## 3 Rural Area Features and Topology Design  
In this section, we explain the place where we set up our deployment and the main features of a rural area in order to introduce the reader to the main issues that should be taken into account in designing the wireless network. We also study the number of devices needed per coverage area. The rural environment, where our test bench is being developed, is a 2 Km diameter circle (see Figure 1). It is located in \"El Encin\", Alcala de Henares, Madrid, Spain. \"Explora El Encin\" is a popular scientific project of the \"Instituto Madrileno de Investigacion y Desarrollo Rural, Agrario y Alimentario (IMIDRA)\". IMIDRA is entirely dedicated to research, innovation and scientific spreading tasks. One of the main objectives is to present the surroundings closest to Madrid, its agriculture and its researches to the citizens. It is uninhabited. There are different types of cereal cultivation (wheat, barley, oats, maize, etc. ), vegetables (chick-peas, lentils, peas, etc. ), grapevines and other types of plants, with different production systems. The area also has different types of trees, with a great fauna and flora variety. The main focus of \"Explora el Encin\" is to show the natural environment to people who have some physical or sensorial disability. Current society feels more and more that this type of natural space should be protected in order to conserve many species of animals and native plants. Because of the environmental importance, and the great variety of species cultivated inside, we were required to deploy a system to detect a fire, using wireless multisensors, and verify it, using wireless cameras, in order to decrease the reaction time and to avoid a big disaster. A rural environment video-surveillance design is very different compared to home or enterprise designs. The presence of animals and the reduction in coverage because of the vegetation has to be considered. It involves the following issues:  
* We have to minimize the visual impact of the data network in the rural environment. So, data wires should be avoided. * We have to avoid the use of electric wires because it could damage animals, so the power has to be obtained using batteries and solar panels. It implies that the devices have to be low power consumption to minimize costs and visual impact (the greater the power consumption, the bigger the solar panel). Figure 1: The rural area where the test bench has been performed. * The video camera has to be very small in order to reduce the visual impact to animals, but it should have enough quality to obtain good images. * Enough bandwidth is needed in the wireless network to be able to stream video from different video camera devices. * The rural area has plenty of trees, animals and vegetation. These objects diminish the received power, so we must be sure that the received signal in our wireless network has enough power. * Nowadays an 802.11g WLAN has a maximum bandwidth rate of 54 MBps (close to 30 Mbps of effective bandwidth), so we should test how many wireless cameras and multisensors could transmit to a single access point without having a video quality reduction. Our design uses one or several 802.11g access points (depending on the number of wireless cameras and the number of fire detectors) placed on a visible position from all parts of the rural area. We use wireless IP cameras with high gain antenna (to reach large distances). The wireless multisensors are distributed strategically around the rural or forest area, but always located inside the coverage area of the wireless access points (see Figure 2). Both, multisensors and cameras are under the coverage area of an access points. The access points of the network are connected wirelessly using IEEE 802.11g (if they are close enough) or using optic fiber using IEEE 802.3u. The access points of the network allow the connectivity of all multisensors and IP cameras in the network to a central server. The frames are sent through the data link later without the need of any routing protocol in the network.