Push & Pull: autonomous deployment of mobile sensors for a complete coverage

Mobile sensor networks are important for several strategic applications devoted to monitoring critical areas. In such hostile scenarios, sensors cannot be deployed manually and are either sent from a safe location or dropped from an aircraft. Mobile devices permit a dynamic deployment reconfiguration that improves the coverage in terms of completeness and uniformity. In this paper we propose a distributed algorithm for the autonomous deployment of mobile sensors called Push&Pull. According to our proposal, movement decisions are made by each sensor on the basis of locally available information and do not require any prior knowledge of the operating conditions or any manual tuning of key parameters. We formally prove that, when a sufficient number of sensors are available, our approach guarantees a complete and uniform coverage. Furthermore, we demonstrate that the algorithm execution always terminates preventing movement oscillations. Numerous simulations show that our algorithm reaches a complete coverage within reasonable time with moderate energy consumption, even when the target area has irregular shapes. Performance comparisons between Push&Pull and one of the most acknowledged algorithms show how the former one can efficiently reach a more uniform and complete coverage under a wide range of working scenarios.Comment: Technical Report. This paper has been published on Wireless Networks, Springer. Animations and the complete code of the proposed algorithm are available for download at the address: http://www.dsi.uniroma1.it/~novella/mobile_sensors

Dynamic symmetrical topology models for pervasive sensor networks

The success of pervasive computing environments using ubiquitous loco-dynamic sensing devices is very dependent upon the sensor deployment topology (DT) employed. This paper presents a systematic mathematical model for efficient sensor deployment and provides a comparison with other popular topologies. The model focuses upon blanket coverage of a surveillance area using a minimum number of sensing devices, with minimal infra-sensor overlapping to reduce collisions and co-existence problems. Simulation results are presented for the hexagonal, triangular and square grid topologies for various dimensions of surveillance area. The results confirm that the hexagonal model gives optimal performance in terms of requiring the minimal number of sensors. The paper also highlights the improved performance of ubiquitous wireless sensor networks when a hexagonal topology (HT) is used

OLIMPO, An Ad-Hoc Wireless Sensor Network Simulator for Public Utilities Applications

This paper introduces OLIMPO, an useful simulation tool for researchers who are developing wireless sensor communication protocols. OLIMPO is a discreteevent simulator design to be easily recon gured by the user, providing a way to design, develop and test communication protocols. In particular, we have designed a self-organizing wireless sensor network for low data rate. Our premise is that, due to their inherent spread location over large areas, wireless sensor networks are well-suited for SCADA applications, which require relatively simple control and monitoring. To show the facilities of our simulator, we have studied our network protocol with OLIMPO, developing several simulations. The purpose of these simulations is to demonstrate, quantitatively, the capability of our network to support this kind of applications

A Theoretical Review of Topological Organization for Wireless Sensor Network

The recent decades have seen the growth in the fields of wireless communication technologies, which has made it possible to produce components with a rational cost of a few cubic millimeters of volume, called sensors. The collaboration of many of these wireless sensors with a basic base station gives birth to a network of wireless sensors. The latter faces numerous problems related to application requirements and the inadequate abilities of sensor nodes, particularly in terms of energy. In order to integrate the different models describing the characteristics of the nodes of a WSN, this paper presents the topological organization strategies to structure its communication. For large networks, partitioning into sub-networks (clusters) is a technique used to reduce consumption, improve network stability and facilitate scalability

Robust blimps formation using wireless sensor based on Received Signal Strength Indication (RSSI) localization method

This paper suggests the wireless communication technique used to determine the information of blimp localization (distance and orientation) via wireless sensor network (WSN) protocol. In cooperative decentralized system, information exchanges between the agents are crucial. Each agent is required to share data to enable individual decision making task. In this work, the WSN were used as the data communications protocol which provides robust communication using the mesh networking. In order to support the multi agent communication network, the reliability of data needs to be proved. The performances of the communication selection were studied through experimental and simulation approach. The experimental results showed that the RSSI value from the device provided good statically data fit using the R-square with value of 0.947. This paper also proposed a new mobile node arrangement with hexagonal anchor node arrangement based on water particles formation. The node arrangement was simulated using the Senelex™ and showed low absolute error position thus achieving the desired cooperative system requirement

RTXP : A Localized Real-Time Mac-Routing Protocol for Wireless Sensor Networks

Protocols developed during the last years for Wireless Sensor Networks (WSNs) are mainly focused on energy efficiency and autonomous mechanisms (e.g. self-organization, self-configuration, etc). Nevertheless, with new WSN applications, appear new QoS requirements such as time constraints. Real-time applications require the packets to be delivered before a known time bound which depends on the application requirements. We particularly focus on applications which consist in alarms sent to the sink node. We propose Real-Time X-layer Protocol (RTXP), a real-time communication protocol. To the best of our knowledge, RTXP is the first MAC and routing real-time communication protocol that is not centralized, but instead relies only on local information. The solution is cross-layer (X-layer) because it allows to control the delays due to MAC and Routing layers interactions. RTXP uses a suited hop-count-based Virtual Coordinate System which allows deterministic medium access and forwarder selection. In this paper we describe the protocol mechanisms. We give theoretical bound on the end-to-end delay and the capacity of the protocol. Intensive simulation results confirm the theoretical predictions and allow to compare with a real-time centralized solution. RTXP is also simulated under harsh radio channel, in this case the radio link introduces probabilistic behavior. Nevertheless, we show that RTXP it performs better than a non-deterministic solution. It thus advocates for the usefulness of designing real-time (deterministic) protocols even for highly unreliable networks such as WSNs