【摘要】 研究NC-OFDM系统独特的频谱利用方法,探讨其在认知无线电中的应用,对其提高频谱利用率和避免对授权用户造成干扰的特点进行分析。设计NC-OFDM系统的实现方法,给出系统部分模块的仿真结果。对NC-OFDM系统在关闭不同比例子载波时的误码性能进行仿真,并与OFDM系统进行比较。在不同的信道环境中,分别针对不同的调制方式和不同的多普勒频移对NC-OFDM和OFDM系统的误码性能进行仿真比较。仿真结果表明:NC-OFDM系统在避免对授权用户造成干扰的前提下,提高了频谱的利用率,而且具有良好的误码性能。更多还原

【Abstract】 The particular means of using spectrum of NC-OFDM is studied,the implementation of NC-OFDM for cognitive radios and its characteristics of improving the rate of spectrum utilization and avoiding interference with incumbent users are discussed and analysed.The flowchart of NC-OFDM system is designed and the simulation results of some modules are shown.The BER performance of NC-OFDM for different percentages of deactivated subcarriers are simulated and compared with OFDM.In terms of different modulation methods and Doppler frequency shift,the BER performance of NC-OFDM and OFDM systems is simulated and compared.The results indicate that:on the basis of avoiding interference with incumbent users,the NC-OFDM system improves the rate of spectrum utilization and has good BER performance.更多还原