Substantially increasing wireless traffic and extending serving coverage is required with the advent of sixth-generation (6G) wireless communication networks. Reconfigurable intelligent surface (RIS) is widely considered as a promising technique which is capable of improving the system sum rate and energy efficiency. Moreover, full-duplex (FD) multi-input-multi-output (MIMO) transmission provides simultaneous transmit and received signals, which theoretically provides twice of spectrum efficiency. However, the self-interference (SI) in FD system is a challenging task requiring high-overhead cancellation, which can be resolved by configuring appropriate phase shifts of RIS. This paper has proposed an RIS-empowered full-duplex interference cancellation (RFIC) scheme in order to alleviate the severe interference in an RIS-FD system. We consider the interference minimization of RIS-FD MIMO while guaranteeing quality-of-service (QoS) of whole system. The closed-form solution of RIS phase shifts is theoretically derived with the discussion of different numbers of RIS elements and receiving antennas. Simulation results reveal that the proposed RFIC scheme outperforms existing benchmarks with more than 50% of performance gain of sum rate.

翻译：随着第六代（6G）无线通信网络的出现，需要大幅增加无线流量并扩展服务覆盖范围。可重构智能表面（RIS）被广泛认为是一种有前途的技术，能够提高系统的总速率和能量效率。此外，全双工（FD）多输入多输出（MIMO）传输提供同时传输和接收信号，理论上提供了两倍的频谱效率。然而，在FD系统中的自干扰（SI）是一个具有挑战性的任务，需要高开销的消除，这可以通过配置合适的RIS相移来解决。本文提出了一种RIS增强全双工干扰消除（RFIC）方案以缓解RIS-FD系统中的严重干扰。我们考虑最小化RIS-FD MIMO的干扰，同时保证整个系统的服务质量（QoS）。理论上推导了RIS相移的闭式解，并讨论了不同数量的RIS元素和接收天线的情况。仿真结果表明，所提出的RFIC方案优于现有基准，速率总和的性能增益超过50%。