The key advantage of successive relaying (SR) networks is their ability to mimic the full-duplex (FD) operation with half-duplex (HD) relays. However, the main challenge that comes with such schemes is the associated inter-relay interference (IRI). In this work, we propose a reconfigurable intelligent surface (RIS)-enhanced SR network, where one RIS is deployed near each of the two relay nodes to provide spatial suppression of IRI, and to maximize the gain of desired signals. The resultant max-min optimization problem with joint phase-shift design for both RISs is first tackled via the semidefinite programming (SDP) approach. Then, a lower-complexity solution suitable for real-time implementation is proposed based on particle swarm optimization (PSO). Numerical results demonstrate that even relatively small RISs can provide significant gains in achievable rates of SR networks, and the proposed PSO scheme can achieve a near optimal performance.

翻译：连续中继(SR)网络的主要优点是它们能够以半双倍(HD)继电器模仿全双倍(FD)操作。然而,这种计划的主要挑战在于相关的中继干扰(IRI)。在这项工作中,我们提议一个可重新配置的智能增强型SR(RIS)网络,在两个中继节点的每个节点附近部署一个RIS,以提供IRI的空间压抑,并最大限度地获得所希望的信号。由此造成的两个RIS联合分阶段设计的最大优化问题首先通过半成品方案(SDP)方法解决。然后,一个适合实时执行的更低的复杂度解决方案是根据粒子温优化(PSO)提出的。数字结果表明,即使是相对较小的RIS也能够在可实现的SR网络速率上带来重大收益,而拟议的PSO计划可以取得接近最佳的绩效。