Novel Subcarrier Pairing Strategy for DF Relayed Secure OFDMA with Untrusted Users
01 Dec 2017-pp 1-6
TL;DR: It is proven that the optimal SCP intends to pair subcarriers such that the variance between the effective channel gains is minimized and that depending on the individual power budget constraints at source and the relay, SCP can take either a subordinate role for improving the energy efficiency or the main role of improving the spectral efficiency of the system.
Abstract: This paper investigates joint resource allocation problem involving subcarrier allocation, subcarrier pairing (SCP), and power allocation for maximizing sum secure rate in a decode-and-forward (DF) relay assisted OFDMA system with untrusted users Optimal SCP is highlighted as a novel notion of channel gain tailoring rather than conventional channel gain matching It is proven that the optimal SCP intends to pair subcarriers such that the variance between the effective channel gains is minimized It is also shown that depending on the individual power budget constraints at source and the relay, SCP can take either a subordinate role for improving the energy efficiency or the main role of improving the spectral efficiency of the system SCP as a channel gain tailoring strategy and its role in improving the spectral as well as energy efficiency of cooperative secure communication are highlighted through the simulation results
Citations
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TL;DR: The channel gain tailoring property of SCP, various roles of SCP in improving the spectral and the energy efficiency of a cooperative communication system are validated with the help of simulation results.
Abstract: Joint resource allocation involving optimization of subcarrier allocation, subcarrier pairing (SCP), and power allocation in a cooperative secure orthogonal frequency division multiple access (OFDMA) communication system with untrusted users is considered. Both amplify and forward (AF), and decode and forward (DF) modes of operations are considered with individual power budget constraints for source and relay. After finding optimal subcarrier allocation for an AF relayed system, we prove the joint power allocation as a generalized convex problem, and solve it optimally. Compared to the conventional channel gain matching view, the optimal SCP is emphasized as a novel concept of channel gain tailoring. We prove that the optimal SCP pairs subcarriers such that the variance among the effective channel gains is minimized. For a DF relayed system, we show that depending on the power budgets of source and relay, SCP can either be in a subordinate role where it improves the energy efficiency, or in a main role where it improves the spectral efficiency of the system. In an AF relayed system we confirm that SCP plays a crucial role, and improves the spectral efficiency of the system. The channel gain tailoring property of SCP, various roles of SCP in improving the spectral and energy efficiency of a cooperative communication system are validated with the help of simulation results.
9 citations
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TL;DR: This chapter introduces the physical layer architectures suitable for the IoT and discusses the technological challenges associated with them, and presents novel optimization techniques and smart green cooperative protocols for maximizing security.
Abstract: With the current advancements in Internet of Things (IoT) technology, which offers connectivity of the physical world with the sophisticated information processing world, the utopian vision of Smart Cities now appears to be a close reality. This, however, opens the possibility of security breaches of data at various levels, from information collection, to processing, and finally, at the actuation. Due to the presence of low-power devices as information collectors and actuators in the IoT, physical layer security is a promising solution for privacy-aware Smart Cities because of its low implementation cost, and relatively low complexity compared with computation-intensive cryptographic techniques. In this chapter, we first introduce the physical layer architectures suitable for the IoT and discuss the technological challenges associated with them. Building upon them, we present novel optimization techniques and smart green cooperative protocols for maximizing security. We conclude the chapter by discussing open research directions that need further investigation for realizing energy-efficient secure Smart Cities.
2 citations
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TL;DR: The investigation demonstrates that an outage enhancement and EE improvement of around 37% and 10% respectively can be achieved over the benchmark schemes and observes the various design insights on optimization of PA and RP in the dual-hop FSO network.
Abstract: Due to the growing demand for high quality of service (QoS) in the already congested radio spectrum, there is a need to design energy-efficient free-space optical (FSO) networks. In this regard, this paper investigates the joint optimization of resources like power allocation (PA) on transmitting nodes and placement of relay node in QoS and energy-aware FSO networks. The performances of the optimizations are measured in a realistic channel incorporating the fading due to three impairments: atmospheric turbulence, pointing error, and angle-of-arrival (AOA) at the receiver. For QoS-aware network, the outage probability based on bit error probability (BEP) is minimized for the error-free transmission, whereas energy-efficiency (EE) is maximized in the energy-aware network. Performances in both the networks are investigated by optimizing the resources using three optimization schemes: (i) optimal PA for a fixed relay placement (RP), (ii) optimal RP for a fixed PA, and (iii) joint optimization of PA and RP. It is shown that the problems for individual optimization of PA and RP are conditionally pseudoconvex which is used to obtain the jointly global solution using joint optimization algorithm. In case of EE maximization, the optimal solutions are obtained through fast converging multi-dimensional golden search algorithms. Numerical results validate the proposed analysis as well as compare the different optimization schemes along with their computational complexities. The investigation demonstrates that an outage enhancement and EE improvement of around 37% and 10% respectively can be achieved over the benchmark schemes. Lastly using the obtained results, we observe the various design insights on optimization of PA and RP in the dual-hop FSO network.
1 citations
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TL;DR: In this paper, the joint resource allocation involving optimization of subcarrier allocation, sub-carrier pairing, and power allocation in a cooperative secure orthogonal frequency division multiple access (OFDMA) communication system with untrusted users is considered.
Abstract: Joint resource allocation involving optimization of subcarrier allocation, subcarrier pairing (SCP), and power allocation in a cooperative secure orthogonal frequency division multiple access (OFDMA) communication system with untrusted users is considered. Both amplify and forward (AF), and decode and forward (DF) modes of operations are considered with individual power budget constraints for source and relay. After finding optimal subcarrier allocation for an AF relayed system, we prove the joint power allocation as a generalized convex problem, and solve it optimally. Compared to the conventional channel gain matching view, the optimal SCP is emphasized as a novel concept of channel gain tailoring. We prove that the optimal SCP pairs subcarriers such that the variance among the effective channel gains is minimized. For a DF relayed system, we show that depending on the power budgets of source and relay, SCP can either be in a subordinate role where it improves the energy efficiency, or in a main role where it improves the spectral efficiency of the system. In an AF relayed system we confirm that SCP plays a crucial role, and improves the spectral efficiency of the system. The channel gain tailoring property of SCP, various roles of SCP in improving the spectral and the energy efficiency of a cooperative communication system are validated with the help of simulation results.
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01 Jan 2020
TL;DR: A suboptimal algorithm with low complexity and satisfactory performance is proposed to solve the formulated non-convex problem of secure resource allocation for an orthogonal frequency division multiple access two-way relay network.
Abstract: The authors investigate secure resource allocation for an orthogonal frequency division multiple access two-way relay network, which has several pairs of mobile users (MUs) and one energy harvesting (EH) relay. In this network, the relay is untrusted and each MU pair may also overhear the other MU pairs' confidential information. In particular, to forward information for each MU, the relay adopts power splitting technique to harvest energy from radio frequency signals emitted by each MU. For this scenario, which has hardly been considered, the joint problem of subcarrier allocation, power control, and power splitting ratio selection is formulated, with the aim to maximise the total secrecy rate of all MUs. A suboptimal algorithm with low complexity and satisfactory performance is proposed to solve the formulated non-convex problem.
References
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TL;DR: A comprehensive review of the domain of physical layer security in multiuser wireless networks, with an overview of the foundations dating back to the pioneering work of Shannon and Wyner on information-theoretic security and observations on potential research directions in this area.
Abstract: This paper provides a comprehensive review of the domain of physical layer security in multiuser wireless networks. The essential premise of physical layer security is to enable the exchange of confidential messages over a wireless medium in the presence of unauthorized eavesdroppers, without relying on higher-layer encryption. This can be achieved primarily in two ways: without the need for a secret key by intelligently designing transmit coding strategies, or by exploiting the wireless communication medium to develop secret keys over public channels. The survey begins with an overview of the foundations dating back to the pioneering work of Shannon and Wyner on information-theoretic security. We then describe the evolution of secure transmission strategies from point-to-point channels to multiple-antenna systems, followed by generalizations to multiuser broadcast, multiple-access, interference, and relay networks. Secret-key generation and establishment protocols based on physical layer mechanisms are subsequently covered. Approaches for secrecy based on channel coding design are then examined, along with a description of inter-disciplinary approaches based on game theory and stochastic geometry. The associated problem of physical layer message authentication is also briefly introduced. The survey concludes with observations on potential research directions in this area.
1,108 citations
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TL;DR: This article provides a comprehensive summary of recent advances in the area of physical-layer security that guarantees confidentiality by using cooperative techniques unique to the wireless medium that guarantee confidentiality against eavesdropping attacks where an unauthorized entity aims to intercept an ongoing wireless communication.
Abstract: Wireless communications systems are particularly vulnerable to security attacks because of the inherent openness of the transmission medium. In this article, we focus on guaranteeing confidentiality against eavesdropping attacks where an unauthorized entity aims to intercept an ongoing wireless communication, and we provide a comprehensive summary of recent advances in the area of physical-layer security that guarantees confidentiality by using cooperative techniques unique to the wireless medium. These cooperative techniques consist of carefully designed coding and signaling schemes that are able to harness the properties of the physical layer and to ensure some level of information-theoretic security.
202 citations
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TL;DR: This letter will provide the proof which verifies that OSP is optimal for both amplify-and- forward (AF) and decode- and-forward (DF) relay links when optimal power allocation is applied.
Abstract: We consider a two-hop relay link in which orthogonal frequency division multiplexing (OFDM) is used on both hops. Under a joint sum-power constraint, our aim is to allocate power over subcarriers on the two hops such that the instantaneous rate of the relay link is maximized. Ordered subcarrier pairing (OSP) has been proposed in the literature to further improve the relay link rate; however, the optimality of OSP has been proven only for equal power allocation and the proof of its optimality under optimal power allocation has not been available yet. In this letter, we will provide our proof which verifies that OSP is optimal for both amplify-and-forward (AF) and decode-and-forward (DF) relay links when optimal power allocation is applied.
164 citations
"Novel Subcarrier Pairing Strategy f..." refers methods in this paper
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TL;DR: It is shown that the proposed suboptimal solution for secrecy rate maximization in a multicarrier decode-and-forward relay system is asymptotically optimal in the limit as the number of subcarriers goes to infinity.
Abstract: We study power allocation for secrecy rate maximization in a multicarrier decode-and-forward relay system, where an eavesdropper exists. We consider three transmission modes: in no communication, the source and the relay do not transmit at all; in direct communication, the source broadcasts signals during the first time slot and the relay does not forward any signal during the second time slot; in relay communication, the source broadcasts signals during the first time slot and the relay forwards the reencoded signals to the destination during the second time slot. Determining the transmission strategy adaptively on each subcarrier, the optimal source power and the optimal relay power over all subcarriers are derived to maximize the sum secrecy rate under a total system power constraint. In addition, a suboptimal power allocation scheme is proposed to substantially reduce the computational complexity. It is shown that the proposed suboptimal solution is asymptotically optimal in the limit as the number of subcarriers goes to infinity. Extensive numerical results are presented for various scenarios. In particular, the performance of the suboptimal scheme is very close to that of the optimal scheme even if the number of subcarriers is moderately small.
103 citations
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TL;DR: It is shown that with L-superadditive relay (performance) functions a simple ranking of subchannels leads to the optimal assignment with a very low computational complexity.
Abstract: The paper studies subchannel assignment in a two-hop OFDM relay system in which the transmitting nodes (source and relay) have access to channel information and interference-related information. We show that with L-superadditive relay (performance) functions a simple ranking of subchannels leads to the optimal assignment with a very low computational complexity. Numerical results quantify the benefit of subchannel assignment in a frequency-selective channel.
60 citations
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