A Self-organized Wireless Sensor Network (WSN) for a Home-event Managed System : Design of a cost efficient 6LoWPAN-USB Gateway with RFID security

Abstract: Wireless Sensor Networks (WSN) have existed for many years in industry applications for different purposes but their use has not been fully extended to the global consumers. Sensor networks have lately resulted to be greatly helpful to people in everyday life, specially in home automation applications for monitoring events, security, and control of devices and different elements in the house by using actuators. One of the main barriers to overcome in order to increase their popularity and achieve an worldwide deployment are costs and integration within other networks. This Thesis investigates the most appropriate choices to avoid those impediments from a hardware and software design perspective, trying to find a cost-efficient solution for the implementation of a simple and scalable wireless sensor network. The present work studies the elements that form part of a constrained network and focuses on the design by analysing several network protocol alternatives, radio transmission mechanisms, different hardware devices and software implementations. Once an optimal solution is found, the construction of a gateway board that starts and coordinates a sensor network will be the main target of this document including the development of an application that manages the sensors. The network is designed to be compliant with the TCP/IP stack by means of 6LoWPAN, an adaptation layer protocol used for comprising IPv6 headers over IEEE 802.15.4 radio links in constrained networks. In addition, a small implementation of CoAP (Constrained Application Protocol) is developed that allows interoperability with the sensor nodes on the application layer, similarly as HTTP does in IP networks. The controller device (gateway) acts as a client for the remote sensor devices (nodes) that behave as servers in the CoAP application. The gateway exchange data and is managed from outside the WSN through a USB interface that can be connected to a computer. Security mechanisms are also considered by providing packet encryption and a method for identification of nodes. The authorization of new nodes entering the network is performed by an RFID reader connected to the gateway. An RFID tag is attached to the sensor nodes with authentication information stored in it. The gateway reads that information through the RFID modules and handle it internally to give access to that node. As a result of this, it is proven from the conclusions of the study the implementation of the gateway that inexpensive, self-managed, scalable WSNs provided with a robust security mechanism can be achieved and easily deployed . The work presented in this document is part of a larger project that also includes the design of sensor boards and the acquisition and analysis of sensor data. These works are mentioned and referenced in the related parts in this text.