Two-way Scheme Research Articles

Total Secrecy From Anti-Eavesdropping Channel Estimation

Anti-eavesdropping channel estimation (ANECE) is useful for a network of cooperative full-duplex radio devices/users. Using ANECE, a secret key can be generated by each pair of users, and additional secret information can be transmitted between a pair of users. This paper analyzes the capacity of the secret key based on ANECE, and compares it with the conventional method for channel training. The paper also analyzes the secrecy capacity of information transmission using an one-way scheme, and compares it with a two-way scheme. It is shown that the total amount of secrecy generated from ANECE can be substantially larger than that based on the conventional method especially when an eavesdropper may have an unlimited number of antennas. The paper also formulates a total secure degree of freedom (TSDoF) of the ANECE based scheme, and compares it with a prior scheme of secret information transmission from a multi-antenna node to another against a multi-antenna eavesdropper where channel state information is unknown everywhere initially. The comparison shows that there is a substantial gain of TSDoF by exploiting full-duplex radios and reciprocal channels via ANECE. Most of the key insights are highlighted in twelve proven properties.

TWO-WAY AUTHENTICATION FOR ENHANCING SECURITY IN HETEROGENEOUS WIRELESS SENSOR NETWORKS

In wireless sensor networks, each sensor node nowadays is responsible for the exchange of sensory data with high performance in terms of QoS such as network throughput and delay under energy restrictions. Besides network performance, network security plays an important role in designing a wireless sensor network. One of current challenges is to design efficiently lightweight security methods to achieve highly secured transmissions and prolonged network lifetime. In this paper, we introduce an end-to-end two-way authentication scheme for WSNs under the heterogeneous assumption. By drawing on the benefit of lightweight homomorphic encryption and watermark data, numerical evaluations and security analysis show that our proposed method can prolong the network lifetime with the enhancement in network security.

Cancel‐Decode‐Encode Processing on Two‐Way Cooperative NOMA Schemes in Realistic Conditions

This paper considers the effects of perfect/imperfect successive interference cancellation (SIC) and perfect/imperfect ` information (CSI) in a multiple‐relay two‐way cooperative network using nonorthogonal multiple access (NOMA) and digital network coding (DNC). In this model, a relay is selected by maximizing estimated channel gains to enhance the decoding capacity of the nearer source and minimize the collection time of imperfect CSI. Spectrum utilization efficiency is enhanced two times by a mixture of the SIC and DNC techniques at the selected relay (called as the SIC‐2TS protocol). The system performance is considered through analysis of the exact and asymptotic expressions of the system outage probabilities and throughput. The major thing is exposed as the proposed SIC‐2TS protocol can reach the best performance at optimal positions of the selected relay. Besides, the system throughput of the proposed protocol outperforms a SIC‐utilized two‐way relaying scheme without the DNC (called as the SIC‐3TS protocol) and a conventional two‐way scheme (called as the CONV‐4TS protocol) for all signal‐to‐noise ratio regions. Lastly, the validity of the analytical expressions is verified by the Monte Carlo simulation results.

Direct Numerical Simulation of Gas–Particle Flows with Particle–Wall Collisions Using the Immersed Boundary Method

We investigated particulate flows by coupling simulations of the three-dimensional incompressible Navier–Stokes equation with the immersed boundary method (IBM). The results obtained from the two-way coupled simulation were compared with those of the one-way simulation, which is generally applied for clarifying the particle kinematics in industry. In the present flow simulation, the IBM was solved using a ghost–cell approach and the particles and walls were defined by a level set function. Using proposed algorithms, particle–particle and particle–wall collisions were implemented simply; the subsequent coupling simulations were conducted stably. Additionally, the wake structures of the moving, colliding and rebounding particles were comprehensively compared with previous numerical and experimental results. In simulations of 50, 100, 200 and 500 particles, particle–wall collisions were more frequent in the one–way scheme than in the two-way scheme. This difference was linked to differences in losses in energy and momentum.

A positive–negative delayer for slotted OBS networks to enhance two-way signaling scheme

Optical burst switching (OBS) is a promising technology for next-generation optical networks and slotted OBS is one of its improved versions. Contention between bursts is the main defect in OBS (as well as slotted OBS) networks. Different strategies are proposed to resolve contentions, such as using fiber delay line (FDL) to delay one of the conflicting bursts, or adopting two-way signaling scheme to gather states of links in advance. Unfortunately, the above two strategies cannot be used together, because FDL would deviate a burst from its planned trajectory, which would eliminate the effect of link state gathering in two-way scheme. In this paper, we design a novel delayer with ordinary FDLs, which can generate both positive and negative delay. The delayer can be used in two-way scheme without affecting the efficacy of link state gathering. Simulation results show that the delayer can greatly reduce the blocking rate of two-way scheme, by just a slight expense of average delay.

Hybrid fiber links for accurate optical frequency comparison

We present the experimental demonstration of a local two-way optical frequency comparison over a 43-km-long urban fiber network without any requirement for measurement synchronization. We combined the local two-way scheme with a regular active noise compensation scheme that was implemented on another parallel fiber leading to a highly reliable and robust frequency transfer. This hybrid scheme allowed us to investigate the major limiting factors of the local two-way comparison. We analyzed the contributions of the interferometers at both local and remote locations to the phase noise of the local two-way signal. Using the ability of this setup to be injected by either a single laser or two independent lasers, we measured the contributions of the demodulated laser instabilities to the long-term instability. We show that a fractional frequency instability level of 10−20 at 10,000 s can be obtained using this simple setup after propagation over a distance of 43 km in an urban area.

An Adaptive Transmission Scheme for Two-Way Relaying With Asymmetric Data Rates

In this paper, we address the problem of asymmetric data rates in two-way communication systems. In particular, we propose an adaptive transmission scheme that combines network coding (NC) and opportunistic user selection (OUS) with a threshold that determines which transmission mode to use. The underlying system model comprises two source nodes communicating with each other through a relay node. The source nodes are assumed to have different data rate requirements; therefore, they employ different modulation schemes. As per the proposed scheme, if the end-to-end (E2E) signal-to-noise ratio (SNR) of both users are above a specified threshold, both sources transmit over orthogonal channels, and the relay node uses hierarchical modulation and NC to relay the combined signals to both sources in the third time slot. Otherwise, the user with the better E2E SNR transmits, whereas the other user remains silent. The advantage of the proposed scheme is that it compromises between throughput and reliability. That is, when both users transmit, the throughput improves, whereas when the better user transmits, multiuser diversity is achieved. Assuming asymmetric channels, we derive exact closed-form expressions for the E2E bit error rate (BER), access probability, and throughput for this scheme and compare its performance with existing schemes. We also investigate the asymptotic performance of the proposed scheme at high SNRs where we derive the achievable diversity order for both users. We show through analytical and simulation results that the proposed scheme improves the overall system throughput, the fairness between the two users, and the transmission reliability. This all comes while achieving full spatial diversity for both users.

Energy-Efficient Joint Power Allocation and Relay Selection in Bit Error Rate Constrained Two-Way Relay Network

In this paper, the authors have proposed energy efficient power allocation and relay selection scheme in a two-way amplify-and-forward (AF) relay under bit error rate (BER) constrained network. They have derived an expression for the overall BER for Rayleigh fading channel. Based on minimum power consumption in the network, the authors have addressed the problem of power allocation by converting geometric programming to a convex optimization problem. A closed form solution of power allocation is found, which aims at minimizing total transmit power for the overall BER constrained network. The authors have evaluated minimum total transmit power for two-way AF relay network. Based on minimum total transmit power, a novel relay selection scheme has been proposed. Simulation results demonstrate that the proposed two-way power allocation and relay selection scheme can significantly minimize power consumption under BER constrained network as compared to the existing relay transmission. The proposed power allocation scheme gives 3 dBW gain than one-way relay transmission. The proposed relay selection method also outperforms the random relay selection by 24 dBW. The simulation results are corroborated with the analytical result

An integrated numerical methodology for describing multiscale interactions on atmospheric flow and pollutant dispersion in the urban atmospheric boundary layer

Interactions between different spatial and temporal scales play a major role in determining the flow structure over the urban canopy in densely built agglomerations. Aiming to address the limitations which arise as a result of the physical disparities between the different modelling scales, a two-way scheme has been introduced for coupling the mesoscale model MEMO and the microscale model MIMO, utilising a collection of interpolating metamodels. The coupled system was used to simulate meteorological fields over the Greater Paris area during a multi-day wintertime case study. Its performance as a meteorological driver model was further evaluated by introducing the calculated meteorological fields as driving input in air quality calculations performed using the Eulerian chemical dispersion model MARS-aero.

CFD–DEM Model for Simulation of Non-spherical Particles in Hole Cleaning Process

During the well drilling process, particles are produced in different shapes. The shape of particles can influence the characteristics of particles transport process. The aim of this work is to analyze the effects of particle shape on the transportation mechanism. For this purpose, a three-dimensional model is prepared for simulation of particle transportation with spherical and non-spherical shapes, during deviated well drilling. The motion of particles and the non-Newtonian fluid flow are simulated via discrete element method and CFD, respectively. The two-way coupling scheme is used to incorporate the effects of fluid–particle interactions. Three different samples of non-spherical shapes are constructed using multi-sphere method. The interactions of particle–particle/wall/drill pipe are taken into account via Hertz–Mindlin model. Simulations are carried out for some laboratory-scale configurations and fair agreements with the experimental data available in the literature are established.

Performance of optimal three‐phase two‐way system with relay interference

In this work, the authors consider an amplify-and-forward (AF)-based three-phase two-way system with interference at the relay. An optimum scheme to minimise the outage probability is formulated, and a closed form expression for the ‘channel-dependent’ combining coefficient ‘α’ at the relay is derived. A novel approach is presented to derive an expression for the overall outage probability of the proposed three-phase outage-optimal two-way relaying (3P-OTWR) system. The authors also perform finite signal-to-noise (SNR) diversity-multiplexing tradeoff and throughput analysis of the system. Furthermore, the problem of outage-optimum power allocation is investigated. Using the asymptotic expression for the outage probability, it is shown that there is loss of diversity owing to interference at the relay. The authors perform Monte Carlo simulations to demonstrate that the 3P-OTWR system outperforms a conventional three-phase two-way scheme. With outage-optimum power allocation, the proposed scheme achieves a gain of approximately 3 dB in the medium-to-high SNR regime over a conventional scheme with α = 0.5 and equal power at terminals. The proposed three-phase scheme in presence of co-channel interference can provide a better throughput for higher transmission rates as compared with a two-phase scheme when operated in the high SNR regime. Numerical results demonstrate accuracy of the derived expressions.

An Integration of Source and Jammer for a Decode-and-Forward Two-way Scheme Under Physical Layer Security

In this paper, we propose and analyze the integration of source and jammer for a decode-and-forward two-way scheme under physical layer security where the source nodes not only transmit data signals, but also transmit jamming signals to degrade the quality of eavesdropping links, and a selected relay forwards the combined data signals using an XOR operation. In this proposed protocol, the best relay is chosen by the maximum end-to-end achievable secrecy rate, and the secrecy system performance is evaluated by the exact and asymptotic secrecy outage probability over flat and block Rayleigh fading channels. The Monte-Carlo results are presented to verify the theoretical analysis.

Physical and numerical modelling of the Severn Barrage

The Severn Estuary has one of the largest tidal ranges in the world and has long been the subject of consideration for tidal energy generation. Whilst plans to build a tidal barrage across the estuary have existed in various forms since the 1920s, the 1989 Severn Tidal Power Group (STPG) proposal is commonly referred to as the original Severn Barrage. The UK government abandoned this ebb generation scheme as a public investment project in 2010. However, plans to build a two-way generation scheme were more recently put forward by a private consortium, namely Hafren Power. To assess the impact that a barrage would have on the hydro-environment in the estuary a number of numerical modelling studies have previously been conducted for the STPG scheme. As this design has now been superseded by the Hafren Power proposal, new studies have been conducted to investigate the impact of a two-way scheme. In this study the hydro-environmental impacts of both ebb-only and two-way schemes were assessed using physical and numerical modelling techniques. Scale model barrages were constructed and testing was carried out using a physical model of the Severn Estuary, located in the hydraulics laboratory at Cardiff University. A depth integrated numerical model, namely DIVAST, was applied to the physical model geometry and modifications were made to simulate the effects of the barrage structures. The numerical model predictions showed good agreement with the corresponding laboratory data. The results were consistent with conclusions from previous studies, relating to the ebb-only scheme. These included an increase in the minimum water levels upstream of the barrage, a reduction in the mean water levels downstream of the barrage and a general reduction in tidal velocities. For a two-way scheme changes in the tidal elevations and velocities depended on the exact operating conditions of the barrage. It was found that with no starting head the tidal regime was similar to the natural state, with little change in the elevations and a slight reduction in the mean velocities. As a starting head was introduced there was still little change in elevations downstream of the barrage, however, there was an increase in the minimum water levels upstream of the barrage, and a further reduction in the mean velocities.

The Vehicle Relocation Problem for the One-way Electric Vehicle Sharing: An Application to the Milan Case

Traditional car-sharing services are based on the two-way scheme, where the user picks up and returns the vehicle at the same parking station. Some services allow also one-way trips, where the user can return the vehicle in another station. The one-way scheme is more attractive for the users, but may pose a problem for the distribution of the vehicles, due to a possible unbalancing between the user demand and the availability of vehicles or free slots at the stations. Such a problem is more complicated in the case of electric car sharing, where the travel range depends on the level of charge of the vehicles. In a previous work, we introduced a new approach to relocate the vehicles where cars are moved by personnel of the service operator to keep the system balanced. Such relocation method generates a new challenging pickup and delivery problem that we call the Electric Vehicle Relocation Problem (EVRP). In this work we focus on a method to forecast the unbalancing of a car-sharing system. We apply such method to the data yielded by the Milan transport agency taking into account the location and capacity of the present charging stations in Milan. In this way, using a Mixed Integer Linear Programming formulation of EVRP, we can estimate the advantages of our relocation approach on verisimilar instances.

Role of Four-Dimensional Data Assimilation on Track and Intensity of Severe Cyclonic Storms

To examine the role of four dimensional data assimilation (FDDA) on prediction of two Severe Cyclonic Storm (Aila (May 23–26, 2009) andJal (Nov 4–8, 2010)), four numerical experiments are performed using WRF-ARW model with three nested domains having two-way interaction and physical parameterization schemes as CPS-BMJ, MP-WSM6, and PBL-YSU. In each experiment, the model integration is started prior to the formation of depression and continued till the observed landfall. For the experiment without FDDA, NCEP-FNL data alone is used as initial and boundary conditions and for the experiments with FDDA, additional observations are used. In all the experiments, FDDA is considered only in the outer domain upto 24 hrs of integration and then the inner domain is introduced. The results are examined in terms of surface circulation, vorticity, CSLP, MSW, and surface track error. FDDA-produced surface circulation and vorticity showed well-organized structure. For the case of Aila, the surface track (maximum track error: 281 km) and landfall position (88°E/21.73°N) in FDDA experiment are predicted better than experiment without FDDA (track error: 445 km and landfall position 87.13°E/20.37°N) whereas the landfall time experiment without FDDA is closer to observations (between 09 and 12 UTC of May 25) than that of experiment with FDDA(06 UTC of May 25). When CSLP and MSW are examined, the overall intensity is well predicted with FDDA experiment except near to the landfall time. For Jal cyclone, FDDA played significant role to improve the landfall position (80.16°E/13.67°N) with a time lead of ~10 hrs but other parameters remain more or less unchanged.

The bank loan approval decision from multiple perspectives

This paper develops a probability model to evaluate the predictive validity of two-way classification schemes in the context of personal credit scoring and bank loan applications. The Bayesian decision model provides a structure for identifying classification rules that lead to optimal-maximum expected payoff or minimum expected cost-classifications. Using payoffs from multiple perspectives allows identifying conditions where the various perspectives produce contradictory classifications generating either profit premiums or cost penalties depending on the perspective.

Leveraging Height in a Jumping Sensor Network to Extend Network Coverage

With respect to ground level, wireless communication signal strength increases with the elevation of communicating wireless sensor network devices, within practical bounds. Jumping sensors are mobile sensors that provide relocation capabilities and a temporary increase in elevation can be utilized for improving communication. This paper provides a comprehensive multidimensional analysis for jumping sensors. It studies the main factors that impact the Received Signal Strength (RSS) in sensor communication, and performs a comparative analysis between theoretical and experimental results. Sensor elevation from ground level is a key factor, which is often neglected, and plays an important role for successful wireless communication. The impact of jump height manipulation on a jumping sensor to the packet transmission goodput is presented. An airborne two-way communication scheme is defined and studied with experiments. The results indicate the effectiveness of utilizing the change in elevation of a jumping sensor to increase communication range. Since energy is at premium in sensor nodes, the operational energy cost of a jumping sensor prototype is studied in detail. A jumping sensor network is simulated with the parameters learned from the experimental results and the jumping sensor prototype analysis. Simulation results show the enhancement in connectivity and the feasibility of a jumping sensor network.

Performance Analysis for the Amplify-and-Forward Two-Way Cooperative Relaying Networks

In this letter, we analyze the amplify-and-forward (AF) two-way cooperative relaying scheme with regard to the average data transmission rate and the symbol error probability. By investigating the Moment-Generating function (MGF) and the k-th moment of “extra-harmonic” mean of two variables, we derive an exact closed-form expression for the symbol error probability (SEP) and the approximate average sum rate. Analysis results show that the proposed scheme achieves higher SEP performance as well as a lower data rate than the conventional AF two-way scheme. Additionally, it also matches the SEP performance of the one-way AF cooperative scheme but attains higher sum rate. Finally, Monte Carlo simulation results will be shown to confirm our analytical results.

One-Way Protocol for Two-Bit Intrinsic Random Key Distribution with Entangled Photon Pairs

Recently, an innovative two-way scheme for two-bit intrinsic random key distribution has been proposed, although an applicable quantum operation-gate required in this protocol is still missing. In this paper, we present a scheme for two-bit intrinsic random key distribution with entangled photon pairs in a feasible one-way configuration. By consuming one maximally entangled photon pair and one-way trip of one particle of the photon pair, first the generation of a quantum public-key pair is achieved by performing a peculiar positive operator-valued measure which is constructed by the cooperation of two distant authorized parties on one traveling qubit of the entangled pair, then two-bit intrinsic random key can be distributed by projection measurement (taking the former as the prepare stage while the latter as the measure one). Hence it can be regarded as the prepare measure protocol via entanglement resource. And the security of our scheme under various kinds of attacks is also investigated.

Evaluation and design of beaconing in mobile wireless networks

One of the intrinsic problems of mobility in wireless networks is the discovery of mobile nodes. A widely used solution for this problem is to use different variations of beacons, such as hello packets. Although a poorly designed beaconing scheme may lead to unnecessary energy usage or poor throughput, a systematic approach to analyze and select beaconing parameters is not provided in the literature. Here, we propose a model to study the beaconing efficiency using some measures such as the link lifetime, the probability of link establishment, and the delay to discover a new neighbor. The model is general and does not adhere to any particular mobility model; the only input from the mobility is the distribution of physical link durations, which not only abstracts away the mobility details but also all effects that contribute to the link stability such as non-perfectly omni-directional antennas and the path loss exponents. Among our results, we prove that the periodic beaconing (which is widely used owing to its simplicity) is the best in terms of beacon hits; we compare one-way and two-way beaconing schemes and study beaconing energy optimization. Finally, the model is applied to three cases of ad hoc, delay-tolerant, and sensor networks, and a simple rule of thumb is proposed to efficiently adjust the beacon interval.