![PSD of some common wireless broadcast and
communication systems.
System Transmission
power
Bandwidth PSD [W/MHz]
Radio 50 kW 75 kHz 666,600
Television 100 kW 6 MHz 16,700
2G Cellular 10 mW 8.33 kHz 1.2
802.11a 1 W 20 MHz 0.05
UWB 1 mW 7.5 GHz 0.013
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Uwb interview presentatin
- 2. OUTLINE Introduction UWB systems Challenges and Issues UWB Antenna-Example Evaluation of Antenna Parameters UWB Antennas Developed at PU • Conclusion 01/26/19 06:51 2
- 3. 3 Ultra-Wide-Band Radio Communication • UWB is a technology developed to transfer large amounts of data wirelessly over short distances over a very wide spectrum of frequencies in a short period of time. • The amount of spectrum occupied by a UWB signal, i.e. the bandwidth of the UWB signal is at least 25% of the center frequency. For example, a UWB signal centered at 2 GHz would have a minimum bandwidth of 500 MHz and the minimum bandwidth of a UWB signal centered at 4 GHz would be 1 GHz. The most common technique for generating a UWB signal is to transmit pulses with durations less than 1 nanosecond. • UWB technology has the capacity to handle the very high bandwidths required to transport multiple audio and video streams. • UWB will be ideally suited for transmitting data between consumer electronics (CE), PC peripherals, and mobile devices within short range at very high speeds while consuming little power. • This technology operates at a level that most systems interpret as noise and, as a result, does not cause interference to other radios such as cell phones, cordless phones or broadcast television sets.
- 5. 5 UWB Advantages • Extremely Difficult to Intercept - LPI/LPD. Wideband pulsed radar spreads the signal and allows more users access to a limited amount of scarce frequency spectrum. • Multipath Immunity - A low path loss and low energy density minimizes interference to other services. UWB is very tolerant of interference, enabling operation within buildings, urban areas, and forests. • Precision Network-wide timing - Real-time, continuous position location down to a centimeter of resolution results in precision geolocation systems. • Low Cost - Requires minimal components resulting in small size and weight • Low Power - Typical consumption is in microwatts
- 6. 6 UWB Applications • Communications - High Speed WLANs, Mobile Ad-Hoc wireless networks, Groundwave Communications, Handheld and Network Radios, Intra-home and Intra-office communication. Stealthy communications provide significant potential for military, law enforcement, and commercial applications. • Sensor Networks - Ground penetrating Radar that detects and identifies targets hidden in foliage, buildings or beneath the ground. Intrusion Detection Radars, Obstacle Avoidance Radars, and Short-range motion sensing. • Tracking/Positioning - Precision Geolocation Systems and high-resolution imaging. Indoor and outdoor tracking down to less than a centimeter. Good for emergency services, inventory tracking, and asset safety and security.
- 7. What is UWB system? Ultra Wideband – High Bandwidth, FCC - 2002 IEEE 802.15.3a Foremost communication systems are based on sinusoidal waves UWB systems are based on exchanging data using short duration pulses of sub nanoseconds which covers a very wide bandwidth in the frequency domain - hence the name Ultra WideBand Pulse width Inter-pulse spacing: uniform or variable
- 8. UWB system … 8 Impulse Modulation 3 10 GHzfrequency UltrawidebandUltrawideband CommunicationCommunication Time-domain behavior Frequency-domain behavior time 1 0 1 (FCC Min=500Mhz) Frequency Modulation 2.4 GHz NarrowbandNarrowband CommunicationCommunication 0 1 0 1
- 9. UWB Synonyms Other terms associated with “Ultra-wideband” Impulse Short-Pulse Non-Sinusoidal Carrier-less Time domain Super wideband Fast Frequency Chirp and Mono-Pulse 9
- 10. Specifications of UWB As per FCC definition, any transmission scheme that has a fractional bandwidth (FBW) greater than or equal to 0.20 or an absolute bandwidth greater than or equal to 500 MHz is said to be UWB system Allocated band for indoor applications :3.1 - 10.6 GHz Maximum allowable emitted power : - 41.3 dBm/MHz FBW = 10 H L c f -f f
- 11. UWB bands in the world 11 Region UWB band United States Single band = 3.1 to 10.6 GHz Europe Lower band = 3.1 to 4.8 GHz Higher band = 6 to 8.5 GHz Japan Lower band = 3.4 to 4.8 GHz Higher band = 7.25 to 10.25 GHz
- 12. UWB system features Unlicensed spectrum Ultra short pulses – High data rate Base band transmission – Simple transceiver design Low duty cycle – High energy efficiency Low probability of detect/intercept –extremely low PSD and pulse width Immunity to multipath fading 12
- 13. By Shannon's capacity theory, It is easier to increase the bit rate (capacity) by increasing the bandwidth instead of the power, given the linear-versus-logarithmic relationship. 13 2 S C = B.log 1 + N ÷ According to the Friis formula, the range It is more efficient to achieve higher capacity by increasing bandwidth instead of power, while it is equally difficult to achieve a longer range. Thus, UWB designers focused on higher-bit-rate, short-range systems. d t r P P ∞
- 14. Comparison of UWB with other standards Property WLAN Bluetooth WPAN ZigBee UWB IEEE Standard 802.11a/b/g 802.15.1 802.15.3 802.15.4 802.15.3a Operating Frequency 5 GHz/ 2.4 GHz/ 2.4 GHz 2.4 GHz 2.4 GHz 2.4 GHz 3.1-10.6 GHz Max. Data Rate 54 Mbps/ 11 Mbps/ 54 Mbps 1 Mbps 55 Mbps 250 Kbps > 100 Mbps Max. Range 100 meters 10 meters 10 meters 50 meters 10 meters 14
- 15. PSD of some common wireless broadcast and communication systems. System Transmission power Bandwidth PSD [W/MHz] Radio 50 kW 75 kHz 666,600 Television 100 kW 6 MHz 16,700 2G Cellular 10 mW 8.33 kHz 1.2 802.11a 1 W 20 MHz 0.05 UWB 1 mW 7.5 GHz 0.013 15
- 16. UWB BASIC CHARACTERISTICS (Cont...) • High spatial capacity: bits/sec/m2 • Low power portable device needed 802.11b Bluetooth 802.11a UWB range (m) 100 10 50 10 BW (MHz) 80 200 7500 data rate (Mbps) 11 1 54 110 spatial cap (b/s/m2 ) 1,000 30,000 83,000 20,00,000
- 17. FCC UWB Device Classifications 5 classes of devices – Different limits for each: • Imaging Systems 1. Ground penetrating radars, wall imaging, medical imaging 2. Thru-wall Imaging & Surveillance Systems • Communication and Measurement Systems 3. Indoor Systems 4. Outdoor Hand-held Systems • Vehicular Radar Systems 5. Collision avoidance, improved airbag activation, suspension systems, etc. 17
- 18. “Effective and Efficient UWB antenna is a critical one over all UWB System design” 01/26/19 06:51 18
- 19. UWB Antenna Classification •Directional Vs Omni Directional: • High gain or directional antennas concentrate energy into a narrower solid angle • An Omni directional antenna has relatively low gain, wide field view and relatively small •Electric Vs magnetic : • Electric antennas are characterized by intense electric fields close to the antenna • Magnetic antennas are characterized by intense magnetic fields close to the antenna 01/26/19 06:51 19
- 20. 01/26/19 06:51 20 Directional Omni Directional Gain High Low Antenna Size Large Small Field of View Narrow Wide
- 21. Types of UWB Antenna •Single band Vs multi-Narrow band: • Typical UWB antennas used in the past are multi-narrow band •Dispersive Vs Non Dispersive: • Desire non-dispersive antennas, with a fixed phase center • Desire similar waveforms in all directions • A multi-band (OFDM) approach may be considered for dispersive antennas 01/26/19 06:51 21
- 22. 22 Dispersive Chirp like waveform Waveform varies at different azimuth angles. Non –dispersive Radiates more compact and non dispersive wave form
- 24. Category of UWB antennas 01/26/19 06:51 24
- 25. Requirements to design UWB Antennas • Capable of receiving all frequencies at the same time • Electrical size must be small with high efficiency • Pulse distortion must be kept to a minimum • It should follow the regulatory requirements • Constant radiation pattern through out the band of operation 01/26/19 06:51 25
- 26. Challenges in UWB Antenna Design • EM aspects of UWB communication systems • Most of the conventional antenna analyses assume harmonic time dependent (not the case in UWB). • Time-domain EM analysis/simulation is needed • Issues in UWB antenna design • Efficient pulse generation/reception • Pulse dispersion problem • Matching/ringing problem 01/26/19 06:51 26
- 27. UWB Antennas • Bow-tie • Relatively high input impedance • Requires a matching balun to make it usable with 50 ohm system • Tapered slot • Two dimensional microstrip • Resister loaded dipole • Low gain and low efficiency • Diamond dipole: developed by Time Domain Corp. • Emits a waveform similar to a Gaussian third derivative • 75 % efficiency with about 3:1 VSWR • Discone • High performance • 3-D structure: difficult to manufacture • Bicone • High performance • 3-D structure: difficult to manufacture • Log-periodic • Spiral01/26/19 06:51 27
- 29. UWB is a short range wireless standard which can support variety of applications “Anywhere Anything Anyone” 29
- 30. Conclusion 1 UWB Antennas must be designed by considering the constraints given by FCC 2 Must be small, non-dispersive and capable of receiving all frequencies at the same time 3 Pattern and matching should be stable across the entire band 4 Antenna designer and transceiver designer should work together to ensure the better system results 01/26/19 06:51 30
- 31. Thank You 01/26/19 06:51 31