Harsh Communication Research Articles

Noise Sources, Effects and Countermeasures in Narrowband Power-Line Communications Networks: A Practical Approach

The integration of Distributed Generation, Electric Vehicles, and storage without compromising the quality of the power delivery requires the deployment of a communications overlay that allows monitoring and controlling low voltage networks in almost real time. Power Line Communications are gaining momentum for this purpose since they present a great trade-off between economic and technical features. However, the power lines also represent a harsh communications medium which presents different problems such as noise, which is indeed affected by Distributed Generation, Electric Vehicles, and storage. This paper provides a comprehensive overview of the types of noise that affects Narrowband Power Line Communications, including normative noises, noises coming from common electronic devices measured in actual operational power distribution networks, and noises coming from photovoltaic inverters and electric vehicle charging spots measured in a controlled environment. The paper also reviews several techniques to mitigate the effects of noise, paying special attention to passive filtering, as for being one of the most widely used solution to avoid this kind of problems in the field. In addition, the paper presents a set of tests carried out to evaluate the impact of some representative noises on Narrowband Power Line Communications network performance, as well as the effectiveness of different passive filter configurations to mitigate such an impact. In addition, the considered sources of noise can also bring value to further improve PLC communications in the new scenarios of the Smart Grid as an input to theoretical models or simulations.

ADA APA DENGAN KOMUNIKASI ORANG TUA-REMAJA?: PENGARUHNYA TERHADAP AGRESIVITAS REMAJA PADA SESAMA

There is a vague link between parent–adolescent communication and adolescents’ aggressiveness. Usually, the agressive perpetrators are the victims from their past experiences of abusive behavior from their surroundings. This present study aimed to examine influence among parent-adolescent communication pattern, parental physically and verbally harsh communication toward adolescents, parents-adolescents mutual avoidance, frequency of adolescents aggressivity toward others, and adolescents aggressiveness. Using Albert Bandura’s learning theoretical framework about violence messages reproduction, this study have been conducted using 367 adolescents sample of Bogor District and City. This report used quantitative and using cross sectional study design. Researcher also employed self-reported, survey methods in order to collect data. Result shown significant relation and influence among parental physically and verbally communication towards adolescents; parents-adolescents mutual avoidance; frequency of adolescents aggressivity toward others; and adolescents aggressiveness. Using Structural Equation Modelling (SEM) analyses, result proved that the victims of violence usually become perpetrators in future life.

Planning and Performance Challenges in Power Line Communications Networks for Smart Grids

The Smart Grid represents a revolution especially at distribution and customer levels, bringing monitoring and control capabilities, traditionally available up to the primary substations, down to the secondary substations, and beyond. Machine-to-Machine (M2M) communications networks are key to enable managing the huge number of sensors and actuators distributed all over the low voltage and medium voltage networks. Such M2M communications networks must meet demanding requirements from the technical perspective (e.g., low latency, high availability), since eventually the stability of the grid may rely on them, and from the economic perspective (e.g., low deployment and operational costs), due to the huge volume of devices to be monitored and controlled. Thus, Power Line Communications (PLC) technologies are winning momentum in these scenarios because they represent a great trade-off between both perspectives. However, electrical networks also represent a harsh communications medium, mainly because they are not designed for data communications, but for power transmission. Consequently, although much research has been carried out on this topic recently, PLC networks still present technological problems and challenges. This paper highlights some of the most relevant challenges in this area and presents a set of cutting-edge software tools which are being developed to overcome them, facilitating the planning, deployment, and operation of this kind of networks.

Automated key exchange protocol evaluation in delay tolerant networks

Cryptographic key exchange is considered to be a challenging problem in Delay Tolerant Networks (DTNs) operating in deep space environments. The difficulties and challenges are attributed to the peculiarities and constraints of the harsh communication conditions that DTNs typically operate in, rather than the actual features of the underlying key management cryptographic protocols and solutions. In this paper we propose a framework for evaluation of key exchange protocols in a DTN setting. Our contribution is twofold as the proposed framework can be used as a decision making tool for automated evaluation of various communication scenarios with regards to routing decisions and as part of a method for protocol evaluation in DTNs.

VALIDATION OF PERFORMANCE ANALYSIS FOR OPTIMIZED VEHICULAR AD HOC NETWORK USING TAGUCHI METHOD

Vehicular Ad Hoc Network (VANET) is quite different from other ad hoc networks in term of functionality because of the variable node density, high node mobility, and unpredictable and harsh communication environment. There are two major application VANETs, namely safety applications and non-safety applications. Network optimization is one way to maintain the existing protocols and other network parameter rather than costly efforts for design and implementing new improved protocols. Motivated with the reasons to save effort of time and cost this paper presents the validation of optimized vehicular network for throughput, average delay and packet delivery ratio using Taguchi method. Highway scenario is chosen as the evaluation condition for this paper. From the performance evaluated the performance of optimized setting gives better results than non-optimized setting for both safety and non-safety applications. It is proved that Taguchi Method is applicable to optimize vehicular ad hoc network.

Maternal Coping and Depressive Symptoms as Predictors of Mother-Child Communication About a Child's Cancer.

This study sought to identify possible associations between maternal coping and depression and subsequent mother-child communication about cancer following the child's diagnosis. Mothers (N = 100) reported on coping and depressive symptoms shortly after the child's diagnosis (M = 1.9 months). Subsequently, we observed children (age 5-17 years; M = 10.2 years; 48% female; 81% White) and mothers discussing cancer and coded maternal communication. Higher primary and secondary control coping, and lower depressive symptoms, were generally correlated with more positive, and less harsh and withdrawn communication. In regression models, higher primary control coping (i.e., coping efforts to change the stressor or one's emotional reaction to the stressor) independently predicted less withdrawn communication, and depressive symptoms mediated relations between coping and harsh communication. Maternal primary control coping and depressive symptoms predict mothers' subsequent harsh and withdrawn communication about cancer.

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

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

BER performance enhancement for secure wireless optical communication systems based on chaotic MIMO techniques

There has been a growing interest in the use of chaotic techniques for enabling secure communication in recent years. This need has been motivated by the emergence of a number of wireless services which require the channel to provide low bit error rates (BER) along with information security. The aim of such activity is to steal or distort the information being conveyed. Optical Wireless Systems (basically Free Space Optic Systems, FSO) are no exception to this trend. Thus, there is an urgent necessity to design techniques that can secure privileged information against unauthorized eavesdroppers while simultaneously protecting information against channel-induced perturbations and errors. Conventional cryptographic techniques are not designed for protecting information integrity when data is being transferred over a harsh communication medium. Hence, a separate channel coding protocol is often necessary to achieve this goal. Our work indicates that the use of a suitable Chaotic Shift Keying (CSK) map combined with an appropriate Space-Time Code (STC) can allow both requirements to be met. In this paper, we have concentrated on investigating the error rate performance of chaotic-wireless optical communication links operating over atmospheric channel, where the turbulence-induced fading is described by the Gamma–Gamma and log–normal distributions. The main aim of the paper is to assess the feasibility of employing Space-Time Coded chaotic communications over Multiple Input Multiple Output (MIMO) communication channels. Our simulations indicate that the combination of the STC and tent map provides the best BER performance in addition to security when compared to the choice of other maps.

Multimedia Transmission in Multi Hop Wireless Sensor Network

Quality of Service (QoS) is a requirement for proper functioning of traditional and modern networks. Wireless Sensor Networks (WSN) is adversely affected because of mobility, harsh communication medium, and environment behavior. Quality of Service is a crucial aspect in WSN design information sent by nodes and delivered according to QoS requirements to provide outside observers accurate vision of monitored phenomena. In WSNs for effective transmission of still images, audio, and video information enforces rigorous necessities on the energy consumption and throughput. In this paper, it is proposed to investigate the performance of routing traffic for multimedia traffic in WSN for multihop nodes from the sink.

Differentiated service strategies for ad-hoc wireless sensor networks in harsh communication environments

In some wireless sensor network applications, sensor nodes will be deployed in harsh communication environments. In such environments, the deployment may not be adequately controlled, and nodes may have to communicate with a single destination node. For nodes to alert the destination on critical data that has been sensed, in addition to the harsh communication environment, contention resulting from both the deployment and network density must be appropriately overcome. In this paper, we create theoretical models for the behavior of Timeout-MAC (T-MAC) protocol, and evaluate five possible solutions, each designed to be easy to implement on a device by simply tuning T-MAC parameters, so as to overcome these environment-specific issues and effectively alert the destination to critical data. Our results indicate that slight changes to the behavior of the network can improve the awareness of the destination to critical regions in the environment, and that these changes have different levels of effectiveness at different network densities.

Vehicle Platoon Control in High-Latency Wireless Communications Environment

Recent developments in vehicle onboard computers and vehicle-to-vehicle communications technology allow automatic control of vehicles and the organization of vehicles into platoons with short intraplatoon distances. One of the major issues with platoon control is latency in wireless communications. Latency has a negative impact on safety and disrupts the stability of platoons. A decentralized longitudinal platoon-controlling mechanism that uses a model predictive control approach to control vehicles safely, even in harsh communications environments, is proposed. The sensitivity of this method was analyzed to derive the conditions for this method to work safely. A simulation test bed for this control method was implemented to test effectiveness and safety under two communications latency settings. The results showed that the model predictive control method could safely control the platoon even in harsh communications environments.

On the reliability and performance of real-time one-hop broadcast MANETs

Recently, broadcast communications in mobile ad hoc networks (MANETs) have been deployed in many mission-critical applications. So far, most investigations of such broadcast networks focus on multi-hop connectivity taking all one-hop links for granted. In this paper, the reliability and performance of real-time one-hop broadcast services in IEEE 802.11 based MANETs are investigated analytically and by simulation. Having specified possible applications and the features of IEEE 802.11 broadcast communication in dynamically self-organized networks under harsh communication environment, analyses are conducted to derive closed form expressions of the reliability and performance indices for both one-dimensional (1-D) and two-dimensional (2-D) broadcast MANETs: packet reception rate (PRR) and packet transmission delay. The proposed analytical models account for the impact of broadcast hidden terminal problem, message arrival interval, backoff counter process, space distributions of nodes, and fading transmission channel on the reliability and performance of the broadcast MANETs. As an example, the proposed models are applied to the evaluation of safety-related inter-vehicle communication on a highway. From the obtained numerical results under various offered traffic and network parameters, new observations and effective enhancement suggestions are given.

An experimental investigation of the dilemma of delivering bad news

Objective This randomly controlled experiment tested a theory of how experienced physicians solve the dilemma of communicating bad news by using implicit language. Methods 8 physicians delivered both bad and good news to 16 analogue patients. Microanalysis of their news delivery reliably identified departures from explicit language. Results As predicted, the physicians used implicit language at a significantly higher rate when delivering bad news than good news. For bad news, they tended to use alternative terms for the diagnosis, to qualify their evaluation, to underemphasize certainty, and to subtly separate the patient from the disease. The evidence both within and after the interview indicated that recipients still understood the bad news. Conclusion (1) The skilful use of implicit language is a solution to the dilemma of honest but not harsh communication of bad news. (2) Experimental methods can complement surveys and qualitative studies for investigating bad news delivery by providing a theoretical foundation and controlled conditions. Practice implications Physicians can deliver bad news honestly without being blunt by skilfully incorporating implicit language. The theory, data, and examples presented here provide insights into the nature and functions of implicit language, from which students and practitioners can develop their individual styles.

A technique to exploit cooperation for packet retransmission in wireless ad hoc networks

In wireless data communication systems, retransmission of an erroneous packet is inevitable due to the harsh communication environment. In this paper, an efficient retransmission scheme using cooperation from neighboring nodes is investigated. In the cooperative retransmission scheme, an erroneous packet is transmitted to the destination by cooperative nodes which have favorable channels. This cooperative retransmission scheme requires no a priori information of neighboring nodes and has no limitation on the number of cooperating nodes. Distributed beamforming is used to accommodate multiple cooperating nodes. Phase and frequency offsets of cooperating signals are extracted from the NACK message and used to co-phase retransmitted data packets. The outage probability of the cooperative retransmission scheme is analyzed for the case of perfect synchronization and when the offsets are estimated. To reduce the impact of the residual phase and frequency offsets in cooperating signals, a low-rate feedback scheme is also investigated. It is shown that improved outage probability and reduced packet error rate (PER) performance can be achieved even for long data packets. The proposed cooperative retransmission scheme is found to outperform simple retransmission by the source as well as decode-and-forward cooperation.