Hamid Sharif

A Survey on Smart Grid Communication Infrastructures: Motivations, Requirements and Challenges

A communication infrastructure is an essential part to the success of the emerging smart grid. A scalable and pervasive communication infrastructure is crucial in both construction and operation of a smart grid. In this paper, we present the background and motivation of communication infrastructures in smart grid systems. We also summarize major requirements that smart grid communications must meet. From the experience of several industrial trials on smart grid with communication infrastructures, we expect that the traditional carbon fuel based power plants can cooperate with emerging distributed renewable energy such as wind, solar, etc, to reduce the carbon fuel consumption and consequent green house gas such as carbon dioxide emission. The consumers can minimize their expense on energy by adjusting their intelligent home appliance operations to avoid the peak hours and utilize the renewable energy instead. We further explore the challenges for a communication infrastructure as the part of a complex smart grid system. Since a smart grid system might have over millions of consumers and devices, the demand of its reliability and security is extremely critical. Through a communication infrastructure, a smart grid can improve power reliability and quality to eliminate electricity blackout. Security is a challenging issue since the on-going smart grid systems facing increasing vulnerabilities as more and more automation, remote monitoring/controlling and supervision entities are interconnected.

A Survey on Cyber Security for Smart Grid Communications

A smart grid is a new form of electricity network with high fidelity power-flow control, self-healing, and energy reliability and energy security using digital communications and control technology. To upgrade an existing power grid into a smart grid, it requires significant dependence on intelligent and secure communication infrastructures. It requires security frameworks for distributed communications, pervasive computing and sensing technologies in smart grid. However, as many of the communication technologies currently recommended to use by a smart grid is vulnerable in cyber security, it could lead to unreliable system operations, causing unnecessary expenditure, even consequential disaster to both utilities and consumers. In this paper, we summarize the cyber security requirements and the possible vulnerabilities in smart grid communications and survey the current solutions on cyber security for smart grid communications.

Adaptive radio channel allocation for supporting coexistence of 802.15.4 and 802.11b

As the explosive growth of the ISM band usage continues, there are many scenarios where different systems operate in the same place at the same time. One of growing concerns is the coexistence of wireless systems [18]. For the successful deployment of mission-critical systems such as wireless sensor networks, it is required to provide a solution for the coexistence. In this paper, we propose a new scheme using multiple radio channels for the coexistence of 802.15.4 LRWPAN and 802.11b WLAN. To evaluate the effectiveness of the proposed scheme, measurement and simulation study are conducted. The simulation results show that the proposed scheme is effective in performance improvement for multi-hop largescale network of 802.15.4. Keywords-component; coexistence; interference; ISM band; 802.15.4; 802.11b

Modeling Discharge Behavior of Multicell Battery

Multicell battery has been widely used in various electrical and electronics devices. To achieve the optimal multicell battery design, accurately modeling battery discharge behavior of multicell battery is crucial. However, modeling discharge behavior of multicell battery is very challenging due to the nonlinear battery effects, nonuniform cell quality, and various cell connections. In this paper, we develop a circuit-based multicell battery model to accurately model the multicell battery discharge behavior in terms of available capacity, output voltage, and internal resistance with consideration of nonlinear battery effect and nonuniform cell quality. It also characterizes the cell discharge current distribution of cell strings in parallel connection. The proposed multicell battery model has been validated by extensive simulation and experimental results under various load conditions.

A Novel Adaptive Distributed Cooperative Relaying MAC Protocol for Vehicular Networks

Explosive growth in Information Technology has enabled many innovative application areas such as large-scale outdoor vehicular networks for vehicle-to-vehicle communications. By providing time-sensitive and location-aware information, vehicular networks can contribute to a safer and more efficient driving experience. However, the performance of vehicular networks requires robust and real-time data communications and is impacted by high mobility, intermittent connectivity, and unreliability of the wireless channel. In this paper, a novel adaptive distributed cooperative medium access control (ADC-MAC) protocol is proposed in order to address the inherent problems in the IEEE 802.11 standard when employed in vehicular networks. ADC-MAC exploits spatial diversities to maximize the system throughput as well as the service range of vehicular networks. This is accomplished through adaptively selecting the most suitable helper and transmission mode for transmit/receive pairs among direct transmission (DT), cooperative relay (CR) transmission and two-hop relay (TR) transmission, in accordance with the channel quality and the positioning of relay nodes. Both our Markov Chain modeling based theoretical analysis and ns-2 simulation experiments show that our ADC-MAC protocol outperforms existing schemes under the same network scenarios and maximizes the achieved system throughput and service distance.

A Survey of Energy-Efficient Compression and Communication Techniques for Multimedia in Resource Constrained Systems

Advances in wireless multimedia communication technologies enable new types of pervasive and ubiquitous applications such as mobile health care, environmental monitoring, facility monitoring and traffic surveillance. Among different factors concerned, energy efficiency is one of the most challenging issues in multimedia communication due to the resource constraints, and the requirements for high bandwidth and low transmission delay. In this survey, we provide a broad picture of the state-of-the-art energy efficient techniques that have been proposed in wireless multimedia communication for resource-constrained systems such as wireless sensor networks and mobile devices. Following the essential stages required for multimedia communication, we categorize these techniques into two groups: multimedia compression techniques and multimedia transmission techniques. In the first group, we introduce the state-of-the-art compression algorithms and perform analyses and evaluations on energy efficiency in applying these compression algorithms to resource-constrained multimedia transmission systems. In the second group, we will further categorize the energy efficient transmission techniques into two sub-categories according to their different communication architectures. We review both cross-layer communication, including Unequal Error Protection (UEP), and independent-layer communication, focusing on Routing, MAC, and Physical layer protocols. We present the basic problem statement and objectives of these techniques, and survey multiple potential approaches that have been reported in the literature. Our focus in this survey is to provide insight into different research directions to improve energy efficiency in wireless multimedia communication protocols for future developments.

An enhanced circuit-based model for single-cell battery

Battery performance prediction is crucial for battery-aware power management, battery maintenance, and multi-cell battery design. However, the existing battery models cannot capture the circuit characteristics and nonlinear battery effects, especially recovery effect. This paper aims to fill this gap by developing an enhanced circuit-based model for single-cell battery. The proposed model is validated by comparing simulation results with experimental data collected through battery testbed. The comparison shows that the proposed model can accurately characterize and predict the single-cell battery performance with considerations of various nonlinear battery effects under both constant and variable loads.

A secure and reliable in-network collaborative communication scheme for advanced metering infrastructure in smart grid

We consider various security vulnerabilities of deploying Advanced Metering Infrastructure (AMI) in smart grid, and explore the issues related to confidentiality for customer privacy and customer behavior as well as message authentication for meter reading and control messages. There are only a very few research work on AMI authentications, and no work exists on confidentiality for user privacy and user behavior, from the best of our knowledge. In this paper, we propose an in-network collaborative scheme to provide secure and reliable AMI communications in smart grid, with smart meters interconnected through a multihop wireless network. In this approach, an AMI system can provide trust services, data privacy and integrity by mutual authentications whenever a new smart meter initiates and joins the smart grid AMI network. Data integrity and confidentiality are fulfilled through message authentication and encryption services respectively using the corresponding keys established in the mutual authentications. A transmission scheme is proposed to facilitate the data collection and management message delivery between smart meters and a local collector for AMI communications. Simulation results show that the proposed method has a better end-to-end delay and packet losses comparing with a basic security method, and the proposed method can provide secure and reliable communications for AMI in smart grid systems.

Survey and evaluation of real-time fall detection approaches

As we grow old, our desire for independence does not diminish; yet our health increasingly needs to be monitored. Injuries such as falling can be a serious problem for the elderly. If a person falls and is not able to get assistance within an hour, casualties arising from that fall can result in fatalities as early as 6 months later [1]. It would seem then that a choice between safety and independence must be made. Fortunately, as health care technology advances, simple devices can be made to detect or even predict falls in the elderly, which could easily save lives without too much intrusion on their independence. Much research has been done on the topic of fall detection and fall prediction. Some have attempted to detect falls using a variety of sensors such as: cameras, accelerometers, gyroscopes, microphones, or a combination of the like. This paper is aimed at reporting which existing methods have been found effective by others, as well as documenting the findings of our own experiments. The combination of which will assist in the progression towards a safe, unobtrusive monitoring system for independent seniors.

Energy-Constrained Distortion Reduction Optimization for Wavelet-Based Coded Image Transmission in Wireless Sensor Networks

Image transmissions in wireless multimedia sensor networks (WMSNs) are often energy constrained. They also have requirement on distortion minimization, which may be achieved through unequal error protection (UEP) based communication approaches. In related literature with regard to wireless multimedia transmissions, significantly different importance levels between image-pixel-position information and image-pixel-value information have not been fully exploited by existing UEP schemes. In this paper, we propose an innovative image-pixel-position information based resource allocation scheme to optimize image transmission quality with strict energy budget constraint for image applications in WMSNs, and it works by exploring these uniquely different importance levels among image data streams. Network resources are optimally allocated cross PHY, MAC and APP layers regarding inter-segment dependency, and energy efficiency is assured while the image transmission quality is optimized. Simulation results have demonstrated the effectiveness of the proposed approach in achieving the optimal image quality and energy efficiency. The performance gain in terms of distortion reduction is especially prominent with strict energy budget constraints and lower image compression ratios.