The ability to cancel an OFDM signal is important to many wireless communication systems including Power-Domain Non-orthogonal Multiple Access (PD-NOMA), Rate-Splitting Multiple Access (RSMA), and spectrum underlay for dynamic spectrum access. In this paper, we show that estimating the windowing applied at the transmitter is important to that cancellation. Windowing at the transmitter is a popular means to control the bandwidth of an Orthogonal Frequency Division Multiplexed (OFDM) symbol and is overlooked in most literature on OFDM signal cancellation. We show the limitation to the amount of cancellation that can be achieved without knowledge of OFDM windowing. We show that the window can be estimated from received samples alone, and that window estimate can be used to improve the signal cancellation. The window is estimated in the presence of noise and imperfect estimates of the center frequency offset (CFO) and the channel. We conclude with results using synthetic and over-the-air data where we demonstrate a 5.3 dB improvement to OFDM signal cancellation over existing methods in an over-the-air experiment.

翻译：OFDM信号对消能力对多种无线通信系统至关重要，包括功率域非正交多址接入（PD-NOMA）、速率分裂多址接入（RSMA）以及用于动态频谱接入的频谱底层技术。本文证明，估计发射端采用的加窗处理对实现该对消功能具有重要意义。发射端加窗是控制正交频分复用（OFDM）符号带宽的常用手段，但多数OFDM信号对消文献均忽视了这一因素。我们揭示了在不了解OFDM加窗信息时所能达到的对消性能极限。研究表明，仅通过接收样本即可实现窗函数估计，且该窗估计可用于改善信号对消效果。在存在噪声且中心频率偏移（CFO）与信道参数估计不完美的情况下，我们完成了窗函数估计。最后通过合成数据与空中数据实验验证了方法的有效性：在真实无线环境实验中，该方法相较现有方案将OFDM信号对消性能提升了5.3 dB。