[Energy Detection Technique in Spectrum Sensing For Wireless Communications Systems]

By

[Name of the Author]

TABLE OF CONTENTS

CHAPTER 1: INTRODUCTION5

1.1 Background of the Study5

1.1.1 Federal Communications Commission Spectrum Policy Task Force7

1.2 Rationale of the Study9

1.3 Purpose of the Study11

CHAPTER 2: LITERATURE REVIEW13

2.1 Components of a Wireless Network18

2.2 Problems and Limitations21

2.3 Wireless Connections22

CHAPTER 3: METHODOLOGY24

3.1 Research design24

3.2 Research Approach24

3.2.1 Energy Detector Based Sensing25

3.2.2 Waveform-Based Sensing25

3.2.3 Cyclostationarity-Based Sensing25

3.2.4 Radio Identification Based Sensing26

3.2.5 Matched-Filtering26

3.2.6 Other Sensing Methods26

3.2.7 Comparison of Various Sensing Methods26

CHAPTER 4: DISCUSSION AND SIMULATION RESULTS28

4.1 Threshold Calculation through a Predetermined Value of Probability29

4.2 Energy Detection for Known and Unknown Noise Variance30

4.3 Simulation Results31

CHAPTER 5: CONCLUSION35

5.1 Future Perspective36

REFERENCES37

CHAPTER 1: INTRODUCTION

1.1 Background of the Study

The need for higher data rates is increasing as a result of the transition from voice-only communications to multimedia type applications. Given the limitations of the natural frequency spectrum, it becomes obvious that the current static frequency allocation schemes cannot accommodate the requirements of an increasing number of higher data rate devices. As a result, innovative techniques that can offer new ways of exploiting the available spectrum are needed. Cognitive radio arises to be a tempting solution to the spectral congestion problem by introducing opportunistic usage of the frequency bands that are not heavily occupied by licensed users.

While there is no agreement on the formal definition of cognitive radio as of now, the concept has evolved recently to include various meanings in several contexts. In this paper, we use the definition adopted by Federal Communications Commission (FCC) (Federal Communications Commission, 2005): “Cognitive radio: A radio or system that senses its operational electromagnetic environment and can dynamically and autonomously adjust its radio operating parameters to modify system operation, such as maximize throughput, mitigate interference, facilitate interoperability, access secondary markets.” Hence, one main aspect of cognitive radio is related to autonomously exploiting locally unused spectrum to provide new paths to spectrum access.

One of the most important components of the cognitive radio concept is the ability to measure, sense, learn, and be aware of the parameters related to the radio channel characteristics, availability of spectrum and power, radio's operating environment, user requirements and applications, available networks (infrastructures) and nodes, local policies and other operating restrictions. In cognitive radio terminology, primary users can be defined as the users who have higher priority or legacy rights on the usage of a specific part of the spectrum. On the other hand, secondary users, which have lower priority, exploit this spectrum in such a way that they do not cause interference to primary users (Cabric & Brodersen, 2006, pp. 1-7). Therefore, secondary users need to have cognitive radio capabilities, such as sensing the spectrum reliably to check whether it is being used by a primary user and to change the radio parameters to exploit the unused part of the spectrum.

In the majority of cases (excluding the important case of ISM bands), the radio spectrum access is handled by the attribution of a license to a user, often referred to as primary user. Cognitive radio devices can, nevertheless, ...