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Interference Effects of Multi-User Ultra-wideband Systems

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Operates below noise floor of narrowband devices. Possibility of 500Mbps short range ... I attempt to develop a model representing the noise level in a victim ... – PowerPoint PPT presentation

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Title: Interference Effects of Multi-User Ultra-wideband Systems


1
Interference Effects of Multi-User Ultra-wideband
Systems
  • Anup Doshi
  • Carnegie Mellon University
  • Advisor Dr. Carl Baum

Introduction
Random-Distance Model
  • Transmitters uniformly distributed over a
    circular area, accounting for near-field effects

What is Ultra-wideband?
Models and Results
  • Short impulses in succession
  • Bandwidth gt 25 of center frequency
  • Used computer simulation to produce results
  • Probability of Outage and Expected Time of Outage
    both increase dramatically when units are
    distributed within circular area
  • Max and mean power levels rise above allowed
    interference levels quickly as number of units
    increases

Transmitters Noise Level
  • Model each transmitter as turning on and off in a
    2-state Markov Process
  • Total Number of units on is a Markov Chain
  • Noise from each transmitter can be modeled as
    Gaussian Noise
  • Total NoiseN0M(t)N1

Time until onExp(?) Time until offExp(µ) Rho
?/µ
(µ1)
  • Low power levels spread over large spectrum
  • Operates below noise floor of narrowband devices
  • Possibility of gt500Mbps short range

Ambient Noise Floor (kTw)
Power Received at Victim from UWB Signal
(µ10)
Total Number of Units On
Number of Transmitter Units On
  • Numerous Applications
  • Personal Area Networks
  • Entertainment
  • Computing Devices
  • Through-wall Imaging
  • Sensor Networks

Constant-Distance Model
  • All transmitters a constant distance away from
    receiver

Source Intel
  • Average Probability of Error
  • Not very insightful because
  • of averaging

Problem
Conclusions
  • Multiple transmitters will cause major problems
    in worst cases
  • Such situations may soon arise in real-life
    situations
  • Important to consider every possible case in
    testing
  • Acknowlegdements
  • Dr. Baum, Dr. Noneaker, Dr. Xu, NSF
  • What happens when lots of UWB devices are
    transmitting in close proximity?
  • Will the combined noise level be too much for a
    victim narrowband receiver?
  • I attempt to develop a model representing the
    noise level in a victim receiver to determine
    interference levels

(µ1)
  • Probability of Outage
  • P(outage)Pr(Perrgt.01)
  • Expected Time of Outage

(µ10)
(µ1)
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