ARTICLE IN PRESS JID: CAEE [m3Gsc;April 6, 2017;15:50] Computers and Electrical Engineering 000 (2017) 1–15 Contents lists available at ScienceDirect Computers and Electrical Engineering journal homepage: www.elsevier.com/locate/compeleceng Delay-aware heterogeneous cluster-based data acquisition in Internet of Things  Nandhakumar Ramachandran * , Varalakshmi Perumal Department of Computer Technology, Anna University, Chennai, Tamil Nadu 600044 India a r t i c l e i n f o Article history: Received 9 December 2016 Revised 18 March 2017 Accepted 20 March 2017 Available online xxx Keywords: Multifarious sensor cluster Intra-quartile aggregation IoT Delay-aware networks a b s t r a c t The environmental conditions of a wildlife habitat are monitored using many heteroge- neous sensors, including temperature, humidity, pressure, and water-level sensors. Sensor data are collected from various regions for knowledge retrieval about the various param- eters to analyse the wildlife habitat and take necessary actions. The Delay-Aware Hetero- geneous Cluster-based Data Acquisition (DA-HCDA) technique is proposed, which ensures maximum coverage. A multifarious Sensor-based Cluster Formation Algorithm (MSCFA) is used to from the cluster and elect the controllers to handle the different types of sensors. A multi-tier aggregation function called Quartile Aggregation is proposed, which elimi- nates the redundancy of aggregated data at the controller. Thus, the proposed DA-HCDA and Quartile Aggregation mechanism improve the network lifetime and end-to-end delay across the wildlife habitat reserve. © 2017 Elsevier Ltd. All rights reserved. 1. Introduction The Internet of Things (IoT) contains groups of interrelated devices that are able to exchange data. It brings the Internet into the physical world such that the objects can be tracked and managed remotely. A thing within the Internet of Things can be someone with a cardiac-monitoring implant, an automobile with inbuilt sensors that alert the driver when tire pressure is low or any other natural or man-made object that has been allotted an IP address. The primary aim of the IoT is to create a better world for people, where things around us communicate with one another and know what we like, what we want, and what we need and act accordingly without specific instructions. We consider the three layers of IoT architecture [15,16,17,21], namely, the Application layer, Network layer and Physical layer, which are shown in Fig. 1. The edge devices, such as light sensors, humidity sensors, temperature sensors, and pressure sensors, are in the physical layer. Data collection, parameter tuning and the transmission of collected data are the main functions of the physical layer. Communication technologies such as WiFi, Bluetooth, and 3G are the facilities in the network layer, which helps in providing the communication facility. The application layer has, for instance, monitoring devices, smart watches, and tablets and is where data storage, data processing and decision-making are performed. As the sensors are energy-constrained devices, sensor data is periodically collected and stored in some database [13]. The application layer processes the collected data and provides services to the end users. The network layer consists of middleware devices, such as WiFi, WiMax, and ZigBee. Middleware devices act as bridges between applications and the underlying hardware. They are used to transfer information over a large area. The sensing layer (physical layer) consists of various sensing devices such as  Reviews processed and recommended for publication to the Editor-in-Chief by Associate Editor Dr. S. Smys. * Corresponding author. E-mail addresses: nandhakumarr03@gmail.com (N. Ramachandran), varanip@annauniv.edu (V. Perumal). http://dx.doi.org/10.1016/j.compeleceng.2017.03.018 0045-7906/© 2017 Elsevier Ltd. All rights reserved. Please cite this article as: N. Ramachandran, V. Perumal, Delay-aware heterogeneous cluster-based data acquisition in In- ternet of Things, Computers and Electrical Engineering (2017), http://dx.doi.org/10.1016/j.compeleceng.2017.03.018