Study On Emergency Communication System Based On Cognitive Radios

The motivation of the design in this paper comes from our understanding of the situation and the demands of emergency communications, and our thinking for some of the problems about emergency communications. We put forward feasible schemes pointed to the characteristics, current situation and problems about emergency communications. In recent years, earthquakes, tsunamis, typhoon and other natural disasters have happened from time to time, some serious natural disasters such as the Yushu big earthquake have caused serious economic damage and casualties. With the ground facilities, roads being destroyed, the relief work is difficult to be carried out. Communication is very important to the rescue work and interchanging information in the disaster area, but because the original communication facilities have been completely destroyed, and due to the bad environment cable facilities is very difficult to be rebuilt, moreover, cable facilities should be laid only after reasonable planning, otherwise it will make trouble to later work, so rebuilding cable facilities is not adapted to the emergency communications. Obviously, only wireless communication is able to play a role in emergency conditions. We can build wireless communication facilities to use traditional networks; the advantage of doing so is that there is no too big difficulty for the technology. We can restore communication completely according to the existing mature technical. However, because the environment is so complex, and subject to change, while traditional network usually requires stable communication environment. So, the traditional network can’t meet the requirements of the emergency communication. This article puts forward improvement for emergency communication from an angle or a side, cognitive radio will be used in emergency communications.At home and in offices we can use convenient cable network, while in mobile environment wireless networks can provide exciting service for us, however, in emergency environment our communication technology was not so in position. This paper will summarize the cognitive radio theory and its characteristics and then analyze the characteristics of the emergency environment and the demands of emergency communication, and put forward the advantages and prospect of applying cognitive radio technology in emergency communication, and analyze some details.This paper dedicates to solving the following problems:(a) utilization rate of spectrum. In the disaster emergency environment the amount of communication grows quickly, congestion must happen in the network, only making full use of spectrum resources can ensure smooth communication;(b) spectrum access problems. According to analysis, emergency environment application dynamic spectrum access strategy is an inevitable choice; we need to find a reasonable solution of access to ensure the realization of dynamic spectrum access strategies;(c) the spectrum sharing priorities. In dynamic spectrum management conditions, each spectrum users sharing the frequency resources, we need to make sure the priority of the users.