As a popular modulation technique in wireless communications, orthogonal frequency-division multiplexing (OFDM) has two major disadvantages-one is its high peak-to-average power ratio (PAPR), which causes nonlinear di...
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As a popular modulation technique in wireless communications, orthogonal frequency-division multiplexing (OFDM) has two major disadvantages-one is its high peak-to-average power ratio (PAPR), which causes nonlinear distortion, lower power efficiency, and performance losses;the other is its fragility under hostile jamming attacks, where the authorized user asciitext's signal is deliberately interfered by the adversary, leading to communication failures. In this article, first, we reintroduce the IFFT-relocated OFDM (IR-OFDM), which is essentially a single-carrier system with frequency-domain equalization. By relocating the inverse fast Fourier transform (IFFT) block in OFDM from the transmitter to receiver, IR-OFDM can completely liberate OFDM from the barriers of high PAPR while achieving the same spectral efficiency. Second, to combat hostile jamming, especially disguised jamming, where the jamming is highly correlated with the authorized signal, we propose a securely precoded IR-OFDM (SP-IR-OFDM). By integrating the advanced encryption standard (AES) into IR-OFDM transceiver design, we obtain a random (or dynamic) constellation. The shared secure randomness introduced by AES breaks the symmetry between the authorized signal and the jamming interference and, hence, ensures reliable performance of the system under disguised jamming. The efficiency and robustness of IR-OFDM and SP-IR-OFDM are demonstrated through simulation examples. It is shown that IR-OFDM can deliver comparable or better performances than OFDM under multipath propagation, and SP-IR-OFDM can achieve strong resistance under disguised jamming while enjoying low PAPR and relatively high spectral efficiency. Our result indicates that, potentially, SP-IR-OFDM can serve as a promising modulation candidate for next-generation secure and energy-efficient high-speed communications, especially for the resource-constrained Internet of Things (IoT) networks.
Due to its high spectral efficiency and simple transceiver design, OFDM is one of the most popular modulation techniques in wireless communications. However, OFDM has two major disadvantages-one is its high peak-to-av...
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ISBN:
(纸本)9781665457194
Due to its high spectral efficiency and simple transceiver design, OFDM is one of the most popular modulation techniques in wireless communications. However, OFDM has two major disadvantages-one is its high peak-to-average power ratio (PAPR), which causes nonlinear distortion, lower power efficiency and performance losses;the other is its fragility under hostile jamming attacks, where the authorized user's signal is deliberately interfered by the adversary, leading to communication failures. An interesting question is: can we have a better system than OFDM? In this paper, first, we reintroduce the IFFT-Relocated OFDM (IR-OFDM), which is essentially a single-carrier system with frequency domain equalization. By relocating the IFFT block in OFDM from the transmitter to receiver, IR-OFDM can completely liberate OFDM from the barriers of high PAPR while achieving the same spectral efficiency. Second, to combat hostile jamming, especially disguised jamming, where the jamming is highly correlated with the authorized signal, we propose a securely precoded IR-OFDM (SP-IROFDM). By integrating AES into IR-OFDM transceiver design, we obtain a random (or dynamic) constellation. The shared secure randomness introduced by AES breaks the symmetry between the authorized signal and the jamming interference, and hence ensures reliable performance of the system under disguised jamming. The efficiency and robustness of the proposed approach are demonstrated through simulation examples. Our result indicates that, potentially, SP-IR-OFDM can serve as a promising modulation candidate for next generation secure and energy-efficient high-speed communications, especially for the resource-constrained IoT networks.
securely precoded OFDM (SP-OFDM) is a newly proposed secure and efficient anti-jamming scheme designed to enhance the physical layer security of OFDM based 4G and 5G systems under hostile environments. In this paper, ...
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securely precoded OFDM (SP-OFDM) is a newly proposed secure and efficient anti-jamming scheme designed to enhance the physical layer security of OFDM based 4G and 5G systems under hostile environments. In this paper, by exploiting tools in constrained functional optimization, we explore the worst jamming distribution that minimizes the channel capacity of SP-OFDM under practical assumptions, where the transmitted symbols are uniformly distributed over a finite alphabet, and the jamming interference is subject to an average power constraint, but may or may not have a peak power constraint. First, we prove the existence and uniqueness of the worst jamming distribution. Second, by analyzing the Kuhn-Tucker conditions for the worst jamming, we prove that the worst jamming distribution is discrete in amplitude with a finite number of mass points, either with or without peak power constraints. Numerical results are provided on the worst jamming distribution and the minimum channel capacity under disguised jamming. It is shown that the minimum channel capacity of SP-OFDM is guaranteed to be positive under the worst disguised jamming, while the minimum capacity of the traditional OFDM under disguised jamming is zero. Both our theoretical and numerical results demonstrate the robustness of SP-OFDM and also reveal its performance lower bound under disguised jamming.
Distributed antenna (DA) is considered as a strong alternative to conventional centralized multiple-input multiple-output (MIMO), to provide a greener and user-centric network structure. However, physical layer (PHY) ...
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ISBN:
(纸本)9781538680889
Distributed antenna (DA) is considered as a strong alternative to conventional centralized multiple-input multiple-output (MIMO), to provide a greener and user-centric network structure. However, physical layer (PHY) security becomes more challenging in DA systems because of the proximity to the transmitters. In this paper, we jointly optimize DA activation/deactivation and secure precoding to minimize the total power consumption, subjected to legitimate user's (LU) quality-of-service (QoS) and PHY security constraints against potential eavesdroppers (Eves). A practical scenario is considered, where channel state information (CSI) of all the nodes can only be imperfectly obtained. In the presence of infinite probabilities of CSI uncertainties, a deterministic robust based algorithm is designed to always satisfy LU's QoS requirement and address PHY security constraints against Eves. Moreover, essentially different from existing artificial noise (AN)-aided secure transmission schemes, where AN' leakage effect at LU needs to be suppressed, we utilize AN as a beneficial element at LU end while keeping it destructive at potential Eves. Simulation results verify that, the proposed algorithm incurs much lower power consumption compared to its benchmarks, thanks to the additional degrees of freedom of antenna selection and utilizing constructive AN. Last but not least, by adaptively facilitating DA activation/deactivation, the proposed algorithm addresses a user-centric network structure, which is more flexible over the conventional centralized MIMO systems.
In this paper, we address the problem of finding the worst jamming distribution in terms of channel capacity for the securely precoded OFDM (SP-OFDM) system, so as to evaluate the performance of SP-OFDM under destruct...
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ISBN:
(纸本)9781538647271
In this paper, we address the problem of finding the worst jamming distribution in terms of channel capacity for the securely precoded OFDM (SP-OFDM) system, so as to evaluate the performance of SP-OFDM under destructive hostile jamming. We consider a practical communication scenario, where the transmitting symbols are uniformly distributed over a discrete and finite alphabet, and the jamming interference is subject to both average and peak power constraints. Using tools in functional analysis and complex analysis, first, we show the existence and uniqueness of the worst jamming distribution;then we further prove that the worst jamming distribution is discrete in amplitude with a finite number of mass points. Numerical examples are provided under different scenarios to demonstrate our theoretical results.
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