基于改进NC-OFDM算法的仿真设计与分析

Simulation and Analysis on Improved NC-OFDM Algorithm

正交频分复用(Orthogonal Frequency Division Multiplexing,OFDM)是目前为止最有前景的调制技术,已经被大多数无线和有线通信标准采用。N-coutinuous正交频分复用是OFDM与认知无线电技术相结合转换而来的,但它的旁瓣抑制一直是一个需要解决的问题。为在不影响旁瓣抑制性能的基础上降低算法和接收机的复杂性,文中提出了一种符号填充正交频分复用的时域算法,将n-连续OFDM校正符号只插入到保护间隔中,并将每个OFDM符号无缝连接起来,从而抑制了旁瓣。仿真结果表明,所提算法不影响旁瓣抑制性能,且易于实现,复杂度相比传统N-continuous正交频分复用系统有了明显降低。在K=72的不同信道,信号的误码率降低5 dB。文中还用matlab的simulink来模拟现场可编程门阵列(Field-Programmable Gate Array,FPGA)的N-coutinuous正交频分复用系统的仿真。FPGA具有很大的灵活性,在数字信号处理上具有更快的计算速度和较小的面积,其成本低,风险小,时间上亦具有优势。

Orthogonal Frequency Division Multiplexing(OFDM)is the most promising modulation technology so far.It has been adopted by most wireless and wired communication standards.N-coutinuous Orthogonal Frequency Division Multiplexing is a combination of OFDM and cognitive radio technology,but its sidelobe suppression has always been a problem to be solved.In order to reduce the complexity of the algorithm and receiver without affecting the sidelobe suppression performance,a symbol-filled OFDM time-domain algorithm is proposed,it inserts n-continuous OFDM correction symbols only into the protection interval and seamlessly connects each OFDM symbol,thus suppressing side lobes.The simulation shows that the proposed algorithm does not affect the sidelobe suppression performance,and is easy to implement.The complexity is significantly lower than the traditional N-continuous OFDM system.In different channels of K=72,Signal BER reduction by 5dB.The simulink of MATLAB is used to simulate the simulation of N-coutinuous OFDM systems in FPGA.FPGA has great flexibility,and has higher computing speed and smaller area in digital signal processing.Low cost,low risk,time advantage.