CO-OFDM系统中一种改进的基于线性内插的相位噪声补偿算法

为补偿CO-OFDM系统中相位噪声引起的干扰,提出了一种改进的基于线性内插的相位噪声补偿算法.该算法利用共轭导频估计相位噪声的均值,然后通过线性内插获得相位噪声的估计值,最后通过频域补偿来恢复出调制信号.此外针对求幅角的非线性运算中存在的相位周跳的问题,文章提出的修正方法能够有效地改善周跳情况的发生.分析与仿真表明:该算法在不同线宽条件下均能提升一定的SNR增益且算法的复杂度低.     

A novel improved SLM scheme of the PAPR reduction technology in CO-OFDM systems

The higher peak-to-average power ratio (PAPR) is a major shortcoming of coherent optical orthogonal frequency division multiplexing (CO-OFDM) systems. Selective mapping (SLM) technology can effectively reduce the probability of high PAPR, but it has higher computational complexity, and requires additional bandwidth to transmit the side information, which will affect the transmission efficiency of the system. In response to these shortcomings, a novel improved SLM (NI-SLM) scheme with low complexity and without side information is proposed. Simulation results show that the proposed scheme can exponentially reduce the computational complexity, and the bit error rate (BER) performance can greatly approach the original signal. What’s more, it shows the better PAPR reduction performance.     

基于人工蜂群算法的多用户OFDM自适应资源分配方案

针对多用户正交频分复用(OFDM)自适应资源分配中用户公平性和系统容量的问题,本文提出了一种联合子载波分配和功率分配的方案。在子载波分配中,首先确定每个用户需要的子载波数量,然后根据用户的速率比例继续分配子载波,最后分配剩余子载波。在功率分配中,通过人工蜂群(ABC)算法的全局搜索实现在所有用户之间的功率寻优,并利用等功率的分配方式对每个用户的子载波进行单用户功率分配。从仿真结果中可以看出,本文算法不仅可以兼顾用户的公平性,同时也有效地提高了系统的吞吐量,从而证明了本文算法的有效性。