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Introduction to Ultra WideBand Systems

Introduction to Ultra WideBand Systems

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Introduction to Ultra WideBand Systems

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  1. Introduction to Ultra WideBand Systems Chia-Hsin Cheng

  2. Outlines • Introduction • The history of UWB • UWB Regulations (FCC Rules) • UWB signals • UWB in IEEE 802 Standards • The Application of UWB

  3. Introduction • The world of ultra wideband (UWB) has changed dramatically in very recent history. In the past 20 years, UWB was used for radar, sensing, military communications and niche applications. • A substantial change occurred in February 2002, when the FCC (2002a,b) issued a ruling that UWB could be used for data communications as well as for radar and safety applications. • Recently, UWB technology has been focused on consumer electronics and communications. • Ideal targets for UWB systems are low power, low cost, high data rates, precise positioning capability and extremely low interference.

  4. UWB Transmitter Defined • UWB transmitter signal BW: • Or, BW ³ 500 MHz regardless of fractional BW fu-fl 2 ³0.20 fu+fl Where: fu= upper 10 dB down point fl= lower 10 dB down point Source: US 47 CFR Part15 Ultra-Wideband Operations FCC Report and Order, 22 April 2002: http://www.fcc.gov/Bureaus/Engineering_Technology/Orders/2002/fcc02048.pdf

  5. NB 6% bandwidth 20% bandwidth UWB 0 100% bandwidth -40 Random noise signal -80 Frequency (GHz) 3 6 9 12 15 UWB: Large Fractional Bandwidth CDMA: 1.288Mcps/1.8 GHz 0.07% bandwidth one “chip” Power Spectral Density (dB)

  6. Large Relative (and Absolute) Bandwidth • UWB is a form of extremely wide spread spectrum where RF energy is spread over gigahertz of spectrum • Wider than any narrowband system by orders of magnitude • Power seen by a narrowband system is a fraction of the total • UWB signals can be designed to look like imperceptible random noise to conventional radios Narrowband (30kHz) Part 15 Limit ( -41.3dBm/Hz) Wideband CDMA (5 MHz) UWB (Several GHz) Frequency

  7. Why is Ultra Wideband So Effective? • Shannon showed that the system capacity, C, of a channel perturbed by AWGN --- Where: C = Max Channel Capacity (bits/sec) B = Channel Bandwidth (Hz) S = Signal Power (watts) N = Noise Power (watts) Capacity per channel (bps) µ B Capacity per channel (bps) µ log(1+S/N) • Increase B • Increase S/N, use higher order modulation • Increase number of channels using spatial separation • (e.g., MIMO)

  8. Throughput • Low Power UWB Comparable to High Power Wireless Systems UWB throughput between 802.11a and b

  9. UWB Properties • Extremely difficult to detect by unintended users • Highly Secured • Non-interfering to other communication systems • It appears like noise for other systems • Both Line of Sight and non-Line of Sight operation • Can pass through walls and doors • High multipath immunity • Common architecture for communications, radar & positioning (software re-definable) • Low cost, low power, nearly all-digital and single chip architecture

  10. Outlines • Introduction • The history of UWB • UWB Regulations (FCC Rules) • UWB signals • UWB in IEEE 802 Standards • The Application of UWB

  11. The history of UWB Technology • Before 1900: Wireless Began as UWB • Large RF bandwidths, but did not take advantage of large spreading gain • 1900-40s: Wireless goes ‘tuned’ • Analog processing: filters, resonators • ‘Separation of services by wavelength’ • Era of wireless telephony begins: AM / SSB / FM • Commercial broadcasting matures, radar and signal processing • 1970-90s: Digital techniques applied to UWB • Wide band impulse radar • Allows for realization of the HUGE available spreading gain • Now: UWB approved by FCC for commercialization For further details, refer to ref.[1]

  12. What UWB is Today • 7,500 MHz available spectrum for unlicensed use • US operating frequency: 3,100 – 10,600 MHz • Emission limit: -41.3dBm/MHz EIRP • Indoor and handheld systems • Other restrictions and measurement procedures in Report and Order • UWB transmitter defined as having the lesser of • Fractional bandwidth greater than 20% • Occupies more than 500 MHz • UWB is NOT defined in terms of • Modulation • or Carrierless • or Impulse radio

  13. Outlines • Introduction • The history of UWB • UWB Regulations (FCC Rules) • UWB signals • UWB in IEEE 802 Standards • The Application of UWB

  14. Summary of the FCC Rules • Significant protection provided for sensitive systems • GPS, Federal aviation systems, etc. • Lowest emission limits ever by FCC • Incorporates NTIA (National Telecomm. and Info. Administration) recommendations • Allows UWB technology to coexist with existing radio services without causing interference • FCC opened up new spectrum for UWB transmissions • One of the bands is from 3.1GHz to 10.6GHz • Maximum power emission limit is - 41.3dBm/MHz

  15. FCC UWB Device Classifications • Report and Order authorizes 5 classes of devices with different limits for each: • Imaging Systems • Ground penetrating radars, wall imaging, medical imaging • Thru-wall Imaging & Surveillance Systems • Communication and Measurement Systems • Indoor Systems • Hand-held Systems • Vehicular Radar Systems • collision avoidance, improved airbag activation, suspension systems, etc.

  16. FCC First Report and Order Authorizes Five Types of Devices

  17. 3.1 10.6 1.99 GPS Band 1.61 0.96 UWB Emission Limits for GPRs, Wall Imaging, & Medical Imaging Systems Operation is limited to law enforcement, fire and rescue organizations, scientific research institutions, commercial mining companies, and construction companies. Source: www.fcc.gov

  18. GPS Band 1.99 10.6 0.96 1.61 UWB Emission Limits for Thru-wall Imaging & Surveillance Systems Operation is limited to law enforcement, fire and rescue organizations. Surveillance systems may also be operated by public utilities and industrial entities. Source: www.fcc.gov

  19. 3.1 10.6 1.99 GPS Band 0.96 1.61 UWB Emission Limit for Indoor Systems Source: www.fcc.gov

  20. 3.1 10.6 1.99 GPS Band 0.96 1.61 Proposed UWB Emission Limit for “Outdoor” Systems Proposed in preliminary Report and Order, Feb. 14, 2002. Source: www.fcc.gov

  21. EIRP, dBm/MHz -40 -50 -60 -70 -80 0.01 0.1 1 10 100 Frequency, GHz Actual UWB Emission Limit for Hand-held Systems UWB Band-width must be contained here First Report and Order, April 22, 2002.

  22. Outlines • Introduction • The history of UWB • UWB Regulations (FCC Rules) • UWB signals • UWB in IEEE 802 Standards • The Application of UWB

  23. UWB Signals • Monocycle Shapes for UWB • Data Modulation • Modulation Schemes

  24. Monocycle Shapes for UWB • Monocycle shapes will affect the performance • Listed monocycles’ duration is 0.5ns • Gaussian pulse • Gaussian Monocycle • Scholtz’s Monocycle • Manchester Monocycle • RZ- Manchester Monocycle • Sine Monocycle • Rectangle Monocycle

  25. Monocycle Shapes for UWB (cont.) • Gaussian Pulse

  26. Monocycle Shapes for UWB (cont.) • Gaussian monocycle • Similar to the first derivative of Gaussian pulse

  27. Monocycle Shapes for UWB (cont.) • Scholtz’s monocycle • Similar to the second derivative of Gaussian pulse

  28. Monocycle Shapes for UWB (cont.) • Manchester Monocycle • It has amplitude A during half of the monocycle width and has amplitude –A during the other half.

  29. Monocycle Shapes for UWB (cont.) • RZ- Manchester Monocycle • It has amplitude A and –A only a portion of each half monocycle width.

  30. Monocycle Shapes for UWB (cont.) • Sine Monocycle • Just a period of sine wave

  31. Monocycle Shapes for UWB (cont.) • Rectangle Monocycle • It has uniform amplitude A during the whole pulse width.

  32. Data Modulation • A number of modulation schemes may be used with UWB systems. The potential modulation schemes include both orthogonal and antipodal schemes. • Pulse Position Modulation (PPM) • Pulse Amplitude Modulation (PAM) • On-Off Keying (OOK) • Bi-Phase Modulation (BPSK)

  33. Modulation Schemes • Many different pulse generation techniques may be used to satisfy the requirements of an UWB signal. • The FCC requires that the fractional bandwidth is greater than 20 %, or that the bandwidth of the transmitted signal is more than 500MHz, whichever is less. • The most common UWB concepts • Time-hopping (TH) technique • Direct-Sequence (DS) technique • Multi-band (MB) technique

  34. TH-UWB • TH-PPM 1. transmitting 0 pulse wtr(t) Str(t) Tc t Tf Ts : data symbol time

  35. TH-UWB • TH-PPM 2 . transmitting 1 d d d d Str(t) Tc t Tf Ts

  36. DS-UWB • DS-UWB

  37. Multiband UWB • Refer to OFDM course

  38. Outlines • Introduction • The history of UWB • UWB Regulations (FCC Rules) • UWB signals • UWB in IEEE 802 Standards • The Application of UWB

  39. UWB in IEEE 802 Standards • IEEE 802 Organization • IEEE 802.15.3a • IEEE 802.15.4a

  40. IEEE 802 Organization LAN/MAN Standards Committee (Wireless Areas) MBWA IEEE 802.20 WLAN™ IEEE 802.11 WPAN™ IEEE 802.15 WMAN™ IEEE 802.16 Coexistence TAG IEEE 802.19 Regulatory TAG IEEE 802.18 802.15.1 “Bluetooth” 802.15.3 “High Data Rate” MAC & 2.4 GHz PHY Task Group 3a Alt PHY (UWB) 802.15.2 Coexistence 802.15.4 “Zigbee” 2.4 GHz Study Group 4a (UWB?) Mini-Glossary: WLAN-wireless Local Area Network; MAN-Metropolitan Area Network; TAG-Technical Advisory Group;-MBWA-Mobile Broadband Wireless Access Based on: “Overview of 802.15.3 and 3a,” R. F. Heile, Workshop on Current Developments in UWB, Institute for Infocomm Research, Singapore

  41. IEEE Project 802 Local and Metropolitan Area Network Standards Committee • Accredited by ANSI, Sponsored by IEEE Computer Society • Ethernet, Token Ring, Wireless, Cable Modem Standards • Bridging, VLAN, Security Standards • Meets three times per year (400-600 individuals, 15% non-US) • Develops equivalent IEC/ISO JTC 1 standards JTC 1 series of equivalent standards are ISO 8802-nnn • IEEE URLs • 802 http://grouper.ieee.org/groups/802/ • 802.15 http://grouper.ieee.org/groups/802/15/

  42. Standards : Range and Data Rate

  43. Candidate UWB Systems

  44. 802.15.3a – high data rate WPAN standard • Direct sequence (DS-UWB) • Championed by Motorola/XtremeSpectrum • Classic UWB, simple pulses, • 2 frequency bands: 3.1-4.85GHz, 6.2-9.7GHz • CDMA has been proposed at the encoding layer • Spectrum dependent on the shaping filter – possible differing devices worldwide • Multiband Orthogonal Frequency Division Multiplexing (MB-OFDM) • Intel/TI/many others • Similar in nature to 802.11a/g • 14 528MHz bands (simplest devices need to support 3 lowest bands, 3.1GHz – 4.7 GHz) • Spectrum shaping flexibility for international use

  45. Detail of DS-CDMA Candidate for 802.15.3a • Multi-band DS-CDMA Physical Layer Proposal • Summary from IEEE document 15-03-0334-02-003a-Merger-2-CFP-Presentation.ppt

  46. Two Band DS-CDMA Low Band High Band 3 4 5 6 7 8 9 10 11 3 4 5 6 7 8 9 10 11 • Low Band (3.1 to 5.15 GHz) • 25 Mbps to 450 Mbps • High Band (5.825 to 10.6 GHz) • 25 Mbps to 900 Mbps Multi-Band 3 Spectral Modes of Operation With an appropriate diplexer, the multi-band mode will support full-duplex operation (RX in one band while TX in the other) 3 4 5 6 7 8 9 10 11 • Multi-Band (3.1 to 5.15 GHz plus 5.825 GHz to 10.6 GHz) • Up to 1.35 Gbps

  47. 0 1 -5 -10 0.5 dB -15 LongWavelet -20 0 -25 -30 -0.5 -35 GHz -40 -1 1 3 4 5 6 7 8 9 10 11 -1 0 1 0 0.5 -5 Mid Wavelet -10 0 -15 dB -20 -25 -0.5 -30 -35 -1 GHz -1 0 1 -40 11 3 4 5 6 7 8 9 10 Example DuplexWavelet 1 0 -5 dB -10 0.5 -15 -20 0 -25 -30 -0.5 -35 GHz -40 -1 3 4 5 6 7 8 9 10 11 -1 0 1 Joint Time Frequency Wavelet Family

  48. Spectral Flexibility and Scalability • PHY Proposal accommodates alternate spectral allocations • Center frequency and bandwidth are adjustable • Supports future spectral allocations • Maintains UWB advantages (i.e. wide bandwidth for multipath resolution) • No changes to silicon Example 2: Support for hypothetical “above 6 GHz” UWB definition Example 1: Modified Low Band to include protection for 4.9-5.0 GHz WLAN Band 3 4 5 6 7 8 9 10 11 Note 1: Reference doc IEEE802.15-03/211 3 4 5 6 3 4 5 6

  49. Detail of OFDM Candidate for 802.15.3a • Multi-band OFDM Physical Layer Proposal • Summary from IEEE document 03267r1P802-15_TG3a-Multi-band-OFDM-CFP-Presentation.ppt

  50. Overview of Multi-band OFDM • Basic idea: divide spectrum into several 528 MHz bands. • Information is transmitted using OFDM modulation on each band. • OFDM carriers are efficiently generated using an 128-point IFFT/FFT. • Internal precision is reduced by limiting the constellation size to QPSK. • Information bits are interleaved across all bands to exploit frequency diversity and provide robustness against multi-path and interference. • 60.6 ns cyclic prefix provides robustness against multi-path even in the worst channel environments. • 9.5 ns guard interval provides sufficient time for switching between bands.