# 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 Aerospace
#### 4.1.4 Transmission Information System for Taxiing on the Aprons and Taxiways Using RFID Technology  
Along with the progressing automation of aircraft control processes, the reliability and quality expectations of these processes are increasing, not only in the air but also on the airport apron. And taxiways. Each valid flight begins and ends at the airport apron, which must be navigated properly and efficiently in order to maintain a high level of airport safety and airport capacity [41].  
There are two basic types of taxiways: normal taxiways and expressways. Their parameters are standardized and depend, among other things, on the air traffic and its intensity, which makes it easier to quickly release the runway to serve other aircraft [42].  
For navigation on the airport apron, pilots use horizontal and vertical signs, as well as automatic control systems, which are based on more and more perfect vision systems. Global positioning systems such as GPS, GALILEO and, among others, radars, which co-create anti-collision systems, are also used for airport navigation [43; 44; 45; 46].  
In order to increase security, the diversification of information sources is used. For this purpose, an additional RFID-based navigation system may be applied [47; 48].  
This technology is widely known and used, also in aviation, among others, for monitoring and tracking components and analyzing their wear [43].  
This system enables the transfer of information in an object or group of objects. It is based on cooperating transponders (passive or active) and a reader, stimulating them to operate and read the information sent [49].  
In airport navigation, RFID technology can be used to wirelessly transmit the following data to an aircraft [47; 50; 51]:  
* information (e.g., about the position on the taxiway, about other airplanes nearby) or commands (stop, continue taxiing).  
Transponders can be installed directly on the surface (Figure 6) or combined with taxi lamps. In the second case, they can be active transponders that use lamp power [47].  
A beneficial effect of using this type of solution is [47]:  
* Possibility of transmitting additional information to the automatic taxi control system, such as: the position on the taxiway, about an upcoming intersection, about other nearby objects, and commands for the automated taxi system.  
Figure 6: Examples of placing RFID transponders on the airport apron.  
It provides additional information to increase the crew's situational awareness, such as: warnings about approaching a taxiway/runway intersection and information about geographic location.
* Possibility of replacing other, completely passive systems, based on graphic signs--so that the information transmitted to the aircraft may change, be programmed remotely, due to the current traffic situation, weather, and others;
* Easy for configuration infrastructure;
* Flexible system structure.
* This solution has also some weaknesses:
* The range between devices is limited to a maximum single tens meters
* Different frequencies engaged depending on the region of the World, so multi frequency devices are required to increase flexibility and portability of RFID based systems,
* Sensitivity to short contact time. The communication could not be established if visible time was too short because of capacitors' performances and limitations.  
The above-mentioned solution has been tested under laboratory conditions. During the tests, the control system responded to the transmitted information and steered the model as intended. The operational range of transponders and readers was also checked in airport conditions by testing the possibility of transmitting information to the aircraft. The obtained results suggest the option of using this type of solution in both manned and unmanned aviation.