Analog Network Research Articles

An Opportunistic Source Selection Spectrum Sharing Protocol for Overlay Cognitive Two-Way Relaying System

In this paper, an overlay two-way relaying spectrum sharing protocol is proposed by employing an opportunistic source selection strategy. In this protocol, a secondary user acts as a relay and allocates a fraction of its transmit power to assist two-way communication between two primary users (PUs), thus, gaining spectrum sharing as long as without degrading the primary system performance. Moreover, to exploit the multiuser diversity inherent in the multiuser primary systems, the two PUs transmit their own messages in an opportunistic manner, depending on the instantaneous channel conditions. Specifically, at each transaction, only one of the PUs is selected for transmission such that the instantaneous mutual information on the whole primary network is maximized and as a result, the multiuser diversity gain is achieved by the primary system. Then, we derive the exact closed-form outage probabilities for both the primary and secondary systems. To gain more insights, closed-form asymptotic outage probability expressions are also derived. Based on the approximations, we further obtain analytical results on the diversity order of the primary system and the power-allocation threshold above which the spectrum sharing is allowed for secondary transmission. Numerical results are presented to verify our analysis and highlight the advantages of our proposed scheme compared to another two-phase spectrum sharing protocol based on analog network coding.

網膜における視覚情報処理機構に基づくアナログネットワークの構築と検討(アナログ・デジアナ・センサ, 通信用LSI)

網膜における視覚情報処理機構に基づくアナログネットワークの構築と検討(アナログ・デジアナ・センサ, 通信用LSI)

Optimization of Cognitive Two-Way Networks With Energy Harvesting Relays

This letter investigates the performance of an analog network coding based underlay cognitive two-way energy harvesting relay network. The amplify-and-forward relay harvests energy using the power-splitting relaying (PSR) protocol. Using approximate expressions for the terminal outages, throughput, and ergodic sum-rate, we derive insights into performance. Specifically, we derive closed-form expressions for the throughput maximizing interference temperature apportioning parameter (ITAP) and the PSR parameter, and show that they can be optimized separately. We also derive a closed-form expression for the ergodic sum-rate maximizing PSR parameter, and show that an ITAP of half maximizes ergodic sum-rate. Simulations demonstrate the accuracy of the derived expressions.

Broadband Analog Network Coding With Robust Processing for Two-Way Relay Networks

In this letter, we study the robust processing for a single carrier two-way relay network with broadband analog network coding and imperfect channel state information. Based on a statistical model for channel estimation error, we derive the optimal coefficients of self interference cancellation and linear frequency domain equalization in the sense of minimizing the conditional mean square error given a channel estimate. Simulation results show that the proposed robust design can achieve better bit error rate performance than the conventional non-robust scheme.

Performance of Analog Network Coding Based Two-Way EH Relay With Beamforming

In this paper, we investigate the performance of an analog network coding based two-way relay system with multiple-antenna source terminals and single-antenna energy harvesting (EH) relay. We consider time-switching relaying protocol to perform EH and information processing at the amplify and forward EH relay. Assuming that the multiple-antenna source with a better link beamforms energy to the relay, we derive expressions for the system outage, ergodic sum-rate, and sum symbol error rate. In the analysis, we take into account the sensitivity of the energy harvesting circuit. We investigate the problem of throughput maximization by optimizing the fraction $\alpha $ of time spent on EH, and derive closed-form expressions for optimum $\alpha $ in important special cases. We analyze the problem of relay location for fixed $\alpha $ , and show that the optimum location varies with source terminal antennas. We further show that joint optimization of relay location and $\alpha $ yields best throughput performance. We show through simulations that unlike throughput, the optimum $\alpha $ that maximizes the ergodic sum-rate does not show much variation with system parameters. Simulation results with practical parameter values demonstrate the accuracy of the derived analytical expressions.

Joint impact of nodes-mobility and channel estimation error on the performance of two-way relay systems

This paper presents the performance analysis of a two-way relay system with nodes-mobility (NM) and channel estimation errors (CEE) under time-varying Rayleigh fading. Herein, analog network coding protocol is employed at the relay node. All the participating nodes are half-duplex and equipped with single-antenna devices. Specifically, we utilize first-order Markovian model to characterize the impact of NM in the channel. Along with the NM, we also consider that the CEE may exist in practical scenarios, where nodes require to estimate the channel state information. By incorporating these factors, we first derive the instantaneous end-to-end (e2e) signal-to-noise ratios (SNRs) at two source nodes. Then, we obtain the exact closed-form expressions for distribution and density functions of the two e2e SNRs. After that, we derive the accurate expressions of various performance metrics, viz., sum-bit error rate, overall outage probability, and ergodic sum-rate. Further, to attain more insights into the considered system, we deduce the asymptotic behavior of these performance metrics. Finally, numerical and Monte-Carlo simulation results are provided to validate our theoretical analysis and to illustrate the impact of NM and CEE on the performance measures of the considered system.

Analogous elastic network for the analysis of power system energy structure

A new approach to the analysis of the transient energy interaction in power systems is presented in this work on the basis of an analogous elastic network. A power system is first rigorously mapped to an elastic network consisting of elastic branches with different elasticity coefficients. On the basis of elasticity mechanics and the analogous elastic network, the transient energy of the different parts, such as the synchronous generators, branches, and loads, is defined and has been proved to agree with the law of energy conservation. Subsequently, based on the law of energy conservation and energy feature analysis, the concept of the power system energy structure (PSES) is built to exhibit the distribution and interaction of transient energy in the power system. Wide area and local area transient energy interaction can be analysed using the measurement-based energy structure, which shows obvious potential in on-line monitoring and analysis of power system oscillation. Finally, the simulations of Western Systems Coordinating Council (WSCC) three-generator test system and a practical power system are performed and analysed to verify the rationality of the analogous elastic network and the validity of the proposed PSES.

A QoS-Oriented High-Efficiency Resource Allocation Scheme in Wireless Multimedia Sensor Networks

Deadline constrained packet scheduling and transmission are important in real-time multimedia applications. This is because packets missing their deadlines would become useless and are frequently dropped, which seriously degrade the quality of service (QoS). As the utilization of Internet of Things has become mature, multimedia data transmission is a key component to promote the QoS of citizens. To fulfill the QoS requirement in wireless sensor networks (WSNs) with multimedia content, the combination of multiple transmission methods is encouraged for packet forwarding, including conventional network coding, analog network coding, plain routing, and direct transmission (i.e., no-relaying, NR). The diversity of transmission method is helpful to lower packet dropping probability, while complicating the packet transmitting and scheduling process instead. Therefore, we first introduce an exhaustive search method to obtain the optimal scheduling sequence and corresponding transmission method for deadline constrained multimedia transmissions in WSNs. With the objective of promoting computing efficiency for the formulated problem, we then propose two heuristic methods based on the Markov chain approximation and the dynamic graph, respectively. Simulation results illustrate that our methods can effectively reduce packet dropping probability and simulation time, so that QoS of individuals can be promoted.

Time Switching-based Analog Network Coding for Maximizing the Minimum Required Secrecy Capacity in Energy Harvesting Networks

Time Switching-based Analog Network Coding for Maximizing the Minimum Required Secrecy Capacity in Energy Harvesting Networks

A Novel Cooperation-Based Network Coding Scheme for Walking Scenarios in WBANs

In Wireless Body Area Networks (WBANs), the tradeoff between network throughput and energy efficiency remains a key challenge. Most current transmission schemes try to cope with the challenge from the perspective of general Wireless Sensor Networks (WSNs), which may not take the peculiarities of WBAN channels into account. In this paper, we take advantage of the correlation of on-body channels in walking scenarios to achieve a better tradeoff between throughput and energy consumption. We first analyze the characteristics of on-body channels based on realistic channel gain datasets, which are collected by our customized wireless transceivers in walking scenarios. The analytical results confirm the rationale of our newly proposed transmission scheme A3NC, which explores the combination of the aggregative allocation (AA) mechanism in MAC layer and the Analog Network Coding (ANC) technique in PHY layer. Both theoretical analyses and simulation results show that the A3NC scheme achieves significant improvement in upload throughput and energy efficiency, compared to the conventional approaches.

Power Splitting-based Analog Network Coding for Improving Physical Layer Security in Energy Harvesting Networks

Power Splitting-based Analog Network Coding for Improving Physical Layer Security in Energy Harvesting Networks

Analog-Network-Coded Two-Way Relaying Under the Impact of CSI Errors and Network Interference

In this paper, we study a two-way relaying system with analog network coding whereby both the relay and the two sources are under the effect of erroneous channel state information (CSI) and network interference that originate from a Poisson field of interferers. Our contribution is twofold: 1) We characterize the interference affecting the aforementioned nodes by presenting a general model that incorporates the expected correlation of the interference process that affects the relay, which in turn affects the two sources; 2) by deriving the interference statistics, particularly its first moment, we also derive analytical formulas for the distribution of the signal-to-interference-plus-noise ratio (SINR) of the two sources in the high-SINR region, which reveal that in that region, the amount of correlation between the interference processes affecting the relay and the two sources does not affect the SINR distribution. These statistics are subsequently used to derive analytical expressions of the average sum symbol error rate (SER) and the achievable average sum rate of the system. Finally, the theoretical results are corroborated by means of Monte Carlo simulations.

Multimodal vibration damping of a plate by piezoelectric coupling to its analogous electrical network

Multimodal damping can be achieved by coupling a mechanical structure to an electrical network exhibiting similar modal properties. Focusing on a plate, a new topology for such an electrical analogue is found from a finite difference approximation of the Kirchhoff–Love theory and the use of the direct electromechanical analogy. Discrete models based on element dynamic stiffness matrices are proposed to simulate square plate unit cells coupled to their electrical analogues through two-dimensional piezoelectric transducers. A setup made of a clamped plate covered with an array of piezoelectric patches is built in order to validate the control strategy and the numerical models. The analogous electrical network is implemented with passive components as inductors, transformers and the inherent capacitance of the piezoelectric patches. The effect of the piezoelectric coupling on the dynamics of the clamped plate is significant as it creates the equivalent of a multimodal tuned mass damping. An adequate tuning of the network then yields a broadband vibration reduction. In the end, the use of an analogous electrical network appears as an efficient solution for the multimodal control of a plate.

Modeling Current-Voltage Charateristics of Proteorhodopsin and Bacteriorhodopsin: Towards an Optoelectronics Based on Proteins.

Current-voltage characteristics of metal-protein-metal structures made of proteorhodopsin and bacteriorhodopsin are modeled by using a percolation-like approach. Starting from the tertiary structure pertaining to the single protein, an analogous resistance network is created. Charge transfer inside the network is described as a sequential tunneling mechanism and the current is calculated for each value of the given voltage. The theory is validated with available experiments, in dark and light. The role of the tertiary structure of the single protein and of the mechanisms responsible for the photo-activity is discussed.

Synthesis and Characterization of Polyurethane Networks Derived from Soybean-Oil-Based Cyclic Carbonates and Bioderivable Diamines

Nonisocyanate polyurethane (NIPU) thermoset networks were produced from a novel soybean-oil-derived poly(vinyl ether) (i.e., poly[(2-vinyoxy)ethyl soyate]) possessing cyclic carbonate functional groups in the fatty acid ester side chains of the polymer. Three different linear aliphatic diamines, namely, 1,6-hexamethylenediamine, 1,9-nonanediamine, and 1,13-tridecanediamine, were used to cross-link the cyclic carbonate-functional poly[(2-vinyoxy)ethyl soyate] [C-poly(2-VOES)]. All three of these diamines can be readily obtained from renewable resources. For comparison purposes, analogous NIPU networks were produced using cyclic carbonate-functional soybean oil (CSBO) in place of the C-poly(2-VOES). The chemical, thermal, viscoelastic, and mechanical properties of the six NIPU networks were characterized. With regard to the chemical nature of the soy-based, carbonate-functional component, it was found that the polymeric nature of C-poly(2-VOES) resulted in very different NIPU properties compared to analogou...

An electrical network for evaluating monitoring strategies intended for hydraulic pressurized networks

This paper presents a study of similarities between electrical and hydraulic pressurized networks. The primary objective is to examine whether or not it is possible to use electrical laboratory networks measuring voltage to study leak-region detection strategies measuring flow in water-distribution networks. In this paper, the strategy used to compare the networks is error-domain model falsification, a previously developed methodology for data interpretation that combines engineering knowledge with models and data to enhance decision making. Simulation results obtained for a part of the water-supply network from the city of Lausanne are compared with an analogous electric network. The electrical network is simulated using resistors to mimic the pipes. The consequence is that the electrical model is linear. The resistance values are obtained by computing the hydraulic resistance for each pipe, given by the Hazen-Williams equation. The compatibility of the two networks is evaluated through simulations in three ways: (1) comparing flow predictions obtained by simulating several leak scenarios; (2) comparing the expected identifiability (performance) of the two networks; and (3) comparing sensor placement configurations. The analyses show that even though the models have varying characteristics of underlying physical principles (the electrical model is linear while the hydraulic model is non-linear), the results are within generally accepted engineering limits of similarity (10%). This indicates that measurements on electrical laboratory networks have the potential to illustrate the efficiency and adaptability of leak-detection methodologies for full-scale water-supply and other pressurized hydraulic networks. Finally, two electrical laboratory physical networks, including an electrical model of part of the water network in Lausanne, were constructed and used in case studies to illustrate this adaptability.

Electrical equivalent thermal network for direct contact membrane distillation modeling and analysis

Membrane distillation (MD) is an emerging water desalination technology that offers several advantages compared to conventional desalination methods. Although progress has been made to model the physics of the process, there are two common limitations of existing models. Firstly, many of the models are based on the steady-state analysis of the process and secondly, some of the models are based on partial differential equations, which when discretized introduce many states which are not accessible in practice. This paper presents the derivation of a novel dynamic model, based on the analogy between electrical and thermal systems, for direct contact membrane distillation (DCMD). An analogous electrical thermal network is constructed and its elements are parameterized such that the response of the network models the DCMD process. The proposed model captures the spatial and temporal responses of the temperature distribution along the flow direction and is able to accurately predict the distilled water flux output. To demonstrate the adequacy of the proposed model, validation with time varying and steady-state experimental data is presented.

High speed and low sensitive current-mode CMOS perceptron

The paper presents a prototype of a perceptron network working in the current mode, with a digital interface for applications in analog-to-digital systems. The presented implementation makes it possible to create a network using the standard nanometer CMOS technology, to use a row strategy for designing a topography, as well as to place an analog network IPcore on a silicon substrate, common with the digital part. The work introduces an implementation of a CMOS axon with a monotonic, differentiable and sigmoid activation function. It also introduces an implementation of a dendrite with a fully digital interface. The obtained dendrite weight mapping error was 0.072%. The article discusses routing neurons based on using weight values including an elimination of the CMRR concurrent component and reducing power consumption. The work presents a strategy for programming weights including completely eliminating the mismatch process. The works included a mismatch analysis of the operation of the network and a verification of the signal processing accuracy. A sample 7.8MHz multi-layer implementation with 16 weights yielded precision=94.62%, and a 5Ms/s multi-layer implementation of 1098 weights: precision=93.28%.

Computational Method for the Systematic Identification of Analog Series and Key Compounds Representing Series and Their Biological Activity Profiles.

A computational methodology is introduced for detecting all unique series of analogs in large compound data sets, regardless of chemical relationships between analogs. No prior knowledge of core structures or R-groups is required, which are automatically determined. The approach is based upon the generation of retrosynthetic matched molecular pairs and analog networks from which distinct series are isolated. The methodology was applied to systematically extract more than 17 000 distinct series from the ChEMBL database. For comparison, analog series were also isolated from screening compounds and drugs. Known biological activities were mapped to series from ChEMBL, and in more than 13 000 of these series, key compounds were identified that represented substitution sites of all analogs within a series and its complete activity profile. The analog series, key compounds, and activity profiles are made freely available as a resource for medicinal chemistry applications.

Impact of channel estimation error on zero‐forcing‐based multiple‐input–multiple‐output two‐way relaying

In this study, the authors investigate the impact of channel estimation error (CEE) on the performance of a multiple-input–multiple-output (MIMO) two-way relay system under Rayleigh fading. Herein, transmit/receive zero-forcing (ZF) is employed at the two source nodes, whereas analogue network coding is used at the relay node. Fundamentally, for making use of transmit/receive ZF, all nodes must be aware of channel state information (CSI). As perfect CSI may not always be available in practical scenarios, the CEE does exist in the considered system. By taking the imperfect CSI into account, they enucleate that the residual self-interference and additional noise pertaining to the CEE have effect of reducing end-to-end signal-to-noise ratios (SNRs) at the two source nodes. Based on the statistical characterisations of these post-processing SNRs, they carry out the overall system outage probability analysis. Further, they investigate the asymptotic outage behaviour to deduce the achievable diversity order. They substantiate that the diversity order may reduce to zero under severe impact of CEE. In addition, they derive a closed-form expression of ergodic sum-rate of the considered system with CEE. Numerical and simulation investigations are conducted to support all the theoretical findings using various values of CEE and antenna configurations.