This paper introduces a self-interference cancellation (SIC) technique for data over cable service interface specification (DOCSIS) 3.1 uplink system with full duplex. At DOCSIS 3.1 uplink environment with full duplex, cable modems (CMs) transmit their request information (upstream) to CM termination system (CMTS), and CMTS transmits its broadcasting data (downstream) through the same frequency band at the same time. Therefore, the upstream becomes a signal of interest (SoI), and consequently the high-power feedback downstream causes self-interference (SI) signal against SoI. However, under the practical DOCSIS 3.1 uplink environment, achieving time and frequency synchronization between upstream and downstream is a challenging problem and additional signal processing technique should be applied. Therefore, in order to improve the processing efficiency and to reflect practical communication environment, the time-domain SIC technique, which does not require any synchronization between upstream and downstream is proposed. Furthermore, since the proposed scheme can consider various practical signal processing aspects, such as multi-path fading channel estimation and nonlinear element estimation of SI signal, it can be efficiently applied for the practical DOCSIS 3.1 uplink system. Test results indicate that the uplink system with 1024QAM (mandatory maximum constellation) can be operated in the case that there is SI estimation interval with two OFDM symbols.

中文翻译：

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全双工DOCSIS 3.1上行链路系统时域自干扰消除

本文介绍了一种用于全双工有线数据服务接口规范 (DOCSIS) 3.1 上行链路系统的自干扰消除 (SIC) 技术。在具有全双工的 DOCSIS 3.1 上行链路环境中，电缆调制解调器 (CM) 将其请求信息（上行）传输到 CM 终端系统（CMTS），而 CMTS 同时通过相同的频段传输其广播数据（下行）。因此，上游成为感兴趣的信号 (SoI)，因此下游的高功率反馈会导致针对 SoI 的自干扰 (SI) 信号。然而，在实际的 DOCSIS 3.1 上行环境下，实现上行和下行之间的时间和频率同步是一个具有挑战性的问题，应该应用额外的信号处理技术。所以，为了提高处理效率和反映实际通信环境，提出了不需要上下行同步的时域SIC技术。此外，由于所提出的方案可以考虑各种实际信号处理方面，例如多径衰落信道估计和SI信号的非线性元素估计，因此可以有效地应用于实际的DOCSIS 3.1上行链路系统。测试结果表明，1024QAM（强制最大星座）上行系统可以在两个OFDM符号存在SI估计区间的情况下运行。由于所提出的方案可以考虑各种实际信号处理方面，例如多径衰落信道估计和SI信号的非线性元素估计，因此可以有效地应用于实际的DOCSIS 3.1上行链路系统。测试结果表明，1024QAM（强制最大星座）上行系统可以在两个OFDM符号存在SI估计区间的情况下运行。由于所提出的方案可以考虑各种实际信号处理方面，例如多径衰落信道估计和SI信号的非线性元素估计，因此可以有效地应用于实际的DOCSIS 3.1上行链路系统。测试结果表明，1024QAM（强制最大星座）上行系统可以在两个OFDM符号存在SI估计区间的情况下运行。