Nadjib Achir

A Tabu Search WSN Deployment Method for Monitoring Geographically Irregular Distributed Events

In this paper, we address the Wireless Sensor Network (WSN) deployment issue. We assume that the observed area is characterized by the geographical irregularity of the sensed events. Formally, we consider that each point in the deployment area is associated a differentiated detection probability threshold, which must be satisfied by our deployment method. Our resulting WSN deployment problem is formulated as a Multi-Objectives Optimization problem, which seeks to reduce the gap between the generated events detection probabilities and the required thresholds while minimizing the number of deployed sensors. To overcome the computational complexity of an exact resolution, we propose an original pseudo-random approach based on the Tabu Search heuristic. Simulations show that our proposal achieves better performances than several other approaches proposed in the literature. In the last part of this paper, we generalize the deployment problem by including the wireless communication network connectivity constraint. Thus, we extend our proposal to ensure that the resulting WSN topology is connected even if a sensor communication range takes small values.

Differentiated Underwater Sensor Network Deployment

Underwater sensors technology has experienced a tremendous development over the last decade. They have generated considerable community enthusiasm, which applied them to a wide range of cases that could enhance human and animal habitat conditions e.g. climate changes prediction or pollution surveillance. In this paper, we address the issue of deploying a UWSN in an area characterized by the geographical irregularity of the sensed event. Our specific application context regards the monitoring of the water quality in a small closed area (e.g. a lake). For this purpose, we propose a differentiated deployment algorithm (DDA) based on a mesh representation method inspired from the image processing and 3D modeling field.

Artificial potential field approach in WSN deployment: Cost, QoM, connectivity, and lifetime constraints

In this paper, we address a wireless sensor network deployment problem. It is considered when the deployment field is characterized by a geographical irregularity of the monitored event. Each point in the deployment area requires a specific minimum guarantee of event detection probability. Our objective is to generate the best network topology while minimizing cost of deployment, ensuring quality of monitoring and network connectivity, and optimizing network lifetime. The problem is formulated as combinatorial optimization problem, which is NP-complete. Unfortunately, due to the large solution state space and the exponential computational complexity, the exact methods can be applied only in the case of small-scale problem. To overcome the complexity of an optimal resolution, we propose new scalable deployment heuristics based on artificial potential field and Tabu search metaheuristic, namely potential field deployment algorithm (PFDA) and multi-objective deployment algorithm (MODA). We compare our proposal to the related deployment strategies, the obtained results show that PFDA and MODA obtain the best performances.

Multi-Objective WSN Deployment: Quality of Monitoring, Connectivity and Lifetime

In this paper, we will address a WSN deployment problem. The main objectives are i) reduce the cost of deployment, ii) ensure the requested event detection probabilities, iii) guarantee the network connectivity, and iv) maximize the lifetime of the network. We will formalize the problem as multi-objective combinatorial optimization problem. To resolve the problem, we will propose a new deployment algorithm named \texttt{MODA}. It will be based on evolutionary and neighborhood search algorithms. The obtained results are better than the deployment strategies found in the literature.

Potential Field Approach to Ensure Connectivity and Differentiated Detection in WSN Deployment

This paper addresses the issue of Wireless Sensor Network (WSN) deployment. We investigate this problem in the case where the monitored area is characterized by a geographical irregularity of the sensed events. Precisely, we consider that each point of the deployment area requires a minimum threshold guarantee on the event detection probability. Our proposed scalable deployment method, named Potential Field-based Deployment Algorithm (PFDA), is based on the Potential Field and the Virtual Force approaches. Our proposal is able to (1) satisfy the required event detection probability threshold for each point, in a large-scale area, while minimizing the number of deployed sensors and (2) to ensure the network connectivity. The results and evaluation analysis show that PFDA outperforms the other strategies proposed in literature.

Heuristic Deployment to Achieve Both Differentiated Detection and Connectivity in WSN

In this paper, we extend the differentiated deployment method which we have proposed in our previous paper by adding the connectivity constraint. We assume a fixed communication ray and a probabilistic detection model. We also consider that to each point in the deployment area is associated a detection probability threshold, which must be satisfied by our deployment method. Finally, we suppose that the detection probabilities thresholds of the area are geographically nonuniformly distributed. Our differentiated deployment problem is modeled as multi-objectives optimization problem, which we resolve using our proposed Tabu Search-based algorithm. A comparison is made with the methods found in the literature. The performances obtained by our method are much better in term of required number of sensors, generated detection probabilities, while ensuring the network connectivity.

A gradient approach for differentiated wireless sensor network deployment

In this paper, we propose a new sensor deployment strategy by considering both a probabilistic sensor detection model and a monitored area with geographical irregularity requirement of the sensed events. In this case, each point in the deployment field needs a specific minimum guarantee in event detection probability. The main objective is to find the minimum number of senors and their positions, in order to guarantee the requirement event detection threshold. Thus, we propose a new scalable deployment strategy based on virtual forces. The fundamental idea of our proposal is to adjust the number and the position of sensors according to virtual forces that must be computed for each sensor. The performance evaluation shows that our proposal obtained the best results compared to several other sensor deployment strategies founded in the literature.

Content-Aware ARQ for H.264 Streaming in UTRAN

In this paper we propose a new content-aware ARQ scheme for H.264 video streaming over UMTS wireless links. We propose a new scheme which assesses the importance of each packet using the FMO (Flexible Macro-block Ordering) tool, a novel error robustness tool of H.264 video encoding standard. Temporal values are then given to video packets in respect to their importance. Carried out simulations show good improvement in video quality of the proposed mechanism.

Path planning of unmanned aerial vehicles with terrestrial wireless network tracking

The UAVs (Unmanned Aerial Vehicles) market is projected to grow, sustained by the technological progress in different domains related to UAVs and by the emergence of new civilian applications. However, this economical development might be held back due to increased regulation constraints. A major concern of public authorities is to ensure a safe sharing of the airspace, especially over populated areas. To reach this aim, a fundamental mechanism is to provide a permanent tracking of UAVs. In this paper, we investigate the path planning of autonomous UAVs with tracking capabilities provided by terrestrial wireless networks. We formalize this problem as a constrained shortest path problem, where the objective is to minimize the delay for reaching a destination, while ensuring a certain delivery ratio of messages reporting the drones positions.

WLAN Planning: Separate and Joint Optimization of Both Access Point Placement and Channel Assignment

In this paper, we are interested to the problem of designing wireless local networks (WLANs), which involves deciding where to install the access points (APs), and assigning frequency channels to them with the aim to cover the service area and to guarantee enough capacity to users. Our proposal provides different solutions to the problems related to the WLAN design and can be divided into two main parts. In the first part, we focus on the problem of designing a WLAN by treating separately the AP positioning and the channel assignment problems. For AP positioning issue, we formulate it as a set covering problem. Since the computation complexity limits the exact solution, we propose two heuristics to offer efficient solution. While, for the channel assignment, we define this issue as a minimum interference frequency assignment problem and propose three heuristics. Two heuristics aim to minimize the interference at AP locations. Whereas, the objective of the third heuristic is to minimize the interference at the TPs level. In the second part, we treat jointly the two aforementioned issues based on the concept of virtual forces. In this case, we start from an initial solution provided by the separated approach and try to enhance it by adjusting the APs’ positions and reassigning their operating frequencies. In each part of this work, we start first by describing the problem, then presenting the algorithms proposed to resolve it efficiently and finally we illustrate the obtained results and analyze them.