56 Int. J. Ad Hoc and Ubiquitous Computing, Vol. 12, No. 1, 2013 Copyright © 2013 Inderscience Enterprises Ltd. Data aggregation and pipelining scheduling protocols for real-time wireless sensor networks Sofane Ouni*, Salsabil Gherairi and Farouk Kamoun CRISTAL laboratory, Ecole Nationale des Sciences de l’Informatique, Manouba, Tunisia E-mail: Sofane.ouni@insat.rnu.tn E-mail: salsabil.gherairi@gmail.com E-mail: frk.kamoun@planet.tn *Corresponding author Abstract: Critical applications in real-time wireless sensor networks require bounded service latency and energy consumption optimisation. This motivates us to design a novel scheduling approach, which integrates communications with pipelining and data aggregation. The aim of our aggregation technique is to reduce the number of messages, which consequently reduces energy consumption. However, our pipelining technique is defned to minimise communication latency. Our approach is applied on tree wireless sensor networks and in a real-time context, which requires communications without interference. Thus, we use TDMA and a multi-frequency access method based on parent relationship clustering. In this context, we made the necessary mathematical formulation to determine communication response time and to predict the impact of real-time constraints, particularly deadlines, on communication delay. Our simulations outperform the effciency of our approach to comprise between communication delay and energy consumption constraints. Keywords: WSN; wireless sensor networks; real-time; data-aggregation; energy consumption; communication delay. Reference to this paper should be made as follows: Ouni, S., Gherairi, S. and Kamoun, F. (2013) ‘Data aggregation and pipelining scheduling protocols for real-time wireless sensor networks’, Int. J. Ad Hoc and Ubiquitous Computing, Vol. 12, No. 1, pp.56–64. Biographical notes: Sofane Ouni is an Associate Professor in the Department of Computer Science and Mathematics at the Institut National des Sciences Appliquees et de Technologie (INSAT), Tunisia. His research interests include wireless, ad hoc and sensor networks with hard real-time guarantee. Salsabil Gherairi is an Assistant Professor in the Department of Computer Science at the Institut Superieur des Etudes Technologiques de Bizerte, Tunisia. His research interests include sensor networks. Farouk Kamoun is Professor of Computer Science at Ecole Nationale des Sciences de l’Informatique (ENSI) of Tunisia. In 1999, he founded the ‘CRISTAL’ laboratory at ENSI. He is an author and co-author of over 100 scientifc publications, technical and strategic reports. His research work is focused on the QoS and multimedia communications for the internet, security, mobility, wi-f and ad hoc networks, as well as e-commerce. 1 Introduction A wireless sensor network (WSN) is created by the deployment of many sensor nodes, which communicate with each other to perform a common task. In this paper, we suppose, as in most cases, a tree topology of sensor networks in which the sensor nodes collect data from the environment and send it through a path to a single sink node (also called the base station). We assume a multi-hope network with sensor nodes having the ability to forward messages through a path to the sink. A new generation of real-time traffc communications and high data rate sensor applications has appeared, such as structural health monitoring and control (Durga, 2008). The main problems in such applications are energy conservation (Ouadoudi et al., 2010; 2011) and the real time constraints guarantee to respect deadlines and minimise communication delay. To resolve these constraints, we must get mechanisms for optimising energy consumption and communication delays at the same time.