多载波CDMA子载波频率盲估计算法及其性能分析*

针对频谱感知和多载波CDMA信号解调的实际应用，根据多载波CDMA信号的循环平稳特性，提出了一种利用高阶循环累积量估计多载波CDMA信号子载波频率的方法。由于高阶循环累积量可以有效地抑制平稳噪声和非平稳高斯噪声，通过理论分析可以证明在上述噪声背景下，子载波采用BPSK调制的多载波CDMA信号的四阶循环累积量仅在循环频率为子载波频率处存在，可以通过检测此循环频率来实现子载波的估计。考虑到多载波CDMA信号发端可以采用不同的窗函数以降低频谱泄露，以常见的几种窗函数为例进行了算法仿真，发现本算法对窗函数的变化不

Blind estimation algorithm of multi-carrier CDMA sub-carrier frequencies and its performance analysis

Aiming at the practical application of spectrum sensing and multi-carrier CDMA signals demodulation, this paper proposed a method to estimate sub-carriers frequency of multi-carrier CDMA signals utilizing higher-order cyclic cumulants based on the cyclic stationary characteristic of multi-carrier CDMA signals. Because higher-order cyclic cumulants could effectively suppress stationary noise and non-stationary Gaussian noise, through theoretical analysis, it could prove that the fourth-order cyclic cumulant of the multi-carrier CDMA signal using BPSK modulation only exist in the cycle frequency of sub-carrier frequencies under the above noise background, so it could estimate the sub-carrier frequency of multi-carrier CDMA signals by detecting the of peak of cyclic frequencies. Duo to the fact that the multi-carrier CDMA signal could use different window function to reduce spectral leakage, by using several common window functions in the algorithm simulation, found that the algorithm is not sensitive to the changes of the window function, with highly robustness. Simulation results have verified the correctness and effectiveness of the algorithm.