• Abstract and Figures
• Public Full-text

MINIMIZATION OF RADIATION EXPOSURE FROM MOBILE PHONE BASE STATIONS BY POWER CONTROLLING AND COORDINATED MULTIPOINT JOINT TRANSMISSION by Molla Md. Zubaer A thesis submitted in partial fulfillment of the requirements for the Degree of MASTER OF SCIENCE IN ELECTRICAL AND ELECTRONIC ENGINEERING Department of Electrical and Electronic Engineering Bangladesh University of Engineering and Technology July 2017 Approval Certificate The thesis titled “Minimization of Radiation Exposure from Mobile Phone Base Stations by Power Controlling and Coordinated Multipoint Joint Transmission” submitted by Molla Md. Zubaer, Roll No – 0411062256, Session: April, 2011 has been accepted as satisfactory in partial fulfillment of the requirements for the degree of Master of Science in Electrical and Electronic Engineering on 31 July, 2017. Board of Examiners …………………………………… 1. Dr. Md. Forkan Uddin Chairman Associate Professor, Department of EEE, BUET, Dhaka (Supervisor) …………………………………… 2. Dr. Quazi Deen Mohd Khosru Member Professor and Head, Department of EEE, BUET, Dhaka (Ex-Officio) …………………………………… 3. Dr. Satya Prasad Majumder Member Professor, Department of EEE, BUET, Dhaka …………………………………… 4. Dr. Md. Saiful Islam Member Professor, IICT, BUET, Dhaka (External) i DECLARATION I, hereby declare that this thesis is based on the results found by myself. Materials of work found by other researchers are mentioned by reference. This thesis, neither in whole nor in part, has been previously submitted for any degree. Signature of the Candidate ……………………. Molla Md. Zubaer ii DEDICATION To the people and creations, who are affected by radiation exposure. iii ACKNOWLEDGEMENT First and above all, I praise the Almighty Allah, the Creator and the Guardian and to whom I owe my very existence. I am grateful to Him for providing me the opportunity and granting me the competence, fortitude and courage to proceed with my research. His constant grace and compassion was with me throughout my life and even more during this whole time of my research period. I would like to express my deepest thanks to my supervisor Dr. Md. Forkan Uddin, Associate Professor, Department of EEE, BUET, for accepting me as his student and for the thoughtful guidance, warm encouragement, critical comments and corrections he has given me throughout my tenor of research. I am exceptionally lucky to have a caring, considerate and attentive supervisor like him. He is a man of knowledge and principles, who has enormously guided me to reach my goal successfully with my research. I would also like to express my gratitude to the members of my thesis examination board, Dr. Quazi Deen Mohd Khosru, Dr. Satya Prasad Majumder and to Dr. Md. Saiful Islam for their excellent advices, detailed reviews and comments on my research work. I am thankful to my colleagues who have helped and provided me sufficient support for successful completion of my research. Most significantly, my research would not be completed without the continuous support and encouragement of my family members. I would like to express my heartfelt thanks to my family. iv ABSTRACT Radiation hazard from rapidly increasing BSs of cellular communication network is a burning issue of the day. A significant number of studies have been done on the effect of electromagnetic radiation. The number of research work on measuring the power density from mobile phone BSs is also notable whereas the research on the reduction of radiation from mobile phone BSs is insignificant. There are few ideas available to reduce radiation i.e., power control, use of distributed antenna system (DAS) and coordinated multi point joint transmission (CoMP-JT). However, there is hardly any study on how to use these techniques and how much radiation can be reduced by applying these techniques. In this thesis, the problem of reduction of radiation from mobile phone BSs is considered. For the study, a hexagonal cellular system with downlink traffic and frequency division duplex (FDD) technique is considered. First, the traditional cellular system is considered where all the BSs use the same transmission power. An analytical model is used to determine radiation exposure to the cell phone users. Applying this model in a typical cellular network, it is found that the radiation exposure from mobile phone BSs is significant. The effects of antenna height and traffic intensity on the radiation exposure are also studied. The safe distances under various standards are also determined for a given BS transmit power. Next, power control and user scheduling problems are considered for the reduction of radiation exposure to the users. An algorithm is developed for configuring the transmit power and user scheduling to reduce the power density to the users by satisfying the required downlink traffic of the users. The performance of the algorithm is evaluated and demonstrated that the algorithm is very effective in reducing power density to the mobile phone users. It is found that the radiation density under proposed algorithm is approximately 1/106 times of that of the traditional system. Finally, CoMP-JT technique is considered to reduce radiation exposure from mobile phone BSs. An algorithm is developed to configure the transmit power and CoMP-JT scheduling to reduce radiation exposure to the mobile phone users by satisfying the traffic requirement of the users. The performance of the developed algorithm is evaluated and found to be effective. It is also found that the developed algorithm can help in the reduction of a significant amount of radiation exposure when the edge users are located at equidistance from the BSs. v CONTENTS APPROVAL CERTIFICATE i DECLARATION ii DEDICATION iii ACKNOLEDGEMENT iv ABSTRACT v Contents vi List of Tables x List of Figures xi List of Symbols xiii List of Abbreviation xiv 1. CHAPTER 1 : Introduction 1 1.1 Cellular Communication System 1 1.2 Base Transceiver Station (BTS) Installation and Operation 4 1.3 Frequency and power uses in cellular systems. 5 1.4 Antenna System Cellular Networks 6 1.5 Radiation Exposure From Cellular System and its Effect 6 1.6 Standards of Radiation Exposure and Practices in Different Countries 7 1.6.1 Science-based Limits 8 vi 1.6.2 Precautionary limits 9 1.6.3 IEEE Standards 11 1.7 Radiation in Traditional Cellular System 12 1.8 Coordinated Multipoint(CoMP) 12 1.8.1 Coordinated Scheduling/Beamforming (CS/CB) 12 1.8.2 Joint Processing (JP-CoMP) 13 1.9 Reduction of Radiation in Cellular system 15 1.10 Motivation 16 1.11 Contributions 17 1.12 Outline of the Thesis 17 2. CHAPTER 2 : Related Work 18 2.1 Estimation of Radiation Exposure 18 2.2 Reduction of Radiation 19 2.3 Summary 19 3. CHAPTER 3 Radiation Exposure in Traditional Cellular System 20 3.1 Network architecture 20 3.1.1 User distribution 20 3.1.2 BS distribution 20 3.2 Traffic Model 20 3.3 Frequency distribution 21 3.4 Transmission scheme 21 3.5 Radio Frequency ( RF) Propagation Model 21 3.6 RF radiation exposure model 22 3.7 Data Rate Model 22 3.8 Analytical Model to Determine Radiation Exposure 22 3.9 Model to Calculate τ푖 23 3.10 Results 23 3.10.1 Network and system parameter 23 vii 3.10.2 Radiation Exposure 25 3.10.3 Variation of Radiation Exposure due to Changing the BS Antenna Height 27 3.10.4 Safe Radiation for Radiation Exposure 28 3.10.5 The Effect of Downlink Traffic on Power Density 29 3.11 Summary 31 4. CHAPTER 4: Reduction of Radiation by Power Controlling 32 4.1 System Model 32 4.2 Scheduling and Power Allocation Algorithm 32 4.2.1 Transmission Time of User 32 4.2.2 Total Transmission Time in a BS 33 4.2.3 Transmission Time Allocation to a User 33 4.2.4 Power Allocation for Transmission to a User 35 4.3 Analysis of Radiation Exposure under the Proposed Scheduling and Power Allocation Algorithm 35 4.4 Results 36 4.4.1 Comparison with the Traditional System 36 4.4.2 Comparison of Radiation of the Proposed Algorithm with another Existing Scheme 38 4.4.3 Reduction of Radiation Exposure 39 4.5 Summary 39 5. CHAPTER 5: Reduction of Radiation by CoMP-JT 40 5.1 Network Architecture 40 5.2 Selection of Users for CoMP-JT 40 5.3 Measurement of Channel Rate for Selected User without CoMP-JT 41 5.4 Measurement of Channel Rate for Selected User with CoMP-JT 41 5.5 Calculation of The Transmission Power for CoMP-JT 41 5.6 Comparison of Radiation Exposure between Individual Transmission vs . CoMP-JT Transmission. 42 5.7 Results and Discussion 42 5.8 Summary 50 viii 51 6. CHAPTER 6: Conclusion and Future Works 51 6.1 Conclusion 51 6.2 Future Works 52 6.2.1 Optimization of the Proposed Algorithms 52 6.2.2 Impact of Fading and Shadowing on the Proposed Algorithms 6.2.3 Impact of Sectoral Antenna and Directivity Gain on the Proposed 52 . Algorithm 6.2.4 Reduction of Radiation Exposure Based Proposed Algorithms by 52 Applying Available Modulations and Channel Capacity . REFERENCES 53 ix List of Tables Table 1.1: TRX power class and RF power output Table 1.2: Country with RF Exposure Limit Table 1.3: Radiation exposures limits of various Organizations Table 1.4: Radiation exposures limits of various Counties Table 1.5: MPE Limits for Controlled Environments Table 1.6: MPE Limits for Uncontrolled Environments Table 1.7: Radiation exposure from Traditional Cellular system for Pt=20W and Gt=17dBi Table 3.1: System Parameters Table 4.1: System Parameters Table 5.1: System Parameters x List of Figures Fig 1.1: A Typical Cellular Network with its Subsystems. Fig 1.2: Covering area of different types of cells.

Load more

  74

Copy Link