Sensors The Next Tier of the Internet

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infrastructure, and Bluetooth any day now Smart Dust vision complete (albeit very limit) computing system in mm 3 expected in 10 15 years The Systems Urgency Only 10 years to get the systems &

1 Sensors The Next Tier of the Internet David E. Culler BSAC IAB Wireless Workshop: WSN, Cellular, Sensors Sept 21, 2007 BSAC-WW 9/21/ Years Berkeley Post-PC age had arrived The Palm Pilot in hand, massive computing clusters in the infrastructure, and Bluetooth any day now Smart Dust vision complete (albeit very limit) computing system in mm 3 expected in years The Systems Urgency Only 10 years to get the systems & networking right! Power profile of embedded PCs / Laptops / PDAs / Cells orders of magnitude off from where we needed to be. None of the Mobile Ad Hoc networks worked, Results streaming in from the world beyond Estrin PC104-WiFi Testbed» None of the beautiful networking ideas mattered because ALL the energy went into idle listening of MAC. Many researchers solving imaginary problems BSAC-WW 9/21/

The Mote Platform LWIM-III (UCLA) WINS (UCLA/ROckwell) Intel rene Intel/UCB dot zeevo BT

rene2 XBOW mica XBOW cc-dot Bosch cc-mica digital sun rain-mica XBOW mica2 Dust Inc blue

CENS STC NETS/ NOSS Cyber- Physical BSAC-WW 9/21/2007 3 A World of Systems and Networking

2 The Mote Platform LWIM-III (UCLA) WINS (UCLA/ROckwell) Intel rene Intel/UCB dot zeevo BT Intel cf-mica Intel imote BTNode Intel MOTE2 Eyes trio SmartDust WeC Rene Mica Telos XBOW rene2 XBOW mica XBOW cc-dot Bosch cc-mica digital sun rain-mica XBOW mica2 Dust Inc blue cc-ti XBOW micaz 97 DARPA LWIM SENSIT Expedition NEST NSF CENS STC NETS/ NOSS Cyber- Physical BSAC-WW 9/21/ A World of Systems and Networking Wireless Sensor Networks SmartDust NEST Wireless Storage Sensors Processing BSAC-WW 9/21/

3 Reliable, Low-Power Wireless Routing BSAC-WW 9/21/ Communication Power Passive Vigilance I Sleep ~10 ua Transmit ~20 ma x 1-5 ms [ uas] Time I Listen ~20 ma Receive ~20 ma x 2-6 ms Time BSAC-WW 9/21/

4 3 Basic Listening Techniques Goal: listen only when there is likely to be something useful to hear. Listen during scheduled time slots Arrange a schedule of possible communication opportunities Maintain appropriately coordinated clocks and schedule Only listen during specific slots Many variants: Token-Ring, TDMA, Beacons, Bluetooth piconets, TSMP, Sampled Listening Listen for very short intervals to detect eminent transmissions On detection, listen actively to receive Listen after send (with powered infrastructure) Generally, device is not listening and will not receive. After it transmits to a receptive device, it listens for a time window Many variants: AMAT, Key fobs, remote modems, BSAC-WW 9/21/ Meanwhile in the internet BSAC-WW 9/21/

frequ ency 0 2 4 6 8 10 12 14 16 18 Time (sec)

billions of information devices embedded in the

Serial GPRS HTTP / FTP / SNMP Ethernet TCP /

5 Low resol ution Sensor, Test4, Increasing frequ ency Time (sec) The Next few billion network nodes Acceleration (g) BSAC-WW 9/21/ THE Question If Wireless Sensor Networks represent a future of billions of information devices embedded in the physical world, why don t they run THE standard internetworking protocol? Web Services XML / RPC / REST / SOAP / OSGI Serial GPRS HTTP / FTP / SNMP Ethernet TCP / UDP IP Plugs and People Sonet a b g RFM,CC10k,, Self-Contained BSAC-WW 9/21/

6 The Answer They should Substantially advances the state-of-the-art in both domains. Implementing IP requires tackling the general case, not just a specific operational slice Interoperability with all other potential IP network links Potential to name and route to IP devices within security domain Robust operation despite external factors» Coexistence, interference, errant devices,... While meeting the critical embedded wireless requirements High reliability and adaptability Long lifetime on limited energy Manageability of many devices Within highly constrained resources BSAC-WW 9/21/ Internet Standards The Internet Engineering Task Force (IETF), formed in 1986, is a large open international community of network designers, operators, vendors, and researchers concerned with the evolution of the Internet architecture and the smooth operation of the Internet Layered architecture provides interoperability for diverse applications across broad and evolving communications technology Today: Half a billion to a billion IP hosts demonstrated scale Diverse Object and Data Models (HTML, XML, ) Applications (Telnet, FTP, SMTP, SNMP, HTTP) Transport (UDP/IP, TCP/IP) Network Internet - Internet Protocol Protocol (IP) Routing (IP) Addressing, Routing Serial Modem ISDN DSL GPRS X3T9.5 FDDI Sonet Ethernet 802.3a Token Ring Ethernet 802.3i Ethernet 10b y Ethernet 802.3ab 10bT 100bT Ethernet 802.3an 1000bT Ethernet 1G bt WiFi a WiFi b g WiFi n WiFi WiFi LoWPAN BSAC-WW 9/21/

7 Many Advantages of IP Demonstrated scaling (up, down, over time, technologies, applications) Extensive interoperability Other wireless embedded network devices (entire goal of Zigbee, ) Devices on any other IP network link (WiFi, Ethernet, GPRS, Serial lines, ) Established security Authentication, access control, and firewall mechanisms Network design and policy determines access, not the technology Established naming, addressing, translation, lookup, discovery Established proxy architectures for higher-level services NAT, load balancing, caching, mobility Established application level data model and services HTTP/HTML/XML/SOAP/REST, Application profiles Established network management tools Ping, Traceroute, SNMP, OpenView, NetManager, Ganglia, Transport protocols End-to-end reliability in addition to link reliability Most industrial (wired and wireless) standards support an IP option BSAC-WW 9/21/ Long road toward sensor integration 1950: 4-20 ma current loop Common signal wiring, ADC, and calibration Vast diversity in excitation, configuration, interpretation 1980: HART (Highway Addressable Remote Transducer) 1200 baud, half-duplex digital communication over 4-20 wiring Rosemount proprietary protocol => open => Fieldbus Fixed packet format for command / response» Process Variable, Host->Device Commands, Status & Diagnostic Alerts, Device Id, Calibration and Limits 1987: BACnet (Building Automation and Control Network) RS232, RS485, ARCnet, ethernet, LONTalk, BACnet/IP Device = Collection of Objects; 23 object types Data types, packet formats, and object defined in Abstract Syntax (ASN.1) Protocol services, Data Sharing, Alarm and Events, Trending, Scheduling, Remote Device and Network Management 1994: CIP (Common Industrial Protocol) Device Net (CAN), ControlNet, EtherNet/IP Devices as physical instances of classes. Communication between objects is independent of physical links providing transport Fixed binary encodings of data types, object types, classes 200x: Zigbee, ZWave, Wireless HART, SP100.11a, IEEE radio BSAC-WW 9/21/

8 IP-Based Instrumentation and Control Critical Success Factors XML, HTML, REST / SOAP / SIP HTTP / FTP / SNMP / SMTP / DNS - Application profiles - Non-mixing profiles - Local scope only - Closed sub-system 10/100/1000 Ethernet TCP / UDP Diversity and fast innovation in application services IP Dial-Up, DSL, a/b/g, Cable, FTTH 2.5G/3G Cell Internet Architecture Zigbee, - Monolithic stack - Radio dependent - Local scope only - Not future proof Reliability and scalability through protocol layering Coexistence and fast innovation in link technologies Diversity and fast innovation in device types BSAC-WW 9/21/ Relationship to Industrial Interconnects BACnet RS-232 & RS-485 => IEEE via BACnet/IP LONworks Twisted Pair & Power Line => LonTalk/IP Common Industrial Protocol (CIP) CAN & ControlNet => EtherNet/IP SCADA Prop. RS-485 & Leased Line & Prop. Radios => ModBUS => Ethernet => TCP/IP FieldBus Modbus, Profibus, Ind. Ethernet, Foundation HSE, H1, SP100.11a? Object and Data Model Implementation Glue TCP/UDP/IP Many IP links Specific Legacy Physical Link In 2000, ODVA and CI introduced another member of the CIP family: EtherNet/IP, where IP stands for Industrial Protocol. In this network adaptation, CIP runs over TCP/IP and therefore can be deployed over any TCP/IP supported data link and physical layers, the most popular of which is IEEE , commonly known as Ethernet. The universal principles of CIP easily lend themselves to possible future implementations on new physical/ data link layers. [The Common Industrial Protocol (CIP) and the Family of CIP Networks (Pub 123 )] BSAC-WW 9/21/

9 But, isn t IP too heavyweight for low-power, wireless, microcontroller based devices? No! 6lowpan compression with high quality multihop routing Reliability and lifetime of the best mesh Interoperability of IP BSAC-WW 9/21/ Making sensor nets make sense Web Services XML / RPC / REST / SOAP / OSGI HTTP / FTP / SNMP TCP / UDP Proxy / Gateway LoWPAN % of power, easier to embed, as easy to use bit MCUs with KBs, not MBs. Off 99% of the time IP Ethernet Sonet , IETF 6lowpan BSAC-WW 9/21/

10 Key Factors for IP over Header Standard IPv6 header is 40 bytes [RFC 2460] Entire MTU is 127 bytes [IEEE ] Often data payload is small Fragmentation Interoperability means that applications need not know the constraints of physical links that might carry their packets IP packets may be large, compared to max frame size IPv6 requires all links support 1280 byte packets [RFC 2460] Allow link-layer mesh routing under IP topology subnets may utilize multiple radio hops per IP hop Similar to LAN switching within IP routing domain in Ethernet Allow IP routing over a mesh of nodes Options and capabilities already well-defined Various protocols to establish routing tables IPv6 IPv4 and IPv6 IPv6 IPv6 BSAC-WW 9/21/ IEEE The Low Power Wireless Link Standard D pan Dst EUID 64 S pan Src EUID 64 Max 127 bytes preamble SFD Len FCF DSN Dst16 Src16 Network Header Application Data Fchk Low bandwidth (250 kbps), low power (1 mw) radio Moderately spread spectrum (QPSK) for robustness Small packets for lower error rates and media sharing Simple MAC allows diversity of networking protocols TinyOS-based protocols (MintRoute, LQI, BVR, ), TinyAODV, Zigbee, SP100.11, Wireless HART, New recommended choice for interoperability: IP with 6LoWPAN HW choice now available with many semiconductor suppliers BSAC-WW 9/21/

11 6LoWPAN: IPv6 over IEEE IEEE Frame Format D pan preamble Dst EUID 64 S pan Src EUID 64 SFD Len FCF DSN IETF 6LoWPAN Format Dst16 Src16 dsp Network Header 127 bytes Application Data Fchk Uncompressed IPv6 address [RFC2460] 40 bytes HC1 Fully compressed: 1 byte Source address Destination address Traffic Class & Flow Label Next header : derived from link address : derived from link address : zero : UDP, TCP, or ICMP Deep compression by breaking the layering abstraction and putting it all back together again. BSAC-WW 9/21/ LoWPAN Format Design Orthogonal stackable header format Almost no overhead for the ability to interoperate over radio Pay for only what you use IEEE Frame Format D pan Dst EUID 64 S pan Src EUID 64 preamble SFD Len FCF DSN Dst16 Src16 IETF 6LoWPAN Format Dispatch: coexistence Header compression Mesh (L2) routing dsp HC1 HC2 mhop dsp HC1 mhop Message > Frame fragmentation frag Max 127 bytes Network Header Application Data frag IP UDP dsp dsp HC1 HC1 Fchk BSAC-WW 9/21/

12 What s the energy Cost? uas per Packet Energy Cost of Packet Communication vs. Data Size Global Internet Scope: Overhead < 20% Pay when needed! Energy Δ for fixed payload * RCV 6LoWPAN Local <= Global RCV 6LoWPAN Local <= Local RCV Raw TX 6LoWPAN Local => Global TX 6LoWPAN Local => Local TX Raw Local Mesh Scope: Overhead =< Zigbee * Max Payload * fully compressed header * additional 16-byte IPv6 address Bytes of Payload BSAC-WW 9/21/ Leverage what doesn t need inventing RFC 768 UDP - User Datagram Protocol [1980] RFC 791 IPv4 Internet Protocol [1981] RFC 792 ICMPv4 Internet Control Message Protocol [1981] RFC 793 TCP Transmission Control Protocol [1981] RFC 862 Echo Protocol [1983] RFC 1101 DNS encoding of network names and other types [1989] RFC 1191 IPv4 Path MTU Discovery [1990] RFC 1981 IPv6 Path MTU Discovery [1996] RFC 2131 DHCPv4 - Dynamic Host Configuration Protocol [1997] RFC 2375 IPv6 Multicast Address Assignments [1998] RFC 2460 IPv6 [1998] RFC 2463 ICMPv6 - Internet Control Message Protocol for IPv6 [1998] RFC 2765 Stateless IP/ICMP Translation Algorithm (SIIT) [2000] RFC 3068 An Anycast Prefix for 6to4 Relay Routers [2001] RFC 3307 Allocation Guidelines for IPv6 Multicast Addresses [2002] RFC 3315 DHCPv6 - Dynamic Host Configuration Protocol for IPv6 [2003] RFC 3484 Default Address Selection for IPv6 [2003] RFC 3587 IPv6 global Unicast Address Format [2003] RFC 3819 Advice for Internet Subnetwork Designers [2004] RFC 4007 IPv6 Scoped Address Architecture [2005] RFC 4193 Unique Local IPv6 Unicast Addresses [2005] RFC 4291 IPv6 Addressing Architecture [2006] And --- in RFC "Transmission of IPv6 Packets over IEEE Networks" BSAC-WW 9/21/

13 Connecting IP Networks to Wireless Embedded Devices LoWPAN-Extended IP Network IP Network (powered) IP/6LoWPAN Border Router IPv6/6LoWPAN Sensor Router IP Device RFC 4944: 6LoWPAN (IPv6 for Low Power Wireless Personal Area Networks) Adapts full-fledged IPv6 to run over embedded wireless networks BSAC-WW 9/21/ IP Devices Directly Configure and Control Embedded Nodes LoWPAN-Extended IP Network IP Network (powered) IP/6LoWPAN Border Router IP Device IPv6/6LoWPAN Sensor Router BSAC-WW 9/21/

14 Embedded Nodes Send Data to Servers Across IP Networks LoWPAN-Extended IP Network IP Network (powered) IP/6LoWPAN Border Router IP Device IPv6/6LoWPAN Sensor Router BSAC-WW 9/21/ IP Firewalls and Security Models are Understood and Proven 128-Bit AES Link-Layer Encryption LoWPAN-Extended IP Network Border Firewalls IP Network (powered) Border Firewalls IP/6LoWPAN Border Router Internal Firewalls IP Device IPv6/6LoWPAN Sensor Router BSAC-WW 9/21/

15 Embedded IP Gives You a Choice: Proxies and Routers Sensor Node IP/6LoWPAN Proxy Gateway Server Router Web, HTTP, XML, SNMP, SMS, Ping, Telnet, Sockets TCP, UDP, ICMP IPv4, IPv6 Ethernet, WiFi BSAC-WW 9/21/ Embedded IPv6 programming sockaddr_in6_t m_dest; uint8_t m_buf[buflen]; call IPv6Addresses.pton( fd01::1234, &m_dest.sin6_addr ); m_dest.sin6_port = 2724; call UdpSend.sendto( m_buf, BUFLEN, &m_dest ); event void Tcp.connected() { call Tcp.send( m_buf, BUFLEN ); call Tcp.close( TRUE ); } BSAC-WW 9/21/

16 What it means for you Reliable, low-power forwarding on links now understood and demonstrated Requires attention to detail, Continuous monitoring of link quality Multiple forms of diversity (temporal, spatial, frequency) Requires retransmission, rerouting, With radios off 99.5% of the time None of these issues are dictated by the application profile HART, BACNet, Zigbee, XML, Wireless sensor networks are not an Island Work with other networks, other kinds of devices Cannot afford to return to the N^2 problem Internet architecture allows link technology and applications to improve additional defensive measures for reliability in the face of change and imperfection Allows vast body of existing tools and standards to be applied to Wireless Sensor Networks Just one more member of the family BSAC-WW 9/21/

TinyOS meets IP -- finally

TinyOS meets IP -- finally David E. Culler THE Question If Wireless Sensor Networks represent a future of billions of information devices embedded in the physical world, why don t they run THE standard