Resource Allocation in OFDM Based Wireless Relay Networks ...

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1.1 Overview of Relay Networks the signal transmitted by the relay, if, e.g., the channel gain of the direct link is degraded due to obstacles or/and path losses. The history of relay channels can be dated back to the 70s [3]-[5], when Cover [5] proposed several relaying schemes and studied the corresponding system capacity. Despite its early discovery, research on relay network did not become popular until the topic re-attracted the research community in late 90s after the work presented in [6] and [7]. Later Laneman applied the theory to cooperative communication scenario to develop low-complexity cooperative diversity protocols in [8]. The multihop communication has been proposed in the emerging Fourth Generation (4G) standards such as Long Term Evolution Advanced (LTE-Advanced) developed under 3rd Generation Partnership Project (3GPP) [9] and IEEE 802.16j to fulfil the high data rate requirements for a comparatively low cost. Depending on the distance between the two communication terminals and the nature of surrounding particles, one or more relays can be used to assist the communication for coverage enhancement. Further, cooperative diversity has been proposed as an alternative solution to the multiple antennas where the transmission between the source and the destination is performed with the assistance of a number of relay nodes each with one antenna [10]. In particular, the source node selects one or more relays and forwards its data to them. Then, the source and relays coordinate their transmissions in such a way that the maximum multiplexing/diversity gains are achieved at the destination node. Generally speaking, there are two modes of relaying transmission: • Amplify-and-Forward (AF): In AF mode the received signal at the relay node is directly amplified and is retransmitted to the next station. The AF scheme is easy to implement and can be easily upgraded to the new coding schemes. However, the noise effect is propagated to the next node which reduces the effective signal to noise ratio (SNR) in the final destination. • Decode-and-Forward (DF): In DF mode the relay decodes the information bits and re-encodes the data for further transmission. The main advantage of DF protocol is that the noise effect can be removed if the information bits are 3
1.2 Overview of OFDM Figure 1.2: The OFDM symbol with cyclic prefix. correctly decoded. However, if wrong detection appears, the error will be propagated into the next station. Moreover, DF requires energy consumption and time delay for decoding and encoding the massage. Based on the topology, a network can have a single or multiple relay nodes to transmit data from the source to the destination. In single relay system, relay receives a signal from the source and forwards it to the destination after processing. The multi-relay networks could be further categorized into two types: parallel relay networks and multi-hop networks. In parallel relay networks, more than one nodes are deployed between two communication terminals such that the source transmits to all relays at the first hop and the relays forward this information to the sink at the second hop. The relays do not communicate with each other under the parallel relay model. The dual hop transmission (single or multi-relay) may not be sufficient to provide ubiquitous data rate between two nodes if the end-to-end SNR is very low. A promising solution is to place more than one interconnected relay nodes such that the transmission from the source to the destination occurs in multiple hops. 1.2 Overview of OFDM OFDM is a commonly used multi-carrier transmission technique to combat the frequency selective channels as well as the inter-symbol interference (ISI). The history of OFDM could be traced back to the mid 60’s, when Chang proposed 4
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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 and 16: List of Acronyms IEEE MU RS AWGN OW
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Page 21 and 22: 1.3 Basics of the Optimization Theo
Page 23 and 24: 1.3 Basics of the Optimization Theo
Page 25 and 26: 1.4 Resource Allocation Problem is
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
Page 37 and 38: 2.3 Resource Allocation Schemes opt
Page 39 and 40: 2.3 Resource Allocation Schemes ( )
Page 41 and 42: 2.3 Resource Allocation Schemes and
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
Page 49 and 50: 2.4 Generalization to Multiple Rela
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
Page 65 and 66: 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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