认知无线电系统功率控制和频谱分配技术研究

西安交通大学硕士学位论文ABSTRACTCognitive Radio technology can detect the utilization of the spectrum initiatively,andchange its communication parameters adaptive ly.On the premise of no prejudice to licensedusers,cognitive radio can choose the idle spectrum of licensed users to communicate inproper opportunities.For its advantages of agility,and high spectrum utilization,cognitiveradio has been concerned widely by the scholars at home and abroad.Because licensed usersshare spetrum resource with cognitive users and have the highest priority,the technologies incognitive radio have new characteristics.The technologies of power control and spectrumallocation in cognitive radio systems is researched,and close loop power control module incognitive radio experimental system is designed and implemented in this thesis.Firstly,based on the analysis of adaptive and interactive decision process in cognitive radio,a game theory model of power control is established.Aimed at cognitive radio system basedon exclusive model,a power control game algorithm based on arctan function is proposed.The simulation results show that new algorithm not only guarantees the cognitive users'SINR,but also imporves the system throughput compared with other algorithms.Aimed atcognitive radio system based on common model,the utility function is improved,and apower control game algorithm based on exponent chastisement factor is proposed.Thesimulation results show that new algorithm guarantees the SINR of cognitive users and lowenough outage probability of licensed users,and the transmitting power is controlledeffectively.Secondly,aimed at the contradiction between number of occupied channels and time cost inOFDM cognitive radio system.a goodput concept and an optimal spectrum allocationstrategy based on this concept are proposed.And a method based on genetic algorithm forthe solution of the optimal strategy is designed.The simulation results show that when thespectrum resource allocated to the cognitive users is small,the goodput increases with theincrease of allocated spectrum resource;when the occupied spectrum resource by cognitiveusers increases further,the conflict probability to licensed users increases,and the goodputdecreases monotonically with the increase of allocated spectrum resource.This strategyproposed in the thesis optimizes the number of occupied channels by cognitive users,andimproves the OFDM cognitive radio system performance.Finally,close loop power control module in cognitive radio experimental system is designedand implemented based on debugging of RF module in experimental system.The debuggingresults show that transmitting power can be controlled accurately and in real-time by thismodule based on RF module's normal operation;when the experimental terminal is moving,