Terahertz (THz) wireless communication is envisioned as a promising technology, which is capable of providing ultra-high-rate transmission up to Terabit per second. However, some hardware imperfections, which are generally neglected in the existing literature concerning lower data rates and traditional operating frequencies, cannot be overlooked in the THz systems. Hardware imperfections usually consist of phase noise, in-phase/quadrature imbalance, and nonlinearity of power amplifier. Due to the time-variant characteristic of phase noise, frequent pilot insertion is required, leading to decreased spectral efficiency. In this paper, to address this issue, a novel pilot design strategy is proposed based on index modulation (IM), where the positions of pilots are flexibly changed in the data frame, and additional information bits can be conveyed by indices of pilots. Furthermore, a turbo receiving algorithm is developed, which jointly performs the detection of pilot indices and channel estimation in an iterative manner. It is shown that the proposed turbo receiver works well even under the situation where the prior knowledge of channel state information is outdated. Analytical and simulation results validate that the proposed schemes achieve significant enhancement of bit-error rate performance and channel estimation accuracy, whilst attaining higher spectral efficiency in comparison with its classical counterpart.

中文翻译：

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具有灵活指数调制辅助导频设计的太赫兹无线通信


太赫兹（THz）无线通信被认为是一项有前途的技术，能够提供高达每秒太比特的超高速率传输。然而，在太赫兹系统中不能忽视一些硬件缺陷，这些缺陷在现有文献中通常被忽视，涉及较低的数据速率和传统的工作频率。硬件缺陷通常包括相位噪声、同相/正交不平衡以及功率放大器的非线性。由于相位噪声的时变特性，需要频繁插入导频，导致频谱效率下降。为了解决这个问题，本文提出了一种基于索引调制（IM）的新型导频设计策略，其中导频的位置在数据帧中灵活改变，并且可以通过导频索引来传达附加信息位。此外，还开发了一种turbo接收算法，该算法以迭代方式联合执行导频索引检测和信道估计。结果表明，即使在信道状态信息的先验知识过时的情况下，所提出的涡轮接收器也能很好地工作。分析和仿真结果验证了所提出的方案与经典方案相比，可以显着提高误码率性能和信道估计精度，同时获得更高的频谱效率。