Nasim Arianpoo

A survey on security issues in smart grids

A key feature of the smart grid is the introduction of two-way data communications into the power grid. This brings many security challenges, because of the large-scale, difficult-to-secure environment, complexity of smart grid systems, and resource limitations of the smart grid deployments. In this paper, we focus on security and privacy concerns in the context of the smart grid. Existing security mechanisms developed for traditional information technology systems can be used as a basis for designing security measures for the smart grid. However, new methods that meet the special requirements and characteristics of the smart grid are also required. In spite of the obstacles against developing detailed security solutions for the future smart grid, such as uncertainty of the architecture and lack of practical experiences with security attacks, some research has been performed in this area over the last few years. We survey the existing literature on different security aspects of the smart grid and provide directions for further research. Copyright

Intrusion detection in advanced metering infrastructure based on consumption pattern

In this paper, we present a novel approach for detecting intrusions in the advanced metering infrastructure (AMI). Unlike traditional intrusion detection systems that use the network features and system behavior for attack detection, we leverage the predictability property of the AMI data. Electricity usage reports and pricing information constitute the major parts of the data traffic in AMI. Considering that electricity consumption patterns of customers follow a statistical model, which is a function of time and price, we introduce long-term anomaly detection and instantaneous anomaly detection of consumption patterns to detect adversarial activities in AMI with long term and short term effects, respectively. The feasibility and efficiency of the proposed approach in detecting various types of adversarial activities against AMI is demonstrated through simulations.

Analysis of Distributed Reservation Protocol for UWB-Based WPANs with ECMA-368 MAC

The recent ECMA-368 standard specifies the use of ultra wideband (UWB) technology for high rate communications in wireless personal area networks (WPANs). This paper proposes an analytical model for the performance analysis of the medium access control (MAC) protocol standardized in ECMA-368. The MAC protocol uses a superframe structure. Each superframe has a beacon period, a distributed reservation protocol (DRP) period, and a prioritized contention access (PCA) period. By using the Markovian arrival process (MAP) and phase type distribution (PH), we model this MAC layer as a MAP/PH/1 queueing system, and focus our study on the performance of the DRP period in this paper. The probability mass function of the number of DRP packets in the system, as well the cumulative distribution of the DRP packets waiting time are derived and compared with the simulation results in OPNET.

Spoofing detection in IEEE 802.15.4 networks based on received signal strength

The shared medium used in wireless networks makes them vulnerable to spoofing attacks, in which an adversary masquerades as one or more legitimate nodes to disturb normal operation of the network. In this paper we present a novel spoofing detection method for static IEEE 802.15.4 networks based on spatial correlation property of received signal strength (RSS). While most existing RSS based techniques directly process RSS values of the received frames and rely on multiple traffic air monitors (AMs) to provide an acceptable detection performance, we extract features of RSS streams to reduce data redundancy and provide a more distinguishable representation of the data. Our algorithm employs two features of RSS streams, summation of detailed coefficients (SDCs) in discrete Haar wavelet transform (DHWT) of the RSS streams and the ratio of out-of-bound frames. We show that in a typical scenario, a single AM with SDC as detection parameter, can theoretically outperform a system with 12 AMs which directly applies RSS values as detection parameter. Using ratio of out-of-bound frames facilitates detection of high rate attacks. In addition, we suggest adaptive learning of legitimate RSS values which enhances the robustness of the attack detector against environmental changes. Using both magnitude and frequency related features, we achieved high detection performance with a single AM; this enables development of preventive measures for spoofing attacks. The performance of our approach was evaluated through an IEEE 802.15.4 testbed in an office environment. Experimental results along with theoretical analysis show that the proposed method outperforms the existing RSS-based spoofing detection solutions. Using a single AM, we were able to attain 94.75% detection rate (DR) with 0.56% false positive rate (FPR). For 4 AMs, the results improved to 99% DR and 0% FPR.

Spoofing prevention using received signal strength for ZigBee-based home area networks

In this paper we present a novel spoofing prevention system (SPS) for ZigBee based home area networks (HANs) within smart grids. The proposed SPS uses the spatial correlation of received signal strength (RSS) in order to detect attacks and filter malicious frames. The SPS consists of a spoofing detection module which is installed on the security center in the HAN, as well as spoofing prevention agents installed on network nodes. Once an attack is detected, the agents differentiate and filter malicious frames by analyzing the RSS values of received frames. Two methods are introduced and investigated for attack prevention, static threshold and dynamic threshold. The former has very low computational requirements, yet due to high false positive rate introduces some network overhead during the attack. The latter needs more computations; however, it has a higher performance and a very low network overhead. The soundness of the proposed method is proved through both theoretical analysis, as well as experiments.

Network coding: A remedy for receiver buffer blocking in the concurrent multipath transfer of data over multi-hop wireless networks

Multi-homed wireless devices equipped with multiple network interfaces that support the Concurrent Multipath Transfer (CMT) of data are an inevitable part of future wireless networks. The Stream Control Transmission Protocol (SCTP) is a multi-homed transport layer protocol that can support CMT. However, the receiver buffer blocking issue causes throughput degradation and prevents CMT from realizing its vast potential over multi-hop wireless networks. This paper is focused on integrating network coding with SCTP-based CMT to resolve the receiver buffer blocking problem. We propose an adaptive network coding mechanism for SCTP-CMT to desensitize the receiver against packet reordering and consequently eliminate the receiver buffer blocking problem. Our state-of-the-art network coding scheme uses a Q-learning algorithm to control the number of redundant packets based on the network dynamics. The effectiveness and soundness of the proposed scheme is demonstrated through simulations and proved to outperform original SCTP-CMT up to a factor of 62% in the presence of severe path dissimilarities and limited receiver buffer. Our proposed scheme is one step forward towards future multi-homed devices over multi-hop wireless networks.

Enhancing TCP performance in wireless mesh networks by cross layer design

Wireless mesh network (WMN) is an emerging technology for last-mile broadband Internet access. Despite extensive research on and even commercial implementations of WMNs, there are still some serious performance issues in the transport layer, where the performance of Transmission Control Protocol (TCP) degrades dramatically as the number of hops increases. Improving TCP performance over WMNs is a research area that has attracted a lot of attention in recent years and the focus of this paper. We take a cross-layer design approach to improve the performance of TCP for nodes farther from the Internet gateways by giving a higher priority to the packets that have traversed a larger number of hops over the WMN. The proposal changes the way that routing and scheduling algorithms work together and can be easily implemented in IEEE 802.16d WMNs. Extensive simulation results show that the proposed method successfully improve the TCP throughput by as much as three times over a small number of hops, whereas TCP generally performs poorly when the number of hops is large.

A smart fairness mechanism for Concurrent multipath transfer in SCTP over wireless multi-hop networks

The emerging use of multihomed devices in wireless multi-hop networks has increased the demand for multipath transport protocols, such as Concurrent multipath transfer in Stream control transmission protocol (CMT-SCTP). The fairness of CMT-SCTP over wireless multi-hop settings is a critical issue since it can harm the performance of the existing legacy protocols such as Transmission control protocol (TCP) and single-homed SCTP. As such, in this paper, we study the fairness behavior of CMT-SCTP on a multi-hop wireless testbed. The investigation reveals that CMT-SCTP is significantly unfair towards flows coming from farther away hops. Consequently, we introduce a distributed Q-learning mechanism to enhance the fairness of CMT-SCTP association towards other flows. The proposed method uses Reinforcement learning (RL) to acquire knowledge about network dynamics. The acquired knowledge is used to choose the best action to improve the fairness index of the network. We compare our proposal with standard CMT-SCTP and Resource pool CMT-SCTP (CMT/RP-SCTP). Extensive experimentation confirms that our proposal significantly outperforms the available fairness mechanisms for CMT-SCTP.

Network Coding as a Performance Booster for Concurrent Multi-Path Transfer of Data in Multi-Hop Wireless Networks

The emerging use of multi-homed wireless devices along with simultaneous multi-path data transfer offers tremendous potentials to improve the capacity of multi-hop wireless networks. The use of simultaneous data transfer over separate disjoint paths in multi-hop wireless networks to increase network capacity is a less explored subject, mainly because of the challenges it triggers for the reliable transport layer protocols. Reliable transport layer protocols generally use packet sequence number as a mean to ensure delivery. As such, the out-of-order packet arrival in reliable transport layer protocols triggers receiver buffer blocking that causes throughput degradation and prevents the reliable multi-path transport layer protocol to realize its vast potential. This paper focuses on integrating network coding with a reliable multi-path transport layer protocol to resolve the receiver buffer blocking problem. We propose an adaptive network coding mechanism to desensitize the receiver against packet reordering and consequently eliminate the receiver buffer blocking problem. Our state-of-the-art network coding scheme uses a combination of Q-learning and logistic regression for rare data events to control the number of redundant packets based on the network dynamics. We confirmed the veracity of our proposed scheme by a queuing theory based mathematical model. Moreover, the effectiveness of the proposed scheme is demonstrated through simulations and testbed experiments.

Applications of network coding to improve TCP performance over wireless mesh networks: a survey

There is growing interest in the use of wireless mesh network WMN as a last-mile option for Internet access. Despite the many benefits of WMNs, the performance of Internet access may not be ideal. One of the main issues is the interaction of transmission control protocol TCP with the underlying network. The poor performance of TCP over multi-hop networks is well-documented, and extensive research exists, which addresses TCPs foible and enhance TCP performance for multi-hop environments. This paper provides a thorough survey of TCP performance issues over WMNs and the available solutions to address these issues. Among the existing methods, we focused on network coding NC and the ways that TCP interacts with network coded systems. NC is a technique that encodes the received packets in each node before forwarding them towards the destination. The use of NC in the transport layer to address performance issues raised by wireless access is a recent research topic. This paper presents a detailed study of TCP interaction with NC. Some open research areas in this field are suggested. Copyright