Wireless sensor networks in autonomic environments

1. Wireless sensor networks in autonomic environments Shuping Liu Networking Lab HUT

2. Agenda • What is sensor? • What is WSN? • Communication topology • Why we need it? • WSN special characters • Some filed interesting • A programmable routing for autonomic WSN • Data dissemination in autonomic WSN

3. What is sensor?

4. What is WSN? Habitat monitoring on the Great Duck Island (USA Maine. 2002/2003. UCB & Intel & Atlantic Univ.)

5. Communication topology

6. Why we need it? • Seamless and Ubiquitous communication with the real world. • Wide usages Military application Environmental application Health application Home application Traffic Surveillance Other commercial applications ……

7. WSN special characters • Person unattended, inaccessible  autonomic • Limited resource: power, memory, MPU… • Topology changes / breaks frequently (war field, etc.) • High density employed, broadcast communication paradigm (normal ad-hoc networks uses point-to-point communications)  Must be self-organized, self-maintaining and operate at low duty cycle.

8. Some fields interesting • Efficient routing • Data dissemination • Low power • Security • Programming the Ensemble (configuration)  WSN is a new field, especially in autonomic environment. I will introduce some work in the first two topics in autonomic WSN

9. A programmable routing for autonomic WSN (1/19) • The goal of a WSN is to collect, process, and forward sensed data to other sensor nodes and/or base stations. • Therefore, the proper routing algorithm is essential to WSN applications, which must be lightweight, due to limited available resources.

10. A programmable routing for autonomic WSN (2/19) • Several existing routing for WSN GPSR: Greedy Perimeter Stateless Routing GEAR: Geographical Energy Aware Routing TBF: Trajectory Based Routing DD: Directed-Diffusion TTDD: Two-Tier Data-Dissemination CBM: Content-Based Multicast RR: Rumor-Routing ……

11. A programmable routing for autonomic WSN (3/19) • These routings have distinct properties, Try to meet the resource-limited requirements Different from traditional routing such as OSPF,RIP,BGP (see table 1 for difference in details) • Each of them is designed to meet specific goals and therefore is not efficient for all applications. e.g. DD is more energy-efficient than TTDD when the number of sink nodes is large, while TTDD is better when the number of sink nodes is small • There is a need to have a routing for WSN that can adapt to different applications and different network conditions  autonomic WSN

12. A programmable routing for autonomic WSN (4/19) Table 1. Comparison of routing services in WSN and Traditional Networks

13. A programmable routing for autonomic WSN (5/19) • Currently, it is very difficult, if not impossible, to change a routing service in a large WSN because the service is statically pre-configured into each node, which is often unattended. • Yu He et. al. in USC propose a programmable routing for autonomic WSN. • Their work includes a universal routing service and an autonomic deployment service.

14. A programmable routing for autonomic WSN (6/19) • The universal routing service allows the introduction of different services through its tunable parameters and programmable components. • The deployment service completes the configuration of the universal routing service throughout a WSN in an autonomic and energy-efficient way. • Through this deployment service, a self-configuration ability is realized for sensor routing service. • With the changeable parameters and programmable components of the universal routing service, the self-optimizing as well as other autonomic abilities can be explored.

15. A programmable routing for autonomic WSN (7/19) Sensor node architecture with programmable routing

16. A programmable routing for autonomic WSN (8/19) Table 2. shows the data-forwarding and state-collecting functions of the existing routing is covered by the programmable structure

17. A programmable routing for autonomic WSN (9/19) • The suggested architecture is proposed to cover all existing routing services and to introduce new services for WSN. • The state information is a list of neighbor entries, each of which consists of four parts, Neighbor description (id, location, direction, distance, energy reading, etc.) Neighbor interest (type, rate, duration, etc.) Neighbor data availability (type, duration, etc.) Neighbor’s latest data copy (data, timestamp, etc.)  the above state involves only local information and thus is scalable

18. A programmable routing for autonomic WSN (10/19) • Different packets are used to collect each part of the state information, (state collecting) Neighbor description – hello / announcement / query packets Neighbor interest – query packets Neighbor data availability – announcement / data packets Neighbor latest data copy – data packets

19. A programmable routing for autonomic WSN (11/19) • The deployment service receives deployment packets that contain parameters or modules of the programmable routing services and deploy services according to packet content. • There are three levels of deployment, (1) the deployment service only changes parameters to the state-collecting and/or data-forwarding modules. (least bandwidth requirement relatively frequently) (2) either of the two modules is replaced. (middle case) (3) the entire routing service is changed. (most overhead only occasionally)

20. A programmable routing for autonomic WSN (12/19) • Note that this deployment service allows different routing services to reside in different parts of WSN. For example, GPSR service and RR (Rumor-Routing) service can be deployed in heterogeneous parts of a WSN.

21. A programmable routing for autonomic WSN (13/19) • Now let us consider a case with complex routing service, then we will deploy a large code. • Transferring the large routing code can be very expensive in WSN where energy is a very scarce resource. • A. Boulis et. al. proposed a separate running environment for deployment service. But it is computation inefficiency. • A deployment approach for routing services should be both energy-efficient and computation-efficient.

22. A programmable routing for autonomic WSN (14/19) • The approach proposed by Yu He. et. al. is to move a part of routing service code into WSN, which contains common routing services operations and is designed as a shared library, before deploying routing service modules. • With shared library, the written routing modules have small code size while keeping the computation efficiency.

23. A programmable routing for autonomic WSN (15/19) A sample node architecture with shared library

24. A programmable routing for autonomic WSN (16/19) • The deployment discussed above assumes that all nodes in a network can be reached at one time. • But this is generally not the case for WSN because, Sensor node is prone to fail due to running out of energy Communication failure due to lossy channel or obstacles Sensor node sleep periodically or dynamically for some time due to energy-saving mechanisms  inconsistency among nodes for deployed services

25. A programmable routing for autonomic WSN (17/19) • Yu He et. al. proposed a synchronization protocol that enables a sensor node to make itself consistent with its neighbors in an energy-efficient way. • Each node runs this protocol after waking up from sleeping or after a period. • Each node maintains a version number for each deployed component (a parameter or a module).

26. A programmable routing for autonomic WSN (18/19) • A broadcasts an initial request among its neighbors  each neighbors Ni with greater version number starts a timer after timeout, the neighbor sends an initial reply to A A also starts a timer after sending initial request A sends formal request to the node with higher version number  reply with formal reply  complete synchronization

27. A programmable routing for autonomic WSN (19/19) Deployment synchronization from neighbors

28. Data dissemination in autonomic WSN (1/5) • In WSNs, data communication, from the point of view of the communication entities, can be divided into three cases, From sensor to a monitoring node Among neighboring sensors From a monitoring node to sensors

29. Data dissemination in autonomic WSN (2/5) Data communication schemes in WSNs

30. Data dissemination in autonomic WSN (3/5) • Reliable data dissemination is crucial to WSN since a monitoring node has to perform some specific activities, such as Change the operational mode of part or entire WSN Broadcast a new interest to the network Activate / deactivate one or more sensors Send queries to the network ……

31. Data dissemination in autonomic WSN (4/5) • Max do Val Machado et. al. proposed a new data dissemination algorithm, TEDD (Trajectory and Energy-based Data Dissemination). • The key idea is to combine concepts presented in TBF (Trajectory-Based Forwarding) with the information provided by the energy map of the network to determine routes in a dynamic fashion, according to the energy level of the sensor nodes.

32. Data dissemination in autonomic WSN (5/5) • Simulation result revealed that the energy spent with the data dissemination activity can be concentrated on nodes with high-energy reserves, whereas low-energy node can use their energy only to perform sensing activity or to receive information addressed to them.

33. Thanks!Any comments and questions?