Lossy Communication Channels Research Articles

StegaStyleGAN: Towards Generic and Practical Generative Image Steganography

The recent advances in generative image steganography have drawn increasing attention due to their potential for provable security and bulk embedding capacity. However, existing generative steganographic schemes are usually tailored for specific tasks and are hardly applied to applications with practical constraints. To address this issue, this paper proposes a generic generative image steganography scheme called Steganography StyleGAN (StegaStyleGAN) that meets the practical objectives of security, capacity, and robustness within the same framework. In StegaStyleGAN, a novel Distribution-Preserving Secret Data Modulator (DP-SDM) is used to achieve provably secure generative image steganography by preserving the data distribution of the model inputs. Additionally, a generic and efficient Secret Data Extractor (SDE) is invented for accurate secret data extraction. By choosing whether to incorporate the Image Attack Simulator (IAS) during the training process, one can obtain two models with different parameters but the same structure (both generator and extractor) for lossless and lossy channel covert communication, namely StegaStyleGAN-Ls and StegaStyleGAN-Ly. Furthermore, by mating with GAN inversion, conditional generative steganography can be achieved as well. Experimental results demonstrate that, whether for lossless or lossy communication channels, the proposed StegaStyleGAN can significantly outperform the corresponding state-of-the-art schemes.

Regression-Based Self-Triggered Control of Distributed Economic Dispatch over Lossy Communication Channels

An essential building block of today’s smart grids is the integration of various renewable power generators into the system. Renewable distributed generators (DGs) provide environment friendly energy at a low cost. In this work, a distributed economic dispatch (ED) system is considered for renewable DGs to address the scalability challenge and reduce single points of failure compared to a centralised ED system. A consensus control mechanism is devised to achieve the incremental cost (IC) consensus among the DGs and utilise a self-triggered control (STC) mechanism to reduce the communication of the distributed DG system. A lossy communication channel between local DGs is considered in this work, which can arise from power lines or congestion on noisy wireless communication channels. A regression-based estimation approach is proposed to account for lost or corrupted data. The proposed method is compared with a centralised ED system and periodic communication. The proposed STC approach achieves the same level of performance as periodic communication while using half the communication resources.

Federated Learning Over Wireless IoT Networks With Optimized Communication and Resources

To leverage massive distributed data and computation resources, machine learning in the network edge is considered to be a promising technique, especially for large-scale model training. Federated learning (FL), as a paradigm of collaborative learning techniques, has obtained increasing research attention with the benefits of communication efficiency and improved data privacy. Due to the lossy communication channels and limited communication resources (e.g., bandwidth and power), it is of interest to investigate fast responding and accurate FL schemes over wireless systems. Hence, we investigate the problem of jointly optimized communication efficiency and resources for FL over wireless Internet of Things (IoT) networks. To reduce complexity, we divide the overall optimization problem into two subproblems, i.e., the client scheduling problem and the resource allocation problem. To reduce the communication costs for FL in wireless IoT networks, a new client scheduling policy is proposed by reusing stale local model parameters. To maximize successful information exchange over networks, a Lagrange multiplier method is first leveraged by decoupling variables, including power variables, bandwidth variables, and transmission indicators. Then, a linear-search-based power and bandwidth allocation method is developed. Given appropriate hyperparameters, we show that the proposed communication-efficient FL (CEFL) framework converges at a strong linear rate. Through extensive experiments, it is revealed that the proposed CEFL framework substantially boosts both the communication efficiency and learning performance of both training loss and test accuracy for FL over wireless IoT networks compared to a basic FL approach with uniform resource allocation.

Networked supervisor synthesis against lossy channels with bounded network delays as non-networked synthesis

In this work, we study the problem of supervisory control of networked discrete event systems. We consider lossy communication channels with bounded network delays, for both the control channel and the observation channel. By a model transformation, we transform the networked supervisor synthesis problem into the classical (non-networked) supervisor synthesis problem (for non-deterministic plants), such that the existing supervisor synthesis tools can be used for synthesizing networked supervisors. In particular, we can use the (state-based) normality property for the synthesis of the supremal networked supervisors, whose existence is guaranteed by construction due to our consideration of command non-deterministic supervisors. The effectiveness of our approach is illustrated on a mini-guideway example that is adapted from the literature, for which the supremal networked supervisor has been synthesized in the synthesis tools SuSyNA and TCT.

H∞ Optimal control of jump systems over multiple lossy communication channels

Abstract In this paper, the $H_{\infty }$ optimal control problem for a Markovian jump linear system (MJLS) over multiple lossy communication channels is considered. It is assumed that the controller communicates with each actuator through a different communication channel. We solve the $H_{\infty }$ optimization problem for the system with a Transmission Control Protocol (TCP) using the theory of dynamic games and obtain a state feedback controller. The infinite horizon $H_{\infty }$ optimization problem is analysed as a limiting case of the finite horizon optimization problem. Then, we obtain the corresponding state feedback controller and show that it stabilizes the closed-loop system in the face of random packet dropouts. A novel and relaxed condition for stability of the closed-loop system with the saddle-point policy is also presented. Further, we show that a weaker notion of observability is sufficient to establish our results.

Stochasticity in Feedback Loops: Great Expectations and Guaranteed Ruin

Stochastic components in a feedback loop introduce state behaviors that are fundamentally different from those observed in a deterministic system. The effect of injecting a stochastic signal additively in linear feedback systems can be viewed as the addition of filtered stochastic noise. If the stochastic signal enters the feedback loop in a multiplicative manner, a much richer set of state behaviors emerges. These phenomena are investigated for the simplest possible system: a multiplicative noise in a scalar, integrating feedback loop. The same dynamics arise when considering a first-order system in feedback with a stochastic gain. The dynamics of this form arise naturally in a number of domains, including compound investments in finance, chemical reaction dynamics, population dynamics, epidemiology, control over lossy communication channels, and adaptive control. Understanding the nature of such dynamics in a simple system is a precursor to recognizing them in more complex stochastic dynamical systems.

Robust Stability and Stabilization Conditions for Nonlinear Networked Control Systems With Network-Induced Delay via T–S Fuzzy Model

Robust stability and stabilization problems for a class of discrete-time nonlinear systems are studied in this article. The control signal is transmitted to the nonlinear systems through a lossy communication channel in which time-varying network-induced delay occurs. A Takagi–Sugeno (T–S) fuzzy model is used to represent the nonlinear systems. Using membership function boundary information, a novel membership-function-dependent (MFD) analysis approach is presented. Unlike most previous results, the proposed MFD analysis approach does not need to increase the number of slack variables to reduce conservatism. Combining auxiliary matrices and this approach, we propose some new fuzzy Lyapunov–Krasovskii functionals (FLKFs) that do not require the restrictions of positive definiteness imposed on Lyapunov matrices. Using the FLKF and MFD analysis approach, a sufficient condition in the form of linear matrix inequalities (LMIs) is developed to guarantee the stability of T–S fuzzy time-varying delay systems. Based on the results for stability, less conservative stabilization conditions are also derived. Finally, numerical examples show that less conservative results can be obtained by the proposed approach. The inverted pendulum system with state delay or network-induced delay is also studied to verify the effectiveness of the suggested approach.

Formula omitted] optimal control over multiple Gilbert–Elliott type communication channels

This paper considers the design of an H∞ optimal controller for a linear time-invariant system over multiple Gilbert–Elliott type lossy communication channels. The problem is formulated as a two-player zero-sum game. For the finite horizon case, we have derived conditions that ensure the existence of a unique saddle-point. Further, the value of the game along with the corresponding optimal input and optimal disturbance trajectories are obtained. These results have then been extended to the infinite horizon case. It has been shown that if a unique saddle-point exists then the optimal control law stabilizes the system while the L2 gain from the disturbance input to the controlled output will be less than or equal to certain γ>0.

Static output feedback control of uncertain systems over uncertain communication links with guaranteed H∞ performance

AbstractThis article is concerned with the problem of robust static output feedback H∞ control for networked control systems (NCSs) by considering uncertainties in both controlled‐plant and communication subsystems. Markov chains are employed to model the bounded random network‐induced delays occurring in the communication channels. This modeling framework can be used to describe the packet dropout phenomena over a lossy communication channel as well. It is assumed that the transition probabilities of the Markov chains are uncertain but lying within given intervals. By utilizing the augmentation technique, the NCS model is transformed into a delay‐free Markovian jump linear system. A new sufficient condition is derived for the problem of robust H∞ control using static output feedback in NCSs with network‐induced delays. This design condition is expressed in terms of linear matrix inequalities without requiring any constraints on the matrix variables. Furthermore, the proposed method is extended to the case of NCSs with bounded Markovian packet dropouts. Numerical examples are provided to make comparisons with other works and demonstrate the advantages of the proposed method.

Stability Analysis and Performance Evaluation of Delayed Bilateral Telerobotic Systems over a Lossy Communication Channel

The focus of this paper is to address a novel control technique for stability and transparency analysis of bilateral telerobotic systems in the presence of data loss and time delay in the communication channel. Different control strategies have been reported to compensate the effects of time delay in the communication channel; however, most of them result in poor performance under data loss. First, a model for data loss is proposed using a finite series representation of a set of periodic continuous pulses. To improve the performance and data reconstruction, a holder circuits is also introduced. The passivity of the overall system is provided via the wave variable technique based on the proposed model for the data loss. The stability analysis of the system is then derived using the Lyapunov theorem under the time delay and the data loss. Finally, experimental results are given to illustrate the capability of the proposed control technique.

Remote Entanglement via Adiabatic Passage Using a Tunably Dissipative Quantum Communication System.

Effective quantum communication between remote quantum nodes requires high fidelity quantum state transfer and remote entanglement generation. Recent experiments have demonstrated that microwave photons, as well as phonons, can be used to couple superconducting qubits, with a fidelity limited primarily by loss in the communication channel [P. Kurpiers etal., Nature (London) 558, 264 (2018)NATUAS0028-083610.1038/s41586-018-0195-y; C. J. Axline etal., Nat. Phys. 14, 705 (2018)NPAHAX1745-247310.1038/s41567-018-0115-y; P. Campagne-Ibarcq etal., Phys. Rev. Lett. 120, 200501 (2018)PRLTAO0031-900710.1103/PhysRevLett.120.200501; N. Leung etal., npj Quantum Inf. 5, 18 (2019)2056-638710.1038/s41534-019-0128-0; Y. P. Zhong etal., Nat. Phys. 15, 741 (2019)NPAHAX1745-247310.1038/s41567-019-0507-7; A. Bienfait etal., Science 364, 368 (2019)SCIEAS0036-807510.1126/science.aaw8415]. Adiabatic protocols can overcome channel loss by transferring quantum states without populating the lossy communication channel. Here, we present a unique superconducting quantum communication system, comprising two superconducting qubits connected by a 0.73m-long communication channel. Significantly, we can introduce large tunable loss to the channel, allowing exploration of different entanglement protocols in the presence of dissipation. When set for minimum loss in the channel, we demonstrate an adiabatic quantum state transfer protocol that achieves 99% transfer efficiency as well as the deterministic generation of entangled Bell states with a fidelity of 96%, all without populating the intervening communication channel, and competitive with a qubit-resonant mode-qubit relay method. We also explore the performance of the adiabatic protocol in the presence of significant channel loss, and show that the adiabatic protocol protects against loss in the channel, achieving higher state transfer and entanglement fidelities than the relay method.

Output feedback stochastic MPC with packet losses

The paper considers constrained linear systems with stochastic additive disturbances and noisy measurements transmitted over a lossy communication channel. We propose a model predictive control (MPC) law that minimizes a discounted cost subject to a discounted expectation constraint. Sensor data is assumed to be lost with known probability, and data losses are accounted for by expressing the predicted control policy as an affine function of future observations, which results in a convex optimal control problem. An online constraint-tightening technique ensures recursive feasibility of the online optimization and satisfaction of the expectation constraint without bounds on the distributions of the noise and disturbance inputs. The cost evaluated along trajectories of the closed loop system is shown to be bounded by the optimal predicted cost. A numerical example is given to illustrate these results.

Feasibility of twin-field quantum key distribution based on multi-mode coherent phase-coded states.

In this paper we propose feasibility demonstration of twin-field quantum key ditribution system based on multi-mode weak coherent phase-coded states. Their utilization provides indisputable advantages described in the paper. We also provide the detailed description of nontrivial interference scheme for those states and derive detection and quantum bit error rates. Since we propose the feasibility scheme we present in this paper only asymptotic secure key estimation and show that in principle it can beat well-known fundamental limit of repeaterless quantum communications , i.e., the secret key capacity of the lossy communication channel. Also we present here the experimental setup and provide the experimental values of detection rates dependence on the modulation signals phase difference.

Reduction of Padding Overhead for RLNC Media Distribution With Variable Size Packets

Random linear network coding (RLNC) can enhance the reliability of multimedia transmissions over lossy communication channels. However, RLNC has been designed for equal size packets, while many efficient multimedia compression schemes, such as variable bitrate (VBR) video compression, produce unequal packet sizes. Padding the unequal packet sizes with zeros to the maximum packet size creates an overhead on the order of 20%–50% or more for typical VBR videos. Previous padding overhead reduction approaches have focused on packing the unequal packet sizes into fixed size packets, e.g., through packet bundling or chaining and fragmentation. We introduce an alternative padding reduction approach based on coding macro-symbols (MSs), whereby an MS is a fixed-sized part of a packet. In particular, we introduce a new class of RLNC, namely MS RLNC which conducts RLNC across columns of MSs, instead of the conventional RLNC across columns of complete packets of equal size. Judiciously arranging the source packets into columns of MSs, e.g., through shifting the source packets horizontally relative to each other, supports favorable MS RLNC coding properties. We specify the MS RLNC encoding and decoding mechanisms and analyze their complexity for a range of specific MS arrangement strategies within the class of MS RLNC. We conduct a comprehensive padding overhead evaluation encompassing both previous approaches of packing the unequal size packets into fixed size packets as well as the novel MS RLNC approaches with long VBR video frame size traces. We find that for small RLNC generation sizes that support low network transport delays, MS RLNC achieves the lowest padding overheads; while for large generation sizes, both the previous packing approaches and the novel MS RLNC approaches effectively reduce the padding overhead.

Stability Analysis of Event-Triggered Anytime Control With Multiple Control Laws

To deal with time-varying processor availability and lossy communication channels in embedded and networked control systems, one can employ an event-triggered sequence-based anytime control (E-SAC) algorithm. The main idea of E-SAC is, when computing resources and measurements are available, to compute a sequence of tentative control inputs and store them in a buffer for potential future use. State-dependent random-time drift (SRD) approach is often used to analyze and establish stability properties of such E-SAC algorithms. However, using SRD, the analysis quickly becomes combinatoric and hence difficult to extend to more sophisticated E-SAC. In this technical note, we develop a general model and a new stability analysis for E-SAC based on Markov jump systems. Using the new stability analysis, stochastic stability conditions of existing E-SAC are also recovered. In addition, the proposed technique systematically extends to a more sophisticated E-SAC scheme for which, until now, no analytical expression had been obtained.

Networked control of uncertain systems via the coarsest quantization and lossy communication

We study a networked control problem of uncertain systems based on quantized signals sent over unreliable, lossy communication channels. The coarsest quantization is characterized for attaining the objective of quadratic stability of the overall closed-loop system in a stochastic sense. Our result indicates that the coarsest quantization is given by the logarithmic type and that more information is required through finer quantization for more uncertain systems and more unreliable channels. The characterization provides an analytic upper bound for the coarseness, which is tight for some special cases and generalizes known results for systems without uncertainties and for channels without losses.

Complete elimination of information leakage in continuous-variable quantum communication channels

In all lossy communication channels realized to date, information is inevitably leaked to a potential eavesdropper. Here we present a communication protocol that does not allow for any information leakage to a potential eavesdropper in a purely lossy channel. By encoding information into a restricted Gaussian alphabet of squeezed states we show, both theoretically and experimentally, that the Holevo information between the eavesdropper and the intended recipient can be exactly zero in a purely lossy channel while minimized in a noisy channel. This result is of fundamental interest, but might also have practical implications in extending the distance of secure quantum key distribution.

Networked Control of Uncertain Systems via the Coarsest Quantization and Lossy Communication

In this paper, we study a networked control problem of uncertain systems based on quantized signals sent over unreliable, lossy communication channels. The coarsest quantization is characterized for attaining the objective of quadratic stability of the overall closed-loop system in a stochastic sense. Our result indicates that the coarsest quantization is given by the logarithmic type and, furthermore, more information is required through finer quantization for more uncertain systems and more unreliable channels. The characterization provides an analytic upper bound for the required coarseness, which is tight for some special cases, generalizes conventional results for systems without uncertainties and for channels without losses.

Quantum repeaters using continuous-variable teleportation

Quantum optical states are fragile and can become corrupted when passed through a lossy communication channel. Unlike for classical signals, optical amplifiers cannot be used to recover quantum signals. Quantum repeaters have been proposed as a way of reducing errors and hence increasing the range of quantum communications. Current protocols target specific discrete encodings, for example quantum bits encoded on the polarization of single photons. We introduce a more general approach that can reduce the effect of loss on any quantum optical encoding, including those based on continuous variables such as the field amplitudes. We show that in principle the protocol incurs a resource cost that scales polynomially with distance. We analyse the simplest implementation and find that whilst its range is limited it can still achieve useful improvements in the distance over which quantum entanglement of field amplitudes can be distributed.

Reliable broadcast in anonymous distributed systems with fair lossy channels

Reliable Broadcast (RB) is a basic abstraction in distributed systems, because it allows processes to communicate consistently and reliably to each other. It guarantees that all correct process reliable deliver the same set of messages. This abstraction has been extensively investigated in distributed systems where all processes have different identifiers, and the communication channels are reliable. However, more and more anonymous systems appear due to the motivation of privacy. It is significant to extend RB into anonymous system model where each process has no identifier. In another hand, the requirement of reliable communication channels is not always satisfied in real systems. Hence, this paper is aimed to study RB abstraction in anonymous distributed systems with fair lossy communication channels. In distributed systems, symmetry always mean that two systems should be considered symmetric if they behave identically, and two components of a system should be considered symmetric if they are indistinguishable. Hence, the anonymous distributed systems is symmetry. The design difficulty of RB algorithm lies in how to break the symmetry of the system. In this paper, we propose to use a random function to break it. Firstly, a non-quiescent RB algorithm tolerating an arbitrary number of crashed processes is given. Then, we introduce an anonymous perfect failure detector AP?. Finally, we propose an extended and quiescent RB algorithm using AP?.