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Stefan von der Mark Technische Universität BerlinMicrowave Engineering 1 Realisierungskonzepte für drahtlose Sensornetzwerke – Ein Überblick Stefan von.

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Presentation on theme: "Stefan von der Mark Technische Universität BerlinMicrowave Engineering 1 Realisierungskonzepte für drahtlose Sensornetzwerke – Ein Überblick Stefan von."— Presentation transcript:

1 Stefan von der Mark Technische Universität BerlinMicrowave Engineering 1 Realisierungskonzepte für drahtlose Sensornetzwerke – Ein Überblick Stefan von der Mark, Georg Böck

2 Stefan von der Mark Technische Universität BerlinMicrowave Engineering 2 Overview What are Wireless Sensor Networks? Similarities and differences to RFID Some published approaches –PicoRadio/PicoBeacon (Berkeley) –WiseNET (CSEM) –MUSE and ORBIT (WINLAB) The AVM eGrain project –Concept –WakeUp –Demonstrator

3 Stefan von der Mark Technische Universität BerlinMicrowave Engineering 3 What are Sensor Networks? University of Geneva in Switzerland Smart Dust:

4 Stefan von der Mark Technische Universität BerlinMicrowave Engineering 4 Applications Logistics, Locationing –Goods in a warehouse or shopping center –Books in a library Environmental monitoring –Indoor: Temperature, humidity, intruders –Outdoor: Pollution, agricultural research Structural monitoring –Bridges, skyscrapers, large halls –Ageing, stress from snow, earthquakes Military

5 Stefan von der Mark Technische Universität BerlinMicrowave Engineering 5 Properties of Sensor Networks Tiny little low cost sensor nodes Wireless peer to peer communication Self-sustained operation for prolonged time Preferably completely integrated (CMOS) Ad Hoc Networking:

6 Stefan von der Mark Technische Universität BerlinMicrowave Engineering 6 State of the Art Existing sensor arrays are usually wired –Classical: Analog wire from each sensor –More modern: Digital bus systems Existing wireless sensors usually communicate with dedicated access points Sensor communication mostly proprietary, but IEEE standard 802.15.4/ZigBee exists New IEEE 1451.4 plug&play standard for –Sensor ID –Type of measurement (Units!) –Calibration data

7 Stefan von der Mark Technische Universität BerlinMicrowave Engineering 7 Sensor Networks vs. RFID RFIDSensor Networks Transponder and interrogatorAll nodes equal Tags reply only on request of Interrogator All nodes can initiate transmission High transmission power available from interrogator Very low transmission power Transponder usually powered by incoming RF Own power source necessary

8 Stefan von der Mark Technische Universität BerlinMicrowave Engineering 8 Similarities Low data rates Only occasional communication Receivers can be similar But transmission is completely different

9 Stefan von der Mark Technische Universität BerlinMicrowave Engineering 9 Realisation approaches Nothing coming close to the vision has been realized so far Different approaches are being pursued: –Big and power hungry, but functional nodes (for protocol develompment, application research) –Demonstration of particular technologies (low power circuits, sensing, energy scavenging) –Attempts towards complete low power hardware (with reduced functionality) –And anything in between

10 Stefan von der Mark Technische Universität BerlinMicrowave Engineering 10 PicoNode I (UC Berkeley) PicoRadio Project at Berkeley Wireless Research Center, University of California at Berkeley (UCB) Strong ARM CPU Xilinx FPGA Proxim RangeLAN or Bluetooth HW with own protocols 24 hr operation out of 2 x 1200mAh Li-Ion Variety of sensor boards (modular concept)

11 Stefan von der Mark Technische Universität BerlinMicrowave Engineering 11 PicoBeacon (UCB) Energy scavenged from light and vibration –180 W out of 1 cm 3 from vibrations 1.9 GHz transmission (no receiver) 10m range 2.4 x 3.9 cm 2

12 Stefan von der Mark Technische Universität BerlinMicrowave Engineering 12 WiseNet (CSEM) Swiss Center for Electronics and Microtechnology (CSEM) 2 mW RX, 32 mW TX 433 / 868 MHz ISM 25 kbps 25 W for 56 bytes every 100 seconds WiseMAC specialized MAC protocol External Antenna

13 Stefan von der Mark Technische Universität BerlinMicrowave Engineering 13 Mote (Crossbow Inc.) Commercial sensor nodes based on UCB design and TinyOS operating system

14 Stefan von der Mark Technische Universität BerlinMicrowave Engineering 14 Mote (cont.) Variety of different nodes MICA2 or 802.15.4/ZigBee protocols 315/433/868/916 MHz options (MICA) or 2.4 GHz (ZigBee) 1 yr operation out of AAA batteries

15 Stefan von der Mark Technische Universität BerlinMicrowave Engineering 15 MUSE (WINLAB) Wireless Information Network Laboratory, Rutgers University, New Jersey Commercial embedded computers and WLAN transceiver Target is complete integration

16 Stefan von der Mark Technische Universität BerlinMicrowave Engineering 16 ORBIT (WINLAB) 400 nodes Pure software testbed No development of sensor hardware

17 Stefan von der Mark Technische Universität BerlinMicrowave Engineering 17 The AVM eGrain Project AVM – Autarke Verteilte Mikrosysteme 3 year BMBF project with these partners: AVM MWT - ANT - TKN BMBF grant No. 16SV1658

18 Stefan von der Mark Technische Universität BerlinMicrowave Engineering 18 Concept Development of completely autarkic ultra low power pico cell network Nodes are self organizing, no master/slave principle Highly integrated, node size ~1 cm 3 RF frequency 24 GHz Development of low power system architecture Development of ultra low power RF components

19 Stefan von der Mark Technische Universität BerlinMicrowave Engineering 19 Wakeup Strategies Periodic WakeupWakeup Receiver No extra components Network synchronization necessary Waste of power through unnecessary wakeups Delay in communications Immediate response No reference clock Standby power consumption Nodes need to be in a sleep mode most of the time, but how and when to activate them?

20 Stefan von der Mark Technische Universität BerlinMicrowave Engineering 20 Block Diagram of the Wakeup Circuit

21 Stefan von der Mark Technische Universität BerlinMicrowave Engineering 21 Detector Principle Zero bias Schottky Diodes FET size increases from first to third stage

22 Stefan von der Mark Technische Universität BerlinMicrowave Engineering 22 Diode-like behavior of an NMOS Transistor: MOS Diode

23 Stefan von der Mark Technische Universität BerlinMicrowave Engineering 23 Alternative Principle MOS rectifier CMOS compatible, no BiCMOS necessary But: less sensitivity, more standby power

24 Stefan von der Mark Technische Universität BerlinMicrowave Engineering 24 Wake-Up Address Decoder Main requirement: low power consumption Block diagram: Detector PWM-signal serial Input Shift registers Adress correlator A1-A8 Discriminators & Logic serial data (0/1) clock reset Adress preset A1-A8 Wakeup parallel data valid

25 Stefan von der Mark Technische Universität BerlinMicrowave Engineering 25 Prototype of Address Decoder CMOS-technology Low complexity: ca. 470 transistors No oscillator Low data rate: e.g. 50 kb/s Address preset RF Input PWM signal Wakeup- Output Bias Vcc: + 3V

26 Stefan von der Mark Technische Universität BerlinMicrowave Engineering 26 RF Frontend Overview Frontend characteristics –Frequency: 24.125 GHz –Range: ca. 1 m –Transmit power: ca. 1 mW Flip-Chip-Assembly and integrated Antenna IC-Technology: GaAs-HBT-MMICs (FBH) TU Berlin (MWT, ANT), FBH

27 Stefan von der Mark Technische Universität BerlinMicrowave Engineering 27 Heterodyne Concept Standard approach Upconversion and downconversion mixers Good channel selectivity Oscillator needed for Tx and Rx

28 Stefan von der Mark Technische Universität BerlinMicrowave Engineering 28 Zero IF Concept No oscillator needed in the receiver Power consumption determined by LNA Low complexity, low power consumption

29 Stefan von der Mark Technische Universität BerlinMicrowave Engineering 29 Baseband demonstrator Concept Real data transmission at 24 GHz Patch antenna realised on multilayer PCB Minimum component count

30 Stefan von der Mark Technische Universität BerlinMicrowave Engineering 30 Transmitter –On-Off-Keying (OOK) modulation –No power consumption in standby mode –No power consumption for 0 bits

31 Stefan von der Mark Technische Universität BerlinMicrowave Engineering 31 Receiver –Zero IF –No mixer => no LO necessary (power saving!) –LF amplifier has very low current consumption (ca. 100 µA) –Total battery current < 15 mA –Dielectric Resonator as BPF

32 Stefan von der Mark Technische Universität BerlinMicrowave Engineering 32 Detector –Diode type HSCH-3486 (Agilent) –Single stage detector –Other topologies are less efficient (bridge, cascade) –P TX = 0 dBm, Pathloss (1m@24 GHz) = 76 dB => P RX = –76 dBm, Gain LNA = 13 dB => P in, Detector = –63 dBm => U out = 3 µV Matching

33 Stefan von der Mark Technische Universität BerlinMicrowave Engineering 33 LNA Measured LNA performance –14 mA DC @ 2 V –13.3 dB gain @ 24.8 GHz –Bandwidth 4.2 GHz –NF 5.8 dB (simulated) Chipsize 1.1x1.3 mm

34 Stefan von der Mark Technische Universität BerlinMicrowave Engineering 34 Assembly Aperture coupled patch antenna Industry standard multilayer PCB RF Chip Flip-Chip mounted LF electronics in SMD Housing soldered => only standard assembly technologies

35 Stefan von der Mark Technische Universität BerlinMicrowave Engineering 35 Patch Antenna Principle Whole module size is antenna base Great beam collimation –Directivity 19.6 dB –Gain 8.5 dB (theo. Max. 9 dB) Coax feed

36 Stefan von der Mark Technische Universität BerlinMicrowave Engineering 36 Aperture coupled feed Greater bandwidth than for coaxial feed Lower directivity of 15.6 dB Gain 7.8 dB Fabrication much easier than coax feed

37 Stefan von der Mark Technische Universität BerlinMicrowave Engineering 37 Photo 1 cm 3 2 button cell batteries 24 GHz 2400 bps

38 Stefan von der Mark Technische Universität BerlinMicrowave Engineering 38 Future Work CMOS LNA to further reduce power consumption of the receiver (7 mA @ 1.2 V) Integration of detector with LNA –BiCMOS with schottky diodes –Pure CMOS with MOS rectifier Complete integration as SoC

39 Stefan von der Mark Technische Universität BerlinMicrowave Engineering 39 Summary Today the vision is still far from reality But many efforts and progress are made in –Hardware design (digital and RF) –Integration and miniaturization –Energy scavenging and storage –Software design Some day the vision will become reality!

40 Stefan von der Mark Technische Universität BerlinMicrowave Engineering 40 References T. T. Hsieh Using sensor networks for highway and traffic applications IEEE Potentials, vol. 23, no. 2, pp. 13 – 16, Apr-May 2004 Christian C.Enz, Amre El-Hoiydi, Jean-Dominique Decotignie, Vincent Peiris WiseNET: An Ultralow-Power Wireless Sensor Network Solution IEEE Computer, August 2004, p. 62-70 Shad Roundy, Brian P. Otis, Yuen-Hui Chee, Jan M. Rabaey, Paul Wright A 1.9GHz RF Transmit Beacon using Environmentally Scavenged Energy IEEE Int.Symposium on Low Power Elec. and Devices 2003 Stefan von der Mark, Meik Huber, Mathias Wittwer, Wolfgang Heinrich, and Georg Boeck System Architecture for Low Power 24 GHz Front-End Frequenz -Zeitschrift für Telekommunikation, Special Issue Autarkic Distributed Microsystems in Sensor Networks, 3-4/2004, p. 70-73 M. Huber, S.v.d. Mark, N. Angwafo and G. Boeck Ultra low power Wakeup Circuits for Pico Cell Networks, A conceptional View Technical Report of the 1st European Workshop on Wireless Sensor Networks (EWSN), Jan 2004 Stefan von der Mark, Roy Kamp, Meik Huber and Georg Boeck Three Stage Wakeup Scheme for Sensor Networks IEEE/SBMO International Microwave and Optoelectronics Conference IMOC 2005; Brasilia, Brazil, July 25-28 http://tcs.unige.ch/doku.php/web/wirelesssensornetworks University of Geneva in Switzerland http://bwrc.eecs.berkeley.edu BWRC at UCB: PicoRadio, PicoNode, PicoBeacon http://www.csem.ch CSEM: WiseNet http://www.xbow.com Crossbow: Mote http://www.winlab.rutgers.edu WINLAB: Muse, Orbit http://www-mwt.ee.tu-berlin.de Technische Universität Berlin Microwave Engineering: AVM


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