CS 268: Lecture 24 Sensor Network Architecture (SNA)

1. CS 268: Lecture 24 Sensor Network Architecture (SNA) Ion Stoica Computer Science Division Department of Electrical Engineering and Computer Sciences University of California, Berkeley Berkeley, CA 94720-1776

2. Sensor Network Protocols Today Obligatory David Culler Slide… Appln EnviroTrack Hood TinyDB Regions FTSP Diffusion SPIN Transport TTDD Trickle Deluge Drip MMRP Arrive Routing TORA Ascent MintRoute CGSR AODV GPSR DSR ARA GSR GRAD DBF DSDV TBRPF Scheduling Resynch SPAN GAF FPS ReORg Topology PC Yao SMAC WooMac PAMAS BMAC TMAC WiseMAC Link Pico 802.15.4 Bluetooth Phy eyes RadioMetrix CC1000 nordic RFM What if I want to use any two protocols together??

3. Internet Network Model Patch Network Sensor Node • Dense patches of sensing nodes • Many resource constrained • Non-homogeneous • Modalities, roles, HW, SW • Power, BW • Transit tier • Often specialized wireless • Provides gateways • Internet Tier • Multiple connections to infra • Deep storage, proc. Viz • SNA should not require unconstrained nodes • Should utilize unconstrained nodes to reduce burden on constrained ones • Mobility within physically embedded context Sensor Patch Gateway Transit Network Client Data Browsing and Processing Basestation Base-Remote Link Data Service

4. What is an Architecture? • Architecture is how to “organize” implementations • What interfaces are supported • Where functionality is implemented • Architecture is the modular design of the network • Architecture is not the implementation itself

5. Internet goals Interconnect separate networks Resilience to loss and failure Support many comm. services Accommodate variety Distributed management Cost effective Low effort attachment Resource accountability Network Architecture Sensor Nets Resource efficiency Data centric design Deal with intermittent connectivity Self-managed Observation, monitoring of various environments Cost effective Scalability Internet vs Sensor Nets

6. Internet goals Interconnect separate networks Resilience to loss and failure Support many comm. services Accommodate variety Distributed management Cost effective Low effort attachment Resource accountability Network Architecture Sensor Nets Dense real world monitoring Resilience to loss, failure and noise Support many applications Scale to large, small, long Cost effective Evolvable in resources Composable Security Internet vs Sensor Nets

7. Why not IP? • One or very few applications running on a sensornet vs huge number running in the Internet • Large variety of traffic patterns (most not point-to-point): • Any-to-any, many-to-one, many-to-few, one-to-many • Inneficient to impl. these patterns over point-to-point • IP does not address (well): • Resource and energy constraints • Unattended operation • Intermittent connectivity • Space embeded nodes • ...

8. A Sensor Network Architecture (SNA) • Narrow waist: Sensornets Protocol (SP) • Goals: generality and efficiency • Position: between data-link and network layers • Service: best-effort, single hop • Common to both single- vs multiple-hop deployments

9. Properties of SP • SP provides mechanisms for network protocols to operate • Network protocols may introduce policy • Three key elements of SP: • Data Reception • Data Transmission • Neighbor Management

10. Collaborative Interface • Control • Reliability Best effort to transmit the msg • Urgency Priority mechanism • Feedback • Congestion Was the channel busy? • Should I slow down? • Phase Was there a better time to send? • Decouple appl sampling from communication

11. Message Reception Receive • Message arrives from link • SP dispatches • Network protocols establish • naming/addressing • filtering SP

12. Msg Pool Message Transmission Send Receive • Messages placed in shared message pool • All entries are a promise to send a packet in the future • Messages include • Pointer to first packet and # of packets • Control information: reliability and urgency • Feedback information: congestion and phase SP

13. Neighbor Table Msg Pool Neighbor Management Neighbors Send Receive • SP provides a shared neighbor table • Cooperatively managed • SP mediates interaction using table • No policy on admission/eviction by SP • Scheduling information SP

14. Network Service Manager Network Protocol 1 Network Protocol 2 Network Protocol 3 Neighbors Send Receive SP SP Adaptor A Msg Pool SP Adaptor B Link Estimator Link Estimator Neighbor Table Data Link A Data Link B PHY A PHY B SP Architecture

15. Msg Pool Neighbor Table Neighbor Table Message Pool sp_message_t Neighbor Required Link Network 1 destinationmessage quantity urgent reliability phase congestion address_t 1st TOSMsg to send# of pkts to send on or off on or off D adjustment true or false 2 control addresstime on time off listen quality address_t local time node wakes local time node sleeps true or false estimated link quality feedback SP

16. Submit an SP Message for Transmission Message added to message pool SP requests the link transmit the 1st packet Link tells SP the transmission completed SP asks protocol for next packet Protocol updates packet entry in message pool Msg Pool SP Message Futures Network Protocol SP Message packets 1st packet (1) Next PacketHandler (5) (6) Send (2) Message Dispatch msg* SP transmit completed inspect (3) (4) Link Protocol

17. What SP Isn’t • SP does not dictate any header fields • Messages are opaque to SP • Instead, rely on abstract data types • Can query for address, length, etc • No explicit security mechanism • Message content opaque to SP • Link, Network, and App security can be built transparently to SP

18. Benchmarks • Minimal performance reduction in single hop • Compare to B-MAC paper • Compare to IEEE 802.15.4 • Simpler multihop/network protocol code • Power consumption • Network protocol co-existence

19. Results: mica2 Throughput

20. Results: mica2 Throughput

21. Results: mica2 Throughput

22. Results: mica2 Throughput

23. Results: mica2 Throughput

24. Results:Single Hop Benchmarks (802.15.4)

25. Conclusion • SNA: provide context for sharing our community work and accelerate the development and deployment of sensornet applications • Effective link abstraction, SP, allows network protocols to run efficiently on varying power management schemes