The Evolving Paradigm for Aerospace Sensor Networks

The collaboration between wireless sensor networks and the distributed robotics has prompted the making of mobile sensor networks. However, there has been a growing enthusiasm in developing mobile sensor networks, which are the favoured family of wireless sensor networks in which autonomous movement assumes a key part in implementing its application. By introducing mobility to nodes in wireless sensor networks, the capability and flexibility of mobile sensor networks can be enhanced to support multiple mansions, and to address the previously stated issues. The reduction in costs of mobile sensor networks and their expanding capacities makes mobile sensor networks conceivable and useful. Today, many types of research are focused on the making of mobile wireless sensor networks due to their favourable advantage and applications. Allowing the sensors to be mobile will boost the utilization of mobile wireless sensor networks beyond that of static wireless sensor networks. Sensors can be mounted on, or implanted in animals to monitor their movements for examinations, but they can also be deployed in unmanned airborne vehicles for surveillance or environmental mapping. Mobile wireless sensor networks and robotics play a crucial role if it integrated with static nodes to become a Mobile Robot, which can enhance the capabilities, and enables their new applications. Mobile robots provide a means of exploring and interacting with the environment in more dynamic and decentralised ways. In addition, this new system of networked sensors and robots allowed the development of fresh solutions to classical problems such as localization and navigation beyond that. This article presents an overview of mobile sensor network issues, sensor networks in robotics and the application of robotic sensor networks.

Although advance network planning and dense node deployment, wireless sensor networks (WSNs) may achieve the required performance, it still face the fundamental challenge of meeting stringent power and time requirements using nodes with limited sensing capacities. To better cope with the power consumption problem, mobile sensor nodes can be introduced to dynamically reconfigure the sensor network capacity in an on-demand manner. Through data gathering and relaying, mobile nodes can reduce the amount of data transmitting between the static nodes then conserve the power of these nodes to prolong the lifetime of network. In this paper we describe the DataTruck, a new open-source sensing platform specifically designed to support our experimental research in mobile sensor networks, which is used to collect or relay data from static sensors. The DataTruck node is designed around the S3C2440A ARM920T RISC microprocessor and the IEEE 802.15.4 compliant CC2431 radio from Chipcon. Mobility is enabled with an additional accessory board that allows the node to drive its 4 linear motion actuators. To reduce power consumption, a long term sleep mode is supported through different power supplying methods for main board and clock. Furthermore, we integrated a smart antenna system to gather the data from multiple static nodes concurrently which transmitting data using the same frequency of channel. The experiments show that DataTruck collects data efficiently to reduce the average data transmission delay by using SDMA technology.

Certain popular wireless sensor network applications, including disaster recovery, battlefield communication and athlete monitoring, are characterized by extensive node mobility, intermittent contact between nodes and a highly dynamic network topology. Traditional routing protocols and security schemes are designed for essentially static networks and do not perform well in this case. This has given rise to a new multi-hop routing paradigm, that of ldquomobility-assistedrdquo routing in which nodes make strategic data store-and-forward decisions on a per-hop basis. In this paper we discuss the security challenges relevant to mobility-assisted routing and propose a scheme to secure data communication between nodes in highly mobile sensor networks. Our solution utilizes symmetric-key encryption to ensure data confidentiality and varies encryption key in a verifiable, non-forgeable manner to allow easy authentication. This scheme also provides data freshness, semantic security and per-hop encryption to enable secure data aggregation. To validate our basic assumptions and fine-tune our scheme, we collect and analyze link connectivity statistics from a dynamic sensor network application, athlete monitoring during a first-division university soccer club match. We show that our scheme is well-suited for certain dynamic environments and serves as an effective first step towards securing communications for mobile sensor networks.

This paper introduces the abstraction of energy reserves for sensor networks that virtualizes energy sources. It gives each of several applications sharing a platform the illusion of having its own private energy source. Energy virtualization is the next logical step in embedded systems after visualizing communication links and CPU capacity. Energy virtualization has not been addressed in past sensor network literature because most current wireless sensor networks feature single-user applications. To amortize deployment costs, future sensor networks, deployed in remote or hard- to-access areas, will likely be leveraged by scientists from different disciplines, each having their independent application for their individual research purposes. Platforms, planned for such deployment, will befitted with the union of sensors needed, but independent applications will share the remaining resources such as in-field storage and communication bandwidth, calling for quotas and isolation mechanisms. The most expensive resource shared in sensor networks is energy. This paper provides an energy isolation mechanism, called the virtual battery, that logically divides energy among applications to provide each its private energy reserve. An application can manage its private energy independently as if it were running alone on the platform. The application is terminated when its reserve is depleted. We implement and evaluate this abstraction on MicaZ motes running LiteOS. Our results show that the virtual battery mechanism succeeds at exporting the private reserve abstraction accurately and at a low overhead.

We present a programming approach to let a multitude of simple mobile computational “particles” (i.e. sorts of tiny mobile robots) to self-organize their respective locations to assume a coherent global formation (i.e. shape). The problem has a variety of applications in mobile robotics, modular robots, sensor networks, and computational self-assembly. Here we show how the TOTA (“Tuples On The Air”) middleware can be effectively exploited to enable self-organization of spatial shapes in mobile particles with minimal capabilities. The key idea in TOTA is to rely on spatially distributed tuples, spread across the network, to drive particles' movements and activities. Several experiments are reported showing the effectiveness of the approach.

Wireless sensor networks (WSNs) present design issues and challenges in both hardware and software platform development. This paper presents the implementation of a hardware-dependent component library that extends TinyOS in order to create an abstraction layer on top of a dynamically reconfigurable hardware architecture. Such hardware architecture is based on a SPARC-compliant processor and it is the core component of a generic sensor node platform targeted for future smart sensor networks. Considered as an application programming interface (API), the components of the implemented library allow the application developer to fully exploit the functionality of the dynamically reconfigurable function unit (RFU). Besides the RFU, the library also provides an interface to other standard system peripherals such as a timer, sensor, and radio transceiver. A simple TinyOS application, which includes gathering data from an attached sensor and wirelessly communicating to other sensor nodes has been demonstrated on the prototype nodes. In addition, a software visualization tool has been developed and integrated to a commercial logic simulator in order to facilitate software debugging during the cycle-accurate simulation of the hardware architecture model, described in the VHDL.

Energy hole is inherently problematic for sensor networks because of their many-to-one architectures, and a feasible solution has not yet been discovered. This paper aims to provide a possible solution for future underwater sensor networks with the ability of depth control only depending on the buoyancy of water currents. We propose a Depth Rotation-based traffIc oFfloading sTrategy (DRIFT) to balance the traffic load over the entire network. DRIFT joint considers the network deployment and energy allocation to obtain a maximized network lifetime. We provide an approach to calculate the precise rotating scheduling cycle and energy allocation based the proposed network model. Extensive simulation shows that when a network lifetime ends, less than 0.5% of the initial energy is wasted, and the network lifetime is prolonged on average by more than a 5-fold factor.

In sensor network applications, data gathering mechanisms, which are based on multi-hop forwarding can be expensive in terms of energy. This limitation reduces the lifetime of the network and challenges the use of sensor networks for applications that demand a predefined operational lifetime. To avoid this problem, the benefits of using mobile gateway to prolong sensor life-time have been explored in the literature. However, practical considerations such as the gateway speed and route planning, sensor buffer size and data frequency generation constraints impose limits on the mobile elements. In this work, we consider the natural hybrid solution that combines the two approaches of mobile gateways and multi-hop forwarding to address more constraints for sensor applications. We provide algorithmic solutions that attempt to balance the benefits of both approaches. Based on a given predetermined time deadline, a gateway tour will be established to involve a subset of the sensors. These selected sensors will work as gathering points and will aggregate the other sensors' data. The gathering points/nodes are selected with the aim of reducing the energy expenditures due to multi-hop forwarding. Using approximation-preserving reductions, we discuss the hardness of this problem. We also present a heuristic-based solution and validate its performance through an extensive set of experiments.

It is our great pleasure to welcome you to the 3rd ACM Workshop on Security of Ad Hoc and Sensor Networks (SASN'05), held in conjunction with the 12th ACM Conference on Computer and Communications Security (CCS'05), November 7, 2005, in Alexandria, Virginia.This year we received a total of 39 submissions on various aspects of ad-hoc and sensor network security. The program committee selected 6 as regular papers that cover a variety of topics, including trust establishment in Mobile Ad-Hoc Networks (MANETs), security of vehicular ad-hoc networks, secure group communication, key pre-distribution for sensor networks, jamming attacks against sensor network MAC protocols, and defense against Denial-of-Service (DoS) attacks. This year we continue the tradition of SASN'03 and SASN'04 to encourage the presentation and discussion of work-in-progress on ad-hoc and sensor network security. Among the 39 submissions, the program committee selected 7 papers to present in work-in-progress sessions, covering topics on anonymous routing for MANETs, key distribution for inter-group multicast in ad-hoc networks, improved topology assumptions for threshold cryptography in MANETs, RFID security, tracing in mobile wireless sensor networks, time synchronization attacks in sensor networks, and coordinated deployment for improving secure communications and sensing coverage in wireless sensor networks. In addition, the program includes a panel on Advances in Sensor and Ad-hoc Network Security and an invited keynote talk by Radha Poovandran (University of Washington) on Information Assurance in MANETs and Wireless Sensor Networks. We hope that these proceedings will serve as a valuable reference for security researchers and developers.

A large number of potential applications for Wireless Sensor and Actuator Networks (WSAN) have yet to be embraced by industry despite high interest amongst academic researchers. This is due to various factors such as unpredictable costs related to development, deployment and maintenance of WSAN, especially when integration with existing IT infrastructure and legacy systems is needed. Service-Oriented Architecture (SOA) is seen as a promising technique to bridge the gap between sensor nodes and enterprise applications such as factory monitoring, control, and tracking systems where sensor data is used. To date, research efforts have focused on middleware software systems located in gateway devices that implement standard service technology, such as Devices Profile for Web Services (DPWS), for interacting with the sensor network. This paper takes a different approach-deploying interoperable Simple Object Access Protocol (SOAP)-based web services directly on the nodes and not using gateways. This strategy provides for easy integration with legacy IT systems and supports heterogeneity at the lowest level. Twofold analysis of the related overhead, which is the main challenge of this solution, is performed; Quantification of resource consumption as well as techniques to mitigate it are presented, along with latency measurements showing the impact of different parts of the system on system performance. A proof-of-concept application using Mulle-a resource-constrained sensor platform-is also presented.

The paper presents LA-MAC, a low-latency asynchronous access method for efficient forwarding in wireless sensor networks. It is suitable for current and future sensor networks that increasingly provide support for multiple applications, handle heterogeneous traffic, and become organized according to some complex structure (tree, DAG, partial mesh). It takes advantage of the network structure so that a parent of some nodes becomes a coordinator that schedules transmissions in a localized region. Allowing burst transmissions improves the network capacity so that the network can handle load fluctuations. At the same time, the method reduces energy consumption by decreasing the overhead of node coordination per frame. The paper reports on the results of extensive simulations that compare LA-MAC with B-MAC and X-MAC, two representative methods based on preamble sampling. They show excellent performance of LA-MAC with respect to latency, delivery ratio, and consumed energy.

The large Peak-to-Average Power Ratio (PAPR) is a serious problem in wireless communication systems for mobile and sensor network applications. This paper presents efficient non-linear techniques to solve the large PAPR problem in Single-Carrier Frequency Division Multiple Access (SC-FDMA) system and Wireless Sensor Network (WSN) systems. The performance of the proposed techniques is investigated over a realistic channel model. Simulation results reveal PAPR reduction while preserving low Bit Error Rate (BER) levels.

The Wireless sensor network has a great applied prospect, so the military, academia and industry pay more and more extensive attention. The first, this article introduces the concept of sensor networks and development background; the second, compared with traditional networks, it summarizes the characteristics of sensor networks. In this basis, the application of the sensor network and the direction of the current study are a given brief introduction and a further discussion.

Many sensor network applications, such as object tracking and disaster monitoring, require effective techniques for event detection. In this paper, we propose a novel event detection mechanism based on matching the contour maps of in-network sensory data distribution. Our key observation is that events in sensor networks can be abstracted into spatio-temporal patterns of sensory data and that pattern matching can be done efficiently through contour map matching. Therefore, we propose simple SQL extensions to allow users to specify common types of events as patterns in contour maps and study energy-efficient techniques of contour map construction and maintenance for our pattern-based event detection. Our experiments with synthetic workloads derived from a real-world coal mine surveillance application validate the effectiveness and efficiency of our approach.

In this paper, we study the problem of identifying the partial topology of complex dynamical networks via a pinning mechanism. By using the network synchronization theory and the adaptive feedback controlling method, we propose a method which can greatly reduce the number of nodes and observers in the response network. Particularly, this method can also identify the whole topology of complex networks. A theorem is established rigorously, from which some corollaries are also derived in order to make our method more cost-effective. Several numerical examples are provided to verify the effectiveness of the proposed method. In the simulation, an approach is also given to avoid possible identification failure caused by inner synchronization of the drive network.