Research Of Complex Wireless Channel And Signal Receiving Module Based On A Localization System For Disaster Situations

Natural disasters are unpredictable, and always lead to great loss of property and life. Due to the collapsed buildings after disaster, many of the victims are buried and in desperate need of rescue. However, blaming the technical limitation of traditional search methods, such as rescue dogs and life detectors, a good amount of victims fail to get timely rescue. Nowadays, mobile phones become very prevalent, and from the radio signal of mobile phones, a lot of important information can be extracted, such as signal intensity, arrival time, phone number and so on. Besides, the signal is more intense than vital signs, such as breathing, heartbeat and the human body infrared. Therefore, it’s a very promising approach to detect the buried victims via their mobile phones for disaster relief.This thesis presents a phone-based localization system for search and rescue purpose in the disaster situation. The system realizes the communication with victims’ mobile phones by improving the broadcast signal power of pseudo base station, which leads to the re-election of the cell. Upon the investigation of the radio channel in disaster scenarios, the location of the mobile phones is calculated via an effective hybrid localization algorithm, which is based on the signal strength of arrival and the time differrence of arrival methods. In this thesis, some key technologies of the phone-based localization system are studied in-depth.1) The signal receiving module of the localization system is designed and implemented in this thesis. In order to verify the localization algorithm, this thesis proposes a handheld localization algorithm validation system, and designs a power measurement module. Besides, the receiving subsystem of the pseudo base station, including RF front-end circuit, baseband transformation circuit and AD conversion circuit are designed, manufactured and debugged in this thesis.2) The propagation characteristics of complex channel in disaster situation were studied in this thesis. Firstly, a simulation model is built, based on which the obstacle blocking effect on the radio propagation is analyzed. Secondly, measurement campaigns are carried out both in 3-meter Semi-Anechoic Chamber and outdoor environment. Finally, based on the simulated and measured results, the characteristics of the complex channel are summarized.