# Integration of a Mobile Node into a Hybrid Wireless Sensor Network for Urban Environments +
## 2 Description of the Static Wireless Sensor Network
### Implementation  
The proposed system has been developed on the basis of hardware components provided by Libelium (Zaragona, Spain) [59]. The transmitter nodes share a basic module, called Waspmote V. 1.2 (Libelium, Zaragoza, Spain) The addition of an XBee Pro S2 communications module (Digi, Minnetonka, MN, U.S.A.) provides the capability of using protocols like ZigBee or DigiMesh. The Receiver node is based on a multiprotocol router named Meshlium, also from Libelium, configured to work with ZigBee, WiFi, Bluetooth, and 3G/GPRs protocols, and including a GPS. The link between the Transmitter nodes and the Receiver node has been implemented using the ZigBee protocol (2.4 GHz). It can transmit small information packages with a range of over 700 meters (depending on visibility conditions). Network setup is fast and simple, and so is adding new nodes.  
As mentioned above, several Transmitter nodes have been developed, including different sensors. This way, a UIS deployment can include the following types of nodes:  
* UIS Bluetooth node. It includes a BLUEGIGA WT12 Bluetooth module to the Waspmote V1.2 platform, along with the communications module XBee Pro S2, programmed to work with ZigBee wireless and Bluetooth 2.1 + EDR protocols simultaneously.
* UIS Ultrasound node. It adds an XL-MaxSonar-WR1 ultrasonic sensor (Maxbotix, Brainerd, MN, U.S.A.) to the initial configuration. These sensors operate at a frequency of 42 KHz, and reach the maximum range of 6 m with a sensitivity of 3.2 mV/cm to 3.3 V, or 7 m and a sensitivity of 4.9 mV/cm to 5.5 V.
* UIS Laser node. It is based on a Nano Pico ITX 1.2 GHz processor board (Via Technologies Inc., Taiwan) including 4 GB RAM DDR3 memory and a solid-state hard disk with a capacity of 60 GB. The laser sensor is a Hokuyo model UTM-30 LX-EW (Osaka, Japan). It is intended to classify the types of vehicles crossing a given section.
* UIS Environmental Pollution node. It includes a dust sensor (GP2Y1010 AU0F, Sharp, Osaka, Japan) a light intensity sensor (GL5528 photoresistor, Lida Optical&Electronic Co. Ltd., Henan, China) and a noise sensor (WM-61a, Panasonic, Osaka, Japan).  
Figure 1: System architecture of the UIS static Wireless Sensor Network.  
* UIS Gas node. It is composed of several gas sensors: O2 (SK-25, from Figaro, Osaka, Japan), O3 (MICS-2610, from E2V, Essex, U.K.), CO2 (TGS 4161, from Figaro), CO (TGS 2442, from Figaro), NH3 (TGS 2444, from Figaro), VOC (TGS 2600, from Figaro). Additional sensors include humidity (J808H5V5, from Jin Zon Enterprise Co. Ltd., Taiwan), atmospheric pressure (MPX4115A, from Motorola, Tokyo, Japan) and temperature (MCP9700/9701, from Microchip, Arizona, U.S.A.).
* GPS node. It includes a Jupiter N3 GPS module from Telit (London, U.K.).  
All transmitter nodes are mounted in IP 67 boxes, so that the system can be deployed outdoors in adverse weather condition. Figure 2 shows different nodes of the UIS platform.  
The information gathered from the area of interest is sent to the Receiver node, and stored as tables in its internal database. These tables are synchronized with a relational database implemented with MySQL v.7.0 (Oracle, Redwood City, CA, U.S.A.) in an external server. Synchronization is performed via 3G communication, or Wi-Fi if it is available. This database is the input for an HMI developed for this application using LabVIEW, v. 2015 (National Instruments, Austin, TX, U.S.A.), where the information acquired by the sensors is displayed according to their geographic location. The HMI synchronizes with the external database through a connection string using ODBC v. 13.1 (Microsoft, Redmond, WA, U.S.A.). A more detailed review of the UIS can be found at [7].