Parag S. Mogre

Survey on Wireless Sensor Network Technologies for Industrial Automation: The Security and Quality of Service Perspectives

Wireless Sensor Networks (WSNs) are gradually adopted in the industrial world due to their advantages over wired networks. In addition to saving cabling costs, WSNs widen the realm of environments feasible for monitoring. They thus add sensing and acting capabilities to objects in the physical world and allow for communication among these objects or with services in the future Internet. However, the acceptance of WSNs by the industrial automation community is impeded by open issues, such as security guarantees and provision of Quality of Service (QoS). To examine both of these perspectives, we select and survey relevant WSN technologies dedicated to industrial automation. We determine QoS requirements and carry out a threat analysis, which act as basis of our evaluation of the current state-of-the-art. According to the results of this evaluation, we identify and discuss open research issues.

AntSec, WatchAnt, and AntRep: Innovative Security Mechanisms for Wireless Mesh Networks

Wireless mesh networks (WMNs) build on user nodes to form the networks routing infrastructure. In particular, the correct forwarding behaviour of each intermediate node on a multihop path from a source node to a destination node is crucial for the functioning of the mesh network. However, current secure routing solutions and misbehaviour detection mechanisms are not sufficient and are mostly inapplicable in mesh networks based on state-of-the-art wireless technology. In particular, hop- by-hop per-link encryption mechanisms break solutions that are based on the overhearing of the wireless channel, which leads to severe problems in the presence of misbehaving nodes. We present AntSec, WatchAnt, and AntRep, which together address the above security gap. AntSec guarantees integrity and authenticity of routing messages, WatchAnt detects misbehaviour in forwarding data messages as well as routing messages and in addition is able to cope with per-link encryption at the MAC layer. AntRep is a reputation management system and helps take punitive action against misbehaving nodes. AntSec, WatchAnt, and AntRep are well suited for WMNs with a quasi-static network topology. Through a thorough evaluation we show the improved routing performance of AntSec working together with WatchAnt and AntRep.

A survey on real world and emulation testbeds for mobile ad hoc networks

Mobile ad hoc networks allow for the spontaneous formation of communication networks without dedicated infrastructure. Ad hoc networks are not yet ready for large-scale deployment, because several unsolved research challenges persist. Evaluation methods such as analytical modeling, simulation, emulation, and real world experiments aid in addressing these challenges. There is a strong need for tools to support the task of modeling and evaluation to allow for protocol validation, performance analysis, or proof-of-concept implementations. The choosing of appropriate tools is a time-consuming process, which is often unnecessarily repeated, due to limited knowledge-transfer. We contribute an extensive survey covering real world and emulation testbeds to simplify the choice of appropriate research tools and methodologies in the domain of mobile ad hoc networks. In particular, we identify the key attributes of the aforementioned classes of testbeds and thoroughly discuss the state-of-the-art in literature to form a comprehensive classification of available testbeds

Performance Analysis of the Real-time Capabilities of Coordinated Centralized Scheduling in 802.16 Mesh Mode

The IEEE 802.16-2004 standard specifies wireless broadband networks with optional support for multi-hop mesh operation (mesh mode). The provision and support of high-quality real-time services such as voice over IP is crucial, if wireless networks based on the IEEE 802.16-2004 standard are to challenge wired network services. In this paper we investigate and identify critical factors in enabling real-time services in 802.16 based networks operating in the mesh mode. We present an analytical performance analysis and a simulation study investigating the coordinated centralized scheduling mechanism as specified in the 802.16-2004 standard. Our results show that the scalability and efficiency of such mesh networks with respect to real-time services are at stake. Our results, moreover, aid in the adjustment of critical system parameters allowing for optimized network performance

SmartMeter.KOM: A low-cost wireless sensor for distributed power metering

Most current smart metering solutions aim at increasing user awareness for their households electrical energy consumption. Although some smart meters make use of wireless data transfers between their sensor and display units, their integration into existing wireless sensor networks is hampered by proprietary communication interfaces and their lack of re-programmability. Furthermore, the sole availability of aggregate consumption values renders current meters insufficient for novel application scenarios like smart home automation, for which information at device-level granularity and high resolution is vital. We address these shortcomings of existing solutions by presenting SmartMeter.KOM, our wireless sensor node capable of determining the current consumption of individual electrical appliances at high resolution. The platform is based on low-power hardware and incorporates a reprogrammable microcontroller which allows developers to easily deploy new algorithms. Its IEEE 802.15.4-compliant radio transceiver makes its integration with existing sensor networks possible, and thus enables their integration in smart buildings. We demonstrate the versatility of SmartMeter.KOM by presenting prototypical implementations of smart applications and identifying further research directions.

A security framework for wireless mesh networks

The class of Wireless Mesh Networks (WMN) supports an ample set of applications including wireless community networks, radio access networks in rural or metropolitan areas, or wireless backbones for factory/process automation. Guaranteeing security is crucial for within these application scenarios. While contemporary wireless technologies, such as the IEEE 802.16 or the IEEE 802.11s standard, provide the basic protocol mechanisms for mesh networking, they lack in comprehensive security mechanisms. Additionally, novel security features of the above standards such as per-link encryption break existing security solutions that rely on overhearing of the wireless channel. We close this gap by developing a holistic approach toward securing WMNs with particular focus on the network layer. We perform a threat analysis and then develop solutions (1) guaranteeing the integrity and authenticity of routing messages, (2) to locally and globally detect misbehavior of nodes in forwarding data or routing messages even for settings that do not allow for overhearing the channel, and (3) to dynamically manage reputation of nodes throughout the network. The combination of these building blocks enables to provide for secure, self-organizing WMNs. As a proof-of-concept, we tailor and implement our solutions for the setting of a realistic IEEE 802.16 mesh network; we discuss the protection achieved and assess selected performance trade-offs for the developed mechanisms. Copyright

Detection of Colluding Misbehaving Nodes in Mobile Ad Hoc and Wireless Mesh Networks

Ubiquitous network connectivity and mobile communications have recently attracted remarkable attention. Wireless multihop networks such as Mobile Ad hoc Networks or Wireless Mesh Networks have been proposed to cater to the arising needs. Various security challenges persist, esp. because these networks build on the premise of node cooperation. Secure routing protocols and mechanisms to detect routing misbehavior in the direct neighborhood exist; however, collusion of misbehaving nodes has not been adequately addressed yet. We present LeakDetector, a mechanism to detect colluding malicious nodes in wireless multihop networks. In combination with proactive secure multipath routing algorithms, LeakDetector enables the calculation of the packet-loss ratio for the individual nodes. We perform an experimental analysis, which shows the excellent detection quality of LeakDetector.

Trimming the tree: tailoring adaptive huffman coding to wireless sensor networks

Nodes in wireless sensor networks are generally designed to operate on a limited energy budget, and must consciously use the available charge to allow for long lifetimes. As the radio transceiver is the predominant power consumer on current node platforms, the minimization of its activity periods and efficient use of the radio channel are major targets for optimization. Data compression is a viable option to increase the packet information density, resulting in reduced transmission durations and thus allowing for an optimized channel utilization. The computational and memory demands of many current compression algorithms however hamper their applicability on sensor nodes. In this paper, we present a novel variant of the adaptive Huffman coding algorithm, operating on reduced code table sizes and thus significantly alleviating the resource demands for storing and updating the code table during runtime. An implementation for tmote sky hardware proves its adequacy to the capabilities of sensor nodes, and we present its achievable compression gains and energy requirements in both simulation and real world experiments. Results anticipate that overall energy savings can be achieved when transferring packets of reduced sizes, even when increased CPU utilization is incurred.

A new QoE model and evaluation method for broadcast audio contribution over IP

Available objective Quality of Experience (QoE) assessment methods for speech and audio quality evaluation are not directly usable for quality rating of professional broadband audio communication applications over IP such as audio contribution links for broadcasting. To fill this gap, we designed a dedicated non-intrusive parametric QoE model for conversational quality rating based on the E-model approach. With this the QoE of Audio Contribution over IP (ACIP) can be monitored. Moreover, the estimated QoE scores can be used for a perceptually-driven Quality of Service (QoS) optimization for ACIP, which has different requirements and characteristics compared to Voice over IP (VoIP). In this paper, we present our ACIP QoE model and propose an objective QoE metric for assessing the listening-only quality in ACIP. The latter is used by us for intrusive QoE evaluations, which are necessary for the derivation of a parametric QoE model. Our experimental methodology is illustrated in depth and we give exemplified results. Finally, we demonstrate the application of our model in perceptually-driven QoS optimization.

Incorporating spatial reuse into algorithms for bandwidth management and scheduling in IEEE 802.16j relay networks

The IEEE 802.16 Standard recently introduced an additional relay mode of operation permitting coverage extension of the Point-to-Multipoint (PMP) based WiMAX networks. Relays can further aid in increasing the achievable data rates for Subscriber Stations (SS) in the network. Although bandwidth management and scheduling have been studied in some detail in traditional IEEE 802.16 PMP networks, the corresponding study for relay networks is far from complete. A trivial extension to the scheduling and bandwidth allocation algorithms used in the PMP mode for the relay networks leads to inefficient bandwidth utilization and allocation. Of particular interest here is the possibility of spatial reuse of allocated blocks of bandwidth which is permissible in relay networks. This paper investigates and designs bandwidth allocation and scheduling algorithms for IEEE 802.16 based relay networks, considering the support for spatial reuse to additionally improve the throughput while at the same time supporting quality of service (QoS). We research the issues which need to be considered when designing bandwidth allocation algorithms for relay networks. Finally, as a proof of concept we provide a thorough simulation study to investigate the performance of the designed algorithms. The results validate the design choices we presented, and also provide insights into areas for further research in WiMAX relay networks.