Industrial Wireless Sensor Networks Stephen Smith Teja Kuruganti Wayne Manges Tim McIntyre Wireless Industrial Sensor Networks Wireless Enables Ubiquitous Sensing . National Research Council – “advanced wireless sensors” identified as a critical research need. President ’ s Committee of Advisors on Science and Technology – “wireless sensors can improve efficiency by 10% and cut emissions by more than 25%” . Industrial Wireless Workshop – trade throughput for reliability . DOE Industrial Wireless Program . The four parameters are non-orthogonal Reliability . Deployment demands performance Latency . Understanding environment is the key . Wireless – radio, packaging, antenna . Industrial – harsh, fault tolerant, safety related, cost Throughput . Sensor – filters, sampling, sensitivity, interferers, Security controls . Networks – real-time, latency, throughput, security, integrity, vertical integration 2 Managed by UT-Battelle for the U.S. Department of Energy 2 “Engineered” vs. “Can you hear me now?!!” Transmitter • RF channel is dynamic and time-varying RX 1 Receiver • Fast site-specific radio channel path-loss s data for use in wireless network simulations RX 2 • Robust channel models can be created • Characterize common environmental Simulated vs Measured Simulated elements among data centers -40 -45 Measured -50 -55 -60 -65 Path Loss Path -70 -75 WISN QoS -80 WISN QoS -85 steps Center Trashcan Pedestal 1 Fire Hose Management NSD Corner far light pole Management WISN Application Specific QoS 5200 pedestal Light Pole- Café Light Pole- Brian Roundabout drain Location RF EnvironmentEnvironment Parameter Sensing Network Network Estimation Dynamic RF Environment . Closed-loop control requires Dynamic RF EnvironmentQoS Assessment Assessment deterministic quality of service WISN with with & QoS Self Self Test Test Feedback . Robust channel models will help develop novel estimation techniques QoS Based for stable controls Feedback 3 Managed by UT-Battelle for the U.S. Department of Energy Thrust Areas for Advanced Wireless Communications R&D at ORNL • Robust communication systems – improving the robustness and reliability of communication systems by developing advanced signal processing techniques in the areas of spread-spectrum modulation, space- time coding, iterative error-correcting decoding, interference cancellation, bandwidth-efficient modulation, and rapid synchronization • Cognitive communications – allows communications mode to adapt based on local knowledge of the environment and adequate decision- making processes • Ubiquitous wireless sensor/actuator networks – enables a pervasive and ubiquitous communications (monitoring and control) presence by addressing key issues like self organization, seamless integration, security, scalability, mobility, and energy constraints • Bio-inspired communications – building micro- and nano-scale communication systems that take advantage of the computational and organizational strategies used by biological organisms to solve complex problems in real time 4 Managed by UT-Battelle for the U.S. Department of Energy 4 The Wireless Landscape IEEE 802.15.4 ISA100.11a IEEE802.15.4 Wireless HART 5 Managed by UT-Battelle for the U.S. Department of Energy Industrial Wireless: A Network of Networks 6 Managed by UT-Battelle Co-resident Wireless Systems for the U.S. Department of Energy Early Adopters – Blazing the Wireless Trail! Wireless Vibration Sensor 7 Managed by UT-Battelle for the U.S. Department of Energy Why Develop a Global Industrial Wireless Standard? Because I always know where my signals are going! 8 Managed by UT-Battelle for the U.S. Department of Energy Why Develop a Global Industrial Wireless Standard? Because somebody will always invent an adapter! 9 Managed by UT-Battelle for the U.S. Department of Energy What is ISA100? Family of standards designed from the ground up for many industrial wireless applications ISA100 Timeline Currently Issued To Develop Future Developing Process Apps (ISA100.11a) Discrete Apps Physics of Radio Location & Tracking Long Distance Apps Emerging Apps (non-normative) (ISA100.21) Industrial Facility Apps ISA100 Family of Standards: One-Stop Standardization Designed to Accommodate all Your Plant Needs 10 Managed by UT-Battelle for the U.S. Department of Energy Interference: Broadband high- powered ~ 0.65ms ~ 0.65ms 11 Managed by UT-Battelle for the U.S. Department of Energy More interference: ambient channel noise 12 Managed by UT-Battelle for the U.S. Department of Energy Multipath Interference LONG-PATH REFLECTION TRANS. RCVR. SHORT-PATH REFL. Differential delays are approx. 1 ns per foot Short-path delays (indoors) are typically < 0.1µs HSS Spread-spectrum modulation can largely cancel long-path effects 13 Managed by UT-Battelle for the U.S. Department of Energy Time-Domain Representation Fig. 1. Typical RF Indoor Signal-Delay Profile Typical indoor (large room) multipath delay profile. Presentation_name 14 Managed by UT-Battelle for the U.S. Department of Energy Frequency-Domain Effect of Multipath Vector cancellations due to multiple paths (some out-of-phase) result in signal “notches” at specific frequencies as determined by dimensions of RF-reflective environment. DS Signal 1 2 3 4 5 Standard FH Signals Frequency Notch (Attenuated Signal) Produces signal “dead spots” 15 Managed by UT-Battelle for the U.S. Department of Energy Close-Up on 2.45-GHz ISM Band 802.11 802.15.4 Bluetooth Wireless USB ZigBee 802.15.4-compliant devices must yield to 802.11 traffic, while real candidate industrial and SG technologies may not. 16 Managed by UT-Battelle for the Department of Energy ORNL’s Solution: Hybrid Spread Spectrum • Novel, adaptive technique (U.S. Patents 7,092,440; 7,656,931; 7,660,338). • HSS: a synergistic, programmable combination of DS, FH, and TH. • Advantages: – Adaptive Hybrid Spread-Spectrum (HSS) modulation format combines DSSS and frequency/time hopping in a multi-dimensional, orthogonal signaling scheme. – Capable of excellent LPI, LPD & security properties (programmable). – Adaptive, robust protocol for high QoS applications. – Can be operated in burst mode for very low power drain. – Superior resistance to multipath and jamming (high process gain). – Easily deployed with modern chip technology. – Compliant with existing government rules for license-free ISM bands. – Ideally implemented via modern FPGA-based electronics, ASICs, and software-defined radio (SDR) techniques. 17 Managed by UT-Battelle for the Department of Energy DIRECT-SEQUENCE SPREAD-SPECTRUM SIGNALS PN Clock Local PN Clock Local PN Sequence PN Sequence Carrier Generator Carrier DS Generator Signal ±1 ±1 Wide Narrow Phase Data Data BP Filter BP Filter Demod Data ±1 Clock Power Power Power Spectral Spectral Spectral Density Density Density “Spread” RFI RFI f f f Frequency c Frequency c Frequency c Original narrowband, high Narrow spectrum at Spectrum has wider bandwidth power density spectrum is and lower power density after restored if local PN sequence is output of modulator spreading with PN sequence same as and lined up with before spreading (PN Rate >> Data Rate) received PN sequence 18 Managed by UT-Battelle for the Department of Energy FREQUENCY-HOPPING SPREAD-SPECTRUM PN Clock Local PN Clock PN Sequence PN Sequence Generator Generator … FH … Signal RF RF ±1 Wide Narrow Data Data Data Frequency Frequency Synthesizer BP Filter Synthesizer BP Filter Demod. Data Clock Power RFI Spectral Data Power Density RFI causes Spectral Output errors Density t t t t0 t t t1 4 2 6 3 5 t0 t1 t2 t3 t4 t5 t6 f f Frequency c Frequency c Time (hops) t Original narrowband, high Narrow spectrum at Spectrum has same bandwidth power data stream is restored if output of modulator and power density after hopping local PN sequence is same as while hopping with PN sequence (PN Rate << and lined up with received PN Data Rate for standard FHSS) sequence 19 Managed by UT-Battelle for the Department of Energy HYBRID SPREAD-SPECTRUM (DS/SFH) PN Clock Local PN Clock PN Sequence PN Sequence Generator Generator … DS/FH … ±1 Signal RF RF Wide Narrow Data Data Data Frequency Frequency Synthesizer BP Filter Synthesizer BP Filter Demod. Data Clock Power Power Spectral RFI Data Spectral Density Output Density RFI Reduced by DS PG t t t t0 t t t1 4 2 6 3 5 t0 t1 t2 t3 t4 t5 t6 f f Frequency c Frequency c Time (bits) t Spectrum has same bandwidth Original narrowband, high DS (wide) spectrum at power data stream is restored if and power density after hopping local PN sequence is same as output of modulator with PN sequence (PN Rate << while hopping and lined up with received PN Data Rate for standard HSS; sequence >> for FastHSS™) 20 Managed by UT-Battelle for the Department of Energy FAST HYBRID SPREAD-SPECTRUM (DS/FFH) PN Clock “FastHSS™” Local PN Clock PN Sequence PN Sequence Generator Generator … DS/FH … ±1 Signal RF RF Wide Narrow Data Data Data Frequency Frequency Synthesizer BP Filter Synthesizer BP Filter Demod. Data Clock Power Power Spectral RFI Data Spectral Density Output Density RFI Reduced by DS PG! t11 t20 t21 t00 t30 t01 t10 t00 t01t 10 t11 t20 t21 t30 t31 t40 t41t 50 t51t 60 t61 t40 t61 t60 t31 t41 t50 t51 f f Frequency c Frequency c Time (chips) t Original narrowband, high DS (wide) spectrum at Spectrum has same bandwidth power data stream is restored if output of modulator and power density after hopping local PN sequence is same as while hopping with PN sequence (PN Rate >> and lined up with received PN Data Rate for FastHSS™; e.g., as sequence above, 2 hops per bit). Gp(FH/DS) dB = Gp(FH) dB + Gp(DS)dB = 10 log (no. of hopping channels) + 10 log (BWDS/Rinfo) 21 Managed by UT-Battelle for the Department of Energy HSS is a Multidimensional Signal • HSS can be defined in 3 axes Frequency (code, frequency, and time). (C4,F2,t0) • Each dimension is orthogonal with the others. Code • Permissible signal spaces along an axis (C2,F1,t0) may also be ~ orthogonal. (C3,F0,t1) • Codes • Frequencies (C ,F ,t ) 0 0 0 (C1,F2,t2) • Time slots • Easily adaptable to exploit many degrees of freedom to meet system requirements.