存在射频损伤的OTFS的同步与信道估计
Synchronization and Channel Estimation of OTFS with RF Impairments
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中文总结 AI 辅助
针对高移动性场景下OTFS系统的射频损伤问题，本文提出基于PCP导频的同步与信道估计框架，联合估计CFO与有效信道，仿真验证了所提技术的有效性。
中文摘要 AI 辅助
正交时频空间（OTFS）调制是未来无线网络极具前景的波形，但其对射频（RF）损伤的鲁棒性仍相对缺乏研究。低成本射频前端对下一代无线系统至关重要，但其性能常受射频损伤劣化，如发射端同相-正交相不平衡（IQI）、相位噪声（PN）、定时偏移（TO）和载波频率偏移（CFO）。因此，本文针对高移动性场景下OTFS系统中这些射频损伤的估计与补偿展开研究。本文构建了统一系统模型，将TO、CFO、PN、IQI及其他信道效应纳入有效信道表示；采用循环前缀导频（PCP，一种适合OTFS的低峰均功率比（PAPR）导频），提出导频辅助的同步与估计框架，所提TO估计技术利用了PCP的双重周期性；还提出基于最大似然的技术，采用复指数基扩展模型（CE-BEM）联合估计CFO与有效信道；最终在延迟-多普勒域构建线性检测模型，以缓解射频损伤导致的残余干扰。仿真结果证实了所提同步与信道估计技术的有效性。
英文摘要
Orthogonal Time Frequency Space (OTFS) modulation is a promising waveform for future wireless networks. However, its resilience to RF impairments remains relatively understudied. Low-cost RF front ends are crucial for next-generation wireless systems, yet their performance is often degraded by RF impairments such as transmit IQ imbalance (IQI), phase noise (PN), timing offset (TO), and carrier frequency offset (CFO). Hence, this paper addresses the estimation and compensation of these RF impairments in OTFS systems under high mobility. A unified system model is developed that incorporates TO, CFO, PN, IQI and other channel effects into an effective channel representation. Using the pilot with cyclic prefix (PCP), a low-peak to average power ratio (PAPR) pilot suitable for OTFS, we propose a pilot-aided synchronization and estimation framework. The dual periodicity of PCP is exploited in our proposed TO estimation technique. A maximum-likelihood-based technique is also proposed to jointly estimate the CFO and effective channel using a complex exponential basis expansion model (CE-BEM). Finally, a linear detection model is formulated in the delay-Doppler domain to mitigate residual interference caused by RF impairments. Our simulation results corroborate the efficacy of our proposed synchronization and channel estimation techniques.
