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Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)

Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: FM-UWB: A Low Complexity Constant Envelope LDR UWB Communication System Date Submitted: 16 July, 2007 Source: John F.M. Gerrits CSEM Systems Engineering

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Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)

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  1. Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: FM-UWB: A Low Complexity Constant Envelope LDR UWB Communication System Date Submitted: 16 July, 2007 Source: John F.M. Gerrits CSEM Systems Engineering Jaquet Droz 1, CH2002 Neuchatel, Switzerland Voice: +41 32 720 56 52, FAX: +41 32 720 57 20, E-Mail: john.gerrits@csem.ch Re: This document is CSEM’s response to the Call For Application from theIEEE P802.15 Interest Group on BAN. Abstract:This document presents FM-UWB: a constant envelope LDR UWB air interface for short range BAN applications. Notice:This document has been prepared to assist the IEEE P802.15. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein. Release:The contributor acknowledges and accepts that this contribution becomes the property of IEEE and may be made publicly available by P802.15. John F.M. Gerrits / John R. Farserotu, CSEM

  2. FM-UWB: A Low Complexity Constant Envelope LDR UWB Communication System John F.M. Gerrits & John R. Farserotu Wireless Communication Department CSEM Systems Engineering Switzerland John F.M. Gerrits / John R. Farserotu, CSEM

  3. Presentation Outline • Definition of and Applications for UWB • Principles and Performance of FM-UWB • Multiple-Access Techniques • FM-UWB Performance with Frequency-selective Fading • Influence of FM-UWB on IR-UWB • Conclusions • References John F.M. Gerrits / John R. Farserotu, CSEM

  4. Definition of UWB • Bandwidth > 500 MHz for operation above 3.1 GHz • No particular air interface or modulation scheme specified • Signal needs to comply with the local spectral mask Over time, UWB has become less and less wideband.. John F.M. Gerrits / John R. Farserotu, CSEM

  5. Potential for UWB • High Data Rate MBOFDM 480 Mbps • Robust MDR, • Localization/tracking Impulse Radio 1-10 Mbps • Very Robust LDR FM < 250 kbps Very promising Business Potential. [http://www.techworld.com/mobility/] John F.M. Gerrits / John R. Farserotu, CSEM

  6. Low power consumption potential of UWB • The low radiated power of a UWB transmitter in principle may also yield • low power consumption. May yield, since power may be required to meet, • e.g., phase noise specifications or to perform baseband processing. • Usually, the receiver requires more power than the transmitter • (LNA gain, filtering, dynamic range) • A MB OFDM transceiver will never be the champion of the low power contest. John F.M. Gerrits / John R. Farserotu, CSEM

  7. Low-complexity UWB applications • Short range (1-10m) Wireless Sensor Networks for monitoring and control: • Applications: • Health monitoring BAN • Home automation • Security and alarms • Requirements: • Low cost, low power systems (mW - mWs) • Portable (go anywhere) • Robust and reliable • Good coexistence with other RF systems • Fast access (short synchronization time) BAN [IMEC2006] John F.M. Gerrits / John R. Farserotu, CSEM

  8. Robust constant–envelope UWB: analog spread-spectrum • FM-UWB is an analog implementation of a spread-spectrum system: • Spreading in transmitter by analog wideband FM (b = 500) • Despreading in receiver wideband FM demodulator, • yielding bandwidth reduction from 500 MHz to 200 kHz John F.M. Gerrits / John R. Farserotu, CSEM

  9. FM-UWB features • True Low-Compexity and Robustness to interference and multipath • - Relaxed hardware specs (phase noise) > very low power potential • - No carrier synchronization but instantaneous despreading • - CSMA techniques may enhance performance • - Antennas are not critical • - Steep spectral roll-off John F.M. Gerrits / John R. Farserotu, CSEM

  10. Analog spreading in transmitter BW: 50 kHz 200 kHz >500 MHz freq: baseband 1 -2 MHz 4.5 & 6-9 GHz FSK FM Sub carrier Data RF modulation spreading • An analog FM signal can have any bandwidth independent of modulation frequency or bit rate. • This is analog spread spectrum, i.e., multiple (b) copies of the FSK subcarrier signal. John F.M. Gerrits / John R. Farserotu, CSEM

  11. Data Subcarrier RF Data, subcarrier and FM-UWB signal in time domain John F.M. Gerrits / John R. Farserotu, CSEM

  12. Direct Digital Synthesis subcarrier generation No look-up tabe is required for the generation of a triangular waveform Data pre-filtering lowers subcarrier sidelobes to an acceptable level. fSUB = 1 MHz DfSUB = 50 kHz John F.M. Gerrits / John R. Farserotu, CSEM

  13. Relaxed phase noise requirements A Low-Power Ring Oscillator can do the job: Unmodulated at 4.5 GHz FM-UWB with Df = 250 MHz John F.M. Gerrits / John R. Farserotu, CSEM

  14. FM-UWB spectrum and Regulations FM-UWB fits everywhere; even in the European 4.2 – 4.8 and 6 – 9 GHz spectrum. FM roll-off TX phase noise TX white noise John F.M. Gerrits / John R. Farserotu, CSEM

  15. Instantaneous despreading in the receiver BW: >500 MHz 200 kHz 50 kHz freq: 4.5 & 6-9 GHz 1 -2 MHz baseband Subcarrier RF Data instantaneous despreading FSK demodulation 250 MHz GPdB = 34 dB @ 100 kbps GPdB = 44 dB @ 10 kbps 1 John F.M. Gerrits / John R. Farserotu, CSEM

  16. Receiver processing gain Only noise/interference in the subcarrier banwidth is taken into account. This bandwidth reduction after the wideband FM demodulator yields real processing gain: 250 MHz 1 Processing gain increases for lower bit rates: GPdB = 34 dB @ R = 100 kbps GPdB = 44 dB @ R = 10 kbps John F.M. Gerrits / John R. Farserotu, CSEM

  17. Wideband FM demodulator Phase det. FM>PM [ECWT2006] John F.M. Gerrits / John R. Farserotu, CSEM

  18. Multiple RF and subcarrier signals in receiver At receiver input: 3 - 5 GHz (no multipath) After FM demod: FSK subcarriers: 1 – 2 MHz John F.M. Gerrits / John R. Farserotu, CSEM

  19. Receiver synchronization time Due to the instantaneous despreading, only bit synchronization is required like in a narrowband FSK system! John F.M. Gerrits / John R. Farserotu, CSEM

  20. Multiple-access techniques • Multiple users can be accommodated in a number of ways: • IEEE 802.15.4 MAC (TDMA) for standard applications • RF FDMA, highest for QOS (no multiple-access interference) • Sub-carrier FDMA (“MAC-less”) for ultra low power applications • Proprietary MAC (TDMA) for sensor networks, e.g., WISENET John F.M. Gerrits / John R. Farserotu, CSEM

  21. RF FDMA techniques • Multiple users use different RF and sub-carrier frequencies • Highest QOS, since no multiple-access interference occurs • (no spectral overlap) John F.M. Gerrits / John R. Farserotu, CSEM

  22. Subcarrier FDMA techniques • Multiple users can share the same RF center frequency • And distinguish themselves using different subcarrier frequencies Subcarrier filtering, multiple-access interference and phase noise determine the performance limits. [WPMC2005] John F.M. Gerrits / John R. Farserotu, CSEM

  23. Some figures on FM-UWB robustness1 • Impulse Radio interference with SIR = -14 dB yields BER = 10-3 • MBOFDM interference with SIR = -15 dB yields BER = 10-3 • FM-UWB performs very well in frequency-selective channels • as we will illustrate shortly. 1values mentioned are for a 100 kbps system John F.M. Gerrits / John R. Farserotu, CSEM

  24. FM-UWB Performance with frequency-selective fading Channel impulse response (time domain) CM4 CM1 Channel transfer function (frequency domain) John F.M. Gerrits / John R. Farserotu, CSEM

  25. FM-UWB performs better with strong multipath CM11000 channel realizationsCM4 John F.M. Gerrits / John R. Farserotu, CSEM

  26. Good, flat and bad channels good flat bad John F.M. Gerrits / John R. Farserotu, CSEM

  27. Statistics with various channels Variations in RF sensitivity [dB] based upon 1000 channel realizations [ICUWB2007] John F.M. Gerrits / John R. Farserotu, CSEM

  28. S = Impulse Radio Signal fC 4 GHz t 2 ns, R 10 Mpps Modulation BPAM Envelope Triangular Influence of FM-UWB signal on Impulse Radio UWB I = FMUWB Signal MATLAB simulations show the pulse in the receiver after demodulation. 2 cases: - non-coherent: square-law multiplier + 500 MHz LPF - coherent: downconversion with fC + 500 MHz LPF MATLAB code is available upon request. John F.M. Gerrits / John R. Farserotu, CSEM

  29. IR signal time domainIR signal frequency domain Non-coherent detection SIR = 20 dB Coherent Detection +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 TX RX TX RX John F.M. Gerrits / John R. Farserotu, CSEM

  30. IR signal time domainIR signal frequency domain Non-coherent detection SIR = 0 dB Coherent Detection +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 TX RX TX RX John F.M. Gerrits / John R. Farserotu, CSEM

  31. IR signal time domainIR signal frequency domain Non-coherent detection SIR = -10 dB Coherent Detection +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 TX RX TX RX John F.M. Gerrits / John R. Farserotu, CSEM

  32. Preliminary Results: Detection of raw pulses gets affected when SIR < -14 dB meaning a FM system 5 x closer. Simulation would need to be done with the complete IR receiver chain to get the definitive figures. John F.M. Gerrits / John R. Farserotu, CSEM

  33. Conclusions • FM-UWB is a true Low-Complexity LDR UWB radio for BAN Applications • offering the following advantages: • - Good co-existence with existing air interfaces • - Robustness to interference and multipath (analog spread spectrum) • - Steep spectral roll-off, easy to fit with all spectral masks • - Simple radio architecture: no receiver RX-LO, no carrier synchronization • - Relaxed hardware specifications, enabling low power consumption • - CSMA techniques may be used to enhance performance John F.M. Gerrits / John R. Farserotu, CSEM

  34. References [ECWT2006] John F.M. Gerrits, John R. Farserotu, John R. Long, "A Wideband FM Demodulator for a Low-Complexity FM-UWB Receiver", Proceedings of the 9th European Conference on Wireless Technology, 10 - 12 September 2006, Manchester, UK, pp. 99 - 102. [ICUWB2007] John F.M. Gerrits, John R. Farserotu and John R. Long, "Multipath Behavior of FM-UWB Signals", ICUWB2007, Singapore, September 2007. [IMEC2006]Olivier Rousseaux, “BAN Usage Scenarios and Application”, IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs), April 2006, Jacksonville, Florida, USA, doc.: IEEE 802.15-06-0217-00-0ban. [WPMC2005] John F.M. Gerrits, John R. Farserotu, John R. Long, “Multiple-Access Interference in FM-UWB Communication Systems”, WPMC2005, 19 – 22 September 2005, Aalborg, Denmark, pp. 2027-2031. John F.M. Gerrits / John R. Farserotu, CSEM

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