Quang-Dung Ho

Challenges and research opportunities in wireless communication networks for smart grid

This article begins with a comprehensive presentation of architecture and essential characteristics of a smart grid communication network (SGCN). Then different types of traffic that an SGCN is anticipated to carry are studied along with their QoS requirements. Subsequently, a number of critical challenges from the wireless technology and networking perspectives are addressed. They include wireless mesh routing and QoS provisioning to efficiently support realtime and non-real-time traffic, intelligent data filtering, and fusion to reduce redundancy and minimize network traffic while ensuring information integrity, optimal network design, and, finally, security concerns.

A Wireless Sensor Network Testbed

Key design requirements for wireless sensor network (WSN) applications revolve around long battery life, low cost, small footprint and mesh-networking in supporting communication between large numbers of devices in an interoperable and multi-application environment. This paper presents a WSN testbed that aims to facilitate the developments and experiments of different routing algorithms. Numerous adaptive routing algorithms are implemented to offer self-healing capability for a wide range of WSN applications. Senor nodes in the network can connect together and to sensor gateways in star, mesh, and hybrid topologies. When any sensor node fails due to battery drain, physical destruction, hardware and/or software issues, etc, the network will dynamically route active connections around isolated network segments in order to minimize service interruption.

Opportunistic Multicast Scheduling with Erasure-Correction Coding over Wireless Channels

This paper proposes an opportunistic multicast scheduling scheme using erasure-correction coding to jointly explore the multicast gain and multiuser diversity. The proposed scheme sends only one copy to all users in the multicast group at a transmission rate based on a SNR threshold selected using only the knowledge of the average SNR and fading type of the fading environment. Analytical framework is developed to establish the optimum selection of the SNR threshold and coding rate for given channel conditions in a Nakagami-m fading environment to achieve the best throughput. Numerical results show that the proposed scheme outperforms both the worst-user (WU) and best-user (BU) schemes for a wide range of average SNR and multicast group size. Without the needs of perfect knowledge of the instantaneous channel responses of the user links, the proposed scheme can significantly reduce the overhead required for channel information feedback and is suitable for a fast time-varying fading environment. Another advantage of the proposed scheme is that its achievable normalized throughput is independent of the multicast group size.

Quality of service differentiation for smart grid neighbor area networks through multiple RPL instances

The Smart Grid (SG) optimizes the existing power grid with a reliable and secure SG Communications Network. For uplink data traffic, the Neighbor Area Network (NAN) segments size and converge-cast traffic can be addressed with the Routing Protocol for Low Power and Lossy Networks (RPL). Additionally, a broad range of SG applications, such as monitoring, control and automation applications, have been proposed in order to achieve the anticipated SG goals. These applications, each possessing different Quality of Service (QoS) requirements such as bandwidth, latency, reliability and security, will require traffic prioritization and differentiation. Generally, QoS is addressed through queue scheduling mechanisms or prioritized channel access at the Medium Access Control (MAC) layer. In this paper, extensions to the standard MAC level QoS techniques are explored with an emphasis on network layer QoS mechanisms. Specifically, the effectiveness of multiple instances of the RPL network graph, built upon differing objective functions, for QoS differentiation is investigated. To that effect, three variants of RPL, standard RPL, multi-instance RPL (RPL-M) and multi-instance RPL with prioritized channel backoffs (RPL-M+) along with two distinct traffic classes have been examined as data traffic rate and composition was varied.

Evaluation of an efficient Smart Grid communication system at the neighbor area level

The successful implementation of Smart Grid (SG) requires an efficient communication infrastructure that is cost-effective, scalable and fault-tolerant. This paper aims to study and develop relevant networking techniques for an efficient and reliable SG Communication Network (SGCN). In particular, we propose a viable communication architecture for the interconnection of different radio access technologies along the separate segments of the SGCN. Specifically, WiFi mesh network at the Neighbor Area Network (NAN) level with LTE at the Wide Area Network (WAN) level. Based on this architecture, the performance, transmission latency and Packet Delivery Ratio (PDR), of geographic routing in the NAN segment is considered. Specifically, the scaling of system performance when per-smart-meter data rate, channel shadowing level and the number of smart meters per collector increases is investigated. The results presented in this study can then serve as important guidelines for the design and development of relevant communication infrastructures for SGs.

Performance and applicability of candidate routing protocols for smart grid's wireless mesh neighbor area networks

Neighbor area network (NAN) is one of the most important segments of smart grid communications network (SGCN) since it is responsible for the information exchanges between the utility and a large number of smart meters (SMs) in order to enable various important smart grid (SG) applications. Greedy perimeter stateless routing (GPSR) and the routing protocol for low-power and lossy networks (RPL) have been considered as the most promising layer-3 protocols for wireless mesh NANs. This paper compares the system performance and investigates the applicability of these two protocols in practical NAN scenarios. Specifically, transmission reliability, latency and routing path details of GPSR and RPL are studied by extensive simulations. The advantages and disadvantages of each protocol with respect to the characteristics and required features of NAN are discussed in details. The effects of wireless channel characteristics and network offered load levels are also investigated.

Attainable throughput, delay and scalability for geographic routing on Smart Grid neighbor area networks

Challenges of the existing power grid demand the integration of information and communication technologies into the next-generation electric grid, namely the Smart Grid (SG). This paper focuses on the critical communications segment corresponding to the consumer-premise, the Neighbor Area Network (NAN). For this segment, Greedy Perimeter Stateless Routing (GPSR) protocol is considered for its low complexity and high scalability. In order to provide guidelines for SG communications system designers and network engineers, the performance of GPSR in terms of throughput, latency and scalability is investigated with parametric sweeps of transmission range, data rate and the number of Smart Meters (SMs) per Data Aggregation Point (DAP). The simulation results show that network throughput of hundreds of times the rate required for basic SG applications (e.g., meter reading, service switch, ...) can be achieved while the end-to-end delay can always be maintained below 100 ms. However, the converge-cast nature of the uplink traffic severely limits the SM-to-DAP ratio. Thus, with GPSR at the NAN level, emerging SG applications such as smart metering, real-time pricing, demand response, etc., can be supported.

Challenges of Power Line Communications for Advanced Distribution Automation in Smart Grid

Advanced Distribution Automation (ADA) is one of the key applications of the Smart Grid. Since Power Line Communications (PLC) can offer a cost-effective communication infrastructure supporting data acquisition and automation and IEC 61850 can provide interoperability of all power grid monitoring and control devices, they have appeared to be promising for ADA. However, the applicability of PLC for ADA needs to be investigated carefully since this technology still exhibits some limitations related to data rate, reliability, etc., in ADA scenario. When estimating the bandwidth requirement for ADA applications, previous works tend to make over-simplified assumptions on the numbers of involved communications devices as well as the sizes and the exchange rates of messages generated by those devices. This paper therefore attempts to give a more reasonable bandwidth estimation by incorporating insightful understandings of data modeling and communication services standardized by IEC 61850 together with knowledge on practical power grid infrastructure. The estimation is then used to identify the potential challenges for PLC to support ADA applications.

Wireless Communications Networks for the Smart Grid

This brief presents a comprehensive review of the network architecture and communication technologies of the smart grid communication network (SGCN). It then studies the strengths, weaknesses and applications of two promising wireless mesh routing protocols that could be used to implement the SGCN. Packet transmission reliability, latency and robustness of these two protocols are evaluated and compared by simulations in various practical SGCN scenarios. Finally, technical challenges and open research opportunities of the SGCN are addressed. Wireless Communications Networks for Smart Grid provides communication network architects and engineers with valuable proven suggestions to successfully implement the SGCN. Advanced-level students studying computer science or electrical engineering will also find the content helpful.

Random Linear Network Coding for converge-cast Smart Grid wireless networks

The power electric grid is undergoing a paradigm shift with the inclusion of information and communication technologies that allow for two-way flow of information, automation and distributed intelligence. A reliable and secure Smart-Grid Communications Network (SGCN), is necessary to achieve the SG goals. In particular, the SG Neighbor Area Network (NAN) poses a communications challenge due to the bottlenecks associated with the converge-cast nature of uplink traffic. This can potentially be addressed through network coding. Therefore, this paper aims to determine the feasibility of Random Linear Network Coding (RLNC) at the SG NAN level. Specifically, RLNC is considered in converge-cast scenarios while both network size and link reliability are varied. This preliminary study suggests that inter-session RLNC does achieve throughput enhancements but at the cost of higher network load. Additionally, performance drops sharply with low link reliabilities due to the lack of partial decoding. Therefore, for large converge-cast networks, as in the case of the SG NAN, network coding that allows for partial decoding operations should be more beneficial.