# A Social Environmental Sensor Network Integrated within a Web GIS Platform
## 2 Related Work  
Recent technology advancements have driven Wireless Sensor Network (WSN) systems to become a feasible solution for many innovative applications [9; 10]. Several systems that rely on low-power embedded micro-controller platforms have been proposed [9; 11]. Such systems make use of the digital and analog I/O ports of platforms for sensor extensions alongside with custom or open source software components. For instance, [PERSON] and [PERSON] [10] proposed a system based upon several hardware and software elements. They focused on the development and integration processes. The overall architecture of their system included a base station and a number of distributed wireless sensor nodes. On the hardware side, both nodes and the base station are developed in an assemblage of micro-controllers (uC), a radio transceiver and an environmental sensor measuring humidity and temperature. Specifically, base stations are implemented using a Raspberry Pi Model B [11], taking advantage of its advanced processing capabilities compared to the Arduino Uno [12], which has been used to incorporate the sensors. Connectivity is established with the help of XBee Pro S2B module [13] Data manipulation is performed by applications that have been installed in both sensors and base station. A gateway application that has been installed in the micro-controllers assists the on-board functionality and acts as an intermediate for the sensor network and the MySQL database. Furthermore, the whole system is monitored by a web application which is controlled by the end user and offers data visualization capabilities. Overall, the system proposed by [PERSON] and [PERSON] is low cost, compact and could be easily managed with reduced complexity. On the other hand it has only been deployed for indoor monitoring of temperature and relative humidity and the end user is provided with low data visualization capabilities. Although it shares several fundamental characteristics with our proposed system, we believe that it is strongly differentiated on many aspects. Within our approach, communication is based on Bluetooth protocol and GPRS/WiFi connectivity. Moreover, our approach is structured around cloud computing services and its main aspect is the transmission of produced environmental information; i.e., it has been designed for outdoor use producing seven environmental variables. Finally, our approach strongly focuses on spatial characteristics of natural phenomena and we integrate this on every aspect of our deployment. Similarly, [PERSON] and [PERSON] [14] developed a WSN using open-source hardware platforms for small-scale ecological monitoring and knowledge collection. Both Raspberry pi and a microcontroller were used as a sensor node and base station setup. Each node has embedded software capable to handle recordings to the base station, which is supported by a user friendly web application. Communication is executed by ZigBee protocol (IEEE 802.15.4 standard), which complies to three types of network topology (star, cluster-tree and mesh). Their proposal is adaptive to many ecological monitoring applications due to its compatibility with several open source hardware and software platforms. Indoor Environmental Quality (IEQ) is a concept which concerns the work of [PERSON] et al. [15]. Therein, a WSN has been developed on the purpose of aggregating a set of different categories of comfort, well-being and satisfaction of users of buildings. Sensor nodes were based on an Arduino Uno and monitored air speed, radiant temperature, luminosity and CO\({}_{2}\). Their system, namely nEmOs project, is implemented for recurrence monitoring and improvement of conditions and energy efficiency of buildings. The network's communication is based on WiFi and sensor readings are sent to the Xively [16] cloud service. The notion of base stations is not adopted; instead, an Android App has been developed for the purposes of data distribution and node management.