Nei Kato

Toward intelligent machine-to-machine communications in smart grid

The advanced metering infrastructure of the smart grid presents the biggest growth potential in the machine-to-machine market today. Spurred by recent advances in M2M technologies, SG smart meters are expected not to require human intervention in characterizing power requirements and energy distribution. However, there are many challenges in the design of the SG communications network whereby the electrical appliances and smart meters are able to exchange information pertaining to varying power requirements. Furthermore, different types of M2M gateways are required at different points (e.g., at home, in the building, at the neighborhood, and so forth) of the SG communication network. This article surveys a number of existing communication technologies that can be adopted for M2M communication in SG. Among these, the most reliable technology to facilitate M2M communication in the SG home area network is pointed out, and its shortcoming is also noted. Furthermore, a possible solution to deal with this shortcoming to improve SG communications scalability is also presented.

A survey of routing attacks in mobile ad hoc networks

Recently, mobile ad hoc networks became a hot research topic among researchers due to their flexibility and independence of network infrastructures, such as base stations. Due to unique characteristics, such as dynamic network topology, limited bandwidth, and limited battery power, routing in a MANET is a particularly challenging task compared to a conventional network. Early work in MANET research has mainly focused on developing an efficient routing mechanism in such a highly dynamic and resource-constrained network. At present, several efficient routing protocols have been proposed for MANET. Most of these protocols assume a trusted and cooperative environment. However, in the presence of malicious nodes, the networks are vulnerable to various kinds of attacks. In MANET, routing attacks are particularly serious. In this article, we investigate the state-of-the-art of security issues in MANET. In particular, we examine routing attacks, such as link spoofing and colluding misrelay attacks, as well as countermeasures against such attacks in existing MANET protocols.

A Lightweight Message Authentication Scheme for Smart Grid Communications

Smart grid (SG) communication has recently received significant attentions to facilitate intelligent and distributed electric power transmission systems. However, communication trust and security issues still present practical concerns to the deployment of SG. In this paper, to cope with these challenging concerns, we propose a lightweight message authentication scheme features as a basic yet crucial component for secure SG communication framework. Specifically, in the proposed scheme, the smart meters which are distributed at different hierarchical networks of the SG can first achieve mutual authentication and establish the shared session key with Diffie-Hellman exchange protocol. Then, with the shared session key between smart meters and hash-based authentication code technique, the subsequent messages can be authenticated in a lightweight way. Detailed security analysis shows that the proposed scheme can satisfy the desirable security requirements of SG communications. In addition, extensive simulations have also been conducted to demonstrate the effectiveness of the proposed scheme in terms of low latency and few signal message exchanges.

A handwritten character recognition system using directional element feature and asymmetric Mahalanobis distance

This paper presents a precise system for handwritten Chinese and Japanese character recognition. Before extracting directional element feature (DEF) from each character image, transformation based on partial inclination detection (TPID) is used to reduce undesired effects of degraded images. In the recognition process, city block distance with deviation (CBDD) and asymmetric Mahalanobis distance (AMD) are proposed for rough classification and fine classification. With this recognition system, the experimental result of the database ETL9B reaches to 99.42%.

Device-to-Device Communication in LTE-Advanced Networks: A Survey

Among the LTE-A communication techniques, Device-to-Device (D2D) communication which is defined to directly route data traffic between spatially closely located mobile user equipments (UEs), holds great promise in improving energy efficiency, throughput, delay, as well as spectrum efficiency. As a combination of ad-hoc and centralized communication mechanisms, D2D communication enables researchers to merge together the long-term development achievements in previously disjoint domains of ad-hoc networking and centralized networking. To help researchers to have a systematic understanding of the emerging D2D communication, we provide in this paper a comprehensive survey of available D2D related research works ranging from technical papers to experimental prototypes to standard activities, and outline some open research problems which deserve further studies.

Sage: a strong privacy-preserving scheme against global eavesdropping for ehealth systems

The eHealth system is envisioned as a promising approach to improving health care through information technology, where security and privacy are crucial for its success and largescale deployment. In this paper, we propose a strong privacy-preserving Scheme against Global Eavesdropping, named SAGE, for eHealth systems. The proposed SAGE can achieve not only the content oriented privacy but also the contextual privacy against a strong global adversary. Extensive analysis demonstrates the effectiveness and practicability of the proposed scheme.

On the Partially Overlapped Channel Assignment on Wireless Mesh Network Backbone: A Game Theoretic Approach

The Wireless Mesh Network (WMN) has already been recognized as a promising broadband access network technology from both academic and commercial perspective. In order to improve the performance of WMNs, extensive research efforts have been dedicated towards finding means to increase the number of simultaneous transmissions in the network while avoiding signal interference among radios. In case of WMNs based on IEEE 802.11 b/g standards, most recent research works have relied upon the usage of orthogonal channels for solving the Channel Assignment (CA) problem. In this paper, we explore the possibility of exploiting Partially Overlapped Channels (POCs) by introducing a novel game theoretic distributed CA algorithm. Our proposed algorithm outperforms both the conventional orthogonal channel approach and the recent heuristic CA algorithms using POC. The proposed algorithm is shown to achieve near-optimal performance in the average case. In addition, the upper bound Price of Anarchy for Multi-Radio Multi-Channel (MRMC) networks is derived to evaluate the effectiveness of the proposed approach.

Aeronautical ad hoc networks

There has been an enormous growth in mobile ad hoc networks (MANETs) in land based small to medium size networks with relatively strict power and resources. In this paper the concept of ad hoc networking between aircraft is introduced, which can be considered as a novel approach in increasing the data rate and practicality of future in-flight broadband Internet access. This method also reduces the Internet traffic load on satellite nodes and also propagation delay for real-time traffic transmissions, by effectively bypassing the satellite link for nonreal time data. A dynamic routing algorithm is also proposed for efficient routing in this kind of system. A new cost metric for increasing path duration is introduced to assist routing in the proposed ad hoc network

A Dynamic Anomaly Detection Scheme for AODV-Based Mobile Ad Hoc Networks

Mobile ad hoc networks (MANETs) are usually formed without any major infrastructure. As a result, they are relatively vulnerable to malicious network attacks, and therefore, security is a more significant issue than infrastructure-based wireless networks. In MANETs, it is difficult to identify malicious hosts as the topology of the network dynamically changes. A malicious host can easily interrupt a route for which it is one of the forming nodes in the communication path. In the literature, there are several proposals to detect such malicious hosts inside the network. In those methods, a baseline profile, which is defined as per static training data, is usually used to verify the identity and the topology of the network, thus preventing any malicious host from joining the network. Since the topology of a MANET dynamically changes, the mere use of a static baseline profile is not efficient. In this paper, we propose a new anomaly-detection scheme based on a dynamic learning process that allows the training data to be updated at particular time intervals. Our dynamic learning process involves calculating the projection distances based on multidimensional statistics using weighted coefficients and a forgetting curve. We use the network simulator 2 (ns-2) system to conduct the MANET simulations and consider scenarios for detecting five types of attacks. The simulation results involving two different networks in size show the effectiveness of the proposed techniques.

Device-to-device communications achieve efficient load balancing in LTE-advanced networks

In LTE-Advanced networks, besides the overall coverage provided by traditional macrocells, various classes of low-power nodes (e.g., pico eNBs, femto eNBs, and relays) can be distributed throughout the macrocells as a more targeted underlay to further enhance the areas spectral efficiency, alleviate traffic hot zones, and thus improve the end-user experience. Considering the limited backhaul connections within lowpower nodes and the imbalanced traffic distribution among different cells, it is highly possible that some cells are severely congested while adjacent cells are very lightly loaded. Therefore, it is of critical importance to achieve efficient load balancing among multi-tier cells in LTE-Advanced networks. However, available techniques such as smart cell and biasing, although able to alleviate congestion or distribute traffic to some extent, cannot respond or adapt flexibly to the real-time traffic distributions among multi-tier cells. Toward this end, we propose in this article a device-to-device communication-based load balancing algorithm, which utilizes D2D communications as bridges to flexibly offload traffic among different tier cells and achieve efficient load balancing according to their real-time traffic distributions. Besides identifying the research issues that deserve further study, we also present numerical results to show the performance gains that can be achieved by the proposed algorithm.