ABSTRACT
The aim of this project, the design and implementation of an RF communication link, is to design a communication link between a source and a destination and study the properties of the signal being generated by the source (generator). The area of interest in this work is how the signal suffers limitations like attenuation, interference and distortion etc and to observe how these limitations affect the smooth transmission of the signal as well as the amplitude of the transmitted signal. This study was implemented using simulink and it was discovered that the higher the pathloss, that is, the higher the effect of attenuation, distortion etc, the lower the amplitude. Therefore, for a better signal, that is, with high amplitude, there should be a minimal or no effect of the aforementioned limitations. Also, the maximum Doppler shift of the channel can be varied to achieve desired signal amplitude. In this project, observation has shown that, the higher the maximum Doppler shifts of the Rayleigh channel, the higher the amplitude and the stronger the signal strength.
TABLE OF CONTENTS
Cover Page - - - - - - - - - i
Title Page - - - - - - - - - ii
Approval Page - - - - - - - - - iii
Certification - - - - - - - - - iv
Dedication - - - - - - - - - v
Acknowledgement - - - - - - - - vi
Abstract - - - - - - - - - vii
Table of Contents - - - - - - - - viii
List of Figures/Tables - - - - - - - - xi
CHAPTER ONE
1.0 Introduction to Radio Frequency Communication Link - - 1
1.1 Elements of Radio Frequency Communication Link - - - 1
1.1.1 Free Space Communication - - - - - - 1
1.1.2 Radio Frequency - - - - - - - 1
1.1.3 Transmitter - - - - - - - - 2
1.1.4 Transmission Medium - - - - - - 2
1.1.4.1 Rayleigh Channel - - - - - - - 2
1.1.4.2 Binary Symmetric Channel (BSC) - - - - - 3
1.1.4.3 AWGN Channel (Additive White Gaussian Noise) - - - 3
1.1.4.4 Rayleigh Distribution - - - - - - - 3
1.1.5 Distortion - - - - - - - - 3
1.1.6 Random Signals - - - - - - - 4
1.1.7 Receiver - - - - - - - - 4
1.2 Problem Definition - - - - - - - 4
1.3 Development of System Block Diagram - - - - 5
1.3.1 Rayleigh Channel Link - - - - - - 5
1.3.2 Factors Influencing Radio Frequency Communication Link - - 6
CHAPTER TWO
2.0 Radio Frequency Communication Link Theory - - - 8
2.1 Antenna Gain - - - - - - - - 10
2.2 Noise Link Equation in Rayleigh Channel - - - - 10
2.3 Properties of Rayleigh Channel in Free Space - - - 11
2.3.1 Attenuation - - - - - - - - 11
2.3.2 Noise - - - - - - - - - 12
2.3.3 Interference - - - - - - - - 13
2.4 Free Space Rayleigh Propagation Channel - - - - 13
2.4.1 Transmitting Antenna Gain - - - - - - 15
CHAPTER THREE
3.0 Design Consideration - - - - - - - 16
3.1 Mathematical Analysis of Rayleigh Channel Model Link - - 16
3.1.1 Transmitting Link Noise in Rayleigh Channel - - - 17
3.1.2 Receiving Link Noise in Rayleigh Channel - - - - 18
3.1.3 Raleigh Channel Attenuation Loss - - - - - 18
3.1.4 Carrier-to-Noise Ratio of Link Design at the Transmitter - 19
3.1.5 Carrier-to-Noise Ratio of Link Design at the Receiver - - 19
3.1.6 Transmitting Parameters for RAYLEIGH Link Design - - 19
3.1.7 Transmitter Antenna Gain (Gt) - - - - - 20
3.1.8 Transmitting Power (Pt) - - - - - - 21
3.1.9 Transmitting Frequency in Rayleigh Channel Link - - - 22
3.1.10 Transmitting Signal Energy Link for Rayleigh Channel - - 23
3.2 Receiving Signal Energy for Rayleigh Channel - - - 23
3.3 Free Space Pathloss (PL), Between the Transmitter and Receiver - 25
3.3.1 Rayleigh Channel Attenuation Loss - - - - - 25
3.3.2 For Rayleigh Doppler Shift - - - - - - 26
3.4 Analysis of Receiving Attenuation and Noise Increase on Link Design 27
3.5 Link Design and Analysis - - - - - - 27
3.5.1 Input - - - - - - - - - 27
3.5.2 Random Integer Generator - - - - - - 28
3.5.3 DBPSK - - - - - - - - 28
3.5.4 Complex to Real-Imag 1 - - - - - - 29
3.5.5 Scope 2 - - - - - - - - 29
3.5.6 Rayleigh Channel - - - - - - - 30
3.5.7 Free Space Pathloss - - - - - - - 30
3.5.8 Complex to Real Imag 2 - - - - - - 30
CHAPTER FOUR
4.0 Implementation Model - - - - - - 32
4.1 Analysis of Simulink Blocks - - - - - - 32
4.1.1 Input - - - - - - - - - 32
4.1.2 DBPSK - - - - - - - - 33
4.1.3 Rayleigh Fading Channel - - - - - - 33
4.1.4 Complex to Real-Image 1 - - - - - - 34
4.1.5 Scope - - - - - - - - - 34
4.2 Simulink Connection - - - - - - - 34
4.3 Simulation of Rayleigh Link - - - - - - 35
4.4 Interpretation of Results - - - - - - 36
4.4.1 The Comparison of the Input and Output Waveforms for 0dB, 1dB, 3dB
and 7dB Pathloss at 0.1MHz Maximum Doppler Shift - - 38
4.4.2 Comparison of the Input and Output Signals for 0dB, 3dB and 7dB Pathloss
at 0.05MHz Maximum Doppler Shift - - - - - 44
CHAPTER FIVE
5.0 Conclusion - - - - - - - - 52
5.1 Recommendations - - - - - - - 53
References - - - - - - - - - 54
LIST OF FIGURES/TABLES
List of Figures
Fig. 1.1: Development of System Block Diagram - - - - 5
Fig. 1.2: Block Diagram for Rayleigh Channel - - - - 5
Fig. 2.1: Transmission Antenna - - - - - - 14
Fig. 3.1: Impulse Response of Rayleigh Channel - - - - 16
Fig. 3.2: The Design of Simulink Block for Rayleigh Channel - - 31
Fig. 4.1: Input Waveform for Rayleigh Channel - - - - 36
Fig. 4.2: Output Waveform for Rayleigh Channel at 7dB - - - 37
Fig. 4.3: Input and Output Waveforms for Rayleigh Channel at 0dB Pathloss and
0.1MHz Max. Doppler Shift - - - - - - 40
Fig. 4.4: Input and Output Waveforms for Rayleigh Channel at 1dB Pathloss and
0.1MHz Max. Doppler Shift - - - - - - 41
Fig. 4.5: Input and Output Waveforms for Rayleigh Channel at 3dB Pathloss and
0.1MHz Doppler Shift - - - - - - 42
Fig. 4.6: Input and Output Waveforms for Rayleigh Channel at 7dB Pathloss and
0.1MHz Doppler Shift - - - - - - 43
Fig. 4.7: Input and Output Waveforms for Rayleigh Channel at 0dB Pathloss and
0.05MHz Doppler Shift - - - - - - 47
Fig. 4.8: Input and Output Waveforms for Rayleigh Channel at 1dB Pathloss and
0.0.5MHz Doppler Shift - - - - - - 48
Fig. 4.9: Input and Output Waveforms for Rayleigh Channel at 3dB Pathloss and
0.05MHz Doppler Shift - - - - - - 49
Fig. 4.10: Input and Output Waveforms for Rayleigh Channel at 3dB Pathloss and
0.1MHz Doppler Shift - - - - - - 50
List of Tables
Table 4.1: Input Table for Rayleigh Channel Waveform - - - 36
Table 4.2: Output Table of Rayleigh Channel Link at 7dB - - - 37
Table 4.3: For Input and Output Waveform at 0.1MHz for 0dB - - 39
Table 4.4: For Input and Output Waveform at 0.1MHz for 1dB - - 39
Table 4.5: For Input and Output Waveform at 0.1MHz for 3dB - - 39
Table 4.6: For Input and Output Waveform at 0.1MHz for 7dB - - 40
Table 4.7: Comparing and Contracting the Input and Output Signals at 0.1MHz Max.
Doppler Shift - - - - - - 44
Table 4.8: For Input and Output Waveform at 0.05MHz for 0dB - - 45
Table 4.9: For Input and Output Waveform at 0.05MHz for 1dB - - 45
Table 4.10: For Input and Output Waveform at 0.05MHz for 3dB - - 46
Table 4.11: For Input and Output Waveform at 0.05MHz for 7dB - - 46
Table 4.12: Comparing and Contrasting the Input and Signals at 0.05MHz Max.
Doppler Shift- - - - - - - - 51
