Abstract
Sensor networks have been widely deployed in all kinds of applications. In the near future, we expect to witness the proliferation of sensor networks with a variety of functions that requires a comprehensive collaboration mechanism among them. Specific designs are necessary to manipulate a fabric of multiple sensor networks, facilitate the collaboration among them, and support efficient data sensing, aggregation, storage, transmission, and query processing. In this chapter, through comparison and analysis of existing works, we present a new taxonomy of collaborative sensor networks based on the architectures and the methodologies of organizing different modules of a system. We find that a cross-layer design simultaneously guaranteeing the energy efficiency of underlying sensor networks and the quality of services for users is a challenging issue which has not been well studied. We also discuss the design space in this field and point out potential research directions.
Top1. Introduction
Sensor networks have attracted a lot of attention during the past decade. Due to the recent advances in wireless communication and micro-electronic technologies, both the price and size of sensors decrease quickly. Today’s applications of sensor networks range from personal to mission critical systems including scientific observation, digital life, home automation, environment surveillance, traffic monitoring, and so on (Gao, Massey, Selavo, Welsh, & Sarrafzadeh, 2007; Li & Liu, 2007b; Szewczyk, Mainwaring, Polastre, Anderson, & Culler, 2004; Yang, Li, & Liu, 2007; Zhang, Sadler, Lyon, & Martonosi, 2004). Many of them are developed and promoted by governments, enterprises and public organizations, offering continuous collection of real-time information, satisfying the requirement of people’s daily life.
In the foreseeable future, we expect to witness the proliferation of sensor networks with a variety of functions that requires a comprehensive collaboration mechanism among them. Specific designs are necessary to manipulate a fabric of multiple sensor networks, facilitate the collaboration among them, and support efficient data sensing, aggregation, storage, transmission, and query processing. Previous studies in sensor networks, however, mainly focus on the performance and efficiency inside a single sensor network.
In this chapter, we broaden the view into the scope of multiple sensor networks. The term “collaborative sensor networks” refers to the sensing systems with the following characteristics: first, it is an information system providing live sensing and query processing services; second, multiple heterogeneous sensor networks are integrated in; third, sensor networks in the system collaborate with each other in accomplishing the querying tasks.
We present a new taxonomy for describing and classifying infrastructures and designs of collaborative sensor networks. The taxonomy categorizes the collaborative sensor networks based on their systematical architectures and functionalities. This contributes a deep and comprehensive view to the current studies. We also discuss and summarize the challenging problems and potential issues in the community of collaborative sensor networks.
The remainder of the chapter is organized as follows. Section 2 briefly discusses the state-of-art in sensor networks. An overview of collaborative sensor networks is presented, covering all the elements from a systematical point of view. Section 3 elaborates the taxonomy of collaborative sensor networks. Challenging issues and potential research directions in this field are discussed in Section 4. We conclude this chapter in Section 5.
Key Terms in this Chapter
Query processing: Query processing refers to the process to answer a query to a database or an information system, which usually involves interpreting the query, searching through the space storing data, and retrieving the results satisfying the query.
Query: A query is defined as a precise request for information retrieval from a database or an information system such as a sensor network.
Collaborative sensor networks: Collaborative sensor networks refer to the sensing systems with the following characteristics: first, it is an information system providing live sensing and query processing services; second, multiple heterogeneous sensor networks are integrated in; third, sensor networks in the system collaborate with each other in accomplishing the querying tasks.
Sensor mote: A sensor mote also known as a sensor node, is a sensing device that is capable of performing physical sensing, gathering sensory information, and computing. Usually it is also able to communicate with other connected sensor motes.
Sensor network: A sensor network is a network consisting of spatially distributed sensor motes to cooperatively monitor physical conditions and environments, such as temperature, humidity, vibration, pressure, illumination, sound, images, etc.
Data aggregation: Data Aggregation is an operation that aggregates values from multiple (two or more) contributing data characteristics, such as taking the sum, average, max, or min of the data.
Sensing control: Sensing control refers to the mechanisms, either implemented on the sensor motes or running on the base station(s) of a sensor network, to control, coordinate, and schedule the process of sensing activities of the sensor motes in the network.