NARROWBAND INTERFERENCE MITIGATION IN UWB SYSTEMS

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NARROWBAND INTERFERENCE MITIGATION IN UWB SYSTEMS

• MIGLEN OVTCHAROV
• VLADIMIR POULKOV
• GEORGI ILIEV

TECHNICAL UNIVERSITY OF SOFIA Department of
Telecommunications BULGARIA e-mail
vkp_at_tu-sofia.bg, gli_at_tu-sofia.bg
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CONTENTS

• Introduction
• NBI Cancellation Scheme
• Adaptive Narrowband Filtering
• Simulation Model
• Experimental Results
• Conclusions

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INTRODUCTION

• NBI SUPPRESSION
• avoidance of frequencies with strong narrowband
  interferers
• cancellation of narrowband signals
• PROBLEMS
• high precision ADC
• high complexity DSP elements

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NBI CANCELLATION SCHEME
UWB-OFDM Receiver with NBI Cancellation
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NBI CANCELLATION SCHEME

• Adaptive NBI Filtering Scheme (ANF)

Important Issue NBI should be constantly
monitored
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ADAPTIVE NARROWBAND FILTERING
All-pass Circuit
Notch/Bandpass Filter
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ADAPTIVE NARROWBAND FILTERING
Basic Equations
k1 - cos ?0
k1(n1) k1(n) µe(n)x(n-1) y(n-1)
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SIMULATION MODEL
Convolutional Encoder rate 1/2 FFT 256
points OFDM symbol 128 data bins and 2 pilot
tones Modulation 64 QAM or QPSK CHANNEL multipat
h AWGN NBI IEEE 802.15.3a

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EXPERIMENTAL RESULTS

• Fading Channels

NBI SIR -10 dB
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EXPERIMENTAL RESULTS

• NBI Position

NBI Position
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EXPERIMENTAL RESULTS

• NBI Cancellation

NBI Cancellation
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EXPERIMENTAL RESULTS
Different ADC
IEEE 802.15.3a CM1
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EXPERIMENTAL RESULTS
IEEE 802.15.3a CM1
IEEE 802.15.3a CM2
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CONCLUSIONS

• low computational complexity
• mitigation of the NBI is performed at the input
  of the OFDM receiver, before the variable gain
  amplifier
• monitoring of the NBI is straightforward
• fast convergence
• low sensitivity