# The Latest Advances in Wireless Communication in Aviation, Wind Turbines and Bridges
## 4 WSN Systems in Different Applications: Aerospace, Bridge Structures, and Wind Turbines
### WSN in Bridge Structures  
Modern societies' everyday existence and development are significantly dependent on civil engineering structural objects like bridges, towers, power generation systems, and off-shore platforms. Bridges and viaducts, as structures ensuring the continuity of road infrastructure, ensuring crossing over natural and artificial obstacles, are the key elements of the functioning of modern societies and their economies. Therefore, their safe use is crucial from an economic point of view. Therefore, dedicated SHM systems have been developed for decades. From a whole range of different types of engineering structures, the transportation infrastructure objects are expensive to build and maintain. The consequences of their sudden failure are hazardous and have serious consequences. The examples of civil engineering structures (for instance, bridges, tower buildings, and tunnels) equipped with SHM systems using wireless sensor networks are shown in Figure 7[52]. Figure 7: Civil engineering structures equipped with SHM systems using wireless sensor networks [52]. A special category of structures for which SHM systems have a long history are bridge structures. In the case of bridges, apart from other parts of the system, such as sensors, data acquisition, signal processing, damage detection algorithm, the data transfer, storage, and management system, it is an essential part of the SHM system. Many of the health monitoring systems operating on structures utilize the data communication based on wiring systems. The installation of data wires is often the cause of the complications, generally increasing sensor assembly expenses, conservation and maintenance costs, and results in increased expenditure on repairs. A wireless sensor implementation could eliminate cable-based sensors' drawbacks. Cable based sensors' drawbacks mainly are:  
* costs resulting from the installation of cables intended to provide power and communication for the sensors and protective pipelines,
* influence of ambient temperature on the distortion of sensor data,
* sensor--cabel and cabel--cabel connections which are the source of noises decreasing the quality of the signals. Because the sensors used in the bridge SHM system can be wired or wireless, various data transfer solutions are used. Wired sensors were used in the past, but with research development, reliability, and cost reduction, wireless sensors have become one of the most promising evolving technologies. It is expected that Wireless Sensor Networks (WSN) technology will be the next generation of bridge SHM systems [63; 64; 65]. Figure 8 shows an example of the network used in structural health monitoring in bridge structures. The WSN technology is used for concrete [66; 67], steel [68; 69] and cable-stayed bridge structures [70]. In WSN for SHM, sensors record and collect data such as strain [69; 71], acceleration and velocity [68; 72; 73], temperature, and displacement. The raw data should be processed in order to extract important features, which allow concluding about the state of the structure. The SHM system uses these features for damage detection as well as localization. Figure 8: The hierarchical wireless sensor network for structural health monitoring in bridge structures [66]. In wireless SHM systems for damage detection, modal parameters are commonly used. Estimating modal parameters such as the natural frequency and mode shape is performed both in the time and frequency domains [74]. The basic WSN comprises the sensing, signal processing, and analog-to-digital conversion modules. The filled set is completed by wireless communication and power source units. In more recent years, there has been the emergence of the term 'Smart' WSNs (or Wireless Smart Sensor Node, WSSN), referring to a node that, besides all the above, also has the onboard computational capability and memory storage.