1. Rev PA102/03/20041 Communication Between Peer Wireless Sensor Networks over 2.5G/3G Mobile Networks Srdjan Krco R&D Ericsson Ireland srdjan.krco@ericsson.com

2. Rev PA102/03/20042 About Ericsson Ireland 3G research and development; Training center; Applied Research Lab –Network management; –Wireless sensor networks; –Ad-hoc networks; –Distributed systems;

3. Rev PA102/03/20043 Acknowledgments Skylark project team David Cleary Daryl Parker

4. Rev PA102/03/20044 Presentation outline Introduction; Wireless sensor networks gateway architecture; P2P sensor networks; Conclusion;

5. Rev PA102/03/20045 Introduction – Ericsson Interests Ericsson fields of interest: –Mobile infrastructure; –Mobile services – design and development of new services that will increase number of mobile network subscribers; Sensor networks in mobile networks context; Potential source of new traffic and hence revenue; Issues: –How to connect sensor networks to mobile networks; –How to enable easy access to sensor networks and information they provide; –Impact of numerous sensors connected to a mobile network;

6. Rev PA102/03/20046 Introduction – Wireless Sensor Networks Number of small nodes with sensing, computing and wireless communication capability; Data gathered in one node; Hop-by-hop communication; Redundant number of nodes; Data fusion; Querying and tasking;

7. Rev PA102/03/20047 Introduction – Wireless Sensor Networks Gateway node –injects queries and tasks; –gathers responses; User-gateway communication –using short-range wireless technology or –wide area networks (fixed and mobile); Sensor networks deployed, maintained, operated and used by one organization;

8. Rev PA102/03/20048 Introduction – Wireless Sensor Networks

9. Rev PA102/03/20049 Introduction – Resarch Focus Popular research topics: –Routing; –MAC layer issues; –Data aggregation; –Security; –Middleware; Less popular: –Interaction with external networks; –Interaction between wireless sensors networks;

10. Rev PA102/03/200410 Introduction – Standard Assumptions Users have applications designed for a particular sensor network; Available services known in advance (temperature monitoring, military vehicles tracking); Means for establishing communication links with gateways (protocol, gateway address, etc.) known in advance;

11. Rev PA102/03/200411 Focus of Our Research Design and development of software and protocol architecture of a wireless sensor network gateway –Generic, supports various sensor types and data format; –Independent of underlying transmission technologies; Creation of a peer-to-peer sensor network over a 2.5/3G mobile network, where each sensor network represents one peer node –Peers able to exchange data and provide more complex services; –Users also peers or have access to services provided by any peer via communication with one peer node only;

12. Rev PA102/03/200412 Our Testbed

13. Rev PA102/03/200413 Smart Sensor Micro controller –Controls Bluetooth link; –Implements communication protocol for interaction with gateway; –Controls attached sensors; Memory –Stores sensor data temporarily; Sensors –One or more attached; –Described by attributes;

14. Rev PA102/03/200414 WSN Gateway Implementation Linux OS laptop; Java; Bluetooth PCMCIA card; GPRS PCMCIA card or infrared connection to a GPRS enabled mobile phone;

15. Rev PA102/03/200415 WSN Gateway Entry point into a sensor network; Short-range wireless communication –With sensors; –With users in the vicinity; Wide area network access –Remote users; –Other gateways;

16. Rev PA102/03/200416 WSN Gateway Hides internal organization of the sensor network; Aware of all sensor types in the network and their characteristics –Sensor attributes (sensor type, location, data format, accuracy etc.) described and transferred as XML string; –Sensor querying based on sensor attributes (XML based); –Describes supported functions (max, min, average);

17. Rev PA102/03/200417 WSN Gateway Functionality Discovers smart sensors; Gathers description of available sensors; Controls communication with and functionality of sensors; Creates an object for each available sensor –Has methods for communication with the sensor; –Keeps an up to date description of the sensor; Provides API for access and control of the sensor network;

18. Rev PA102/03/200418 WSN Gateway – Architecture

19. Rev PA102/03/200419 Core Services Common procedures and services required by all layers –Logging; –Scheduling; –Event subscription; –Services required for automatic application start and restart;

20. Rev PA102/03/200420 Sensor Network Communication Interface Transmission technology specific; Provides methods for data transfer to/from sensors over the chosen communication interface; Provides additional, interface specific methods (Inquiry, Service Discovery);

21. Rev PA102/03/200421 Sensor Network Abstraction Layer Each sensor in the network represented as one object: –Methods for sending and receiving data to/from sensors; –Stores the complete description of sensor’s capabilities; Data transmission specifics hidden from users; Uses XML based communication protocol –Discover sensors’ characteristics; –Transfer data and commands; –Change sensor settings; Applications access objects using SN interface; Collected replies are formatted into a structured XML document and forwarded to users;

22. Rev PA102/03/200422 Sensor Network Abstraction Layer – GetData 2 5 min

23. Rev PA102/03/200423 Dublin Woodpark 3 Conference room 12394 Sensor Profile

24. Rev PA102/03/200424 temperature Celsius 4

25. Rev PA102/03/200425 Sensor Network API Generic methods, provide consistent interface regardless of sensor type and characteristics; List of sensors in the network; Description of available sensors (sensor attributes); XML querying based on description of required data; Listeners: –Sensor has been added/removed from the network; –New data available;

26. Rev PA102/03/200426 Sensor Network API – Query Users define data they are interested in (for example: temperature on the first floor in the HQ building) instead of defining the network address of a particular sensor; Query definition similar to the sensor attribute profile; Constraints given in the query compared against characteristics (attributes) of available sensors and returns a list of sensor IDs that correspond to the query;

27. Rev PA102/03/200427 Sensor Network API – Query HQ House 1 4

28. Rev PA102/03/200428 P2P Sensor Networks Sensor networks –Deployed on ad-hoc basis by various entities; –Appear and disappear based on the operator needs, requirements and schedule; Short-range (Bluetooth) and wide-range (UMTS) wireless interface for communication with users; Users interact with networks in an ad-hoc manner based on theirs needs at a given moment and location;

29. Rev PA102/03/200429 P2P Sensor Networks

30. Rev PA102/03/200430 P2P Sensor Networks Users are external to the network –do not know about the existence of the network or services they provide; –Sensor network’s characteristics, type or format of data unknown; Sensor network detection, service discovery and service provision mechanisms required;

31. Rev PA102/03/200431 P2P Sensor Networks Numerous services –Traffic congestion info; –Water pollution of a river; –Weather info; –Personal health care network; –Free spaces in a car park; Not feasible to have a central service listing server;

32. Rev PA102/03/200432 P2P Sensor Networks Individual sensor networks –Cooperate; –Form groups; –Provide more comprehensive service; –Available to more users; Users –Communicate with one sensor network gateway; –Able to get information about/from all other sensor networks in the group;

33. Rev PA102/03/200433 P2P Sensor Networks Possible scenarios: –Users access sensor network over a short-range wireless interface (Bluetooth): Bluetooth Inquiry; Access to information from via the gateway; –Users access sensor network over a mobile network: Join peer group; Access to information using P2P protocols;

34. Rev PA102/03/200434 P2P Sensor Networks and Users

35. Rev PA102/03/200435 P2P Sensor Networks Issues –Detection of other sensor networks; –Information exchange between sensor networks; –Description of sensor network services; –Forwarding users request and sensor network responses to/from proper sensor network;

36. Rev PA102/03/200436 JXTA Network programming and computing platform for creating interoperable P2P applications and services; Designed for ad-hoc, pervasive, multi-hop P2P networks; Allows any connected heterogeneous device on the network (mobile phone, PDA, PC et.) to communicate and collaborate with one another;

37. Rev PA102/03/200437 JXTA - Architecture

38. Rev PA102/03/200438 JXTA – Core Layer Peers: any networked device that implements JXTA; Peer Groups: collection of peers that have a common set of interests; Pipes: the basic communication means – a virtual unidirectional connection between peers; Advertisements: Describe all entities (resources), such as peers, peer groups, pipes, or services; –XML structured documents; Network Transport: provides a mechanism to handle the transmission of data over the network;

39. Rev PA102/03/200439 JXTA – Protocols

40. Rev PA102/03/200440 JXTA – Protocols Peer Resolver Protocol – mechanism by which a peer can send a generic query to other peers; Peer Discovery Protocol (PDP) – used to discover any published resources represented as advertisements. The PDP is based on the use of rendezvous peers; Peer Membership Protocol – mechanism by which peers can organize themselves to form groups. Peer groups are discovered using the PDP; Pipe Binding Protocol – used to establish pipe connections between peers;

41. Rev PA102/03/200441 JXTA - Protocols Rendezvous Protocol – propagates messages within the specified group on behalf of peers from within the same group –primary purpose is to provide a service whereby peers can connect to a rendezvous peer to avail of a service that will propagate messages on their behalf; Rendezvous Peers – Special type of peers with the ability to cache advertisements and forward requests to help peers discover resources; –Interact with different rendezvous peers;

42. Rev PA102/03/200442 JXTA Services Discovery Service –Provides access to the PDP; –Limited to the context of the peer group; –Searches for JXTA resources; Pipe Service –Manages and creates virtual channels of communication between peers in a peer group –Limited to the context of the peer group; Resolver Service –Implements the resolver service to distribute queries among peers;

43. Rev PA102/03/200443 Platform Specific Services Position Service –Provides peer-positioning services by querying the MPS (Mobile Positioning Service) for a given MSISDN embedded within a PeerID; Scheduler service –Allows tasks to be remotely scheduled on peers within our network (scheduled code updates, scheduled migration of services between peers); Sensor Service –JXTA wrapper service around the WSN Gateway functionality; –Communication between peer sensor networks over GPRS network; –Provides remote querying of sensor networks and individual sensors as well as providing sensor event subscription mechanisms;

44. Rev PA102/03/200444 Example Gateway gathers sensor profiles, compiles a list of available services/sensors characteristics (type, location, accuracy, …) and structure it as its advertisement; Rendevouz peer has information about all available sensor services in the peer group; User interacts with a gateway over a short-range interface or becomes a mobile peer; Gets information about all services in the peer group from the local gateway or a rendevouz peer; Query network based on description of available services;

45. Rev PA102/03/200445 Conclusion Gateway architecture: –Supports various types of sensors; –Easily adaptable to different communication technologies; –XML structured sensor profiles and communication protocol; –WSN API supports attribute based querying; JXTA platform can be used as a P2P middleware layer, but: –Poor performance; –Slow, consumes large amount of memory, quite unreliable; Prototype scaling-down required;