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Journal ArticleDOI

A Vector Approach for the Analysis and Synthesis of Directional Modulation Transmitters

01 Jan 2014-IEEE Transactions on Antennas and Propagation (IEEE)-Vol. 62, Iss: 1, pp 361-370
TL;DR: In order to formalize and extend on previous ad-hoc analysis and synthesis methods a theoretical treatment using vector representations of directional modulation systems is introduced and used to achieve DM transmitter characteristics.
Abstract: In order to formalize and extend on previous ad-hoc analysis and synthesis methods a theoretical treatment using vector representations of directional modulation (DM) systems is introduced and used to achieve DM transmitter characteristics. An orthogonal vector approach is proposed which allows the artificial orthogonal noise concept derived from information theory to be brought to bear on DM analysis and synthesis. The orthogonal vector method is validated and discussed via bit error rate (BER) simulations.
Citations
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Journal ArticleDOI
TL;DR: In this paper, a random frequency diverse array-based directional modulation with artificial noise (RFDA-DM-AN) scheme was proposed to enhance physical layer security of wireless communications.
Abstract: In this paper, a random frequency diverse array-based directional modulation with artificial noise (RFDA-DM-AN) scheme is proposed to enhance physical layer security of wireless communications. Specifically, we first design the RFDA-DM-AN scheme by randomly allocating frequencies to transmit antennas, thereby achieving 2-D (i.e., angle and range) secure transmissions, and outperforming the state-of-the-art 1-D (i.e., angle) phase array (PA)-based DM scheme. Then we derive the closed-form expression of a lower bound on the ergodic secrecy capacity (ESC) of our RFDA-DM-AN scheme. Based on the theoretical lower bound derived, we further optimize the transmission power allocation between the useful signal and artificial noise (AN) in order to improve the ESC. Simulation results show that: 1) our RFDA-DM-AN scheme achieves a higher secrecy capacity than that of the PA-based DM scheme; 2) the lower bound derived is shown to approach the ESC as the number of transmit antennas $N$ increases and precisely matches the ESC when $N$ is sufficiently large; and 3) the proposed optimum power allocation achieves the highest ESC of all power allocations schemes in the RFDA-DM-AN.

186 citations

Journal ArticleDOI
TL;DR: A novel and robust DM synthesis method based on conditional minimum mean square error that is capable of substantially improving the bit error rate performance compared with the state-of-the-art methods.
Abstract: Directional modulation (DM) is a secure transmission technology that is able to retain the original constellation of transmitted signals along the desired direction, while distort the constellation in the undesired directions at the same time. In this letter, we develop novel and robust DM synthesis methods for enhancing the transmission performance. Specifically, we first propose a low-complexity dynamic DM synthesis method. In this method, we derive a closed-form expression for the null space of conjugate transpose of the steering vector in the desired direction. Based on the expression derived, we construct a projection matrix in order to form artificial noises to those undesired directions. Then, we focus our attention on more practical scenarios, where there is uncertainty in the estimated direction angle. This uncertainty will cause estimation errors and seriously jeopardize the receiving performance in the desired direction. To mitigate the uncertainty effect, we further propose a robust DM synthesis method based on conditional minimum mean square error. The proposed method aims to minimize the distortion of the constellation points along the desired direction. Simulation results show that our proposed robust DM method is capable of substantially improving the bit error rate performance compared with the state-of-the-art methods.

139 citations


Cites methods from "A Vector Approach for the Analysis ..."

  • ...By contrast, the method in [4] needs to obtain the orthonomal basis of hH (θd), which has a higher computational complexity of O(N3)....

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  • ...In this letter, we 1) propose a novel DM synthesis method with a lower computational complexity compared to [4], and 2) develop, in the first time, a robust solution to combat the estimation errors of the direction angles....

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  • ...Comparison of BER performance between our proposed method and the method in [4]....

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  • ...The figure shows the bit error rate (BER) performances of our proposed method (solid line) and the work in [4] (dotted line) versus various values of the direction angle θ from 0° to 180°....

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  • ...To solve these problems, recent works transfer the design of DM synthesis from the RF frontend to the baseband [4], [5]....

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Journal ArticleDOI
TL;DR: Simulation and analysis show that the proposed scheme actually can achieve a secure and precise wireless transmission of confidential messages in line-of-propagation channel, and the derived theoretical formula of average secrecy rate is verified to coincide with the exact results well for medium and large scale transmit antenna array or in the low and medium SNR regions.
Abstract: In this paper, a practical wireless transmission scheme is proposed to transmit confidential messages to the desired user securely and precisely by the joint use of multiple techniques, including artificial noise (AN) projection, phase alignment/beamforming, and random subcarrier selection (RSCS) based on orthogonal frequency division multiplexing (OFDM), and directional modulation (DM), namely RSCS-OFDM-DM. This RSCS-OFDM-DM scheme provides an extremely low-complexity structure for the desired receiver and makes the secure and precise wireless transmission realizable in practice. For illegal eavesdroppers, the receive power of confidential messages is so weak that their receivers cannot intercept these confidential messages successfully once it is corrupted by AN. In such a scheme, the design of phase alignment/beamforming vector and AN projection matrix depends intimately on the desired direction angle and distance. It is particularly noted that the use of RSCS leads to a significant outcome that the receive power of confidential messages mainly concentrates on the small neighboring region around the desired receiver and only small fraction of its power leaks out to the remaining large broad regions. This concept is called secure precise transmission. The probability density function of real-time receive signal-to-interference-and-noise ratio (SINR) is derived. Also, the average SINR and its tight upper bound are attained. The approximate closed-form expression for average secrecy rate is derived by analyzing the first-null positions of the SINR and clarifying the wiretap region. Simulation and analysis show that the proposed scheme actually can achieve a secure and precise wireless transmission of confidential messages in line-of-propagation channel, and the derived theoretical formula of average secrecy rate is verified to coincide with the exact results well for medium and large scale transmit antenna array or in the low and medium SNR regions.

133 citations


Cites background or methods from "A Vector Approach for the Analysis ..."

  • ...To overcome those disadvantages, instead of the RF frontend, the DM is synthesized on the baseband by the AN-aided orthogonal vector method in [14]....

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  • ...As a key-less physical layer secure transmit way, directional modulation (DM) is attracting an ever-growing interest in [9]–[13] and has made substantial progression in many aspects by using antenna array with the help of aided artificial noise (AN) [14]– [16]....

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Journal ArticleDOI
TL;DR: The concept of directional modulation is employed and a signal processing approach is followed to enhance the security of multiuser multi-input multioutput (MIMO) communication systems when a multiantenna eavesdropper is present.
Abstract: Wireless communication provides a wide coverage at the cost of exposing information to unintended users. As an information-theoretic paradigm, secrecy rate derives bounds for secure transmission when the channel to the eavesdropper is known. However, such bounds are shown to be restrictive in practice and may require exploitation of specialized coding schemes. In this paper, we employ the concept of directional modulation and follow a signal processing approach to enhance the security of multiuser multi-input multioutput (MIMO) communication systems when a multiantenna eavesdropper is present. Security enhancement is accomplished by increasing the symbol error rate at the eavesdropper. Unlike the information-theoretic secrecy rate paradigm, we assume that the legitimate transmitter is not aware of its channel to the eavesdropper, which is a more realistic assumption. We examine the applicability of MIMO receiving algorithms at the eavesdropper. Using the channel knowledge and the intended symbols for the users, we design security enhancing symbol-level precoders for different transmitter and eavesdropper antenna configurations. We transform each design problem to a linearly constrained quadratic program and propose two solutions, namely the iterative algorithm and one based on nonnegative least squares, at each scenario for a computationally efficient modulation. Simulation results verify the analysis and show that the designed precoders outperform the benchmark scheme in terms of both power efficiency and security enhancement.

133 citations


Cites background from "A Vector Approach for the Analysis ..."

  • ...Ashkan Kalantari, Sina Maleki, Symeon Chatzinotas, and Björn Ottersten are with the Interdisciplinary Centre for Security, Reliability and Trust (SnT), The University of Luxembourg, 4 rue Alphonse Weicker, L-2721 Luxembourg-Kirchberg, Luxembourg, (E-mails: {ashkan.kalantari,sina.maleki,symeon.chatzinotas,bjorn.ottersten}@uni.lu)....

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  • ...Ashkan Kalantari, Sina Maleki, Symeon Chatzinotas, and Björn Ottersten are with the Interdisciplinary Centre for Security, Reliability and Trust (SnT), The University of Luxembourg, 4 rue Alphonse Weicker, L-2721 Luxembourg-Kirchberg, Luxembourg, (E-mails:…...

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Journal ArticleDOI
TL;DR: A unified view and classification of precoding techniques with respect to two main axes is presented: 1) the switching rate of the precoding weights, leading to the classes of block-level and symbol-level precoding and 2) the number of users that each stream is addressed to, hence unicast, multicast, and broadcast precoding.
Abstract: Precoding has been conventionally considered as an effective means of mitigating or exploiting the interference in the multiantenna downlink channel, where multiple users are simultaneously served with independent information over the same channel resources. The early works in this area were focused on transmitting an individual information stream to each user by constructing weighted linear combinations of symbol blocks (codewords). However, more recent works have moved beyond this traditional view by: 1) transmitting distinct data streams to groups of users and 2) applying precoding on a symbol-per-symbol basis. In this context, the current survey presents a unified view and classification of precoding techniques with respect to two main axes: 1) the switching rate of the precoding weights, leading to the classes of block-level and symbol-level precoding and 2) the number of users that each stream is addressed to, hence unicast, multicast, and broadcast precoding. Furthermore, the classified techniques are compared through representative numerical results to demonstrate their relative performance and uncover fundamental insights. Finally, a list of open theoretical problems and practical challenges are presented to inspire further research in this area 1 . 1 The concepts of precoding and beamforming are used interchangeably throughout this paper.

119 citations


Cites background or methods from "A Vector Approach for the Analysis ..."

  • ...[177], [181], [184] utilize an orthogonal vector approach to derive the array weights in order to directly modulate the...

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  • ...The work of [184] introduces vector representations to link the...

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References
More filters
Book
01 Jan 1982
TL;DR: The most up-to-date resource available on antenna theory and design as mentioned in this paper provides an extended coverage of ABET design procedures and equations making meeting ABET requirements easy and preparing readers for authentic situations in industry.
Abstract: The most-up-to-date resource available on antenna theory and design Expanded coverage of design procedures and equations makes meeting ABET design requirements easy and prepares readers for authentic situations in industry New coverage of microstrip antennas exposes readers to information vital to a wide variety of practical applicationsComputer programs at end of each chapter and the accompanying disk assist in problem solving, design projects and data plotting-- Includes updated material on moment methods, radar cross section, mutual impedances, aperture and horn antennas, and antenna measurements-- Outstanding 3-dimensional illustrations help readers visualize the entire antenna radiation pattern

14,065 citations


"A Vector Approach for the Analysis ..." refers background in this paper

  • ..., Binomial arrays for lowest sidelobes, Dolph-Chebyschev arrays for controllable and equal sidelobes [23], etc....

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Journal ArticleDOI
01 Jul 1984

5,335 citations


"A Vector Approach for the Analysis ..." refers background in this paper

  • ...Note that these vector paths are different to the phasor diagram [17], in which the excitation strategies are not involved....

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Journal ArticleDOI
TL;DR: This paper considers the problem of secret communication between two nodes, over a fading wireless medium, in the presence of a passive eavesdropper, and assumes that the transmitter and its helpers (amplifying relays) have more antennas than the eavesdroppers.
Abstract: The broadcast nature of the wireless medium makes the communication over this medium vulnerable to eavesdropping. This paper considers the problem of secret communication between two nodes, over a fading wireless medium, in the presence of a passive eavesdropper. The assumption used is that the transmitter and its helpers (amplifying relays) have more antennas than the eavesdropper. The transmitter ensures secrecy of communication by utilizing some of the available power to produce 'artificial noise', such that only the eavesdropper's channel is degraded. Two scenarios are considered, one where the transmitter has multiple transmit antennas, and the other where amplifying relays simulate the effect of multiple antennas. The channel state information (CSI) is assumed to be publicly known, and hence, the secrecy of communication is independent of the secrecy of CSI.

1,846 citations

Proceedings ArticleDOI
01 Dec 2006
TL;DR: The error vector magnitude (EVM) bit error rate (BER) and signal to noise ratio (SNR) and the fact that with such relationship it would be possible to predict or in cases substitute EVM in places of BER or even SNR is presented.
Abstract: In this paper, we relate the error vector magnitude (EVM) bit error rate (BER) and signal to noise ratio (SNR). We also present the fact that with such relationship it would be possible to predict or in cases substitute EVM in places of BER or even SNR. In doing so, we first define EVM with normalization so that the definition stands for multi-modulation systems, viz. binary phas shift keying (BPSK), quadrature phase shift keying (QPSK) etc. We also compare among the different performance metrics and show that EVM can be equivalently useful as signal to noise ratio and bit error rate. The relationships are based on stream based communication systems. A few Monte Carlo simulations are carried out to illustrate the performance of EVM based on these relationships.

621 citations

Journal ArticleDOI
TL;DR: In this paper, an analytical closed-form expression of an achievable secrecy rate was derived for the case of noncolluding eavesdroppers and an upper bound on the secrecy rate is provided.
Abstract: We consider the problem of secure communication with multiantenna transmission in fading channels. The transmitter simultaneously transmits an information-bearing signal to the intended receiver and artificial noise to the eavesdroppers. We obtain an analytical closed-form expression of an achievable secrecy rate and use it as the objective function to optimize the transmit power allocation between the information signal and the artificial noise. Our analytical and numerical results show that equal power allocation is a simple yet near-optimal strategy for the case of noncolluding eavesdroppers. When the number of colluding eavesdroppers increases, more power should be used to generate the artificial noise. We also provide an upper bound on the SNR, above which, the achievable secrecy rate is positive and shows that the bound is tight at low SNR. Furthermore, we consider the impact of imperfect channel state information (CSI) at both the transmitter and the receiver and find that it is wise to create more artificial noise to confuse the eavesdroppers than to increase the signal strength for the intended receiver if the CSI is not accurately obtained.

515 citations