Funkübertragung im Indoor-Bereich für Sensornetzwerke

Transcription

1 Funkübertragung im Indoor-Bereich für Sensornetzwerke AP Challenges IEEE Solutions Coverage Benchmarking Delay Spread and the PSSS Solution Comparing of Wireless Technologies DWW Solutions for WSN and for 100 Gbps 1

2 Wireless Application Challenges Real wireless applications (especially indoor) are challenged by various issues SU1 No coverage Challenging Issues: Interference Multi-path fading Range & coverage NLOS Spectral density (data rate) SU2 Interference/ Multi path BS SU3 No coverage SU n Application demands: Highest reliability / data rate (QoS) Long range / Full coverage Many subscribers (nodes) Low power consumption Low system cost Co-Existence with e.g. WLAN, Bluetooth 2

3 WLAN The short range wireless alphabet soup.a b ULP WLAN.g.n Bluetooth WLAN Bluetooth UWB Bluetooth AFH HDR Bluetooth ULP FSK Proprietary IO-Homecontrol Wireless M-Bus WiBree Z-Wave Z-Wave Alliance Z/IP AEC (Z/IP) IPSO IEEE (Nokia) ZigBee ZigBee 2006 ZigBee 2007 ZigBee Pro 2.4 GHz MAC MAC ZigBee SmartEnergy 868 / 915 MHz 15.4b PSSS IEEE UWB 15.4a COBI IEEE UWB (26 modes) CSS Bernd Grohmann, Babylonisches Sprachgewirr? 7th LEIBNIZ CONFERENCE OF ADVANCED SCIENCE

4 Spectral Density is the Foundation of Wireless Communication Data Streaming (Access Points) Voice & Video Streaming Kbps Voice & Data Communications Bandwidth Spectral Density 5 Mbps 100 Gbps Multi Media & Highspeed Backbones < Kbps Voice Communications Mobile Handsets (Voice) <250 Kbps Sensor Networks Building Automation Building Automation 4

5 Core & Implementation IP Chip & Module Products DWW Product Portfolio Module design ZigBee or IPv4/6 Module ZigBee or IPV4/6 Module Extended 100 Gbps Optical Module 100 Gbps RF Module Application sales Chip design (system on chip) CMOS Chip CMOS Chip Turbo 100 Gbps Optical Chip 100 Gbps RF Chip Chip sales Implementation (IP) Customized Design Customized Design Customized Design Customized Design IP & Design Support Core (IP) Standard TRX-core Standard TRX-core PSSS 100 Gbps Optical TRX-core PSSS 100 Gbps RF TRX-core License sales Intellectual Property (IP) PSSS Version A/B PSSS Version B+ PSSS C PSSS D Patents PSSS: Parallel Sequence Spread Spectrum 5

6 IEEE Standards Data Rate vs. Range PSSS/PHY solution improves existing wireless IC solutions from 20 kbps to 250 kbps with performance mode up to 1000 kbps. Range Indoor [m] Sub 1 GHz IEEE PSSS/PHY (250kbps 1000 kbps) 4) 50m Sub 1 GHz IEEE ZigBee 2) 10m Sub 1 GHz Z-Wave 1) kbps 1 Mbps ) Z-Wave FSK based 10/40 kbps EU/US. No IEEE Standard. 2) IEEE /915 MHz system 20/40 kbps EU/US. 3) In combination with OFDM (high complexity of IC). 4) 1 Mbps proprietary. 5) Draft IEEE Standard. 6) Factor 10 less complex (gate count) then Mimo OFDM. Could be build with today in mass markets available components. 2.4 GHz IEEE ZigBee 2.4 GHz IEEE Bluetooth WLAN IEEE a/g PSSS 100Gbps 6) MIMO IEEE n 5) Data rate [Mbps] 6

7 WSN Products Today FPGA based Development Platform IEEE PSSS 868MHz "TRx154b_Eval" Details PSSS based IEEE Platform even supporting EN FSK (Wireless M-Bus) and proprietary FSK. It contains two PCBs, the radio PCB and on top the FPGA PCB. Main features for IEEE mode are: Sensitivity: About - 101dBm@1%PER with 127Byte PDU. Limited due to FPGA noise floor. Coverage: Unique coverage due to multipath fading resistance. Tx power: +15dBm. Data rate: 250kbps. Proprietary modes with different bitrates, higher link budget are supported. EMV optimized for RF applications. Size LX45 and higher. Applications Embedded System Design for WSN. DWW Services NRE based customization. Radio with FPGA 160 x 100 mm 7

8 Tested Modules and Test Conditions DWW IEEE PSSS 868MHz "TRx154b_Eval Transmit Power 0 dbm and +10 dbm. Even meets ETSI 250 kbps. Real PER testing. 868MHz Wireless M-Bus based Module newest generation. Transmit Power +0 dbm. 16,38 kbps. Real PER testing. IEEE MHz based Module. Transmit Power +16 dbm. 20 kbps Real PER testing. IEEE GHz based Module. Transmit Power +5 dbm. 250 kbps. Only connection loss, no PER testing. FSK proprietary MHz. Transmit Power +10 dbm and + 22 dbm. 37,5 kbps and 150kbps. Real PER testing. Test condition for successful coverage: PER < 1%. 8

9 Indoor Outdoor Results Basement Transmitter Indoor Outdoor Test Points On the floor MHz Wireless M-Bus Transmit Power +0 dbm kbps. PER Testing. IEEE MHz Transmit Power +16dBm. 20 kbps. PER Testing. IEEE GHz Transmit Power +5dBm. 250 kbps. Connection loss, no PER testing. FSK proprietary MHz dbm dbm dbm. PER Testing. DWW IEEE PSSS 868MHz "TRx154b_Eval Transmit Power 0 dbm +10 dbm. 250 kbps. PER Testing. Test points 1,14, 15 and 23 are the coverage limits for 10dBm Tx power. Map Source: Google Earth 9

10 Meßaufbau Gemessen wurde mit zwei Evalboards "TRx154b_Eval. Diese wurden mit der PER (Paket Error Ratio) Firmware betrieben und waren zusätzlich in Blechgehäusen zur magnetischen Schirmung montiert. Die Meßpunkte Tx (Sender) und Rx 1-5 (Empfänger) waren von der DB für deren typische Applikation vorgegeben. Rx1-3 waren an der S-Bahnstrecke, Rx 4-5 an der DB-Strecke. Ein Aufstellen der Module direkt hinter einem Pfeiler wurde vermieden. Die Brücke besteht aus genietetem Stahl. Es wurden die PER Werte nach IEEE evaluiert, auch bei vorbeifahrenden Zügen. Funkverbindung unter allen Testbedingungen mit PER <1% möglich. Unique. 10

11 Reasons for Coverage Advantages High Performance Design of Radio and Carrier Synchronization (DWW patent). Robustness of PSSS (DWW patents) against multipath fading. 11

12 Without Delay Spread Rx Tx Path 1 T 1 Rx Transmission without delay spread 12

13 Received Energy [%] Understanding of Delay Spread Delay Spread is the time in which 85% or 95% of the energy are received, started from the first received signal parts. Tx Path 1 T 1 Path 2 T 2 95% 85% r 1 r 2 Rx T spread85% T spread95% 13

14 PSSS Encoding and Decoding 14

15 No Multipath Fading 2 Chips blue CCF -3 green yellow amplitude threshold Time x 10-4 red sampling signal 15

16 Multipath Fading 2 Chips blue CCF green amplitude Time x 10-3 yellow red threshold sampling signal 16

17 Today s RF technologies provide largely unbalanced answers to a divergent set of requirements Key challenges in RF communication Range Maximize the transmission range for Tx power permitted / choosen Non line of sight environments Transmit reliably in non line of sight environments with multipath fading Interference Operate under disturbances both through human made and atmospheric noise Coexistence Minimize disturbance of other RF systems Efficiency Efficient use of the RF spectrum Support of throughput of 100s of MBit/s Be efficient in power consumption Be efficient in physical implementation Combinations of technologies in today s RF communication standards mitigate the problems and extend applications, but do not solve the underlying issues Today s RF technologies M PSK, QAM, OFDM etc. High single-station throughput High specific and absolute data rates Efficient use of RF spectrum BUT: Low range, susceptible to interference, complex & fragile in implementation, sensitive to multipath fading (except OFDM), high power consumption (especially OFDM) DSSS, O-QPSK Processing gain provides better range and robustness against interference BUT: Low specific data rates, not efficient in use of spectrum, limited throughput in existing bands FHSS Robust against multipath fading Good coexistence with other networks based on same or other RF technology BUT: High effort for management of hopping, inherits issues of underlying modulation, not suitable for high-throughput systems Decreasing data rate caused by multipath fading 17

18 PSSS provides a quantum leap in performance with a better balance of requirements and technology characteristics PSSS characteristics Type of system Spread spectrum, with processing / coding gain of 15 db and higher Throughput Supports from 10s of kbit/s to 100s of Mbit/s Range Typ. 2x...5x increased range over today s systems Efficient use of spectrum Orthogonal coding But no reduction of specfic and effective data rate for spreading But does not require UWB bandwidth (PSSS can provide 2+ GBit/s in UWB) Full performance in traditional bands But not at the cost of efficient use of the RF spectrum 2 bit/s/hz... approx. 40 bit/s/hz But still a single carrier system and not as fragile as MPSK, OFDM, etc. Pseudo-orthogonal coding enables concurrent use of same band But not coordination of transmitter power and no rake receiver required Multipath fading Tolerates multipath fading No add-on of TCM, Viterbi, or pre-coding Symbol errors Noise (atmospheric and human made) Interference from and to other systems Strong robustness through underlying coding technology in PSSS (e.g. tolerates 21 1-value errors in 31-chip sequence) Processing / coding gain reduces influence drasticly Processing / coding gain significantly improves robustness Efficient use of spectrum improves coexistence with other systems But no DSP or complex design needed But not at the cost of data rate But no unknown side-effects PSSS shares DSSS behaviour 18

19 PSSS is implemented entirely based on known technologies that are in use in high-volume systems since many years PSSS implementation Type of Technology Transmitter complexity Receiver complexity Low energy consumption Coding and signal processing Provides it s benefits over practically any modulation technology, e.g. - FM, AM, DSB - MPSK, QAM - OFDM, UWB Single technology layer Shifted register digital structure Tx complexity grows at log2 when increasing data rate Simple integrate and dump decoder Rx complexity grows at log2 when increasing data rate Simple Tx and Rx implementation enables low power implementation Low cost Low complexity and digital processing result in small die sizes Is not dependent of specific modulation technology Based on technologies that are in use in high volume applications since many years But not a layered combination of RF coding technologies No FFT, Viterbi, etc. added, much lower complexity But no critical analogue system Low sensitivity against non-linearity and synchronization jitter No FFT, Viterbi etc. added, much lower complexity But not only for low data rates No power-hungry digital algorithms But does not compromise in throughput and robustness Rapid design & implementation Use of well-known components reduces complexity and risk of chip design Low complexity in analog design No complex digital algorithms 19

20 Impact for Ambient Energy High Coverage due to PSSS usage means even low retransmission rate in a network. That minimizes the needed energy for a successful transmission of the data. ACK PDU are the most transmitted PDU in IEEE WSN. Minimal MAC PDU of IEEE PSSS based is due to DWW synchronization technology about 30% shorter. That minimizes time on air and therefore the needed ambient energy. Data rate of 250 kbps reduces compared to the 100kbps PHY from IEEE time on air about factor 2.5 and therefore even the needed energy for a successful data transmission. Ambient energy is rare. It is necessary to reduce the need of it for wireless transmission. 20

21 Product Roadmap IEEE IEEE PSSS Devices Q2-Q3/2012 Q4/2009 Q1/2012 Single Chip IEEE EN Wireless M-Bus Module IEEE including EN Wireless M-Bus Q1/2009 Module Eval Board FPGA Module Eval Board Prototype Europäische Union Europäischer Fond für regionale Entwicklung. Investition in Ihre Zukunft. Allgemeine Informationen unter PSSS: Parallel Sequence Spread Spectrum 21

22 Other R&D Activities Solar powered Wireless Internet Access for Third World DWW develops 700 MHz PSSS based wireless links. Cooperation with FHG. 100 Gbps Communication PSSS 60 GHz First real world test with data rates up to 6 Gbps over several meters with spectral efficiencies about 2-3 Bit/s/Hz. Actual delay due to radio chip problems. Publication planed for Cooperation with IHP. PSSS USB Cable Real world e-6 BER at 2-3 Bit/s/Hz. With optimized hardware path to 50 Gbps. Parallel usage of cables pairs could enable 100 Gbps. Publication coming soon. Cooperation with IHP. 22

23 Summary PSSS based IEEE platform Best-in-Market spectral efficiency AND all advantages of spread spectrum system. - ½ 4 bit/s/hz compared to 1/16 bit/s/hz in 15.4 / 2.4 GHz. 250 kbps rate plus enhanced modes with up to 2 Mbps. Superior Link Budget of 130dB in low cost single chip. 5 10x range compared to 15.4 / 2.4 GHz due to high link budget and Sub 1GHz band. >5x multipath fading robustness compared to 15.4 / 2.4 GHz >1µs delay spread chip orthogonal PSSS spreading + delay spread adapted code coherence length. Lower analog and digital complexity than 15.4 / 2.4 GHz and COBI (IEEE kbps) designs. ZigBee and TCP/IP and other Stacks available. Lowest energy needed for successful data transmission key to enable energy harvesting. Discrete EVAL available Single chip transceiver in development. New R&D Projects for 60GHz and more. 23

24 Thank You Contact: 24

25 Backup Slides 25

26 DWW Company Overview Position Leading provider of the most competitive wireless solution for Data and Voice/Video Applications Description Established Headquarter Since 2007 by Dr. Andreas Wolf Teltow, Germany Since October 2007 Milestones Established global wireless standard for sensor networks, building automation and security. Developed highly integrated wireless IP solutions. Established strategic alliances with Danfoss, Fraunhofer, Samsung, Eaton, IHP GmbH. Consulting Projects with implementation Know-How. Team Core Competency Target Applications 3 Fulltime; 2 Temporary Wireless IP Standard RF Chip, SoC and PCB Solutions Building Automation, Sensor Networks, Security. 26

27 IEEE Performance Facts/USPs 2.4 GHz based solutions will cause performance problems due to interference with WLAN and Bluetooth. 1) Sub 1 GHz band is highly attractive due to less inference probability and better physical range. 1) Existing Sub 1GHz solutions limited to 20/40 kbps EU/US data rate (IEEE ). Limited number of nodes due to 1% duty cycle limitation by ETSI. Not usable i.e. for Building Automation 2) ZigBee offers 250 kbps in 2.4 GHz. IEEE base for high performance and 250 kbps (USPs due to usage of PSSS) even in Sub 1 GHz (EU and US) with low cost and lower power consumption. 1) Søren Hansen, Danfoss A/S, Nordborg, DK, Experience with Mesh Network Stacks in residential applications, Z-Wave Alliance- Z-Wave vs. ZigBee - CTC - 14 June ) Dipl.-Ing. Kurt Speelmanns, Bundesamt für Bauwesen und Raumordnung, VDI Fortschritt-Berichte VDI, Wireless Technologies, 8. Kongress Sept. 2006, page

28 PSSS Rx Channel ch13rn 6T chip Channel passed Direct received 6T chip 28

29 Urban Test Environment Basement Transmitter Outdoor Test Points On the floor Map Source: Google Earth 29

30 Backside of the Building Basement Transmitter Stairwell & Outdoor Test Points On the floor Map Source: Google Earth 30

31 Basement Street 54 Window Window 51 Basement Transmitter Steel concrete ceilings. 50cm solid walls. Windows with bars. Height of 75 cm. Receiver Test Points Steel concrete ceilings. 50cm solid walls. Windows with bars. Height of 75 cm. Corridor Window 5m Inner Courtyard 31

32 Stair Well & Outdoor Results Basement Transmitter Outdoor & Stair Well Test Points On the floor 868MHz Wireless M-Bus Transmit Power +0 dbm kbps. PER Testing IEEE MHz Transmit Power +16dBm. 20 kbps. 128 kbps. PER Testing. IEEE GHz Transmit Power +5dBm. 250 kbps. Connection loss, no PER testing. FSK proprietary MHz dbm dbm dbm. PER Testing. DWW IEEE PSSS 868MHz "TRx154b_Eval Transmit Power 0 dbm and +10 dbm. 250 kbps. PER Testing. Map Source: Google Earth 32

33 Basement Results Street 54 Window Window 51 Basement Transmitter Basement Test Points On the floor Corridor MHz Wireless M-Bus Transmit Power +0 dbm kbps. PER Testing. IEEE MHz Transmit Power +16dBm. 20 kbps. 128 kbps. PER Testing IEEE GHz Transmit Power +5dBm. 250 kbps. Connection loss, no PER testing. Window FSK proprietary MHz dbm dbm dbm. PER Testing. 45 5m 44 Inner Courtyard DWW IEEE PSSS 868MHz "TRx154b_Eval Transmit Power 0dBm and +10 dbm. 250 kbps. PER Testing. 33

34 Meßergebnisse Für alle Meßpunkte ergab sich ohne Zugstörungen eine PER von < 1e -3. Bei einfahrenden Zügen ergab sich bei direkter Abdeckung durch die Lok ein Anstieg kurzfristig der PER auf 1e -3 < PER < 1e -2. Die PER war immer kleiner als 1e -2. Die PER-Messung gemäß IEEE verwendet 20 Oktett lange PSDU (Physical layer Service Data Unit). Eine PER von 1% ist als Wert für die Reichweitentengrenze definiert. Es konnte unter allen Bedingungen eine Funkverbindung gewährleistet werden. 34

35 Typical Office Environment IEEE Transceiver 2.4 GHz, 250 kbps Received Power in dbm Strong coverage problems due to low signal power LOS area as reference Transmitter NLOS office area 5m 35

36 Typical Office Environment IEEE Transceiver Sub 1 GHz, 250 kbps Received Power in dbm Just small wholes due to low signal power LOS area as reference Transmitter NLOS office area 36

37 Normalized Average Power Diffuse Exponential Model Diffuse each delay bin contains multipath energy 0.25 f ( k) Ce kts /, k 0 Exponential average power decays exponentially C = Normalization Constant T s = Simulation Sample Period Fading - each delay bin has independent Rayleigh fading 0.1 Depicted: = 4T s Single Parameter: - RMS delay spread = - Mean excess delay - Max excess delay (10 db) Max excess delay (20 db) k (Bin #) Source: Paul Gorday IEEE b 37

38 Discrete Exponential Model Example Matlab Code for Baseband Simulation Variable description signal_in = input to channel model signal_out = output of channel model profile = power-delay profile channel = random realization of the channel L = number of samples between rays (RMS delay spread = 1.85LTs) Sample Matlab Code profile = zeros(1,10*l+1); profile(1:l:end) = exp(-(0:10)/2); profile = profile/(sum(profile)); channel = sqrt(profile/2).*(randn(size(profile))+j*randn(size(profile))); signal_out = zeros(size(signal_in)); for k = 0:10 signal_out=signal_out+channel(k+1)*[zeros(1,k*l) signal_in(1:length(signal_in)-k*l)]; end Source: Paul Gorday IEEE b 38

39 802.11a/HIPERLAN/2 Models [3] Channel Environment RMS Delay Spread (ns) A Typical office (NLOS) 50 B Typical large open space (NLOS) 100 C Large open space indoor (NLOS) 150 D Large open space indoor/outdoor (LOS) 140 E Large open space outdoor (NLOS) 250 Source: Paul Gorday IEEE b 39

40 IEEE Handbook [1] Environment RMS Delay Spread (ns) Typical Home < 50 Typical Office ~ 100 Typical Manufacturing Source: Paul Gorday IEEE b 40

41 Factory/Office Measurements [4] Location Type Mean RMS Delay Spread (ns) Max RMS Delay Spread (ns) A Factory B Factory C Factory D Factory E Factory F Office G Office H Office Tx-Rx separation < 30 m Source: Paul Gorday IEEE b 41

42 References [1] B. O Hara and A. Petrick, IEEE Handbook A Designer s Companion, IEEE Press, [2] J. Foester, Channel Modeling Sub-committee Report (Final), IEEE P /490r1-SG3a, Feb [3] J. Medbo and P. Schramm, Channel Models for HIPERLAN/2, ETSI/BRAN doc. No. 3ERI085B, [4] K. Pahlavan and A. Levesque, Wireless Information Networks, John Wiley & Sons, Source: Paul Gorday IEEE b 42

43 Time on Air PSSS versus COBI PPDU Due to 2.5 higher data rate of PSSS compared to COBI for payload for 868 MHz, payload length will be decreased by factor of 2.5. PSSS Min Mac frame length 5 octets = 40 bits = MAC frame length = 2/8 psss symbols = 160µs/160µs for 868/915 MHz. PPDU length minimum (mac frame length + SHR) =400µs/ =300µs for 868/915 MHz COBI Min Mac frame length 5 octets = 40 bits = MAC frame length = 20/10 cobi symbols = 400µs/160µs for 868/915 MHz. PPDU length minimum (mac frame length + SHR) =560µs/ =320µs for 868/915 MHz -> PSSS consumes much less time on air for equal PPDUs (Ack, ). 43