Harbin Institute of Technology (Weihai) 1 Chapter 5 Transmitter Design  5.1 I-UWB signal generators  5.2 Modulators  5.3 I-UWB transmitters  5.4 MC-UWB transmitters  5.5 Spectral encoded UWB communication system

Harbin Institute of Technology (Weihai) I-UWB signal generators  Avalanche( 雪崩 )Pulse Generators  A transistor driven into avalanche breakdown can produce a very fast-rise time pulse.  The device is biased somewhere between BV CEO and BV CEX with the base biased at zero volts or a small negative voltage.

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5 Question:  What can we do if a positive UWB signal is requested?

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7  Step Recovery Diode ( 阶跃恢复二极管 ) Pulse Generators

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10  Tunnel Diode Pulsers  Pulse Circuits Suitable for Integrated Circuits

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Harbin Institute of Technology (Weihai) 13  Differential circuits, the H bridge Gaussian Doublet

Harbin Institute of Technology (Weihai) 14  Programmable CMOS pulse generator

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Harbin Institute of Technology (Weihai) Modulators  Carrier-based system  Amplitude modulation or on/off keying(OOK)  Pulse position modulation (PPM)  Biphase pulse polarity modulation (antipodal PAM)  Pulse width modulation (PWM)

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Harbin Institute of Technology (Weihai) I-UWB transmitters  Time-hopped pulse position modulation (TH-PPM)  Optical orthogonal coded PPM (OOC-PPM)  Direct sequence spread spectrum modulation (DS)  Transmitted reference (TR)  Pilot waveform assisted modulation (PWAM)

Harbin Institute of Technology (Weihai) 19 Time-hopped pulse position modulation (TH-PPM)

Harbin Institute of Technology (Weihai) OOC-PPM

Harbin Institute of Technology (Weihai) DS-UWB

Harbin Institute of Technology (Weihai) Transmitter Reference (TR) UWB

Harbin Institute of Technology (Weihai) MC-UWB transmitters  A single data stream is split into multiple parallel data streams of reduced rate, with each stream transmitted on a separate frequency (subcarrier).  Each carrier is modulated at a low enough rate to minimize inter-symbol interference (ISI).  Subcarriers must be properly spaced so that they do not interfer.

Harbin Institute of Technology (Weihai) 24  For a N subcarrier system, each subchannel is tolerant of N times as much dispersion as the original single carrier system.  MC-UWB use orthogonal UWB pulse trains and multiple subchannels to achieve reliable high bit rate transmission and spectral efficiency.  Advantages: better time resolution->better performance in multipath fading channels; better spectrum utilization->higher bit rate communications; simple decoupled system design->simple transmitter implementation

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Harbin Institute of Technology (Weihai) OFDM-UWB signals

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Harbin Institute of Technology (Weihai) 29 Multi-band OFDM UWB Solution for IEEE a WPANs Marilynn P. Wylie-Green, Pekka A. Ranta and Juha Salokannel Nokia Research Center, P.O. Box 407, FIN Nokia Group, Finland.

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Harbin Institute of Technology (Weihai) 31 IEEE P /268r2

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Harbin Institute of Technology (Weihai) Spectral encoded UWB system  A multiple access scheme with interference suppression capability  Transmitted signal spectrum can be conveniently shaped to suppress NBI.  Signal will be spread in time

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