DSeN OS: A Distributed Operating System for Wireless Sensor Networks

Abstract

With the evolution of sensor networks systems, several operating systems came into being. Typically, these operating systems are less complex than general purpose operating systems, both because of special requirements of sensor networks and because of the inherent resource constraints of the sensor nodes. Most of the times, the ways of accessing sensors depend on the type of the sensor and the location where the sensor node is deployed. Moreover, the operating system is also a main factor that decides the means by which the sensors are accessed. On these grounds, several solutions such as treating the sensor network as a database or a file system have been proposed over the years to fill the void. Most of these approaches are built around a base-station which is a resource rich place with comparison to the other sensor nodes in the system. Other approaches are local to the sensor node which is being accessed. Today, sensor nodes do not only consist of sensors as their names imply. Most of the sensor nodes manufactured today are capable of driving actuators such as relays, electrical motors, piezoelectric actuators, etc. These newly added capabilities allow nodes to react instantly according to what they have sensed without the aid of a base-station. Moreover, nodes can also react collectively rather than individually. A base-station is needed only when analysing the sensed data or when reprogramming the nodes. In order to develop applications to cater the requirements of these types of systems, the application programmer has to be aware and informed of the underlying network as well as the applications logic. Though several sensor network operating systems have emerged, one major barrier that exists between the application developers and these operating systems is the developer familiarity. Though the developer familiarity is not a significant issue for the novel developers, it is a major issue that hinders the productivity of the experienced developers. If the new system is not familiar as the old system, it slows down the overall productivity. From the view of sensor network developers, most of them are already experienced system developers in UNIX-like systems. Therefore, if the application developing environment is familiar to UNIX-like systems, it will dramatically increase the productivity. As a solution to these problems, a new operating system, DSeN OS is presented. DSeN OS is a distributed operating system for wireless sensor networks which provides a location, access and a network transparent device model. In this device model, all the sensors of the sensor network are treated as devices which are connected to a single system. This is the same way a user sees the devices which are connected to a single personal computer system. In other words, an application developer can use the same set of APIs to access the sensors on other nodes in the same way he/she accesses sensors on a local sensor node without considering the underlying topology and protocols of the network. Unlike most of the popular sensor network operating systems, DSeN OS is not limited to the concept of sensors. Anything on the sensor node can be treated as a device. The device abstraction provided by DSeN OS is similar to the hardware abstraction provided in the file system hierarchy of UNIX-like operating systems. A set of APIs which is very similar to the file handling APIs of UNIX-like operating systems is used to access the devices. Moreover, the concept of device drivers is used to make the developing environment more familiar and to make the system scalable