Receiver Design for OTFS with a Fractionally Spaced Sampling Approach
Receiver Design for OTFS with a Fractionally Spaced Sampling Approach
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DOI：
10.1109/twc.2021.3055585
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发表时间：
2021-07-01
影响因子：
10.4
通讯作者：
Ding, Zhi
中科院分区：
文献类型：
--
作者：
Ge, Yao;Deng, Qinwen;Ding, Zhi
最近出现的正交时频空间（OTFS）调制作为一种新的PHY层机制比传统的正交频分复用（OFDM）更适合于高移动性无线通信场景。尽管多项研究已经使用理论和理想基带脉冲形状分析了OTFS性能，但一个具有挑战性和开放性的问题是开发用于必须依赖于非理想脉冲形状进行传输的实际OTFS系统的有效接收器。本工作的重点是OTFS的实际接收机的设计。我们考虑分数间隔采样（FSS）接收机中的采样率是一个整数倍的符号率。对于OTFS传输中使用的矩形脉冲，我们推导出OTFS在延迟-多普勒域中的一般信道输入-输出关系，而不依赖于不切实际的假设，例如理想的双正交脉冲和网格上的延迟/多普勒频移。我们提出了两种均衡算法：迭代组合消息传递（Turbo Message Passing，简称MMS）和Turbo消息传递（Turbo Message Passing，简称TMP），利用延迟多普勒信道稀疏性和信道分集增益通过FSS进行符号检测。我们分析了TMP接收机的收敛性能，并提出了简化的消息传递（MP）接收机，以进一步降低复杂度。我们的FSS接收机表现出更强的性能比传统的接收机和鲁棒性的不完善的信道状态信息的知识。
The recent emergence of orthogonal time frequency space (OTFS) modulation as a novel PHY-layer mechanism is more suitable in high-mobility wireless communication scenarios than traditional orthogonal frequency division multiplexing (OFDM). Although multiple studies have analyzed OTFS performance using theoretical and ideal baseband pulseshapes, a challenging and open problem is the development of effective receivers for practical OTFS systems that must rely on non-ideal pulseshapes for transmission. This work focuses on the design of practical receivers for OTFS. We consider a fractionally spaced sampling (FSS) receiver in which the sampling rate is an integer multiple of the symbol rate. For rectangular pulses used in OTFS transmission, we derive a general channel input-output relationship of OTFS in delay-Doppler domain without the common reliance on impractical assumptions such as ideal bi-orthogonal pulses and on-the-grid delay/Doppler shifts. We propose two equalization algorithms: iterative combining message passing (ICMP) and turbo message passing (TMP) for symbol detection by exploiting delay-Doppler channel sparsity and the channel diversity gain via FSS. We analyze the convergence performance of TMP receiver and propose simplified message passing (MP) receivers to further reduce complexity. Our FSS receivers demonstrate stronger performance than traditional receivers and robustness to the imperfect channel state information knowledge.