Research On Key Technology Of Broadband Wireless Emergency Communication System

With the development of international political and military situation and the sustainable deepening of national reform,the global cultural exchange and collisions are intensifying,the incidence of emergency is on the rise with increasing social impacts,the rapid disposition and control of public emergency in cities is becoming more and more important.In order to better maintain the development of social economy in China and to improve the efficiency of emergency-dealing,it is urgent to speed up the transformation of the emergency disposal team and to put forward new requirements for emergency communication.In this thesis,the key technology of broadband wireless emergency communication system has been studied and discussed.A set of broadband wireless emergency communication system for emergency scene has been constructed to meet the needs of large data application,high definition(HD)video transmission and emergency command and dispatch.Next,the thesis explored the key issues that are physically relevant and network-related in the obtained wireless communication system.Finally,a small and portable preliminary device for emergency communication has been proposed.The major work and achievements of the thesis work are listed as below:1)Under the research of the new requirements of emergency communication system,the thesis presented a construction of self-organizing network for the trunked communication system to achieve dynamic organization and rapid deployment at the scene in emergencies.Based on the new construction emergency communication system,the study explored the self organizing communication waveform of the wireless network in the scene of emergency.2)Our study proposed a novel channel estimation algorithm based on K nearest neighbor noise cancellation in broadband wireless communication,which greatly enhanced the transmission reliability of broadband wireless communication in emergency field.Through the combination of data mining theory and transform domain digital signal processing theory,the recognition of noise and signal has been accomplished based on K nearest neighbor principle in time-domain channel impulse response.The simulation results and physical verification showed that the new algorithm had superior performance gains with lower algorithm complexity costs.3)Following the analysis of the shortage of interference suppressing of existing algorithms,our study proposed a novel algorithm for interference suppression based on machine learning.The new algorithm used K means algorithm to realize the narrowband interference in the frequency domain channel impulse response.Comparison between the simulation results and physical verification showed that with the novel algorithm for interference suppression,the performance loss had been within the allowable range,which greatly improved the reliability of the broadband wireless emergency communication system in the field of sudden events.4)The study analyzed the broadcast protocol of wireless self-organizing network,and put forward a broadcast protocol called Receiver Negotiation Opportunity Broadcast(RNOB),which improved the broadcast transmission efficiency in the emergency field.By establishing the priority of receiver negotiation mechanism,the theory of the point-to-point transmission has been extended to the broadcast service of multipoint,and the transmission performance of broadcast based on the opportunistic routing theory has been deduced.The simulation results and physical verification showed that the broadcast service transmission strategy based on RNOB could make full use of the broadcast characteristics of the wireless signal,and in the case of high broadcast traffic coverage,the nodes participating in the broadcast packet forwarding could be reduced without additional transmission time.All above achievements presented in the thesis have turned into actual equipment.The key algorithms were verified by field test.In sum,our study may help to promote the use of broadband trunking communication system for emergency communication.