Crosstalk in misaligned free space optical interconnects: modelling and simulation

We introduce convenient model and an optimization scheme to optimize the signal-to-crosstalk ratio (SCR) in a free space optical interconnects (FSOIs) system that uses microlenses with finite circular apertures. In this model, we consider both the stray light crosstalk and the crosstalk due to the diffraction at the microlens apertures to evaluate the SCR. Using cylindrical form of Collins diffraction integral and the Laguerre–Gaussian (LG) beam model, we derive an approximate closed form formula for the optical field of a multimode LG beam propagating through circular apertured FSOIs by expanding the hard edge circular aperture function of the microlens in terms of complex Gaussian functions. The analyses indicate that the size of the detector is an important factor to optimize the SCR for both the apertured and the unapertured misaligned FSOIs system. The effect of higher order mode of the laser source on the SCR is also considered.

Improvement of misalignment tolerance in free-space optical interconnects

In this paper, the use of micro lenses with non-uniform transmittance apertures as an alternative to those with uniform transmittance apertures in optical communication systems is proposed. In particular, we consider the use of micro lenses with tapered Gaussian transmittance profiles to improve the misalignment tolerance in optical interconnects. We study the effects of utilizing Gaussian transmittance profiles on the propagation of light beams and the signal to crosstalk ratio of misaligned optical systems. Moreover, we consider the use of uniform transmittance profiles in optical systems for the sake of comparison. To this end, the crosstalk optical noise is modeled at the plane of the detectors array considering the two scenarios of uniform and Gaussian apertures. This was possible after finding the optical field for both scenarios at the of the detectors array. Numerical results clearly demonstrate the significant improvement in decreasing the crosstalk and increasing the signal to crosstalk ratio in the considered optical systems upon utilizing the Gaussian profiles

Bandwidth density optimization of misaligned optical interconnects

In this paper, the bandwidth density of misaligned free space optical interconnects (FSOIs) system with and without coding under a fixed bit error rate is considered. In particular, we study the effect of using error correction codes of various codeword lengths on the bandwidth density and misalignment tolerance of the FSOIs system in the presence of higher order modes. Moreover, the paper demonstrates the use of the fill factor of the detector array as a design parameter to optimize the bandwidth density of the communication. The numerical results demonstrate that the bandwidth density improves significantly with coding and the improvement is highly dependent on the used codeword length and code rate. In addition, the results clearly show the optimum fill factor values that achieve the maximum bandwidth density and misalignment tolerance of the system

BZKP: Blockchain-based zero-knowledge proof model for enhancing healthcare security in Bahrain IoT smart cities and COVID-19 risk mitigation

Smart cities achieved digital transformation of patients’ health records through the use of new technology in IoT healthcare industry. Such technologies of using IoT and remote patient monitoring systems have become dramatically fundamental to reduce the movement of patients, and hence reducing the risk of spreading Covid-19 infection. The Ministry of Health in the Kingdom of Bahrain strives to achieve digital transformation in the healthcare industry, where the National Health Information System (I-SEHA) was launched to provide higher-quality health services. The system interconnects the public healthcare institutes, allowing access to patient’s data from any location without the hassle of moving the files physically. Digitization of medical data of patients and sharing some of the data with other institutions outside the protected networks may lead to major privacy and integrity concerns. This paper introduces Blockchain-based Zero-Knowledge Proof (BZKP) model, which is an IoT-based patient-centric model that fuses a zero-knowledge proof solution to be developed for protecting patient’s privacy, and ensures patients prior consent on any access to their data including their health status and account balance. The proposed model is developed to provide a robust and scalable architecture for data sharing, which protects the privacy of sensitive data while maintaining high availability. It also provides strong trust and integrity of data by using the immutability features of the blockchain. BZKP is based on pre-approved blockchain access tokens to address challenges of accountability and privacy in Bahrain smart cities. As a result, the model provides a secure and trusted access model between different stakeholders to share patient data while maintaining privacy, trust, and high availability. The zero-knowledge proof can be used with the smart contracts, which provides programmable actions that can be used for automating the prescriptions dispensation process for private pharmacies in a decentralized manner with high confidence. Finally, it recommends enhanced electronic key (eKey) procedures used by eGovernment of the Kingdom of Bahrain to update the smart card which stores the personal keys for protecting patient’s privacy and provide better consent

Optimum consultation for serial distributed detection systems

This paper considers a distributed detection system which consists of  sensors that are connected in series. The observations of each sensor in this system design are considered to be statistically independent of all other sensors. In contrast to the popular serial decision fusion systems, we assume that consultations are allowed in a serial manner between successive sensors that make up the system. In addition, the paper demonstrates the similarity between the proposed consulting serial system and the optimal serial one in terms of detection probabilities for a give probability of false alarm. However, it should be emphasized that the proposed system has the benefit of conditional nonrandom consultation among the sensors. Consequently, its survivability is higher than that of serial systems. Numerical evaluations for the cases of two and three sensors are provided and compared with those of the serial as well as the centralized schemes

High Utility Guarantee Video Surveillance System Using IEEE 802.16 WiMAX Networks

Abstract—In video surveillance systems, one of the key design requirements is that video throughput must not fall below a certain limit as the contents must be adequately perceivable. In this paper, we address the problem of guaranteed transportation of critical video flows in wireless WiMAX mesh networks. Our solution is based on the insight that in seeking to construct optimal routing trees and to maximize the network throughput, the problem of assigning the highest possible data rate to source nodes and that of finding the best and efficient forwarding trees from sources to collection points are not independent, the solution of each has a profound impact on the outcome of the other. Therefore, the two problems should ideally be solved jointly. Both problems are essential for the global system performances, in particular in situations of scarce network resources. In this paper, we formulate the global system optimization as an Integer Linear Program (ILP) that maximizes the network utility while satisfying QoS requirements. We also propose a scalable and yet efficient heuristic Joint Routing and Rate Assignment solution, termed JRRA

Optimal Rate Assignment for Higher Utility WiMAX Surveillance Systems

International audience<p>In this paper, we address the problem of guaranteed transmission of video flows in the context of WiMAX mesh networks for video surveillance purposes. The main design issue in such networks is to maximize the number of flows that can be accommodated in critical situations. Guaranteeing a throughput for individual flows in a multi-hop WiMAX network is a challenging task. We consider a specific dedicated architecture where communication interference can be avoided using multi- radio, multi-channel equipments where a certain latitude is offered in the configuration of video camera rates. To this end, we introduce a global utility function for the network based on the accepted video flows, their respective data rates, and the relative importance of these flows (priority). We formulate the rate assignment problem as an Integer Linear Program (ILP) that maximizes the network utility while satisfies the QoS requirements. Since the running time required to obtain the optimal solution increases exponentially with the number of nodes in the network, optimal results are only possible when the problem scale is small. Thus, the optimal solution is used for benchmarking purposes only. In this paper, we also propose new practical tree construction techniques as well as an efficient rate assignment algorithm. We compare the resulting performance of our algorithm with the optimal solution, and show that it closes a considerable portion of the gap from the theoretical optimal solution.</p

Evaluation of Routing Protocols for VANETs in Urban Environments

International audienc

A Topology Control Algorithm with Good Spanner Properties for Wireless Sensor Networks

International audienc

Bandwidth Density Analysis of Coded Free-Space Optical Interconnects

The performance of free-space optical interconnects (FSOIs) system is significantly influenced by noise, similar to any wireless communication system. This noise has a notable impact on both the bandwidth density and data rate of FSOIs system. To address these challenges, this study proposes the utilization of vertical-cavity-surface-emitting laser (VCSEL) arrays on the transmitter side and photodetector arrays on the receiver side for FSOIs. The study investigates the bandwidth density of the system with and without coding while maintaining a specific bit error rate. An analysis is conducted in the presence of higher-order modes in the laser beams of the FSOIs system and a fundamental Gaussian operating mode. The presence of the higher-order modes leads to degradation in the performance of the FSOIs system in terms of bandwidth density. In addition, we examine the impact of the signal-to-noise ratio (SNR) on the system’s bandwidth density for each considered operating mode. The provided simulation results clearly demonstrate that coding significantly enhances the bandwidth density of the systems, with the extent of improvement being closely tied to the employed code rate and codeword length