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，大幅提升无线流量并扩展服务覆盖范围成为迫切需求。可重构智能表面(RIS)被广泛认为是一种能够提升系统总速率和能量效率的 promising 技术。此外，全双工(FD)多输入多输出(MIMO)传输可实现同时收发信号，理论上能提供两倍的频谱效率。然而，FD系统中的自干扰(SI)是一项极具挑战性的任务，需要高开销的消除机制，这可通过配置RIS的适当相移来解决。本文提出了一种RIS赋能的全双工干扰消除(RFIC)方案，以缓解RIS-FD系统中的严重干扰。我们在保证整个系统服务质量(QoS)的前提下，考虑RIS-FD MIMO的干扰最小化问题。通过理论推导给出了RIS相移的闭式解，并讨论了不同数量的RIS单元和接收天线的情况。仿真结果表明，所提出的RFIC方案优于现有基准方案，总速率性能增益超过50%。