Lossy Environment Research Articles

Downward traffic retransmission mechanism for improving reliability in RPL environment supporting mobility

With the diversification of industrial Internet of Things applications, there is a growing demand for mobility support in industrial wireless networking environments. However, the routing protocol for low-power and lossy networks is designed based on a static environment and is vulnerable in a mobility environment. Routing protocol for low-power and lossy networks is an Internet engineering task force standard in the low-power and lossy network environments used mainly in industrial environments. In addition, although routing protocol for low-power and lossy networks is based on collection tree protocol and is suitable for data collection and upward traffic transmission, it struggles with downward traffic transmission in terms of control, actuation, and end-to-end transmission. In this article, the problems caused by mobile nodes in routing protocol for low-power and lossy networks are discussed, and a retransmission scheme named IM-RPL is proposed. This retransmission scheme can improve the performance of downward traffic for the mobile nodes by retransmitting the packets to the neighbor nodes, the mobile node’s new parent sets, and relaying them to the mobile node. Its performance is evaluated through an experiment. The results demonstrate that using OpenMote in OpenWSN’s time slotted channel hopping induces a packet reception ratio improvement and a lower transmission delay as compared to standard routing protocol for low power and lossy.

Efficient Wireless Power Transfer With Capacitively Segmented RF Coils

Wireless power transfer systems have been widely applied in the field of portable and implantable devices, featuring contact-free and reliable energy supply. Novel implant systems, such as brain-computer interfaces, impose the challenges of strong miniaturization and operation under loosely coupled conditions. Therefore, maximizing power transfer efficiency while decreasing the size of transmitter and receiver structures becomes a central research question. This paper presents a unified design strategy of modeling, analyzing and optimizing planar spiral coils with integrated capacitive elements, so-called capacitively segmented coils, for operation in wireless power transfer interfaces. It mathematically analyzes and experimentally verifies that the combination of capacitive coil segmentation, increased operational frequencies and geometrical coil optimization can be used to establish wireless power transfer links with comparatively high efficiency, small size and limited detuning effects in lossy dielectric environments. The paper embraces the formulation and verification of a broadband analytical link model based on partial element equivalent circuits, which is subsequently used to determine dominant coupling and loss mechanisms and to optimize the coils' geometries for high efficiency. Moreover, an extended analysis shows how the capacitive coil segmentation can effectively suppress dielectric losses and non-uniform current distributions by canceling the inductive contribution of every coil segment at the frequency of operation. Utilizing these methods, an exemplary 40.68MHz wireless power link with a 30mm primary and a 10mm secondary coil is designed and evaluated: With a maximum efficiency of up to 31% in biological tissue at 20mm separation distance, it features efficiency levels which are up to ten times higher and a specific absorption rate which is up to five times lower compared to non-segmented systems. When operated at 150MHz in air, efficiency levels are up to 1.5 times higher than in state-of-the-art systems of the same size.

Near‐Unity and Narrowband Thermal Emissivity in Balanced Dielectric Metasurfaces

AbstractNanostructured materials have provided new freedoms for tailoring thermal emissivity in an ultracompact footprint. However, while many designs have demonstrated large absorption amplitude, this often comes at the expense of angular dispersion or the need for a reflective backplane. Furthermore, metal‐based designs generally have broad linewidths due to large nonradiative damping. Here, a unique approach is outlined for obtaining narrowband near‐unity thermal emissivity through spectrally overlapping two orthogonal lossy Mie‐type modes in dielectric metasurfaces operating in the long‐wave infrared. Operating near the transverse optic phonon frequency of a polar dielectric provides a suitably lossy environment, but also one featuring extremely large permittivity, enabling deeply subwavelength resonator sizes, insensitivity to the angle of incidence, and large quality factors even while operating in the long‐wave infrared. Balancing the oscillator strengths and optical losses of the two overlapped resonances maximizes the absorption, resulting in a 3C‐SiC metasurface with 78% absorptance and a quality factor of 170. This balanced metasurface possesses a quality factor on par with some of the narrowest band thermal emitters in the long‐wave infrared, while possessing a simple architecture and prospects for unity emissivity.

Improving TCP Performance in Vehicle-To-Grid (V2G) Communication

On a connected car, the performance of Internet access will significantly affect the user experience. For electric cars that use vehicle-to-grid (V2G) communication to interact with the Internet during charging, the charge cable quality poses a challenge to the V2G communication. Specifically, the performance of Transmission Control Protocol (TCP), the transport protocol that most Internet applications use, may suffer due to the high noise and consequent errors that the charge cable presents. Currently, TCP NewReno is the TCP implementation that ISO 15118 standard stipulates for the V2G communication. However, its congestion control algorithm has been designed for the general Internet environment where congestion, not link errors, account for most of packet losses. Indeed, we confirm that the throughput of TCP NewReno rapidly degrades as the error rate increases on the charge cable. Specifically, we show that other TCP variants such as TCP Illinois far exceeds TCP NewReno in both lossy and non-lossy link environments. Finally, we propose how to configure TCP NewReno parameters to make it achieve the throughput comparable to other TCP variants on V2G communication environments, regardless of the link quality presented by the charging cable.

Flooding Message Mitigation of Wireless Content Centric Networking for Last-Mile Smart-Grid

In view of Smart-Grid architecture, wireless Last-Mile Network (LMN) devices as smart meters and intelligent home control machines are normally installed in harsh and lossy communication environment. In order to improve communication reliability of LMN, we proposed Wireless Topology Aware Content Centric Networking (TOP-CCN) protocol. TOP-CCN reduces channel access overhead of traditional Content Centric Networking and supports efficient multicast message transmission by using Multiple Point Relay (MPR), and Publisher MPR (PMPR). In addition, TOP-CCN LMN provides simple multi-hop forwarding scheme that can reduce the traditional routing control message overhead in multi-hop wireless LMN environment. The simulation result shows TOP-CCN can improve the service provisioning time and reliability compared to traditional IP based network model in LMN.

A Simple And Novel Algorithm For State Estimation Of Continuous Time Linear Stochastic Dynamic Systems Excited By Random Inputs

The major goal of this paper is to explore the effective state estimation algorithm for continuous time dynamic system under the lossy environment without increasing the complexity of hardware realization. Though the existing methods of state estimation of continuous time system provides effective estimation with data loss, the real time hardware realization is difficult due to the complexity and multiple processing. Kalman Filter and Particle Filer are fundamental algorithms for state estimation of any linear and non-linear system respectively, but both have its limitation. The approach adopted here, detect the expected state value and covariance, existed by random input at each stage and filtered the noisy measurement and replace it with predicted modified value for the effective state estimation. To demonstrate the performance of the results, the continuous time dynamics of position of the Aerial Vehicle is used with proposed algorithm under the lossy measurements scenario and compared with standard Kalman filter and smoothed filter. The results show that the proposed method can effectively estimate the position of Aerial Vehicle compared to standard Kalman and smoothed filter under the non-reliable sensor measurements with less hardware realization complexity.

Development of a 2.45 GHz Antenna for Flexible Compact Radiation Dosimeter Tags

Numerous medical operations employ blood transfusions, requiring X-ray irradiated blood for safety concerns. Current irradiation techniques can be significantly improved by replacing standard visual indicators with wireless dosimeter tags that automate the process, reducing inefficiencies, and eliminating blood wastage. A key requirement of the proposed dosimeter tag is flexible and efficient antennas that can be mounted on blood bags. This paper presents the design of a low-cost inkjet-printed dipole antenna on flexible Kapton substrate for a 2.45 GHz radio frequency identification (RFID) dosimeter tag. The tag is to be used in a lossy blood environment, which can severely affect antenna radiation performance. To mitigate this, the concept of artificial magnetic conductor (AMC) unit cells is investigated for best impedance and gain performance. When integrated with a dipole radiator, the fabricated AMC-backed antenna maintains broadside radiation with gains of 4.1–4.8 dBi under planar and bending conditions, and on a lossy blood bag. In a rectenna configuration, the antenna can power sensors for ranges up to 1 m. Measured output dc voltages up to 1.7 V are achieved across a 25 $\text{k}\Omega $ resistor. This antenna design is flexible, compact, efficient on lossy structures, and suitable for direct integration with biomedical sensing chips.

Limitations of teleporting a qubit via a two-mode squeezed state

Recently, a teleportation scheme using a two-mode squeezed state to teleport a photonic qubit, so called a “hybrid” approach, has been suggested and experimentally demonstrated as a candidate to overcome the limitations of all-optical quantum information processing. We find, however, that there exists the upper bound of fidelity when teleporting a photonic qubit via a two-mode squeezed channel under a lossy environment. The increase of photon loss decreases this bound, and teleportation better than this limit is impossible even when the squeezing degree of the teleportation channel becomes infinity. Our result indicates that the hybrid scheme can be valid for fault-tolerant quantum computing only when the photon loss rate can be suppressed under a certain limit.

Simple Impedance Response Formulas for the Dispersive Interaction Rates in the Effective Hamiltonians of Low Anharmonicity Superconducting Qubits

For superconducting quantum processors consisting of low anharmonicity qubits such as transmons we give a complete microwave description of the system in the qubit subspace. We assume that the qubits are dispersively coupled to a distributed microwave structure such that the detunings of the qubits from the internal modes of the microwave structure are stronger than their couplings. We define qubit ports across the terminals of the Josephson junctions and drive ports where transmission lines carrying drive signals reach the chip and we obtain the multiport impedance response of the linear passive part of the system between the ports. We then relate interaction parameters in between qubits and between the qubits and the environment to the entries of this multiport impedance function: in particular we show that the exchange coupling rate J between qubits is related in a simple way to the off-diagonal entry connecting the qubit ports. Similarly we relate couplings of the qubits to voltage drives and lossy environment to the entries connecting the qubits and the drive ports. Our treatment takes into account all the modes (possibly infinite) that might be present in the distributed electromagnetic structure and provides an efficient method for the modeling and analysis of the circuits.

SOS: Standard-Compliant and Packet Loss Tolerant Security Framework for ADS-B Communications

The Automatic Dependent Surveillance - Broadcast (ADS-B) technology, already deployed by the major avionics companies (e.g., QatarAirways and AmericanAirlines), will become mandatory on board of civil and military aircraft flying in Class A, B, and C airspaces by 2020, enabling direct airplanes communications and enhanced flights monitoring. However, ADS-B has been designed without security considerations, thus being vulnerable to a variety of attacks, including message injection and messages order manipulation attacks, that can be easily performed via widely available commercial Software Defined Radios. To address these threats, we present Securing Open Skies (SOS), a standard-compliant, backward-compatible, loss-tolerant, and bandwidth efficient security framework to secure ADS-B communications. SOS leverages the real deployment of densely distributed, participatory ADS-B sensor networks such as OpenSky Network and Flight Radar, and provides message authentication and integrity security services on a time-slot basis, without resorting to any public key cryptography mechanism. Experimental performances obtained through a realistic proof-of-concept, deployed using commercial Ettus Research X310 Software Defined Radios, demonstrate the viability and effectiveness of our solution, even in presence of uniformly at random or burst packet loss events characterizing the ADS-B frequency band. For instance, SOS allows the verification of the authenticity of ADS-B messages requiring less than 50 percent of bandwidth overhead, with a percentage of verifiable slots above 80 percent, even in an highly lossy environment, characterized by a single packet loss probability of 60 percent—the process requiring less than one second: almost one tenth of similar approaches published in the literature. Finally, a thorough comparison against state of the art solutions in the literature highlights the unique security and reliability features enjoyed by SOS, as well as its practical viability.

Topology-Aware Network Coding for Wireless Multicast

In this paper, we present a topology-aware network coding (TANC) technique for wireless multicast systems aiming at reducing packet retransmissions in a lossy propagation environment. In addition to radio channel impacts, packet loss may result from traffic congestion, thereby yielding different retransmission requests. In such a wireless network coding multicast environment, what is the best packet combination to minimize the packet retransmissions for a number of users? We make progress on this problem by taking advantage of the network topology information to select the appropriate lost encoded packets in the encoding phase. We leverage the capability of software-defined networking controller to construct the global network topology in the proposed TANC scheme. Experimental results show that the proposed TANC scheme can reduce 52.4% of packet retransmissions compared to the existing random linear network coding in different environments, including various numbers of uncoded packets, network nodes, and packet loss probabilities.

OMRI–MAC: Optimized Multi-transmission Receiver-Initiated MAC in Underwater Wireless Sensor Networks

Unlike terrestrial environment, the underwater environment possess additional and complicated challenges for wireless communication. For the underwater wireless communication, traditional radio wave communication is not feasible due to high channel fading and packet loss experienced high frequency communication that also reduces the communication range. Acoustic wave communication in dynamic underwater environment naturally inherits its own limitations that include low bandwidth, slow signal propagation speed, high packet loss and short communication range. Considering the UWSNs circumstances, protocols that can counter the high packet loss and low data rate are required. The MAC protocols designed for Underwater Wireless Sensor Network (UWSN) should incorporate changes in such a way that sensor nodes can have seamless and efficient communication while minimizing the effect of imposed constraints. In this paper, we therefore propose Optimized Multi-transmission Receiver-Initiated Medium Access Control (MAC) which considers harsh, lossy, and dynamic underwater environment. Our proposed method transmits optimized number of multiple packets to increase the successful packet delivery in harsh underwater environment with low data rate.

Elastically Reliable Video Transport Protocol Over Lossy Satellite Links

As there is a growing demand for providing high-definition (HD) video and satellite TV services over satellite networks, interconnection and multimedia applications need new-type satellite services to ensure good quality-of-experience (QoE) for these Internet flows. The characteristics of satellite channels (notably the lossy and long-delay environment) can heavily influence transferring protocols exclusively designed for terrestrial network, and using a radically reliable method (TCP) or unreliable method (UDP) is not the best way for the transmission of multimedia applications over satellite networks, such as HD video. In order to cope with the contradiction between high quality and real-time transfer, this paper presents a retransmission-based partially reliable transfer protocol, called automatically partially reliable transfer protocol (APRT). For the purpose of tracing the network status, the hidden Markov model (HMM) is employed to depict reliable level of the transfer strategy. Through off-line training initialization and online prediction, current network status is then mapped to a reliable level, which can represent good video quality and minimum packet delay. Meanwhile, APRT can retransmit the lost packets as the network changing without losing key frames. Extensive simulation results show that for both single and coexisting flow scenarios, APRT can improve video quality of services (QoSs) against reliable and unreliable transfer strategies in terms of different metrics. For single video flow, PSNR of APRT outperforms than that of other strategies under lossy and long-delay networks up to 36.53% and achieves short packet delay. For coexisting scenario, APRT shows good performance in terms of latency and video quality.

R2T: A Rapid and Reliable Hop-by-Hop Transport Mechanism for Information-Centric Networking

Hop-by-hop transport is promising in information-centric networking because of its adaptability to in-network caching and lossy environments. Mobility first transport protocol (MFTP), as a classical example, transports content chunks and waits for the retransmissions of the lost packets in each hop. However, due to its chunk-level reliability, the MFTP hops transport chunks in series rather than in parallel, causing significant longer end-to-end latency than that in transmission control protocol (TCP). To address this issue, we propose a novel hop-by-hop transport mechanism, R2T. In each hop, R2T guarantees the content reliability in packets rather than in chunks. R2T routers immediately forward all the received packets downstream so that the end-to-end latency can be remarkably decreased. With separated packet name space in global and local scale, R2T decouples the hop-by-hop reliability control and the end-to-end content transport, obtaining both performance advantages from MFTP and TCP. The evaluation results show that R2T has as low transport latency as TCP, yet keeps as high bandwidth usage as MFTP. Meanwhile, it is demonstrated that R2T does not suffer significant memory and energy consumption, achieving promising feasibility in real implementations.

On the performance of adaptive coding schemes for energy efficient and reliable clustered wireless sensor networks

Clustering is the key for energy constrained wireless sensor networks (WSNs). Energy optimization and communication reliability are the most important consideration in designing efficient clustered WSN. In lossy environment, channel coding is mandatory to ensure reliable and efficient communication. This reliability is compromised by additional energy of coding and decoding in cluster heads. In this paper, we investigated the trade-off between reliability and energy efficiency and proposed adaptive FEC/FWD and FEC/ARQ coding frameworks for clustered WSNs. The proposed schemes consider channel condition and inter-node distance to decide the adequate channel coding usage. Simulation results show that both the proposed frameworks are energy efficient compared to ARQ schemes and FEC schemes, and suitable to prolong the clustered network lifespan as well as improve the reliability.

Robust entanglement with three-dimensional nonreciprocal photonic topological insulators

We investigate spontaneous and pumped entanglement of two level systems in the vicinity of a photonic topological insulator interface, which supports a nonreciprocal (unidirectional), scattering-immune and topologically-protected surface plasmon polariton in the bandgap of the bulk material. To this end, we derive a master equation for qubit interactions in a general three-dimensional, nonreciprocal, inhomogeneous and lossy environment. The environment is represented exactly, via the photonic Green function. The resulting entanglement is shown to be extremely robust to defects occurring in the material system, such that strong entanglement is maintained even if the interface exhibits electrically-large and geometrically sharp discontinuities. Alternatively, depending on the initial excitation state, using a non-reciprocal environment allows two qubits to remain unentangled even for very close spacing. The topological nature of the material is manifest in the insensitivity of the entanglement to variations in the material parameters that preserve the gap Chern number. Our formulation and results should be useful for both fundamental investigations of quantum dynamics in nonreciprocal environments, and technological applications related to entanglement in two-level systems.

Description of spontaneous photon emission and local density of states in the presence of a lossy polaritonic inhomogeneous medium

We provide a description of spontaneous emission in a dispersive and dissipative linear inhomogeneous medium based on the generalized Huttner-Barnett model [Phys. Rev. A 46, 4306 (1992)]. Our discussion considers on an equal footing both the photonic and material fluctuations which are necessary to preserve unitarity of the quantum evolution. Within this approach we justify the results obtained in the past using the Langevin noise method that neglects the removal of photonic fluctuations. We finally discuss the concept of local density of states (LDOS) in a lossy and dispersive inhomogeneous environment that provides a basis for theoretical studies of fluorescent emitters near plasmonic and polaritonic antennas.

Accurate and Generic Sender Selection for Bulk Data Dissemination in Low-Power Wireless Networks

Data dissemination is a fundamental service offered by low-power wireless networks. Sender selection is the key to the dissemination performance and has been extensively studied. Sender impact metric plays a significant role in sender selection, since it determines which senders are selected for transmission. Recent studies have shown that spatial link diversity has a significant impact on the efficiency of broadcast. However, the existing metrics overlook such impact. Besides, they consider only gains but ignore the costs of sender candidates. As a result, existing works cannot achieve accurate estimation of the sender impact. Moreover, they cannot well support data dissemination with network coding, which is commonly used for lossy environments. In this paper, we first propose a novel sender impact metric, namely, γ, which jointly exploits link quality and spatial link diversity to calculate the gain/cost ratio of the sender candidates. Then, we develop a generic sender selection scheme based on the γ metric (called γ-component) that can generally support both types of dissemination using native packets and network coding. Extensive evaluations are conducted through real testbed experiments and large-scale simulations. The performance results and analysis show that γ achieves far more accurate impact estimation than the existing works. In addition, the dissemination protocols based on γ-component outperform the existing protocols in terms of completion time and transmissions (by 20.5% and 23.1%, respectively).

On the design of coding framework for energy efficient and reliable multi-hop sensor networks

Energy efficiency and reliability are the key requirements for wireless sensor network (WSN), as sensor nodes are expected to be stand-alone for a long time and communication to be successfully carried out. Communication is the most energy consuming process in WSN, especially in lossy environment. In multi-hop WSN, packets are more susceptible to transmission errors which worsens the communication reliability and energy consumption. Therefore, coding schemes are mandatory to cover the channel impairments and save the transmission energy. In this work, we propose an adaptive coding (AC) scheme that can be adapted with the channel state and inter-node distances in order to decode and correct the packets or request for retransmissions. The proposed scheme has proved to be energy efficient and adaptive compared to Automatic Repeat reQuest (ARQ) and Forward Error Correction (FEC) schemes.

An Overview of Security and Privacy Issues for Internet of Things

The Internet of Things (IoT) is defined as a global infrastructure for the Information Society, enabling advanced services by interconnecting (physical and virtual) things based on, existing and evolving, interoperable information and communication technologies by ITU-T. Data may be communicated in low-power and lossy environments, which causes complicated security issues. Furthermore, concerns are raised over access of personally identifiable information pertaining to IoT devices, network and platforms. Security and privacy concerns have been main barriers to implement IoT, which needs to be resolved appropriate security and privacy measures. This paper describes security threats and privacy concerns of IoT, surveys current studies related to IoT and identifies the various requirements and solutions to address these security threats and privacy concerns. In addition, this paper also focuses on major global standardization activities for security and privacy of Internet of Things. Furthermore, future directions and strategies of international standardization for theInternet of Thing's security and privacy issues will be given. This paper provides guidelines to assist in suggesting the development and standardization strategies forward to allow a massive deployment of IoT systems in real world.