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This paper explores optimal array beamforming for secure communication in static multipath propagation environments. The problem is cast as a convex optimization of the average secure key rate achieved in the presence of a passive eavesdropper, and the optimization is performed using semidefinite programming. While representative results are presented for a uniform linear array, the optimization procedure...
We show that entangled photons propagating along the edge of a photonic topological insulator preserve their entanglement despite edge defects of any kind. This represents a novel methodology for the transport of quantum information.
The accuracy of direction of arrival estimation tends to degrade under reverberant conditions due to the presence of reflected signal components which are correlated with the direct path. The recently proposed direct-path dominance test provides a means of identifying time-frequency regions in which a single signal path is dominant. By analysing only these regions it was shown that the accuracy of...
Encryption is a process of hiding significant data so as to prevent unauthorized access and ensure confidentiality of data. It is widely used to transmit data across networks ensuring secure communication. This paper aims at improving the security and efficiency of image encryption by using a highly efficient shuffle based encryption algorithm and an equivalent decryption algorithm based on random...
Direction Of Arrival (DOA) estimation is a well known problem that has been studied through a wide range of different approaches and methods. Most of these methods make use of several snapshots in the array to provide an accurate result but their performance is commonly degraded when only a single snapshot is available. An improved ESPRIT algorithm to the problem of direction of arrival (DOA) estimation...
This work studies the dependency of MIMO performance figures on two characteristic multipath cluster parameters, the innercluster Angular Spread of Arrival (ASA) and the number of clusters. Both these parameters play a vital role in geometric based stochastic channel models as from the WINNER or COST families. Our motivation to the study these parameters is two-fold. First, we study their impact on...
This paper considers the scenario when a mix of signals from multiple acoustic sources is received by a microphone array. The problem is to estimate the waveform of the source of interest located in the near field of the array. The considered problem can arise in many applications such as video conferencing, acoustic room surveillance and others, when it is necessary to capture human speech against...
Detecting the presence of one or multiple signals with unknown spatial signature can be addressed by testing the structure of the observation covariance matrix. The problem can be typically formulated as a sphericity test, which checks whether the spatial covariance matrix is proportional to the identity (white noise), or as a correlation test, which checks whether this matrix has a diagonal structure...
We deal with the problems of blind source separation, dereverberation, audio event detection and direction-of-arrival (DOA) estimation. We previously proposed a generative model of multichannel signals called the multichannel facto rial hidden Markov model, which allows us to simultaneously solve these problems through a joint optimization problem formulation. In this approach, we modeled the spatial...
In the image encryption, chaotic map usually used for pixel permutation, due to it can generate chaotic permutations hence difficult to predict. However chaotic map which is widely used for image permutations like Arnold Cat Map (ACM) has a relatively low recurrence period so vulnerable to the known image attack. Besides, the key space Arnold cat map is also relatively low so vulnerable to brute-force...
Since the angular spread is related to the propagation environment condition, MIMO channel capacity can be improved by increasing the antenna spacing. This paper evaluates the performance of link correlation for 2×2 MIMO deployments using horizontal and vertical UE and BS array configurations with various antenna separations at the UE and BS. The investigation makes use of measured 3D radiation patterns...
Knowing the variation in array factor pattern performance due to relative element mis-positioning of a distributed linear array, work is performed to utilize a minimum variance adaptive array processing method to minimize the effects of the element mis-positioning. The extent of array factor performance enhancement is demonstrated for a linear distributed array design where the unique input to the...
In this paper, a compact planar Ultra-Wideband (UWB) antenna array with 4 monopole radiators is presented. To enhance the isolation, polarization of nearly placed elements is exploited. The proposed MIMO antenna array is electrically small 50 × 39.8 mm2, printed on a low loss 1.524 mm thick Rogers TMM4 laminate with a dielectric constant of 4.5 and a loss tangent of 0.002. Simulation in HFSS and printed...
Device-to-Device (D2D) communication is one of new technologies that appears to be a promising component in next generation communications. Due to the special characteristics of D2D channels, there is a need to establish and evaluate new channel models that help realize the potential advantages of D2D communication. In this paper, a three-dimensional two-cylinder model is introduced, the spatial cross-correlation...
We consider joint adaptive transmit(TX) and receive (RX) beamforming for interference mitigation in array sensing systems. Unlike conventional designs, which only employ adaptive processing for the RX beamforming, we propose a fully adaptive approach that jointly selects the transmit correlation matrix and RX beamformer by maximizing the signal-to-interference-plus-noise ratio (SINR). Due to imprecise...
Side-channel attacks have been a real threat against many embedded cryptographic systems. A commonly used algorithmic countermeasure, random masking, incurs large execution delay and resource overhead. The other countermeasure, operation shuffling or permutation, can mitigate side-channel leakage effectively with minimal overhead. In this paper, we target automatically implementing operation shuffling...
The proposed holographic Shack-Hartmann wavefront sensor can measure a wavefront aberration with large dynamic range. It is realized by introducing a holographic optical element and pattern matching technique. To confirm the flexibility of the sensor, measurements of the wavefronts with various aberrations are numerically demonstrated.
In this paper we examine a number of deployment issues which arise from practical considerations in massive multiple-input-multiple-output (MIMO) systems. We show both spatial correlation and line-of-sight (LOS) introduce an interference component to the system which causes non-orthogonality between user channels. Distributing the antennas into multiple clusters is shown to reduce spatial correlation...
We firstly applied diversity reception technology to a real-time none-light-of-sight (NLOS) ultraviolet (UV) communication system based on a 9.3mW LED array. Field experiment with 4 receivers (Rxs) achieves bit error rate (BER) improvement, and related conclusions on single-input-multiple-output (SIMO) UV system design are given. Innovatively, the correlation characteristics in UV channel are studied...
The high cost and power consumption of the radio frequency chain and data converters at mmWave frequencies introduce hardware limitations into the design of MIMO precoders and combiners. MmWave hybrid precoding overcomes this limitation by dividing the spatial signal processing between the radio frequency and baseband domains. Analog networks of phase shifters have been proposed to implement the radio...
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