Ultra wide band

ELITEX 2007 Seminar on 1Oth January 2007

Ultra Wide Band (UWB) Technology & Its Applications

byDr.A.T.Kalghatgi

Chief ScientistCentral Research LaboratoryBharat Electronics Limited.,Bangalore


Overview

• Trends that drive short range wireless• Definition of UWB• Advantages of UWB• Applications of UWB• UWB Challenges


• The growing demand for wireless data capability in portable devices at higher bandwidth

• Crowding in the spectrum that is segmented and licensed by regulatory authorities in traditional ways.

• The growth of high-speed wired access to the Internet in enterprises, homes, and public spaces.

• Shrinking semiconductor cost and power consumption for signal processing.

Trends that are driving short-range wireless


Communication using Pulse

A pulse is narrow in time and wideband in frequency

Sinusoidal signals are narrow in frequency and "wide" over time


Narrow band ProblemsNarrowband Problems• Multipath fading-Destructive interference of CW signals causes signal loss• Insecure-Narrow Band signals are easily detected and jammed• Poor range resolution-Range resolution for tracking applications is a function of RF bandwidth • Limited data rate-Narrow RF bandwidth means narrow data bandwidth


The UWB solution•Ultimate in spectrum spreading

•GHz of RF bandwidth•Has all the advantages of spread spectrumBut to a much larger extent

•Immune to multipath fading•Virtually undetectable•Unprecedented range resolution•Potential for very high data rates

•Simple to implement•High capacity


Comparison of UWB vs Spread Spectrum and Narrow Band


Definition of UWB

Conventional Definition- Short Pulse • “Carrier Free”,”Baseband” or “Impulse based”• Typically only a Free RF Cycles - Large fractional bandwidth (BW/f)• Very low duty cycles resulting in low average energy densities • Typically generated by impulse or step excited antennas and filters


UWB Pulse Waveforms


UWB Fractional BandwidthAs per FCC guidelines UWB fractional bandwidth is defined by,

Where:fu = upper –10 dB pointfl = lower –10 dB point Either 25% fractional bandwidth criteria should be met or the instantaneous bandwidth of 500 MHz.


Multi Band OFDM


FCC Emission Requirements


Comparison of occupied bandwidths by UWB and other

wireless technologies


Comparison of Spatial Capacity


Comparison of Spatial Capacity of Various Indoor Wireless System

System Maximum Data Rate

[Mbps]

Transmission Distance

[m]

Spatial Capacity [kbps/m2]

Spectral Capacity [bps/Hz]

UWB 100 10 318.3 0.013IEEE

802.11a54 50 6.90 2.7

Bluetooth 1 10 3.2 0.012802.11b 11 100 0.35 0.1317


Comparison of UWB bit rate with other wired and wireless

standardsSpeed (Mbits/second)

Standard

480 UWB,USB2.0200 UWB(4m minimum),1394a (4.5m)110 UWB(10m minimum)90 Fast Ethernet54 802.11a20 802.11g11 802.11b10 Ethernet1 Bluetooth


UWB Major Application Areasa) Communications–Wireless Audio, Data & Video Distribution–RF Tagging & Identification b) Radar–Collision/Obstacle Avoidance–Precision Altimetry–Intrusion Detection (“see through wall”)–Ground Penetrating Radar c) Precision Geolocation–Asset Tracking–Personnel localization


Some of Military & Commercial Applications of UWB


Source:MSSI


Voice and Data Communications

•With increasing congestion in the radio spectrum from communications appliances of all forms, new schemes for allowing more users in a given area are always sought. •UWB allows users to simultaneously share the spectrum with no interference to one another and to apply it in UWB devices, such as high-speed home and business networking devices as well as storage tank measurement.


Ground and Ice Penetrating RADAR

• A system used to detect objects buried in the ground. •A special directional antenna to transmit the stimulus signal into the ground and receive the reflected waves. •Depth of penetration is typically between 0.5 and 10 m, very short pulses are needed to resolve typical buried targets.


Wall Imaging Radar System

•To detect the location of objects contained within a "wall," such as a concrete structure, the side of a bridge, or the wall of a mine. •Operation is restricted by FCC to law enforcement, fire and rescue organizations, to scientific research institutions, to commercial mining companies, and to construction companies.


Through Wall Radar System•Uses very short pulses to provide

detection of objects on the opposite side of a non-metallic wall. •The stimulus signal is transmitted into the wall. A portion of the signal incident on the wall is transmitted through the wall and into the space on the far side.•Objects in the field then reflect the signal back to the wall where part of the signal is transmitted through the wall to the receiver. •Freq of Operation: below 960 MHz or 3.1-10.6 GHz band.


Surveillance Systems•UWB based Surveillance systems operate as "security fences" by establishing a stationary RF perimeter field ("bubble") and detecting the intrusion of persons or objects in that field. •"Bubble" can be established to cover either certain area or certain object, such as aircraft, vehicle etc. •Frequency band 1.99-10.6 GHz.


Vehicular Radar SystemsPotential applications include• collision avoidance,• proximity aids, •intelligent cruise control systems, •improved airbag activation •& suspension systems that better respond to road conditions. •FCC limits operation of vehicular radar to the 22-29 GHz band using directional antennas on terrestrial transportation vehicles provided the center frequency of the emission and the frequency at which the highest radiated emission occurs are greater than 24.075 GHz.


Fluid Level Measurements

UWB distance measuring hardware can be used as an electronic dipstick, to determine the level of a fluid in a tank by measuring the distance between the top of the tank and the interface with the surface of the fluid.


Asset Location• Another form of data communications. • Up-to-date inventory of assets in a given location. • A coded transmitter can be attached to each asset for instantaneous inventory control. • Not only can determine the presence of a particular object, but also provides information as to its exact location.


ID Tags•Similar to asset tracking, ID tags can be used to wirelessly identify individuals with issued ID tags. •Other applications are Intelligent Transportation Systems, Electronic Signs and Smart Appliances


UWB can enable a wide variety of WPAN applications.

• Replacing IEEE1394 cables between portable multimedia CE devices, such as camcorders, digital cameras, and portable MP3 players, with wireless connectivity• Enabling high-speed wireless universal serial bus (WUSB) connectivity for PCs and PC peripherals, including printers,scanners, and external storage devices• Replacing cables in next-generation Bluetooth Technology devices, such as 3G cell phones, as well as IP/UPnP-based connectivity for the next generation of IP-based PC/CE/mobile devices• Creating ad-hoc high-bit-rate wireless connectivity for CE,PC, and mobile devices


PC Clusters interconnected thru UWB enabled Wireless USB


UWB Key Design Challenges• Co-existence with other services Strong narrow band interference • Shaping of spectrum of the TX signal (impulse radio, multi-band OFDM based UWB etc.)• Practical and Simple Receiver Design (Synchronisation/Coherent or non coherent receiver design)• Wideband RF components (antenna,LNA etc.)• Time Domain response of antenna is important since the antenna shapes the pulse•Antennas for impulse radio can no longer be optimized at the carrier frequency•Flat group delay so that high and low frequency signals arrive simultaneously

• High Sampling rate ADCs for digital implementations


For UWB technology to become a widely adopted radio solution, a few key areas need to be resolved:•Performance (including over-the-air data rate performance, power consumption, co-existence with other wireless devices, immunity to interference, and link robustness)•Interoperability•Time-to-market considerations•Ease of product integration and certification•Overall solution cost (to the OEM)•Fulfillment and support•Quality of service•Global spectrum allocation

Other Challenges for UWB


Thank You