Multiple Communication Paths Research Articles

SN-FSAT system for single sensor ultrasonic guided wave beam steering and damage detection

In wireless communications as well as in structural health monitoring (SHM) beam steering presents interesting advantages. In the former it plays an important role for data directivity, which is also a perk for energy efficiency and data security; for the latter, directional inspection through guided waves leads also to energy efficiency, arbitrary dedicated space scanning, multi-function operation through multiple beams and even to application of a base-line free inspection concept. Normally, to enable this simultaneous beam control and data communication in arbitrary spatial directions (2D) over a structure, a large array of transducers is required, arranged to a similarly complex hardware and software support system. In this work, we present a system based on a dedicated sensor node (SN) and frequency steerable acoustic transducer (FSAT) combination. The SN-FSAT system is charged of the adequate power and signal management for acquisition, transmission, processing and data evaluation, required to perform spatial scanning and damage detection, as well as direction focused wireless communication tasks. These were tested over an isotropic aluminum plate-like structure by means of a double symmetric beam, via differential actuation signals, or in a high directive beam in a single direction by means of a quadrature driving signals. The complete guided wave-based setup consists of three SN-FSAT pairs. As damage a pseudo fault of a small added mass with damping tacky tape was used. The results show that damage located in different positions around the FSATs can be detected without a baseline reference and multiple directional communication paths between the SN-FSAT network can be established.

Cryptographic algorithm for multi-path distribution of entangled states of orbital angular momentum based on Fibonacci values

Drawing inspiration from the Fibonacci sequence and its complementary Lucas sequence, this paper introduces an innovative encryption and decryption algorithm tailored for multi-path quantum key distribution. The algorithm capitalizes on the high-quality orbital angular momentum entangled states, harnessing the mathematical elegance of Fibonacci numbers to construct block diagonal matrices. These matrices serve as the foundation for the simultaneous execution of key distribution across multiple communication paths in a structured block distribution format. The encryption process is facilitated through a combination of linear mappings, employing specific transition matrices to manage the cryptographic flow. The security underpinning of this method is firmly rooted in the Heisenberg Uncertainty Principle, a fundamental tenet of quantum mechanics, which ensures the confidentiality and integrity of the quantum communication channel. This approach paves the way for a novel encryption paradigm, fortifying the security framework of quantum communication networks.

A Novel Routing Control Method Using Federated Learning in Large-Scale Wireless Mesh Networks

Currently, the volume of communication by mobile terminals are increasing owing to 5G and other technologies. A robust network and appropriate routing control methods are requied to transmit information in unstable wireless communication environments and avoid congestion. Therefore, in recent years, numerous studies have been conducted on wireless mesh networks (WMNs), which provide a fault-tolerant communication environment by securing multiple communication paths and whose topology can be freely configured and extended. Additionally, machine learning routing is attracting attention as a new routing method for wireless communication environments. However, when performing machine learning on a large WMN, the learning time increases and rapid routing control may be impossible. In this study, we apply federated learning to machine learning and propose a machine-learning-based routing method that can be applied to large-scale WMNs. Furthermore, experimental results demonstrate the effectiveness of the proposed method in various environments: congestion avoidance is achieved in a large-scale WMN by machine-learning routing using federated learning. This study is expected to serve as a basis for significant progress in the realization of large-scale WMNs as wireless communication infrastructure.

Entanglement of Signal Paths via Noisy Superconducting Quantum Devices.

Quantum routers will provide for important functionality in emerging quantum networks, and the deployment of quantum routing in real networks will initially be realized on low-complexity (few-qubit) noisy quantum devices. A true working quantum router will represent a new application for quantum entanglement-the coherent superposition of multiple communication paths traversed by the same quantum signal. Most end-user benefits of this application are yet to be discovered, but a few important use-cases are now known. In this work, we investigate the deployment of quantum routing on low-complexity superconducting quantum devices. In such devices, we verify the quantum nature of the routing process as well as the preservation of the routed quantum signal. We also implement quantum random access memory, a key application of quantum routing, on these same devices. Our experiments then embed a five-qubit quantum error-correcting code within the router, outlining the pathway for error-corrected quantum routing. We detail the importance of the qubit-coupling map for a superconducting quantum device that hopes to act as a quantum router, and experimentally verify that optimizing the number of controlled-X gates decreases hardware errors that impact routing performance. Our results indicate that near-term realization of quantum routing using noisy superconducting quantum devices within real-world quantum networks is possible.

Cyber Physical Systems Security for Maritime Assets

The integration of IT, OT, and human factor elements in maritime assets is critical for their efficient and safe operation and performance. This integration defines cyber physical systems and involves a number of IT and OT components, systems, and functions that involve multiple and diverse communication paths that are technologically and operationally evolving along with credible cyber security threats. These cyber security threats and risks as well as a number of known security breach scenarios are described in this paper to highlight the evolution of cyber physical systems in the maritime domain and their emerging cyber vulnerabilities. Current industry and governmental standards and directives related to cyber security in the maritime domain attempt to enforce the regulatory compliance and reinforce asset cyber security integrity for optimum and safe performance with limited focus, however, in the existing OT infrastructure and systems. The use of outside-of-the-maritime industry security risk assessment tools and processes, such the API STD 780 Security Risk Assessment (SRA) and the Bow Tie Analysis methodologies, can assist the asset owner to assess its IT and OT infrastructure for cyber and physical security vulnerabilities and allocate proper mitigation measures assuming their similarities to ICS infrastructure. The application of cyber security controls deriving from the adaptation of the NIST CSF and the MITRE ATT&CK Threat Model can further increase the cyber security integrity of maritime assets, assuming they are periodically evaluated for their effectiveness and applicability. Finally, the improvement in communication among stakeholders, the increase in operational and technical cyber and physical security resiliency, and the increase in operational cyber security awareness would be further increased for maritime assets by the convergence of the distinct physical and cyber security functions as well as onshore- and offshore-based cyber infrastructure of maritime companies and asset owners.

Robust Clock Skew and Offset Estimation for IEEE 1588 in the Presence of Unexpected Deterministic Path Delay Asymmetries

IEEE 1588, built on the classical two-way message exchange scheme, is a popular clock synchronization protocol for packet-switched networks. Due to the presence of random queuing delays in a packet-switched network, the joint recovery of the clock skew and offset from the timestamps of the exchanged synchronization packets can be treated as a statistical estimation problem. In this paper, we address the problem of clock skew and offset estimation for IEEE 1588 in the presence of possible unknown asymmetries between the deterministic path delays of the forward master-to-slave path and reverse slave-to-master path, which can result from incorrect modeling or cyber-attacks. First, we develop lower bounds on the mean square estimation error for a clock skew and offset estimation scheme for IEEE 1588 assuming the availability of multiple master-slave communication paths and complete knowledge of the probability density functions (pdf) describing the random queuing delays. Approximating the pdf of the random queuing delays by a mixture of Gaussian random variables, we then present a robust iterative clock skew and offset estimation scheme that employs the space alternating generalized expectation-maximization (SAGE) algorithm for learning all the unknown parameters. Numerical results indicate that the developed robust scheme exhibits a mean square estimation error close to the lower bounds.

Multi-Connectivity as an Enabler for Reliable Low Latency Communications—An Overview

Emerging applications such as wireless industrial control or vehicular communications pose strict requirements in terms of latency and reliability on wireless communication systems. Since contemporary communication standards are not able to fulfill all of these requirements, reliable low-latency communication is an important research topic. Using multiple communication paths at once, i.e., multi-connectivity (MC), is a promising approach to get closer to reaching this goal of reliable low-latency communication. In this survey we provide a definition for MC, identify main scheduling categories, compare different network architectures and consider different layers for implementing MC. We provide an overview of MC methods already established in IEEE and 3GPP standardization and discuss recent MC approaches on a layer-by-layer basis. Moreover, we reflect on the existing literature and identify open issues. We suggest further research directions such as the OSI Layer where separation and aggregation of the different paths for MC is performed, the characteristics of the paths to be used for MC and dynamic scheduling techniques for MC settings.

Performance analysis of NLOS ultraviolet communications with correlated branches over turbulent channels

Ultraviolet communication (UVC) is becoming increasingly popular due to its ability to effectively communicate in non-line-of-sight (NLOS) mode, which offers alternative communication system advantages over visible light communication and infrared links. However, the performance of UVC is affected by atmospheric turbulence, which is generally ignored under the assumption of short-distance links. In this paper, we consider a NLOS UVC system experiencing turbulence due to variation in the refractive index of the atmosphere. The atmospheric turbulence results in fading due to fluctuations in the received signal strength, thus deteriorating the quality of communication. Spatial diversity is proven to mitigate the effect of fading by introducing multiple parallel communication paths between the transmitter and receiver. We present a spatial diversity reception in the form of ${N_r}$-branches selection combining at the receiver. The channel coefficients are assumed to be exponentially correlated, and turbulence is modeled using log-normal distribution under weak turbulence conditions. Closed-form expressions for the outage probability and average symbol error rate for general order rectangular quadrature amplitude modulation (RQAM), cross-QAM, and hexagonal QAM schemes are derived. Furthermore, the ergodic capacity of the system is computed as a function of the channel correlation coefficient. The numerical values are compared with computer simulations to validate the accuracy of the theoretical analysis.

AeroMRP: A Multipath Reliable Transport Protocol for Aeronautical Ad Hoc Networks

In order to support Internet of Things, an aeronautical ad hoc network (AANET) has been proposed to solve the problem of air information isolated island. AANET is a special type of heterogeneous ad hoc network between commercial aircraft to share data and in-flight Internet access. Today’s civil airliners are typically equipped with multiple advanced network interfaces, which can form multiple independent communication paths between the source and the destination nodes in AANETs. Thus, users expect to utilize multiple networking interfaces of airliners simultaneously to support data transfer services. In this paper, we present a multipath reliable transport protocol for AANETs, called AeroMRP, which exploits path diversity provided by heterogeneous aeronautical networks. AeroMRP takes advantage of raptor codes to restore from packet loss in the aeronautical network environments while reducing the impact of the head-of-line blocking issue in the networks with multiple paths. A redundancy rate selection algorithm is adopted to determine the redundancy on the fly by considering the characteristics of the target applications and the time-varying aeronautical networks. Moreover, AeroMRP implements feedback-based packet scheduling considering not only aeronautical network status but also the acknowledgment scheme in congestion control for better use of different paths. We evaluate the performance of AeroMRP by ns-3 under a variety of simulation scenarios. The simulations demonstrate that AeroMRP can provide efficient and reliable data transmission services in heterogeneous multipath AANETs.

A novel multiple communication paths for surgical telepresence videos delivery of the maxilla area in oral and maxillofacial surgery

A surgical telepresence between two surgical sites where a local surgeon in the surgery site, who is less experienced, needs help from the expert surgeon located at a remote site. Furthermore, the primary aim of this paper is to improve the quality of surgical video sent and received to-and-from both surgical sites, which has been a major quality issue so far. This work considers flow rate allocation and resource availability to determine the network path quality. Furthermore, a segmented backup path is used to provide a timely recovery in case of failure in the link. A neighbour detection technique in segmented backup is used to reduce the detection latency of the network in case of link failure. The results depict that the proposed system improves the quality of the surgical video by an average of 5.5db over the current system. Furthermore, the neighbour detection technique detects the network failure 40-45% faster than the currently used end-to-end detection system. The experimental results have done on the maxilla areas in oral and maxillofacial surgery. The proposed system concentrates on reducing the network failure detection latency and improves the received and sent video quality by using an enhanced path quality technique. Thus, this study enhances the video quality and provides a backup option in case of failure, which offers timely recovery for communication between two surgeons.

Path Hopping: An MTD Strategy for Long-Term Quantum-Safe Communication

Moving target defense (MTD) strategies have been widely studied for securing computer systems. We consider using MTD strategies to provide long-term cryptographic security for message transmission against an eavesdropping adversary who has access to a quantum computer. In such a setting, today’s widely used cryptographic systems including Diffie-Hellman key agreement protocol and RSA cryptosystem will be insecure and alternative solutions are needed. We will use a physical assumption, existence of multiple communication paths between the sender and the receiver, as the basis of security, and propose a cryptographic system that uses this assumption and an MTD strategy to guarantee efficient long-term information theoretic security even when only a single path is not eavesdropped. Following the approach of Maleki et al., we model the system using a Markov chain, derive its transition probabilities, propose two security measures, and prove results that show how to calculate these measures using transition probabilities. We define two types of attackers that we call risk-taking and risk-averse and compute our proposed measures for the two types of adversaries for a concrete MTD strategy. We will use numerical analysis to study tradeoffs between system parameters, discuss our results, and propose directions for future research.

Estimation Theory-Based Robust Phase Offset Determination in Presence of Possible Path Asymmetries

This paper addresses the problem of robust clock phase offset estimation for the IEEE 1588 precision time protocol in the presence of unknown asymmetric network path delays. The presence of an unknown asymmetry between the path delays can lead to significant degradation in the performance of a phase offset estimation scheme. Assuming multiple master-slave communication paths are available, we first provide lower bounds on the best achievable performance for a phase offset estimation scheme in the presence of asymmetric master-slave communication paths. We then present a novel phase offset estimation scheme that employs the expectation-maximization algorithm to identify the asymmetric master–slave communication paths. After discarding information from these paths, we employ the minimax optimum vector location parameter estimator for estimating the phase offset. Simulation results are presented to show that the proposed phase offset estimation scheme exhibits performance close to the lower bounds in a wide variety of network scenarios.

A multi-channel transmission schedule for remote state estimation under DoS attacks

This paper considers a cyber-physical system (CPS) under denial-of-service (DoS) attacks. The measurements of a sensor are transmitted to a remote estimator over a multi-channel network, which may be congested by a malicious attacker. Among these multiple communication paths with different characteristics and properties at each time step, the sensor needs to choose a single channel for sending data packets while reducing the probability of being attacked. In the meanwhile, the attacker needs to decide the target channel to jam under an energy budget constraint. To model this interactive decision-making process between the two sides, we formulate a two-player zero-sum stochastic game framework. A Nash Q-learning algorithm is proposed to tackle the computation complexity when solving the optimal strategies for both players. Numerical examples are provided to illustrate the obtained results.

Adaptive Flow Assignment and Packet Scheduling for Delay-Constrained Traffic Over Heterogeneous Wireless Networks

Flow assignment and packet scheduling are two processes of deploying limited wireless resources to support high-data-rate transmissions. Optimizing these processes is critical in improving the traffic performance and network utilization. In this paper, we investigate the flow assignment and packet scheduling for multihomed communication of delay-constrained traffic over heterogeneous wireless networks. With regard to the inherent channel diversity and unreliability, large end-to-end delay and burst packet losses pose crucial challenges to guarantee goodput performance of real-time traffic. To address these critical issues, we present an Adaptive Flow Assignment and Packet Scheduling (AFAPS) framework. First, we introduce a “horizontal water filling” algorithm, which effectively integrates the channel resources in heterogeneous wireless networks to maximize the aggregate goodput. Second, we propose an alternative path interleaving scheme, which spreads out the packets' departures over multiple communication paths within the delay constraint to mitigate burst losses. The performance of the proposed AFAPS framework is evaluated through semi-physical emulations in EXata involving real Internet traffic traces. Experimental results show that AFAPS outperforms existing multipath data distribution models, in terms of goodput and end-to-end delay.

Streaming High-Quality Mobile Video with Multipath TCP in Heterogeneous Wireless Networks

The proliferating wireless infrastructures with complementary characteristics prompt the bandwidth aggregation for concurrent video transmission in heterogeneous access networks. Multipath TCP (MPTCP) is an important transport-layer protocol recommended by IETF to integrate different access medium (e.g., Cellular and Wi-Fi). This paper investigates the problem of mobile video delivery using MPTCP in heterogeneous wireless networks with multihomed terminals. To achieve the optimal quality of real-time video streaming, we have to seriously consider the path asymmetry in different access networks and the disadvantages of the data retransmission mechanism in MPTCP. Motivated by addressing these critical issues, this study presents a novel quAlity-Driven MultIpath TCP (ADMIT) scheme that integrates the utility maximization based Forward Error Correction (FEC) coding and rate allocation. We develop an analytical framework to model the MPTCP-based video delivery quality over multiple communication paths. ADMIT is able to effectively integrate the most reliable access networks with FEC coding to minimize the end-to-end video distortion. The performance of ADMIT is evaluated through extensive semi-physical emulations in Exata involving H.264 video streaming. Experimental results show that ADMIT outperforms the reference transport protocols in terms of video PSNR (Peak Signal-to-Noise Ratio), end-to-end delay, and goodput. Thus, we recommend ADMIT for streaming high-quality mobile video in heterogeneous wireless networks with multihomed terminals.

Energy-Minimized Multipath Video Transport to Mobile Devices in Heterogeneous Wireless Networks

The technological evolutions in wireless communication systems prompt the bandwidth aggregation (e.g., Wi-Fi and LTE radio interfaces) for concurrent video transmission to hand-held devices. However, multipath video transport to the battery-limited mobile terminals is confronted with challenging technical problems: 1) high-quality real-time video streaming is throughput-demanding and delay-sensitive; 2) mobile device energy and video quality are not adequately considered in conventional multipath protocols; and 3) wireless networks are error-prone and bandwidth-limited. To enable the energy-efficient and quality-guaranteed live video streaming over heterogeneous wireless access networks, this paper proposes an energy-video aware multipath transport protocol (EVIS). First, we present a mathematical framework to analyze the frame-level energy-quality tradeoff for delay-constrained multihomed video communication over multiple communication paths. Second, we develop scheduling algorithms for prioritized frame scheduling and unequal loss protection to achieve target video quality with minimum device energy consumption. EVIS is able to effectively leverage video frame priority and rateless Raptor coding to jointly optimize energy efficiency and perceived quality. We conduct performance evaluation through extensive emulations in Exata involving real-time H.264 video streaming. Emulation results demonstrate that EVIS advances the state-of-the-art with remarkable improvements in energy conservation, video peak signal-to-noise ratio (PSNR), end-to-end delay, and goodput.

AeroMTP: A fountain code-based multipath transport protocol for airborne networks

Airborne networks (ANs) are special types of ad hoc networks that can be used to enhance situational awareness, flight coordination and flight efficiency in civil and military aviation. Compared to ground networks, ANs have some unique attributes including high node mobility, frequent topology changes, mechanical and aerodynamic constrains, strict safety requirements and harsh communication environment. Thus, the performance of conventional transmission control protocol (TCP) will be dramatically degraded in ANs. Aircraft commonly have two or more heterogeneous network interfaces which offer an opportunity to form multiple communication paths between any two nodes in ANs. To satisfy the communication requirements in ANs, we propose aeronautical multipath transport protocol (AeroMTP) for ANs, which effectively utilizes the available bandwidth and diversity provided by heterogeneous wireless paths. AeroMTP uses fountain codes as forward error correction (FEC) codes to recover from data loss and deploys a TCP-friendly rate-based congestion control mechanism for each path. Moreover, we design a packet allocation algorithm based on optimization to minimize the delivery time of blocks. The performance of AeroMTP is evaluated through OMNeT++ simulations under a variety of test scenarios. Simulations demonstrate that AeroMTP is of great potential to be applied to ANs.

Resource-Optimal Heterogeneous Machine-to-Machine Communications in Software Defined Networking Cyber-Physical Systems

Cyber-physical systems (CPS), emerging as the most promising approach for extensive computing, processing, and remote control to physical entities, rely on reliable and heterogeneous (real-time and non-real-time) data exchanges among machines. However, for CPS exploiting shared network infrastructures, communication links may suffer from various vulnerabilities to harm real-time data exchanges. Providing robustness against link vulnerabilities consequently becomes the most critical requirement. By installing software defined networking (SDN) functions in existing network infrastructures, multiple communication paths can be practically formed to provide robustness if replicates of real-time data are simultaneously forwarded via multiple paths. Furthermore, if each non-real-time data packet is forwarded via distinct paths, packet congestion in certain paths can be avoided. However, the key to practice such SDN robust communications relies on an efficient resource utilization both in the time and the spatial domains. To further support high mobile machines, the efficient resource utilization shall be achieved by a low complexity scheme to rapidly adapt to varying environments. In this paper, we shall consequently develop mathematical foundations of a resource-optimal design for CPS. Achieving the minimum resource usage to support real-time data exchanges, our design further avoids the worst case packet congestion to trace the performance of non-real-time data exchanges to the optimum. By providing the most efficient and low complexity resource management, our design successfully practice robust big data exchanges in CPS.

Distortion-Aware Concurrent Multipath Transfer for Mobile Video Streaming in Heterogeneous Wireless Networks

The massive proliferation of wireless infrastructures with complementary characteristics prompts the bandwidth aggregation for Concurrent Multipath Transfer (CMT) over heterogeneous access networks. Stream Control Transmission Protocol (SCTP) is the standard transport-layer solution to enable CMT in multihomed communication environments. However, delivering high-quality streaming video with the existing CMT solutions still remains problematic due to the stringent QoS (Quality of Service) requirements and path asymmetry in heterogeneous wireless networks. In this paper, we advance the state of the art by introducing video distortion into the decision process of multipath data transfer. The proposed Distortion-Aware Concurrent Multipath Transfer (CMT-DA) solution includes three phases: 1) per-path status estimation and congestion control; 2) quality-optimal video flow rate allocation; 3) delay and loss controlled data retransmission. The term `flow rate allocation' indicates dynamically picking appropriate access networks and assigning the transmission rates. We analytically formulate the data distribution over multiple communication paths to minimize the end-to-end video distortion and derive the solution based on the utility maximization theory. The performance of the proposed CMT-DA is evaluated through extensive semi-physical emulations in Exata involving H.264 video streaming. Experimental results show that CMT-DA outperforms the reference schemes in terms of video PSNR (Peak Signal-to-Noise Ratio), goodput, and inter-packet delay.

A novel scheduling approach to concurrent multipath transmission of high definition video in overlay networks

Recent advancements in network infrastructures provide increased opportunities to support video delivery over multiple communication paths. However, the high definition (HD) video transmissions still pose crucial challenges due to the high throughput demands and large-size video frames. Motivated by optimizing the delay performance for concurrent multipath transmission of HD video, we propose a novel scheduling approach dubbed FSWG (Frame Splitting based on Weibull distribution and Graph theory) that aims to minimize the end-to-end frame delay while alleviating out-of-order arrivals. First, we analytically construct a delay performance model for HD video streaming in multipath overlay networks based on Weibull distribution and graph theory. Second, we formulate the frame splitting over parallel paths as a constrained optimization problem of minimizing total frame delay and derive its solution based on the water filling algorithm. Third, we design a multipath video transmission system to implement the proposed scheduling approach. The performance evaluation is conducted through extensive simulations in QualNet using H.264 video streaming. Experimental results show that FSWG outperforms the existing schemes in terms of Mean Opinion Score (MOS), Peak Signal-to-Noise Ratio (PSNR), and delay performance metrics.