Maximum Communication Research Articles

High-order tracking problem with a time-varying topology and communication delays

Abstract In this paper, tracking problem for high-order agents under uncertain communication topology and time varying delays is investigated. Each tracking agent is assumed only its own and neighbors׳ information is used in their tracking strategy design. The uncertain communication topology is modelled by a finite number of Laplacian matrices with their corresponding scheduling functions. Sufficient conditions for the existence of a tracking strategy have been expressed in terms of the solvability of linear matrix inequalities. Finally, numerical examples are given to verify the effectiveness and advantages of proposed tracking strategy. Through a set of simulations with various control parameters γ, the relationship between γ and the maximum allowable communications delays is tabulated.

Assessment of telemetry and fluidic control system used in the Medstream programmable infusion system: an in vivo and in vitro study.

The MedStream Programmable Infusion Pump, an intrathecal pump indicated for the treatment of chronic intractable pain and severe spasticity (CE-mark) or severe spasticity (US), has a highly accurate medication delivery (within 10% of the programmed flow rate) and is certified for use in 3-Tesla magnetic resonance imaging systems (conditional). Performance of the telemetric link between external control-unit and implanted pump was assessed in sheep (in vivo) up to 26 weeks, resulting in 1040 communication sessions. The telemetric communication envelope (communication distance and maximum antenna tilt angles) and communication duration were characterized in an in vitro test. Capacitance measurements of the piezoelectric actuator of the valve, valve flow rates, and leak rates were measured in an in vitro cyclic accelerated aging test to assess reliability of the valve over 6,200 k cycles. The pump was well tolerated in vivo; all communication sessions between control-unit and pump were successful (P = 6.889 × 10(-14)). Mean communication distance between pump and control-unit was 3.8 cm, with the maximum antenna tilt angles being 40° (θy) and 50° (θx) for all test cases; the maximum communication duration was 5.5 s. Capacitance measurements, flow rates, and leak rates were within ±10 % range up to 6,200 k cycles corresponding to approximately 10 times the valve cycles over the specified service life of the pump (8 years), except for one flow-rate value, which can be explained by the measurement setup. These results demonstrate the reliability of the telemetry link and piezoelectric valve system of the MedStream Programmable Infusion Pump.

Diameter variability of hypercubes

A parallel and distributed system is usually represented by a graph. The maximum communication delay between any pair of processors in a parallel and distributed system can be determined by the diameter of its underlying graph. The diameter of a graph can be affected by the addition or deletion of edges. In this paper, we show that the diameter of an n-dimensional hypercube can be decreased by k with the addition of 22k−1 edges for 1≤k≤⌊n/2⌋.

Impact of Position Errors on Path Loss Model Estimation for Device-to-Device Channels

Many wireless applications require a propagation model that describes the attenuation of the transmitted signal as a function of the distance between devices. Such channel models are derived commonly from signal strength measurements, and assume that the true distances between wireless terminals are known. In practice, however, the true distances may be unavailable or difficult to obtain, for instance in mobile scenarios or in the absence of line-of-sight. These conditions typically occur in forested environments, urban areas, etc. This paper addresses the problem of path loss model parameter estimation in presence of erroneous distance measurements, such as the ones derived from the GPS positions. We provide a model for the uncertainties, and study the impact of distance errors on the estimation of a log-distance channel model. Our main conclusion is that the path loss model can be estimated with a reasonable accuracy from unreliable distances, provided that the measurements are taken at distances beyond a few standard deviations of the GPS positioning error. In case the maximum communication range does not allow such large distances, we provide a method to correct the erroneous channel model. Real-world measurements are used in order to validate our approach.

A Novel Topology Control Approach to Maintain the Node Degree in Dynamic Wireless Sensor Networks

Topology control is an important technique to improve the connectivity and the reliability of Wireless Sensor Networks (WSNs) by means of adjusting the communication range of wireless sensor nodes. In this paper, a novel Fuzzy-logic Topology Control (FTC) is proposed to achieve any desired average node degree by adaptively changing communication range, thus improving the network connectivity, which is the main target of FTC. FTC is a fully localized control algorithm, and does not rely on location information of neighbors. Instead of designing membership functions and if-then rules for fuzzy-logic controller, FTC is constructed from the training data set to facilitate the design process. FTC is proved to be accurate, stable and has short settling time. In order to compare it with other representative localized algorithms (NONE, FLSS, k-Neighbor and LTRT), FTC is evaluated through extensive simulations. The simulation results show that: firstly, similar to k-Neighbor algorithm, FTC is the best to achieve the desired average node degree as node density varies; secondly, FTC is comparable to FLSS and k-Neighbor in terms of energy-efficiency, but is better than LTRT and NONE; thirdly, FTC has the lowest average maximum communication range than other algorithms, which indicates that the most energy-consuming node in the network consumes the lowest power.

Research on Multi-Optimizing Strategy for MVB Sporadic Data of Rail Transit On-Board Network

In order to improve real-time of MVB sporadic data communication, we study and analysis MVB sporadic data communication scheduling modelling and collision event arbitration mechanism, the communication maximum arbitration delay is closely related with concurrent message events, binary tree search algorithm mechanism bring out big communication delay, so, we makes use of multi-optimizing strategies, applying dynamically assigned communication of sporadic data and slave frame stuffing of process data, decreasing communication delay of sporadic data and making sure that emergent sporadic data firstly send, it is a good try to optimize real-time of sporadic data.

Simultaneous Optimal Design of Measurement and Communication Infrastructures in Hierarchical Structured WAMS

The ability of data recovery during communicational failures is one of the significant advantages of the wide area measurement system (WAMS) with hierarchical structure. For this purpose, in addition to the proper partitioning of the WAMS, the relative location of phasor measurement units (PMUs) and phasor data concentrators (PDCs) should be selected so as to maximize the reliability of the communication network. The aim of this paper is to develop an organized method for partitioning the WAMS as well as proposing a new algorithm for the simultaneous optimal placement of PMUs and PDCs. In the proposed method, first it is assumed that PMUs are installed at all of the system buses. Then, redundant PMUs will be omitted sequentially to provide the system observability with the maximum communication reliability. The IEEE 30-, and 118-bus systems are used to demonstrate the proposed algorithm. Contingencies such as PMU loss and line outage are considered in power system observability achievement. Finally, to show the applicability of proposed methods to real dimensional power systems, the IEEE 300-bus power system is also analyzed in the normal operating condition.

Design and Development of Remote Communication System for Mines Detector Robot

This paper describes the design and development of remote communication system for mines detector robot. This project uses a PIC18F4580 microcontroller to control the robot movements and functions. A metal detector will be attached to the robot. The robot will have two operating modes; automatic and manual mode. In automatic mode, the robot will move according to a predefined track. When the robot is moving, the system produces feedbacks given by the sensors on the robot to the remote computer about the surroundings and when potential land mines are detected. In manual mode, the robot will be fully controlled by the remote computer for decision making process. All the controls and monitoring of data are displayed in a graphical user interface (GUI). The wireless module proposed is the XBee RF modules. The XBee modules were found to perform with optimum data transfer reliability at the range equals to 25% of its maximum communication range.

Attacks on Recent RFID Authentication Protocols

The developing of RFID systems in sensitive applications like e-passport, e-health, credit cards, and personal devices, makes it necessary to consider the related issues such as maximum reading distance, communication speed and data security. The use of signal processing methods is an efficient and convenient way to achieve the maximum reading distance and communication rate. However, the signal processing techniques are not adequate to provide a reasonable level of security and privacy for RFID systems. Thus, it is necessary to employ specific authentication protocols which assure data security and preserve the user's privacy. Among other security and privacy characteristic of an RFID authentication protocol, the untraceability and synchronization are the most important attributes. The former is strongly related to the privacy of tags and their holders, while the later has a significant role in the security and availability parameters. In this paper, we investigate two RFID authentication protocols proposed by Duc and Kim, and Song and Mitchell in terms of privacy and security. We analyze the protocol proposed by Duc and Kim and present desynchronization, traceability and forward traceability attacks. Besides, we study the weaknesses in the Song and Mitchell's protocol and address its defects by applying desynchronization, traceability and backward traceability attacks. We also propose our revisions to secure the Song and Mitchell's protocol against traceability and desynchronization attacks.

RSSI Based Monte-Carlo Localization Boxed Algorithm

The maximum communication radius is applied to estimate the distance between one hop nodes in the MCB algorithm. However, the distance is generally less than the communication radius in practical applications which will result in the location error to some extent. So, the distance estimated by the received signal strength indication (RSSI) is used to substitute the communication radius in MCB algorithm to improve the estimation precision. The simulation results show that the average localization accuracy of the proposed algorithm is improved by about 14% comparing with the MCB algorithm.

A PSO multi-robot exploration approach over unreliable MANETs

This paper proposes two extensions of Particle Swarm Optimization (PSO) and Darwinian Particle Swarm Optimization (DPSO), respectively denoted as RPSO (Robotic PSO) and RDPSO (Robotic DPSO), so as to adapt these promising biologically inspired techniques to the multi-robot systems domain, by considering obstacle avoidance and communication constraints. The concepts of social exclusion and social inclusion are used in the RDPSO algorithm as a ‘punish–reward’ mechanism, thus enhancing the ability to escape from local optima. Experimental results obtained in a simulated environment shows the superiority of the RDPSO evidencing that sociobiological inspiration can be useful to meet the challenges of robotic applications that can be described as optimization problems (e.g. search and rescue). Moreover, the performance of the RDPSO is further evaluated within a population of up to 12 physical robots under communication constraints. Experimental results with real platforms show that only 4 robots are needed to accomplish the herein proposed mission and, independently on the number of robots and maximum communication distance, the global optimum is achieved in approximately 90% of the experiments.

Optimal design of wireless monitoring system in mountain citrus orchard and improvement monitoring

In order to monitor in real time the growth environment of a mountain citrus orchard and its variation with spatio-temporal and weather status, the optimal design and evaluation of a wireless monitoring system in a mountain citrus orchard was introduced in this paper. The wireless monitoring system is comprised of end nodes used for obtaining citrus growth environment information including air temperature, air humidity, soil moisture and light; router nodes used to relay citrus growth environment information; and a network coordinator, which performs functions such as managing the nodes, collecting and analyzing the data received from the end nodes, and connecting as a gateway for remote data access. CC2530 is adopted as the core processor of the monitoring system; it has the capability of wireless communication and central processing. The optimal design was introduced in this system including information frame structure suitable for a mountain orchard environment, bidirectional instruction control function, topology discovery, routing monitoring mechanism and node information diversification collection mechanism, so as to effectively enhance the robustness and controllability of monitoring the citrus orchard environment. In this paper, the citrus orchard in the subtropical garden of SCAU (South China Agriculture University) was selected for the test. The orchard hill has sloping terrain; citrus trees are planted by terraced distribution. The average slope is 20 degrees, the citrus trees have a height of 2.8m, their shrub diameters are 3m, and the average spacing of citrus plants is 2.8m. The citrus orchard wireless channel was measured in citrus orchard, and the wireless channel model was established through blocking factor and rain attenuation factor, it was used to guide the evaluation of the wireless monitoring network. Experimental results of RSSI (Receiver Signal Strength Index) and communication quality under different distances and climates show that reliable collection and transmission were available in the mountain citrus orchard when the wireless system was deployed with an antenna height of 1.5m and a maximum single-hop communications distance of 30m. Continuous 744h online test results show that the optimized wireless monitoring system improved the transmission success rate; it has a success rate of at least 99.12% for data transmission within the 30m distance. The system ran well, worked stably, and was suitable for the remote, real-time monitoring of the citrus growth environment in a mountainous orchard.

Optimal Collapsing Protocol for Multiparty Pointer Jumping

In this paper, we study the pointer jumping problem under the one-way number-on-the-forehead (NOF) multiparty communication model. This problem is widely considered to be a candidate for proving strong lower bounds under the NOF model, and has applications to proving lower bounds for many other problems. We investigate the maximum communication complexity of collapsing protocols for pointer jumping, where each player sees all layers behind her and only the composition of layers ahead of her. We present a collapsing protocol in which every player communicates at most $n-\frac{1}{2}\log_{2} n+1$ bits, which tightly matches the lower bound of $n-\frac{1}{2}\log_{2} n-2$ given by Brody and Chakrabarti (in Proc. 25th Annual Symposium on Theoretical Aspects of Computer Science (STACS), pp. 145---156, 2008). Actually, in our protocol only three players need to communicate information: the first player sends log2(n+1) bits, the second to last player sends $n-\frac{1}{2}\log_{2} n+1$ bits, and the last player just outputs the answer. A natural question is whether the log2(n+1) bits communicated by the first player is necessary for achieving a low maximum communication complexity. We make progress towards this question by proving that in any collapsing protocol for the 3-player pointer jumping problem, if the first player only sends one bit, then the second player must communicate at least n?2 bits.

Important Controversies Associated with Isotretinoin Therapy for Acne

Isotretinoin is a remarkably effective drug for severe, recalcitrant acne vulgaris. Soon after the drug's release in the early 1980s, a number of important adverse effects were reported subsequently leading to a variety of medical and medicolegal controversies. Three of these controversies will be highlighted concerning the putative role of isotretinoin in (1) depression and suicide, (2) inflammatory bowel disease, and (3) iPledge and pregnancy prevention programs. It appears that a very small subset of patients receiving isotretinoin for acne are at risk for depression, which is very manageable provided there is adequate patient awareness of the possibility, maximum communication between the patient and physician, and cessation of therapy if clinically important depression occurs (after which the depression rapidly resolves in a week or less). Multiple controlled studies actually suggest a very favorable effect of isotretinoin on depression and anxiety common in the population requiring isotretinoin. With regard to inflammatory bowel disease, in just one study, only ulcerative colitis association with isotretinoin reached statistical significance. The actual incidence of this association is strikingly low. Finally, it is clear that even the most recent pregnancy prevention program (iPledge) is no more successful than prior programs; there will likely always be a small number of female patients becoming pregnant while receiving isotretinoin for acne vulgaris.

Changing the diameter of the locally twisted cube

The hypercube network Q n has been proved to be one of the most popular interconnection networks. The n-dimensional locally twisted cube LTQ n is an important variant of Q n . One of the critical performance factors of an interconnection network is the diameter which determines the maximum communication time between any pair of processors. In this paper, we investigate the diameter variability problems arising from the addition and deletion of edges in LTQ n . We obtain three results in this paper: (1) for any integer n≥2, we find the least number of edges (denoted by ch −(LTQ n )), whose deletion from LTQ n causes the diameter to increase, (2) for any integer n≥2, when ch −(LTQ n ) edges are deleted, the diameter will increase by 1 and (3) for any integer n≥4, the least number of edges whose addition to LTQ n will decrease the diameter is at most 2 n−1.

Event-triggered communication and [formula omitted] control co-design for networked control systems

This paper studies an event-triggered communication scheme and an H∞ control co-design method for networked control systems (NCSs) with communication delay and packet loss. First, an event-triggered communication scheme and a sampled-state-error dependent model for NCSs are presented. In this scheme and model, (a) the sensor takes samples in a periodic manner; (b) a triggering condition is applied to the sampled signal to determine whether a signal is transmitted to the controller or not; and (c) the closed-loop system with a networked state feedback controller is modeled as a time-delay system. Secondly, by constructing a novel Lyapunov–Krasovskii functional, three theorems for the system asymptotical stability subject to imperfect communications are derived. Thirdly, a new algorithm is developed for the triggering condition and the controller feedback gain to meet the specified performance. This design algorithm is based on the two permissible limits on the signal transfer. These limits are: the maximum allowable communication delay bound and the maximum allowable number of successive packet losses, respectively. Finally, the proposed co-design method is demonstrated by two numerical examples.

Source levels of fin whale 20 Hz pulses measured in the Northeast Pacific Ocean

Source levels of fin whale calls can be used to determine range to recorded vocalizations and to model maximum communication range between animals. In this study, source levels of fin whale calls were estimated using data collected on a network of eight ocean bottom seismometers in the Northeast Pacific Ocean. The acoustic pressure levels measured at the instruments were adjusted for the propagation path between the calling whales and the instruments using the call location and estimating losses along the acoustic travel path. A total of 1241 calls were used to estimate an average source level of 189 ± 5.8 dB re 1μPa at 1 m. This variability is largely attributed to uncertainties in the horizontal and vertical position of the fin whale at the time of each call and the effect of these uncertainties on subsequent calculations. Variability may also arise from station to station differences within the network. For call sequences produced by a single vocalizing whale, no consistent increase or decrease in source level was observed over the duration of a dive. Calls within these sequences that immediately followed gaps of 27 s or longer were classified as backbeat calls and were consistently lower in both frequency and amplitude.

空地激光通信链路功率与通信性能分析与仿真

The influences of main parts of an apparatus and channel to power of communication laser on space-ground optical communication slant link were analyzed.Based on the formula for signal-to-noise ratio of receiving detector and bit error rate of communication,the simulation system of space-ground optical communication was established.Using the simulation system,the highest communication rates as to the different atmospheric visibilities were analyzed,the assumptions that bit error rate is superior to 10-7,the minimum transmitter power and the maximum communication distance were discussed in order to achieve the communication rate to 1.5 GHz and bit error rate is superior to 10-7.The result indicates that influence of the atmospheric visibility to the bit error rate is more obvious,when the transmitter power is greater.

LED조명 디바이스를 접목한 무선통신 인터페이스 시스템 모듈 성능 분석

This paper is implemented simple visible light communication system by combining the communications through LED lighting. It uses a variable PD sensor to the receiver and 1~12 the LED light-emitting device to the transmitter to realize LED visible light communication. Initial distance value of the developed transmission and receiver is more than 0~1.5m for LED visible light communication, the overall system transmission rate is organized with thousands kbps variability visible light media transmission system. It was measured the performance experiment during lens wearing or not wearing in order to increase the overall efficiency of the LED module, configures the LED and PD to existing PC module for the performance analysis of the implemented research, experiments the maximum communication distance of the transmitter/receiver according to LED count and the transmission rate, check about application methods and the possibility.

E급 증폭기의 바이어스 스위칭 회로를 이용한 HF-대역 자기장 통신 시스템

In this paper, we implemented a HF-band magnetic-field communication system consisting of an amplitude shift keying(ASK) transmitter, a pair of loop antennas, and an ASK receiver. Especially, we suggested a new ASK transmitter architecture, where a drain bias of class E amplifier is switched alternatively between two voltage levels with respect to input data. A maximum 5 W class E amplifier was designed using a low cost IRF510 power MOSFET at the frequency of 6.78 MHz. A measured sensitivity of the designed ASK receiver is -78 dBm, which consists of a log amplifier, a filter, and a comparator. Maximum communication range of magnetic-wave communication system with loop antennas was calculated using magnetic field equations in both near-field and far-field ranges. Also, in order to verify the calculated values, an indoor propagation loss was measured using a pair of loop antennas whose dimensions are . Maximum operating range is estimated about 35 m in case of transmitter`s output power of 1 W and receiver sensitivity of -70 dBm, respectively. Finally, the communication field test using the designed ASK transmitter and receiver was successfully done at the distance of 5 m.