Appendix G MATLAB Code to get Received Power

167 Pages·2015·5.08 MB·English

Durham E-Theses
Homogeneous Test-bed for Cognitive Radio
CHEEMA, ADNAN,AHMAD
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Homogeneous Test-bed for
Cognitive Radio

by

Adnan Ahmad Cheema

2015
School of Engineering and Computing Sciences,
Durham University, UK
A thesis submitted for the degree of

Doctor of Philosophy
Abstract
In the current frequency allocation scheme, the radio spectrum is found to be
heavily underutilized in time, frequency and space dimensions or any of their
combination. To improve spectrum utilization, the unused contiguous or non-
contiguous portion of the radio spectrum (spectrum hole) can be accessed
opportunistically using cognitive radio technology provided it is interference free to
the local users of the network.
To reliably detect the spectrum holes, which is necessary to limit the
interference, cognitive radio is required to have high time and frequency resolutions
to detect radio technologies (e.g. GSM 900, 2.4 GHz WLAN) at the packet level in
the transmitted channel to avoid misinterpretation of occupancy states in time and
frequency. In addition, having high sensitivity and instantaneous dynamic range can
enable cognitive radio to detect weak received signals and their detection in the
presence of strong received signals. Besides these requirements, a large sensing
bandwidth can increase the chances to find spectrum holes in multiple radio
technologies concurrently.
A chirp channel sounder receiver has been developed according to the
aforementioned requirements with a bandwidth of 750 MHz to provide reliable
detection of received signals in two frequency ranges; 1) 250 MHz to 1 GHz, 2) 2.2
GHz to 2.95 GHz. The developed receiver is capable of finding spectrum holes
having a duration of 204.8 µs and a transmitted channel bandwidth up to 200 kHz. To
explore the spectrum holes in the space dimensions, six chirp channel sounder
receivers have been developed to form a homogeneous test-bed, which can be
deployed and controlled independently.
To experimentally validate the ability of the built receiver, short term
spectrum occupancy measurements have been conducted to monitor 2.4 GHz WLAN
traffic from a real wireless network to quantify the spectrum utilization and duration
of spectrum holes in the time domain. It has been found that the radio spectrum is
underutilized and empirical distribution of the duration of the spectrum hole can be
modelled using lognormal and gamma distributions for prediction using a two state
continuous time semi-Markov model.
To experimentally validate the receiver’s capabilities in both the supported
frequency ranges, long term spectrum occupancy measurements with 750 MHz
sensing bandwidth have been performed and received signals have been detected at
frame or packet level to quantify spectrum utilization. It has been found that the radio
spectrum is highly underutilized at the measurement location and exhibits significant
amount of spectrum holes in both time and frequency.
To experimentally validate the functionalities of the homogeneous test-bed,
short term spectrum occupancy have been performed to monitor 2.4 GHz WLAN
traffic from a real wireless network. The experiment has been conducted using
multiple receivers to quantify the amount of cooperation individual or multiple
cognitive radio users can provide for reliable detection of spectrum holes in time,
frequency and space. It has been found that the space dimension influences strongly
the statistics of cooperation parameters.
Declaration

No part of the work described in this thesis has been submitted in
support of an application for another degree or qualification to this or

any other university o r institute of learning.
Dedication

To my family, specially my life and science companion, Fareena
Acknowledgments
I would like to thank Professor Sana Salous for giving me the opportunity to work on
this exciting research theme, guidance and providing financial support for this PhD.
I would like to thank Dr. Stuart Feeney for the design of analogue circuits,
Nasouruddin for helping in the PCB design, Xavier for discussions and suggestions
on different ideas relating cognitive radio, Odiri for giving updates on world politics
and issues during lunch time, Francesco for discussions on triggering issues and Gao
for always giving big smile. Last but not least, thanks for your long lasting
friendship, cooperation and assistance during the measurement campaigns.
I would like to thank Ian, Neil and Colin from the electronics workshop and Colin
from the mechanical workshop for their support during the hardware development.
I would like to thank the School of Engineering and Computing Sciences, Durham
University, UK for providing partial financial support for this PhD.
In the end, I would like to thank my family for their support and constant
encouragement to complete the voyage of discovery.
List of Abbreviation
CR Cognitive Radio
IDR Instantaneous Dynamic Range
UMTS Universal Mobile Telecommunication system
TV Television
TETRA Terrestrial Trunked Radio
GSM Global System for Mobile
WLAN Wireless Local Area Network
LTE Long Term Evolution
ISM Industrial, Scientific and Medical
CIR Channel Impulse Response
CRN Cognitive Radio Network
FMCW Frequency Modulated Continuous Wave
LOS Line of Sight
PRBS Pseudo Random Binary Sequence
SNR Signal to Noise ratio
STDCC Swept Time Delay Cross Correlation
SAW Surface Acoustic Wave
FFT Fast Fourier Transform
IF Intermediate Frequency
CW Continuous Wave
LO Local Oscillator
ADC Analog to Digital Converter
NI National Instrument
USRP Universal Software Radio Peripheral
VSA Vector Signal Analyzer
BPF Band Pass Filter