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Title Performance Analysis of Two-Hop Cooperative Networks with Single Relay Selection under Realistic Environments
Degree Ph.D.
Author Binh Van Nguyen
Advisor Kiseon Kim
Graduation Date 2016.08.25 File
    Date 2017-03-06 12:09

With the rapid growth of multimedia services, future generations of wireless communications require higher data rates and a more reliable transmission link while keeping satisfactory quality of service. In this respect, multiple-input multiple-output (MIMO) antenna systems have been considered as an efficient approach to address these demands by offering significant multiplexing and diversity gains over single antenna systems. In addition, MIMO technique has also been proven to efficiently combat the effect of multi-path fading phenomena in wireless communication systems. However, in some cases, due to the size, cost, or hardware limitations, a wireless handset may not be able to support multiple antennas. To achieve MIMOs benefits in single-antenna systems, the concept of cooperative communications has been proposed and gained lot of interest in the research community. The key idea is to form a virtual MIMO antenna array by utilizing neighbor terminals, so-called relay nodes, which assist the source-destination communication. After receiving the source signal (thanks for the broadcast nature of the wireless medium), the relays process and forward it to the destination. With this approach, the benefits of MIMO systems can be attained in a distributed fashion. When multiple relays are available, there is a question that how we can efficiently utilize them? To address this question, several schemes are proposed, i.e. orthogonal transmission, distributed space-time coding, distributed beamforming, and single relay selection. Among afore-mentioned schemes, single relay selection (SRS) is a very good option for practical implementation since it provides the best trade-off between system performance and deployment complexity. Although cooperative systems with SRS schemes have been extensively studied, most of the existing works assume perfect conditions. Motivated by this, in this thesis, we take a step further to analyze the performance of cooperative networks SRS schemes under practical constraints such as inter-channel correlations and eavesdropping attack.

The thesis is divided into four major parts. In the first part, we investigate the effect of inter-channel correlations on the performance of an amplify-and-forward (AnF) cooperative system with the best SRS scheme. We show that the correlations between source-relay channels and between relay-destination channels has destruction impact on the system performance. On the other hand, we point out that the correlation between two channels of each relay has construction effect on the system performance. However, the correlation forms considered does not affect the system diversity order. In the second part, we study the secrecy outage probability (SOP) of an AnF cooperative system with the best secure SRS scheme under attack of an eavesdropper. We propose a mathematical framework to derive a tight approximation of the SOP. We show that source-to-relay and relay-to-destination channels can equally affect the system secrecy performance. In the third part, we extend the work in the second part to consider secure communication in a full-duplex cooperative system. We propose novel SRS schemes and derive their SOP. We show that our proposed schemes outperform conventional counterparts. In the last part, we consider a cooperative spectrum sharing network with a secondary transmitter, which can harvest energy from radio frequency (RF) signals transmitted by a primary source, under independent and non-identical Nakagami-m fading. We derive the outage probabilities of primary and secondary systems in integral-based expressions. We then obtain tight approximations of the outage probabilities. Primary and secondary diversity orders are also given. We show that with RF energy harvesting, performance of secondary system is always improved. However, performance primary system is only enhanced if a power sharing coefficient is larger than a threshold.

With the rapid growth of multimedia services, future generations of wireless communications require higher data rates and a more reliable transmission link while keeping satisfactory quality of service. In this respect, multiple-input multiple-output (MIMO) antenna systems have been considered as an efficient approach to address these demands by offering significant multiplexing and diversity gains over single antenna systems. In addition, MIMO technique has also been proven to efficiently combat the effect of multi-path fading phenomena in wireless communication systems. However, in some cases, due to the size, cost, or hardware limitations, a wireless handset may not be able to support multiple antennas. To achieve MIMOs benefits in single-antenna systems, the concept of cooperative communications has been proposed and gained lot of interest in the research community. The key idea is to form a virtual MIMO antenna array by utilizing neighbor terminals, so-called relay nodes, which assist the source-destination communication. After receiving the source signal (thanks for the broadcast nature of the wireless medium), the relays process and forward it to the destination. With this approach, the benefits of MIMO systems can be attained in a distributed fashion. When multiple relays are available, there is a question that how we can efficiently utilize them? To address this question, several schemes are proposed, i.e. orthogonal transmission, distributed space-time coding, distributed beamforming, and single relay selection. Among afore-mentioned schemes, single relay selection (SRS) is a very good option for practical implementation since it provides the best trade-off between system performance and deployment complexity. Although cooperative systems with SRS schemes have been extensively studied, most of the existing works assume perfect conditions. Motivated by this, in this thesis, we take a step further to analyze the performance of cooperative networks SRS schemes under practical constraints such as inter-channel correlations and eavesdropping attack.

The thesis is divided into four major parts. In the first part, we investigate the effect of inter-channel correlations on the performance of an amplify-and-forward (AnF) cooperative system with the best SRS scheme. We show that the correlations between source-relay channels and between relay-destination channels has destruction impact on the system performance. On the other hand, we point out that the correlation between two channels of each relay has construction effect on the system performance. However, the correlation forms considered does not affect the system diversity order. In the second part, we study the secrecy outage probability (SOP) of an AnF cooperative system with the best secure SRS scheme under attack of an eavesdropper. We propose a mathematical framework to derive a tight approximation of the SOP. We show that source-to-relay and relay-to-destination channels can equally affect the system secrecy performance. In the third part, we extend the work in the second part to consider secure communication in a full-duplex cooperative system. We propose novel SRS schemes and derive their SOP. We show that our proposed schemes outperform conventional counterparts. In the last part, we consider a cooperative spectrum sharing network with a secondary transmitter, which can harvest energy from radio frequency (RF) signals transmitted by a primary source, under independent and non-identical Nakagami-m fading. We derive the outage probabilities of primary and secondary systems in integral-based expressions. We then obtain tight approximations of the outage probabilities. Primary and secondary diversity orders are also given. We show that with RF energy harvesting, performance of secondary system is always improved. However, performance primary system is only enhanced if a power sharing coefficient is larger than a threshold.

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