1 research outputs found
무μ μ€κ³ λ€νΈμν¬μμ μ νΈλμ‘μλΉμ λμ λΆν¬ν¨μ κΈ°λ° μ€κ³κΈ° μ ν κΈ°λ²μ μ±λ₯ λΆμ
νμλ
Όλ¬Έ (λ°μ¬)-- μμΈλνκ΅ λνμ : μ κΈ°Β·μ»΄ν¨ν°κ³΅νλΆ, 2015. 8. μ΄μ¬ν.무μ μ€κ³ κΈ°μ μ μ°¨μΈλ 무μ ν΅μ μμ€ν
μμ μꡬλλ λμ μλΉμ€ νμ§ λ° λ°μ΄ν° μ μ‘λ₯ λ¬μ±μ μν΄ κ³ λ €λκ³ μλ λνμ μΈ κΈ°μ μ€ νλμ΄λ€. 무μ μ€κ³ κΈ°μ μ΄ κ°κ³ μλ λ€μν μ₯μ μΌλ‘ μΈν΄ νμ¬κΉμ§ IEEE 802.16j λ° 3GPP LTE-Advanced λ±μ 무μ ν΅μ μμ€ν
νμ€μ λ°μλκΈ°λ νμλ€.
μ€μ§μ μΌλ‘ λ λ
Έλ μ¬μ΄ μ±λμ ν΅κ³μ νΉμ±μ κ·Έλ€μ μμΉμ λ°λΌ λ¬λΌμ§κΈ° λλ¬Έμ κ° μ±λλ€μ ν΅κ³μ νΉμ±μ μλ‘ λμΌνμ§ μλ€. κ° μ±λλ€μ ν΅κ³μ νΉμ±μ΄ λμΌνμ§ μμ λ, 무μ μ€κ³ κΈ°μ μμ κ°μ₯ μ μ©ν κΈ°λ² μ€ νλμΈ μ€κ³κΈ° μ ν κΈ°λ²μ νΉμ μ€κ³κΈ°λ€μ΄ λ μμ£Ό μ νλλ λ±μ 곡μ μ± λ¬Έμ λ₯Ό μ λ°μν¬ μ μλ€. νΉν, μ΄ λ¬Έμ λ μ νλ λ°°ν°λ¦¬λ₯Ό κ°μ§ μ€κ³κΈ°λ€λ‘ ꡬμ±λ λ€νΈμν¬μμ λ€νΈμν¬μ μλͺ
μ μ€μ΄κ² νλ μμΈμ΄ λ μ μλ€. λ°λΌμ μ΄λ¬ν λ€νΈμν¬μμλ μ¬μ©μλ€μ ν΅μ μ λ’°λ λΏλ§ μλλΌ, μ€κ³κΈ°μμμ μ ν 곡μ μ±λ ν¨κ» κ³ λ €ν νμκ° μλ€.
λ³Έ λ
Όλ¬Έμμλ 무μ μ€κ³ λ€νΈμν¬μμ μ¬μ©μλ€μ ν΅μ μ λ’°λμ μ€κ³κΈ° κ°μ μ ν 곡μ μ±μ ν¨κ» κ³ λ €νκΈ° μν΄ μμ μ νΈλμ‘μλΉμ λμ λΆν¬ν¨μλ₯Ό κΈ°λ°μΌλ‘ νλ μλ‘μ΄ μ€κ³κΈ° μ ν κΈ°λ²μ μ μνλ€. μ£Όμν μ°κ΅¬ κ²°κ³Όλ λ€μκ³Ό κ°λ€.
λ¨Όμ , λμΉ΄κ°λ―Έ-m νμ΄λ© μ±λ νκ²½μ κ°μ§ μΌλ°©ν₯ μ€κ³ λ€νΈμν¬λ₯Ό μν νλ‘μ‘ν°λΈ(proactive) λ° λ¦¬μ‘ν°λΈ(reactive) λ°©μμ μμ μ νΈλμ‘μλΉ λμ λΆν¬ν¨μ κΈ°λ° μ€κ³κΈ° μ ν κΈ°λ²μ μ μνλ€. κ°κ°μ μ€κ³κΈ° μ ν κΈ°λ²μ μν΄ μ€κ³κΈ° μ ν νλ₯ μ μ λνμ¬ μ μλ κ° μ€κ³κΈ° μ ν κΈ°λ²λ€μ νκ· μ€κ³κΈ° 곡μ μ±μ λΆμνλ€. λν κ° μ ν κΈ°λ²μ λν λΆλ₯ νλ₯ μ μμμΌλ‘ μ λνκ³ , μ λν λΆλ₯ νλ₯ μ μ κ·Όμ ννμΌλ‘ λνλ΄μ΄ κ° κΈ°λ²λ€μ΄ μ»μ μ μλ λ€μ΄λ²μν° μ°¨μλ₯Ό λΆμνλ€. λͺ¨μμ€νμ ν΅ν΄ μ»μ΄μ§ νκ· μ€κ³κΈ° 곡μ μ±κ³Ό λΆλ₯ νλ₯ μ΄ μ λν νκ· μ€κ³κΈ° 곡μ μ± λ° λΆλ₯ νλ₯ κ°κ³Ό μΌμΉν¨μ νμΈνλ€. κ·Έλ¦¬κ³ μ μλ κΈ°λ²μ΄ μ€κ³κΈ°λ€ μ¬μ΄μ 곡μ μ±μ μλ²½νκ² λ³΄μ₯νκ³ λ€νΈμν¬ μλͺ
μ μ¦κ°μν€λ©°, λ€μ΄λ²μν° μ°¨μκ° μ€κ³κΈ°μ μμ νμ΄λ© νλΌλ―Έν° m κ°μ λ°λΌ λ¬λΌμ§μ νμΈνλ€.
λμ§Έ, λμΉ΄κ°λ―Έ-m νμ΄λ© μ±λ νκ²½μ κ°μ§ μλ°©ν₯ μ€κ³ λ€νΈμν¬λ₯Ό μν νλ‘μ‘ν°λΈ λ° λ¦¬μ‘ν°λΈ λ°©μμ μμ μ νΈλμ‘μλΉ λμ λΆν¬ν¨μ κΈ°λ° μ€κ³κΈ° μ ν κΈ°λ²μ μ μνλ€. μ μλ νλ‘μ‘ν°λΈ λ°©μμ μ€κ³κΈ° μ ν κΈ°λ²μ λν΄μλ μ νν μ€κ³κΈ° μ ν νλ₯ μ μ λλ₯Ό ν΅ν΄ νκ· μ€κ³κΈ° 곡μ μ±μ λΆμνλ€. μ μλ 리μ‘ν°λΈ λ°©μμ μ€κ³κΈ° μ ν κΈ°λ²μ λν΄μλ μ€κ³κΈ° μ ν νλ₯ μ μ λΆ λ° κ·Όμ¬ ννμ μ λνμ¬ νκ· μ€κ³κΈ° 곡μ μ±μ λΆμνλ€. λν κ° μ ν κΈ°λ²μ λν λΆλ₯ νλ₯ μ μμμΌλ‘ μ λνκ³ , μ λν λΆλ₯ νλ₯ μ μ κ·Όμ ννμΌλ‘ λνλ΄μ΄ κ° κΈ°λ²λ€μ΄ μ»μ μ μλ λ€μ΄λ²μν° μ°¨μλ₯Ό λΆμνλ€. λͺ¨μμ€νμ ν΅ν΄ μ»μ΄μ§ νκ· μ€κ³κΈ° 곡μ μ±κ³Ό λΆλ₯ νλ₯ μ΄ μ λν νκ· μ€κ³κΈ° 곡μ μ± λ° λΆλ₯ νλ₯ κ°κ³Ό μΌμΉν¨μ νμΈνλ€. κ·Έλ¦¬κ³ μ μλ κΈ°λ²μ΄ μ€κ³κΈ°λ€ μ¬μ΄μ 곡μ μ±μ μλ²½νκ² λ³΄μ₯νκ³ λ€νΈμν¬ μλͺ
μ μ¦κ°μν€λ©°, λ€μ΄λ²μν° μ°¨μκ° μ€κ³κΈ°μ μμ νμ΄λ© νλΌλ―Έν° m κ°μ λ°λΌ λ¬λΌμ§μ νμΈνλ€.Wireless relay technology is one of the most promising technologies for the future communication systems which provide coverage extension and better quality of service (QoS) such as higher data rate and lower outage probability with few excessive network loads. Due to its advantages, it has been adopted in wireless standards such as IEEE 802.16j and 3GPP LTE-Advanced.
In practice, since statistics of the channel between any two nodes vary depending on their locations, they are not identical which means that channels can experience different fading. When statistics of the channel are not identical, relay selection, which is one of the most useful techniques for wireless relay technology, can cause fairness
problem that particular relays are selected more frequently than other relays. Especially, this problem can cause reduction of lifetime in the network with multiple relays having limited battery power. In this network, it is needed to focus on selection fairness for relays as well as reliability at end-users.
In this dissertation, to focus on both selection fairness for relays and reliability at end-users, we propose novel relay selection schemes based on cumulative distribution functions (CDFs) of signal-to-noise ratios (SNRs) in wireless relay networks. The dissertation consists of two main results.
First, we propose the proactive and the reactive relay selection schemes based on CDFs of SNRs for one-way relay networks over Nakagami-m fading channels. If a relay
is selected before the source transmission, it is called as proactive relay selection. Otherwise, if a relay is selected after the source transmission, it is called as reactive relay selection. For both the proactive and the reactive relay selection schemes, we analyze average relay fairness by deriving relay selection probability. For the proactive
relay selection scheme, we obtain diversity order by deriving the integral and asymptotic expressions for outage probability. Also, for the reactive relay selection scheme, we obtain diversity order by deriving the exact closed-form and asymptotic expressions for outage probability. Numerical results show that the analytical results of the proposed schemes match the simulation results well. It is shown that the proposed schemes guarantee strict fairness among relays and extend network lifetime. Also, it is shown that diversity order depends on the number of relays and fading severity parameters.
Second, we propose the proactive and the reactive relay selection schemes based on CDFs of SNRs for two-way relay networks over Nakagami-m fading channels. For
the proactive relay selection scheme, we analyze average relay fairness by deriving relay selection probability. Also, we analyze diversity order by deriving the integral and asymptotic expressions for outage probability. For the reactive relay selection scheme, we analyze average relay fairness by deriving the integral and asymptotic expressions for relay selection probability. Also, we obtain diversity order by deriving the asymptotic expression for outage probability. Numerical results show that the analytical results of the proposed schemes match the simulation results well. It is shown that the proposed schemes guarantee strict fairness among relays and extend network lifetime. Also, it is shown that diversity order depends on the number of relays and fading severity parameters.Contents
Abstract i
1 Introduction 1
1.1 Background and Related Work . . . . . . . . . . . . . . . . . . . . . 2
1.1.1 Diversity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1.2 Wireless Relay Technology . . . . . . . . . . . . . . . . . . . . 3
1.2 Outline of Dissertation . . . . . . . . . . . . . . . . . . . . . . . . . . 7
1.3 Notations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2 Relay Selection Based on CDFs of SNRs for One-Way Relay Networks
14
2.1 System Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
2.1.1 Proactive CDF-Based Relay Selection . . . . . . . . . . . . . 19
2.1.2 Reactive CDF-Based Relay Selection . . . . . . . . . . . . . . 20
2.2 Performance Analysis of Proactive CDF-Based Relay Selection . . . . 22
2.2.1 Average Relay Fairness Analysis . . . . . . . . . . . . . . . . . 22
2.2.2 Outage Probability Analysis . . . . . . . . . . . . . . . . . . . 27
2.3 Performance Analysis of Reactive CDF-Based Relay Selection . . . . 34
2.3.1 Average Relay Fairness Analysis . . . . . . . . . . . . . . . . . 34
2.3.2 Outage Probability Analysis . . . . . . . . . . . . . . . . . . . 36
2.4 Numerical Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
2.4.1 Average Relay Fairness . . . . . . . . . . . . . . . . . . . . . . 39
2.4.2 Network Lifetime . . . . . . . . . . . . . . . . . . . . . . . . . 48
2.4.3 Outage Probability . . . . . . . . . . . . . . . . . . . . . . . . 53
2.5 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
3 Relay Selection Based on CDFs of SNRs for Two-Way Relay Networks
66
3.1 System Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
3.1.1 Proactive CDF-based Relay Selection . . . . . . . . . . . . . . 68
3.1.2 Reactive CDF-based Relay Selection . . . . . . . . . . . . . . 72
3.2 Performance Analysis of Proactive CDF-Based Relay Selection . . . . 73
3.2.1 Average Relay Fairness Analysis . . . . . . . . . . . . . . . . . 73
3.2.2 Outage Probability Analysis . . . . . . . . . . . . . . . . . . . 74
3.3 Performance Analysis of Reactive CDF-Based Relay Selection . . . . 82
3.3.1 Average Relay Fairness Anlaysis . . . . . . . . . . . . . . . . . 82
3.3.2 Outage Probability Analysis . . . . . . . . . . . . . . . . . . . 86
3.4 Numerical Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
3.4.1 Average Relay Fairness . . . . . . . . . . . . . . . . . . . . . . 89
3.4.2 Network Lifetime . . . . . . . . . . . . . . . . . . . . . . . . . 100
3.4.3 Outage Probability . . . . . . . . . . . . . . . . . . . . . . . . 105
3.5 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
4 Conclusion 116
4.1 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
4.2 Possible Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
4.2.1 Device-to-Device (D2D) Communications . . . . . . . . . . . 118
4.2.2 Low Power Body Sensor Networks . . . . . . . . . . . . . . . 120
4.3 Future Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
Bibliography 122
Korean Abstract 139Docto