Resource Allocation in OFDM Based Wireless Relay Networks ...

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Chapter 1 Introduction In this chapter, we present overview for relay networks, OFDM system, and the resource allocation problem for OFDM based relay networks. We also briefly provide the basics of convex optimization theory. At the end, we describe the major contributions of this work. 1.1 Overview of Relay Networks A typical cellular wireless system consists of a Base Station (BS) and a number of User Equipments (UEs). Due to the rapid development of multimedia application, the current wireless communication systems demand high speed data transmission and better coverage. To fulfil the increasing throughput requirements at higher Quality of Service (QoS), the future wireless systems will be more demanding. The multiple-antenna technologies i.e., Multiple-Input Multiple-Output (MIMO) have been recognized as important solutions [1]. A significant diversity and multiplexing gain can be obtained by using multiple antennas at transmitter and/or receiver [2]. The net effects of these gains are the improvements in terms of network capacity and wireless link quality. However, implementation of multiple antennas in mobile devices may not be possible due to their small sizes and power limitations. A high data rate could be achieved if large bandwidth is allocated to the 1
1.1 Overview of Relay Networks wireless system. A direct result of increased bandwidth is that the required center frequency is high, which significantly increases the signal attenuation during the transmission. Further, due to the path loss of radio propagation, the received signal power decreases with the increasing distance between transmitting and receiving nodes. One of the solution to this coverage and capacity problem is to decrease the cell sizes by installing more BSs in the network, thus making the distance between the BS and the cell edge users smaller. However, the higher cost of deploying a BS makes this option less appealing for the network operators. As a second solution, a better range extension and throughput enhancement could be achieved with increasing the transmit power. The benefit of this strategy is limited by the increased interference to the co-existing networks and is also not recommended due to health issues. In the recent years, relay networks have been proposed to provide a promising solution to capacity and coverage problem in wireless networks. A relay is a node in communication systems that receives a signal from a transmitting node and then forwards this signal to the next node. Due to limitations of current radio technology, a node cannot transmit and receive simultaneously in the same band through the same antenna element. As a result, the relay node must operate in half-duplex mode. Therefore the relay-assisted transmission is carried out in two phases: in the first phase the relay receives the signal from the transmitter and in the second phase it transmits to the destination. Figure 1.1 depicts an example of the relay-assisted transmission in a three-terminal network. The destination can Figure 1.1: Two hop relay transmission combine the transmissions received by the source and the relay or can only receive 2
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Page 3 and 4: Dedications: To my family
Page 5 and 6: Acknowledgment I am greatly thankfu
Page 7 and 8: Contents 2.3.3 Proposed Low-Complex
Page 9 and 10: Abstract The combination of relay t
Page 11 and 12: List of Tables 3.1 Complexity compa
Page 13 and 14: List of Figures 4.1 System model fo
Page 15: List of Acronyms IEEE MU RS AWGN OW
Page 19 and 20: 1.2 Overview of OFDM Figure 1.2: Th
Page 21 and 22: 1.3 Basics of the Optimization Theo
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Page 27 and 28: 1.5 Contribution and Organization o
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Page 31 and 32: 2.1 Introduction allocated to a nod
Page 33 and 34: 2.1 Introduction The main contribut
Page 35 and 36: 2.2 System Model where h m,k denote
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Page 43 and 44: 2.3 Resource Allocation Schemes tha
Page 45 and 46: 2.3 Resource Allocation Schemes 2.3
Page 47 and 48: 2.4 Generalization to Multiple Rela
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Page 51 and 52: 2.5 Simulation Results • OptSol/J
Page 53 and 54: 2.5 Simulation Results 0.9 0.85 0.8
Page 55 and 56: 2.6 Summary 2.6 2.4 2.2 2 Rate (bit
Page 57 and 58: 2.6 Summary 2.4 2.2 2 1.8 N=4 N=3 N
Page 59 and 60: 3.1 Introduction A new technology c
Page 61 and 62: 3.1 Introduction • Broadcast Phas
Page 63 and 64: 3.2 System Model MU MU 3 8 A 1 2 7
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3.4 Joint Resource Allocation Schem
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3.5 Step-Wise Low-Complexity Resour
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3.6 Simulation Results and SNR B m,
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3.6 Simulation Results 3 2.5 2 Uppe
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3.7 Summary 1.8 1.6 1.4 JntOpt SubO
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4.1 Introduction • Non-orthogonal
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4.3 Cooperative Non-Orthogonal Tran
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4.4 Optimization under Orthogonal T
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4.4 Optimization under Orthogonal T
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4.5 Simulations Then, the over all
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4.5 Simulations 40 30 20 Sum−ρ S
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4.6 Summary 0.9 0.8 0.7 JPSC Pow EP
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Chapter 5 Lifetime Maximization in
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5.1 Introduction Figure 5.2: Linear
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5.2 System Model antenna that canno
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5.4 Lifetime Maximization Scheme 5.
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5.4 Lifetime Maximization Scheme wh
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5.5 Simulation Results 150 OPT−SO
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5.6 Summary Lifetime (S) 150 100 50
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Chapter 6 Resource Allocation in Co
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7. Conclusions were considered for
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Bibliography [12] A. Peled, and A.
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Bibliography [36] Z. Luo and S. Zha
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Bibliography [61] D. H. N. Nguyen,
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Bibliography [84] A. Goldsmith, S.
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Bibliography [105] Y. Li, W. Wang,
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Appendix A Derivations of Closed-Fo
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B. Derivations of the Optimal Power
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