In order to improve the performance of the security-reliability tradeoff （SRT）, a joint jammer and user scheduling （JJUS） scheme is proposed. First, a user with the maximal instantaneous channel capacity is selected to transmit its signal to the base station （ BS） in the transmission time slot. Then, when the user transmits its signal to BS, the jammer is invoked for transmitting artificial noise in order to perturb the eavesdropper’s reception. Simulation results show that increasing the number of users can enhance the SRT performance of the proposed JJUS scheme. In addition, the SRT performance of the proposed JJUS scheme is better than that of the traditional round-robin scheduling and pure user scheduling schemes. The proposed JJUS scheme can guarantee the secure transmission even in low main-to-eavesdropper ratio（ MER） regions.
提出了一种新改进的正交频分复用(Orthogonal Frequency Division Multiplexing,OFDM)系统时域帧同步检测方法。该方法使用门限机制的延时相关帧检测原理,利用训练序列的互相关信息共同完成系统的帧同步检测。给出了在不同信道和不同信噪比环境下所进行的仿真结果,仿真结果表明,该方法解决了Schmidl&Cox定时同步算法出现的峰值平台和H.Minn算法的多个高旁峰值问题,提高了同步的精确度,可以对抗较大的频偏,适应性增强,且易于实现。
