • Part I – Context management • Context awareness and definitions • Context Management • Context discovery • Context Maintenance • Part II - Context aware service discovery • Introduction to Personal Networks • Scenarios, components and building blocks • Service discovery in Personal Networks • Requirements • Approach • The principle behind context aware service discovery • Ranking and service/context evaluation • Summary

4. What is context and context awareness? Context is: Any information that can be used to characterize the situation of an entity. An entity is a person, place or object that is considered to be relevant to the interaction between a user and an application, including the user and the application themselves. To be concrete, for PN’s we mean: • User profile: user profile, user activity, health status of user • Network context: link delay, available bandwidth, topology • Environmental context: location, physical attributes, time The objective of managing such information is to enable context awareness: A system is context-aware if it uses context to provide relevant information and/or services to the user, where relevancy depends on user’s task.

5. Why is context and context awareness important? • Light dependent application, e.g. controlling brightness on screen • User profile dependent searches, e.g. preferred restaurants • Location based discoveries, e.g. searches for nearby printers • Network selection based on link parameters as delay, bandwidth for certain services • All these could also occur in combination, e.g. a user prefers cheap printer services that are nearby but do not require much bandwidth for small documents • Context aware application and services take such information into consideration when making decisions of their behavior.

6. Content • Part I – Context management • Context awareness and definitions • Context Management • Context discovery • Context Maintenance • Part II - Context aware service discovery • Introduction to Personal Networks • Scenarios, components and building blocks • Service discovery in Personal Networks • Requirements • Approach • The principle behind context aware service discovery • Ranking and service/context evaluation • Summary

7. Context management • What is context management • The process of discover and maintain a repository of context data, i.e. • Discover where context can be obtained • Maintain value's of the context • What benefits are gained by Context Management • Nodes within a common network domain can share context resources • A uniform API for context information allowing different types of application not to care of: • Inconsistency • Data validity • Context discovery • In case of many user’s, a Context Manager will shift between reactive and proactive management approaches, hereby optimising the balance between generated network traffic and request delay. • What disadvantages are there: • It requires energy for communication, and hereby also uses some of the available bandwidth • It requires processing power and memory of the device

8. Network domain Requesting node Responding node User CM CM Discovery getContext Dt Dt : the time difference between a user’s context request and response General aspect of context management CM: Context Manager User: Any application, service or person that might have interest in context information Dt = tdiscovery + tgetcontext + tcontextprocessing The Dt value must be minimized to achieve best context awareness response

9. Content • Part I – Context management • Context awareness and definitions • Context Management • Context discovery • Context Maintenance • Part II - Context aware service discovery • Introduction to Personal Networks • Scenarios, components and building blocks • Service discovery in Personal Networks • Requirements • Approach • The principle behind context aware service discovery • Ranking and service/context evaluation • Summary

10. Context discovery: Centralized vs. Decentralized

11. Advertisement Req. Resp. Context Discovery: Proactive vs. Reactive

12. Device Device Device Device User CM CM CM CM CT Registry req CT Discovery Dt CT Response Resp Dt : the time difference between a user’s context request and response Centralized Context Discovery

13. Device Device Device Device User CM CM CM CM req CT advertisement Dt resp req CT request Dt CT response CT response resp Dt : the time difference between a user’s context request and response Decentralised Context Discovery

14. Content • Part I – Context management • Context awareness and definitions • Context Management • Context discovery • Context Maintenance • Part II - Context aware service discovery • Introduction to Personal Networks • Scenarios, components and building blocks • Service discovery in Personal Networks • Requirements • Approach • The principle behind context aware service discovery • Ranking and service/context evaluation • Summary

15. Network domain Node with context time Requesting node Update time Update Event ProactiveContext Maintenance • A node reports context to the master node in a cluster • Proactive approaches are done either: • Periodically • On event basis

16. time time Request Update Request Update User request Reactive Context Maintenance • Some node requests a node for context updates • Reactive approaches are done either • Periodically • On events Network domain Node with context Requesting node

17. Content • Part I – Context management • Context awareness and definitions • Context Management • Context discovery • Context Maintenance • Part II - Context aware service discovery • Introduction to Personal Networks • Scenarios, components and building blocks • Service discovery in Personal Networks • Requirements • Approach • The principle behind context aware service discovery • Ranking and service/context evaluation • Summary

18. Remote personal devices Home network Local foreign devices Interconnecting structure etc.) (Internet, UMT S, WLAN, Ad Hoc, Corporate network Smart building Vehicular area network Private PAN PAN Remote foreign devices Introduction to Personal Networks • PN starts from the Private PAN • Short and long term trust relation • Dynamically establishment of secure tunnels between different network domains

19. Content server- entertainment- insurance company- etc. Private Network Internet Doctor’s PAN Home Network Recoveringpatient at home Patient’s PAN PatientRecords Hospital Network HospitalServices Patient moves home Patient’s PAN Home hospital scenario

20. SunWarm Friend’s PAN Friend’s PAN Friend’s PAN Cellular Network Spouse’s PAN Mall Network Electronic billboard Home Network Remote personal sensor Store Network Internet Identification sensor Core PAN Opera server Smart shopping scenario

21. Personal Networks

22. Content • Part I – Context management • Context awareness and definitions • Context Management • Context discovery • Context Maintenance • Part II - Context aware service discovery • Introduction to Personal Networks • Scenarios, components and building blocks • Service discovery in Personal Networks • Requirements • Approach • The principle behind context aware service discovery • Ranking and service/context evaluation • Summary

23. Service Discovery in Personal Networks • Why do we need Service Discovery? • Auto configuration • Each node offers 0 -> k services • Each cluster contains n nodes • PN’s constitutes m numbers of clusters • Result is too many services for the user to manage, i.e. system to assist user finding relevant service is needed. • Why is context aware service discovery needed? • Services within a PN may be at different geographical locations!! • Services within a PN may be in different states (busy, available etc)!! • Other parameters may be intelligently considered, that is not easily determined by the user, which may seem obvious to the user.

24. Requirements to service discovery in PNs It must be • scalable to global level • able to work without infrastructure • able to work in a heterogeneous environment • be context aware • be secure, trustworthy and respect privacy • respect resource limitations

25. Existing Service Discovery systems

26. Service discovery performance parameters • Discovery time • Important for the user: The user have little patience • Network load/generated traffic • It is undesirable that service discovery protocols generates unnecessary high traffic loads, e.g. by blind flooding • Resource usage • It is unwanted that a service discovery protocol takes unnecessary much resources to perform its job, e.g. processor

27. General approach for service discovery in Personal Networks

28. Content • Part I – Context management • Context awareness and definitions • Context Management • Context discovery • Context Maintenance • Part II - Context aware service discovery • Introduction to Personal Networks • Scenarios, components and building blocks • Service discovery in Personal Networks • Requirements • Approach • The principle behind context aware service discovery • Ranking and service/context evaluation • Summary

29. Context Awareness revisited • Being context aware can be defined as: A system is context-aware if it uses context to provide relevant information and/or services to the user, where relevancy depends on user’s task. • Context management plays an important role in this issue, since Dt will have an impact on all kind of context aware applications. • The response time is critical, since context may change, hence making the context sensitive reaction unnecessary, annoying or even wrong. The consequences will differ from application to application.

30. Ranking of services according to context information, i.e. Score above some threshold triggers a response from Node B Infrastructure network A B Requesting node Responding node CPD CID CPD CID Master CPD CID Node CPD: Context Parameter Data CID: Context Information Data The principle behind context aware service discovery

31. Parameter definition and ranking • Parameter definition contains information regarding • Requirement to context value(s) • Requirement to how accurate this must be • What function should be applied in the ranking process • These information are used to describe the ranking functions • Ranking functionality constitutes some functions, e.g.: • Below • Above • - Between • - Avoid

32. Content • Part I – Context management • Context awareness and definitions • Context Management • Context discovery • Context Maintenance • Part II - Context aware service discovery • Introduction to Personal Networks • Scenarios, components and building blocks • Service discovery in Personal Networks • Requirements • Approach • The principle behind context aware service discovery • Ranking and service/context evaluation • Summary

33. Summary • For context awareness, context management will play an important role. This constitutes: • Context discovery: the process of finding the node providing context information • Context management: the process of maintaining context value(s) • Timing, generated network load/traffic, resource usage are very important performance parameters, especially considering context awareness in applications and services. • Several approaches; centralised vs. decentralised, proactive vs. reactive approaches has an impact on these parameters. • With the introduction of new network paradigm such as Personal Networks, service discovery will face a number of unsolved requirements. • Context aware service discovery will become important in Personal Networks and

34. References • MAGNET: http://www.ist-magnet.org • Universal Plug’n’Play: http://www.upnp.org/ • INS/Twine: http://nms.lcs.mit.edu/projects/twine/ • Salutation: http://www.salutation.org/ • Bluetooth SDP: Bluetooth, Tech. Rep. http://www.bluetooth.org/ • IETF SLP: Gutmann, E., Perkins C., Veizades, J. and M. Day, “Service Location Protocol, version 2”, RFC2608, July 1999 • Jini: http://www.jini.org/ • Rasmus L. Olsen, Majid Ghader, Hans-Peter Schwefel, ” Context Management in Personal Networks”, to be published in WPMC’05, September 2005, Aalborg • I. Niemegeers and S. H. de Groot, “From personal area networks to personal networks: A user oriented approach,” Kluiwer Journal, May 2002. • I. Niemegeers and S. H. de Groot, “Personal networks: Ad hoc distributed personal environments,” Med-HocNet, IFIP Conference on Ad-Hoc Networks, September 2002. • R.L.Olsen, H.Murakemi, H.P.Schwefel, and R.Prasad, “User centric service discovery in personal networks,” WPMC04, September 2004. • R. Liscano and A. Ghavam, “Context awareness and service discovery for spontaneous networking,” AdHocNow03, 2003. Available: http://www.site.uottawa.ca/ rliscano/ tutorials/ContextSpontaneousNetworking.pdf

35. References • M. Khedr and A. Karmouch, “Enhancing service discovery with context information,” IEEE Canadian Conference of Electrical and Computer Engineering, 2002. • “Active creation, delivery and management of efficient context aware services,” FIFTH FRAMEWORK PROGRAMME, Tech. Rep., 2003. Available: http://context.upc.es/index.htm

36. Thank you for your attention!Any questions??