摘要
作为一项非常有前景的技术,正交频分复用(orthogonal frequency division multiplexing,OFDM)解决了频谱分配中的带宽不足问题,引领了无线移动通信领域的发展。然而,多普勒频移和本地振荡器频率同步误差的存在会导致载波间干扰(inter carrier interference,ICI),严重影响了正交频分复用。以往文献中提出了许多ICI消除技术,例如自消除法(self-cancellation,SC),最大似然估计法(maximum likelihood estimation,MLE)和加窗法,但需要在带宽冗余和系统复杂度之间权衡。本文基于接收端循环前缀(cyclic prefix,CP)再利用,提出了一种节能且具有有效带宽的新技术来消除ICI。自消除法和最大似然估计法在发送端发送整个OFDM符号数据时会产生冗余,而本文提出的技术仅使用循环前缀数据(仅占总符号带宽的20%)来估计信道,产生与前两者类似结果的同时节省了大量带宽。仿真结果表明,该技术在误差性能方面有显著的改进;并且在实现高带宽增益的同时,能效也得到了实质性的改善。因此,该技术优于传统ICI消除技术。
Orthogonal frequency division multiplexing （OFDM）, a very promising technique that is leading the evolution in wireless mobile communication to sideline the bandwidth scarcity issue in spectrum allocation, is severely affected by the undesirable effects of the frequency offset error, which generates inter cartier interference （ICI） due to the Doppler shift and local oscillator frequency synchronization errors. There are many ICI cancellation techniques available in the literature, such as self-cancellation （SC）, maximum likelihood estimation （MLE）, and windowing, but they present a tradeoff between bandwidth redundancy and system complexity. In this study, a new energy-efficient, bandwidth-effective technique is proposed to mitigate ICI through cyclic prefix （CP） reuse at the receiver end. Unlike SC and MLE where the whole OFDM symbol data is transmitted in duplicate to create redundancy at the transmitter end, the proposed technique uses the CP data （which is only 20% of the total symbol bandwidth） to estimate the channel, and it produces similar results with a huge bandwidth saving. The simulation results show that the proposed technique has a significant improvement in error performance, and a comparative analysis demonstrates the substantial improvement in energy efficiency with high bandwidth gain. Therefore, it outperforms the legacy IC1 cancellation schemes under consideration.
