Abstract
Recent application development in the wireless sensor networks (WSNs) area makes arise problems regarding data aggregation and effective methods to collect data. For addressing these problems, effective procedures are required. A multi-sink sensor network application has been characterized by many-to-many communication, where multiple sources report their data to multiple sinks. This article presents recent techniques for distributed multi-sink environments. The reviewed proposals are classified according to the purpose of the application, such as routing, monitoring of a specific target, data aggregation applications, and others. Finally, we present a discussion on the analysed works.
TopIntroduction
A Wireless Sensor Network (WSN) is composed of a set of hundreds of devices deployed in a common area, which are connected among them. Each device has the same capabilities; it is able to collect information from the surrounding environment through one or more sensors, process this information in a local manner. Data collection is usually made by a sink node or base station. A WSN can be used to control multiple tasks in one environment; the sensors require of data sensed from multiple sources by delivering information to multiple sinks at the same time.
There are a wide variety of current research problems in this area, such as tracking, surveillance, military applications, building automation, disaster management, and agriculture, among others. The applications are designed to obtain precise information from the environment regardless of the human presence. Radio communication, processing, transmission/reception generally are the main cause of power consumption. A multi-sink approach is becoming an efficient scheme to reduce the energy consumption in the whole network, either in a centralized or distributed application. In this paper, distributed techniques are presented and analysed.
The analysis is focused on the used strategies in a multiple sink environment, whether the nodes are static or mobile and how applications can be improved by mixing more than one strategy; the objective of the application such as event detection, following a target, finding the best route, collecting and data aggregation, among others. The survey covers recent and traditional works and presents a discussion of their advantages and drawbacks. A simple and operational distributed algorithm that performs network formation and data collection using a multi-sink environment is presented.
This article is organized as follows: the next section presents the generalities and features of WSNs. The third section presents a classification of distributed approaches based on multi-sink environments; the fourth section describes the classification of the related works and discusses their proposals. The fifth section focuses on the simple and operational proposal of a distributed and multi-sink protocol for a WSN; finally, the last section presents the concluding remarks, which drive further research in the area.
Key Terms in this Chapter
Distributed Strategies: They are schemes in which the task coordination is not performed by a single sensor or sink; instead, the devices interact among them to achieve a common goal through message passing.
Ad-hoc Networks: The network topology is determined by the sensor locations, which are not known a priori, and do not require a router or a controlled wireless base station. The data collection is dynamically defined with the connectivity of the nodes.
Self-Organisation: The coordination and control needed to form a network emerge through the local interaction of a group of sensors/devices from an initially disordered network y/o system.
Sensor Networks: They are formed by a group of tiny, typically battery-powered devices and wireless infrastructure that sense, observe and record conditions in diverse environments.
Wireless Sensors: They are autonomous devices provided with sensing communication capabilities and limited memory and power resources.
Multi-Sink Environments: It is a networking problem in which two or more base nodes or sinks are deployed in an environment to collect data; multiple sinks allow the distribution of traffic with the aim of reducing congestions.