Studies Of Propagation Impairments For Fixed Satellite Communication Links At The Microwave Frequencies In Nigeria

STUDIES OF PROPAGATION IMPAIRMENTS FOR FIXED SATELLITE COMMUNICATION LINKS AT THE MICROWAVE FREQUENCIES IN NIGERIA

Abstract

The study examines how propagation impediments such rain, clouds, and gases

and tropospheric scintillation on an earth-space path for a fixed satellite communication link

37 places in Nigeria will receive frequencies in the Ku, Ka, and V bands between 10 and 50 GHz. Two

the typical elevation angles of 50 and 550, as well as various elevation angles for links to recently

utilized in the calculation of the Nigerian Communication Satellite (NigComsat-1)

limitations in propagation for the 37 locations. Waves with linear and circular polarization were

considered. The investigation of the propagation impairments employed the International Telecommunication Union Radiowave Propagation models (ITURP). The three sections of the study are as follows: first, the gathering and analysis of weather information from Tropical Rain

Measurement Mission (TRMM) and Atmospheric Infrared Sounder (AIRS) satellites, including rain accumulation, temperature, pressure, and relative humidity profiles, as well as surface temperature and pressure, were confirmed against the available ground data in Nigeria to provide statistics on a monthly and annual basis. Reprocessing these results yields propagation characteristics including integrated water vapour content, total cloud liquid water content, and one-minute rainfall rate. Second, each attenuation distribution for a percentage of time unavailable was calculated using an appropriate ITU-RP propagation model for each propagation impairment. Thirdly, the annual cumulative distribution and percentage of time unavailable between 0.01 and 10% were used to integrate the attenuation due to all limitations. The measured mean annual data at each location during a time span of 4 to 9 years are used to calculate the propagation parameters. Additionally, propagation limitations were calculated for links to NigComsat-1 at 0.01 to 10% of time unavailable throughout the course of an ordinary year. A color chart was used to compare the results of every impairment across all 37 locations in Nigeria. According to the predicted propagation impairments, the regions with the most severe rain attenuation are Abakaliki in the South-East (SE), Yenagoa in the South-South (SS), Ibadan in the South-West (SW), Jos in the Middle Belt (MB), Damaturu in the North-East (NE), and Kastina in the North-West (NW), in that order. Abakaliki, in the SE area, has the most severe cloud attenuation, followed, in descending order, by Jos (MB), Gombe (NE), Dutse (NW), Ikeja (SW), and Calabar (SS). Calabar (SS) is the region with the most severe gas attenuation, followed in descending order by Ikeja (SW), Abakaliki (SE), Abuja (MB), Dutse (NE), and Kastina (NW). Tropospheric scintillation is highest in the Calabar (SS region), then Ikeja (SW), Owerri (SE), Abuja (MB), Dutse (NE), and Kastina (NW) regions, in that order. In Abakaliki (SE region), combined impairments resulting from numerous sources of concurrent atmospheric attenuation are extremely severe.

Uyo (SS), Ikeja (SW), Markudi (MB), Maiduguri (NE), and Katsina (NW) regions are next, in descending order. Yenagoa, in the SS area, is the region with the most severe combined impairments for linkages to NigComsat-1, followed in decreasing order by Owerri, in the SE, Ibadan, in the SW, Jos, in the MB, Damaturu, in the NE, and Katsina, in the NW. Overall, Sokoto and Katsina seem to be suitable sites for fixed satellite earth stations (working at Ku band and higher) because the results consistently demonstrated that the two cities are less impacted by all propagation impairments evaluated.

Text Of The Chapter

heading page I

ii Certification

Commitment iii

iv. Acknowledgments

List of contents

Figures List x

Tables List xii

xvi Abstract

Chapiter 1

1.1 Introduction 1

1.2 The Second Statement of the Issue

1.3 Justification for the study

1.4 Purpose and Goals of the Study 4

Apartment Two

Impairments To Propagation And Measurement Techniques 6

2.1 Single-Particle Scattering and Absorption 6

2.1.1 Scattering Amplitude and Cross Section 7

2.2 Mechanisms that Affect Propagation 8

2.3 Rain-Related Impairment 9

2.3.1 Tropical region rainfall characteristics 9

2.3.2 Cloud 10 Types

Rainfall in Stratiform and Convective Systems 12

2.3.4 Size and shape of a raindrop 13

2.3.5 Models for the size distribution of raindrops

2.3.6 Rain Attenuation Statistics Models 16

2.3.7 Techniques for Measuring Rain Attenuation 18

2.3.8 Source of Rain Data 19

2.3.9 Rain Data Processing 20

2.4.0 A software to calculate the rate of rainfall per minute 21

2.4.1Station height above mean sea level 21

Isotherm height and Rain height are 2.4.2 00C and 22.

2.4.3 Using point rainfall rates, calculate statistics for long-term rain attenuation.

2.4.4 Formula for empirical scaling 27

2.4.5 A Few Geometrical Parameters Useful for Researching Rain Attenuation at

37 stations chosen in Nigeria 27

2.5.1 Cloud-Related Impairment 29

2.5.2 Sources of Cloud Data 30

2.5.3 Processing of Cloud Data 31

2.5.4 Method for SVD, TCC, and IWVC evaluation 31

Surface Water Vapour Density (SVD), 2.5.5, 31

2.5.6 Total columnar water content (TCC) in clouds 32

Integrated Water Vapour Content (IWVC), Section 2.5.7

2.5.8 Computer Program for SVD, TCC, and IWVC 34 Evaluation

2.5.9 Evaluation of Cloud Attenuation Procedure 36

Specific Cloud Attenuation Coefficient 36 2.5.9.1

2.5.9.2 Computer Program for Cloud 37 Attenuation

Impairment by Atmospheric Gases, Section 2.6

Gaseous Specific Attenuation, Section 2.6.1

2.6.2 Sources of Input Data for Gaseous Attenuation 39

2.6.3 Method for Gaseous Attenuation Calculation 41

Gaseous Attenuation Along Slant Paths, Section 2.6.4

Computer application for evaluating gaseous attenuation, version 2.6.5

Tropospheric Scintillation 47, 2.7.1

2.7.1 Models for Predicting Amplitude Scintillation 47

2.7.2 Sources of Input Data for Tropospheric Scintillation Evaluation 48

Procedure for assessing the input parameters, Section 2.7.3

2.7.4 Calculation of amplitude statistics across the long and short terms

larger than 4° 49 elevation angle scintillations

2.7.5 Computer Program for Tropospheric Scintillation Evaluation 51

Methods for Combining Impairments in Propagation 54

Combining several attenuation effects in 2.8.1

Equiprobability Summing, Section 2.8.1

2.8.3 Method of convolution 54

55. 2.8.4 Disjoint summing

2.8.5 Adding the roots of the squares 55

56. 2.8.6 Coherent summing

Prediction of Combined Propagation Effects, Section 2.8.7

Estimation of Total Attenuation from Several Sources Operating Concurrently

Attenuation that occurs in the atmosphere

Section Three

Conclusion And Results

3.0 Nigerian Measured Rainguage Data Validation of TRMM Data 59

3.1 Nine-year Rain Event Results as Captured by the TRMM Satellite at

Locations in Nigeria number 37

3.1.1 Variation from year to year of the one-minute Rain rate computed from TRMM Data 65

3.1.2 Cumulative Rainfall Rate Distribution in Six Regions 68

3.1.3 Evaluation of Related Works 69

Results of Rain Attenuation, Section 3.2

3.2.1 Rain Attenuation for Horizontally Polarized Wave Non-availability at Ku, Ka, and V Bands

at the 37 places in Nigeria for 0.01% on average each year 76

3.2.2 NigComSat-1 at Ku and Ka with 0.1% to 1% Rain Attenuation

availability at none of Nigeria’s 37 locations. 80

3.2.3 Results of Rain Attenuation for NigComSat-1 Links at Ku, Ka, and V Downlink

frequency ranges for a VSAT at 0.01 to 10% Average Unavailability at the 37-

Nigerian places 82

Results of cloud attenuations for a 1% absence of an average year are shown in Table 3.3.

3.3.1 Results of cloud attenuations at the Ku, Ka, and V bands for 1% absence of an

Average Year at the 37 Nigerian Locations 90

Cloud Attenuation for NigComSat-1 Links at Ku, Ka, and V-band for

A typical year’s availability ranges from 0.01 to 10%.

Gaseous attenuation at the 37 locations with a 1% annual average unavailability is 3.4.

99 in Nigeria

Gaseous Attenuations at Ku, Ka, and V Bands for 1% Average Average Unavailability

100 Year at the 37 Nigerian Locations

3.4.2 Gaseous Attenuation at Ku, Ka, and V-bands for Links to NigComSat-1

1% Average Unavailability at 37 Locations in Nigeria 103

37 locations in Nigeria have a 3.5 Scintillation Fade depth for 0.01% unavailability at 50 and 550.

3.5.1 Scintillation Fade Depth for the 0.01% Unavailability at the 37 sites in Nigeria 108

3.5.2 NigComSat-1 Scintillation Fade Depth for Links at Ku and Ka for 0.01 to 10% Unavailability on Average at the 37 Locations in Nigeria 111

For frequencies 10 to 50 GHz at the 37 locations in Nigeria, there is a combined attenuation of 3.6 for a 0.01% annual unavailability rate.

3.6.1 Ku, Ka, and V-band combined attenuation for 0.01% unavailability in an average year at the 37 locations in Nigeria 118

3.6.2 Ku, Ka, and V-band Downlink Attenuation for NigComsat-1 at the 37 Locations in Nigeria from 0.01 to 10% Unavailability in an Average Year 121

Chapiter Iv

Conclusions and Summary 129

4.1.1 Rain Attenuation at 10 to 50 GHz Frequencies 129

4.1.2 Study on Rain Attenuation at NigComSat-1 Links at Ku and Ka from 0.01 to 1%

An average year is unavailable 129

4.2. Cloud Attenuation at 10 to 50 GHz Frequencies 130

4.2.1 Study of Cloud Attenuation for NigComSat-1 Links at Ku and Ka from 0.01 to 1%

Unavailability of a Year 130 on Average

4.3 Gaseous Attenuation Study for Frequencies Between at 1% Unavailability

10 to 50 GHz 130

4.3.1 Study of Gaseous Attenuation for NigComSat-1 Links at Ku and Ka for 1%

Average annual unavailability for the 37 locations: 130

Tropospheric Scintillations Study at 0.1% Average Unavailability

37 Locations in Nigeria, Year for Frequencies 10–50GHz, 130

Study for Links to NigComSat-1 at Ku and Ka for Scintillation Fades Depth

Average Unavailability at the 37 Locations ranges from 0.01 to 10%

4.5 Study of Combined Attenuation at 0.01% Lack of an

Average Year for 10 to 50 GHz Frequencies 131

4.5.1 Findings from a Combined Attenuation Study for Downlinks at the Ku, Ka, and V-bands

On an average year at the NigComsat-1 for 0.01 to 10% Unavailability

37 places in Nigeria are listed.

Conclusions and Recommendations, Section 4.6

134 references

142 Appendix

Number Of Figures

Figure Title Page

1.1 Nigerian map displaying the 37 study locations 5

2.1 A single scattering process is illustrated 7

2.2 Cloud Types 10

The Ten Basic Cloud Types, Section 2.3

Size and form of a raindrop: 2.4

2.5 A schematic of an Earth-space path that provides the input parameters for the attenuation prediction algorithm 24

2.6 A-Train Satellites Illustrated 31

Nigeria’s 37 locations’ cumulative distribution of rainfall rates is shown in Table 3.1.

3.2 Attenuation of Rainfall in Nigeria for 0.01% Unavailability of an Average Year for Horizontal Polarization at 50 Elevation 74

3.3 Attenuation of Rainfall in Nigeria for a 0.01% Unavailability of an Average Year for Horizontal Polarization at 550 Elevation 75

Links to NigComsat-1 at Ku”band (11GHz) have a cumulative distribution of 3.4 rain attenuation of 84.

Distribution of links to NigComsat-1 at Ka”band (20GHz) at 3.5 Rain Attenuation is 85

Links to NigComsat-1 at V”band (40GHz) have a cumulative distribution of 3.6 Rain Attenuation (86).

3.7 Cloud Attenuation for 1% of an Average Year at 50 Elevation at the 37 Locations

3.8 Cloud Attenuation for 1% of an Average Year at the 37 Locations at 550 Elevation 89

3.9 Cloud Attenuation Cumulative Distribution from NigComsat-1 for the 37 locations at Ku (11GHz) downlink Frequency

3.9.1 Cloud Attenuation Cumulative Distribution from NigComsat-1 for the 37 locations 95 at Ka (20GHz) downlink Frequency

3.9.2 Cloud Attenuation Cumulative Distribution from NigComsat-1 for the 37 locations at V (40GHz) downlink Frequency

3.10 Gaseous Attenuation for 1% Unavailability at 50 Elevation 98 at the 37 Location in Nigeria

3.11 Gaseous Attenuation for 1% Unavailability at 37 Locations in Nigeria, Elevation 550

3.12 Tropospheric Scintillation for an Average Year at 50 Elevation 106 in Nigeria for 0.01% Unavailability

Tropospheric Scintillation in Nigeria at 550 Elevation for 0.01% Unavailability of an Average Year 107

3.14 Tropospheric Scintillation Cumulative Distribution from NigComsat-1 for the 37 locations at Ku (11GHz) downlink Frequency 112

3.15 Tropospheric Scintillation Cumulative Distribution from NigComsat-1 for the 37 locations at Ka (20 GHz) downlink Frequency

3.16 Tropospheric Scintillation Cumulative Distribution from NigComsat-1 for the 37 locations at V (40GHz) downlink Frequency

3.17 Attenuation of Horizontal Polarization owing to Cloud, Gases, Scintillation, and Rain in Nigeria at 50 Elevation 116

3.18 Attenuation owing to Rain, Scintillation, Gases, and Clouds in Nigeria

in the case of horizontal polarization at 550 meters 117

3.19 Attenuation owing to combined rain, cloud, scintillation, and gas effects at Ku (11GHz) for links to NigComsat-1 122

For linkages to NigComsat-1 123, 3.20 Combined Attenuation owing to Rain, Cloud, Scintillation, and Gases at Ka (20GHz)

3.21 Combined Attenuation owing to Rain, Cloud, Scintillation, and Gases for Links to NigComsat-1 124 at V (40GHz)

Number Of Tables

Page Title for the Table

1.1 Satellite Communication Frequency Bands

Particles That Cause Atmospheric Scattering, Version 2.0 6

2.1 Rough height ranges where cloud bases are located 11

2.2 A list of the input parameters required by models for predicting rain attenuation 17

2.3 Topographic information: Isotherm of zero degrees, Height above Mean Sea Level (m).

For the 37 places in Nigeria, the height (m) and the height of the rain (km)

2.4 A Few Geometrical Parameters Useful for Researching Rain Attenuation at

For the 37 locations, the elevations were 5 and 55 degrees.

2.5 Summary of the climatic input data for gaseous attenuations and clouds

based on AIRS Satellite data between AUG 2002 and JUL 2006 35

2.6 Summary of the input climatological data for gaseous attenuation computation

based on AIRS Satellite data between AUG 2002 and JUL 2006 40

2.7 Summary of the Climatic Parameters Required for Tropospheric

Using AIRS satellite data, the average value of the scintillation was calculated.

52 months, from August 2002 to July 2006.

2.8 Geometrical Parameters Important for Downlink Scintillation Fade Depth

for the 37 locations, from NigSatcom-1

3.1 Seasonal Variation in Mean Precipitation, Mean Bias Error in Percentage, and

Correlation Coefficients Overall 61

3.1b A comparison between the work’s 3-year mean seasonal rainfall (mm/month) and

additional climate zones in Africa 62

3.2 An overview of rainfall events in Nigeria based on TRMM 3B43V6 data

Jan. 1998 – Dec. 2006 64

3.3 Exceeded for Year-to-Year Variations of One-Minute Rainfall Rates (in mm/h)

Based on data from the TRMM 3B43V6 satellite, 0.01% of an average year:

December 2006 to January 1998 66

3.4 Statistical Analysis of Rainfall Rates Exceeded by 0.01% for One Minute

from TRMM 3B43V6 Data, of an Average Year: Jan 1998-Dec 2006 67

Correlation of Derived One-Minute Rainfall Rates with Other Works, Section 3.5

Rates of Measured One-Minute Rainfall in Tropical and Subtropical Areas

compared to several tropical and subtropical stations worldwide

Study of Nigeria for the Present 72

3.6 Calculated Attenuation due to Rain for Ku, Ka, and

V bands Frequencies for Uplink and Downlink for Horizontal Polarization

Nigeria’s State Capitals 78

3.7 Calculated Attenuation due to Rain for Ku, Ka, and

Horizontal Polarization V bands Uplink and Downlink Frequencies in

Nigeria’s State Capitals 79

3.8 A Few Geometrical Parameters Important to the NigComSat-1 Downlink

Future Communication Frequencies at Ku, Ka, and Extended to V Bands

At 0.01% unavailability, satellites, 81

3.9 Calculated Cloud Attenuation for the Ku, Ka, and V Bands at 50 Elevations

The Nigerian State Capitals’ Uplink and Downlink Frequency 91

3.9.1 Calculated Cloud Attenuation at 55

Ku, Ka, and V band elevations are all zero.

92 Uplink and Downlink Frequency for Nigerian State Capitals

3.10 Results of Gaseous Attenuation for Ku, Ka, and V Bands at 5 Degree Elevations

For the 37 locations in Nigeria, the uplink and downlink frequencies are 101

3.11 Results of Gaseous Attenuation for the Ku, Ka, and V Bands at 55 degree Elevations

For the 37 locations in Nigeria, the uplink and downlink frequencies are 102

3.12 Gaseous Attenuation relevant to NigComSat-1 link at 1% Ku unavailability,

Satellite Bands Ka and V 104

3.13 Tropospheric Scintillation Results for 0.01% at 5 Degrees Elevation

Ku, Ka, and V Bands, Uplink and Downlink Frequencies are unavailable for

the Nigerian State Capitals.

3.14 Tropospheric Scintillation Results for 0.01% at 55 degrees elevation

State Capitals in Nigeria are not accessible at Ku, Ka, or V Band Uplink or Downlink Frequencies. 110

State capitals in Nigeria: 3.15 Combined Attenuations due to Cloud, Gas, Rain, and Scintillation at 50 Elevations for Ku, Ka, and V bands Uplink and Downlink Frequencies for Horizontal Polarization 119

3.16 Attenuations owing to Scintillation, Gas, Rain, and Rain at 55

Ku, Ka, and V band uplink and downlink frequencies have zero elevations for

Nigerian State Capitals’ Horizontal Polarization 120

3.17 Total Attenuations at Ku-bands from Cloud, Gas, Rain, and Scintillation

Nigerian State Capitals’ Horizontal Polarization Downlink from NigComsat-1 126

3.18 Total Attenuations at Ka-bands from Cloud, Gas, Rain, and Scintillation

Nigerian State Capitals’ Horizontal Polarization Downlink from NigComsat-1 127

3.19 Total Attenuations at V-bands Downlink from NigComsat-1 for Horizontal Polarization for the State Capitals in Nigeria 128

4.1 Summary of all Nigerian propagation limitations from 10 to 50 GHz 132

Results of Rain Attenuation for 0.01% Unavailability for Vertical Polarization at 5 degrees Elevation (in dB) 143

Results of Rain Attenuation (in dB) for Circular Polarization with 0.01% Unavailability at 5 degrees elevation 144

Results of Rain Attenuation for 0.01% Vertical Polarization Unavailability at 55 degrees Elevation (in dB) 145

Results of Rain Attenuation (in dB) for Circular Polarization with 0.01% Unavailability at 55 degrees elevation 146

Results of Rain Attenuation for Links to NigComsat-1 at 0.01% Horizontal Polarization Unavailability (in dB) 147

Results of Rain Attenuation for Links to NigComsat-1 at 0.01% Vertical Polarization Unavailability (in dB) 148

Results of Rain Attenuation for Links to NigComsat-1 at 0.01% Circular Polarization Unavailability (in dB) 149

Functions in A8 Matlab 7.0 for Computing the Climate-Related Input Parameters Required for Propagation Studies 150

Functions for Calculating Attenuations Due to Rain, Gas, Cloud, and Tropospheric Scintillation in Matlab 7.0 A9

A10 Programs in Matlab 7.0 for Calculating the Climate Input Parameters Required for Propagation Studies 152

Programs in Matlab Version 7.0 for Calculating Attenuations Due to Rain, Gas, Cloud, and Tropospheric Scintillation

Instruments and Flight Characteristics for the A12 TRMM 167

A13 Features of NigComsat-1 170