论文标题
在快速褪色通道上，低复杂频域均衡
Low-Complexity Frequency Domain Equalization over Fast Fading Channels
论文作者
论文摘要
快速褪色通道上的无线通信具有挑战性，需要频繁的通道跟踪或复杂的信号方案，例如正交时间频率空间（OTFS）调制。在本文中，我们提出了基于新型离散延迟时间和频率多普勒通道模型，提出了低复杂性频域均衡来对抗快速褪色。利用频率多普勒通道矩阵的圆条纹对角性质，我们引入了具有完全可分离的多普勒扩散的OTFS系统的低复杂频域最小均方误差（MMSE）均衡。我们还证明，所提出的MMSE均衡适用于常规的正交频施加多路复用（OFDM）和单载频域频率域均衡（SC-FDE）系统，具有短信号框架和可部分解析的多普勒差异。概括输入输出数据符号关系后，我们通过通道矩阵特征值分解分析了均衡性能，并为理论位比率得出了封闭形式的表达。 OTF，OFDM和SC-FDE调制的仿真结果验证了所提出的低复杂频域均衡方法可以有效利用快速褪色通道的时间多样性。即使有部分可分离的多普勒扩散，常规的SC-FDE也可以在接近OTF的情况下实现性能，尤其是在具有主导路径的快速褪色通道中。
Wireless communications over fast fading channels are challenging, requiring either frequent channel tracking or complicated signaling schemes such as orthogonal time frequency space (OTFS) modulation. In this paper, we propose low-complexity frequency domain equalizations to combat fast fading, based on novel discrete delay-time and frequency-Doppler channel models. Exploiting the circular stripe diagonal nature of the frequency-Doppler channel matrix, we introduce low-complexity frequency domain minimum mean square error (MMSE) equalization for OTFS systems with fully resolvable Doppler spreads. We also demonstrate that the proposed MMSE equalization is applicable to conventional orthogonal frequency division multiplexing (OFDM) and single carrier frequency domain equalization (SC-FDE) systems with short signal frames and partially resolvable Doppler spreads. After generalizing the input-output data symbol relationship, we analyze the equalization performance via channel matrix eigenvalue decomposition and derive a closed-form expression for the theoretical bit-error-rate. Simulation results for OTFS, OFDM, and SC-FDE modulations verify that the proposed low-complexity frequency domain equalization methods can effectively exploit the time diversity over fast fading channels. Even with partially resolvable Doppler spread, the conventional SC-FDE can achieve performance close to OTFS, especially in fast fading channels with a dominating line-of-sight path.
