🤖 AI Summary
To address the limited signal routing flexibility in single-RIS indoor systems caused by static reflection, this paper proposes a cooperative dual-reconfigurable intelligent surface (RIS) architecture. The first RIS provides baseline channel enhancement, while the second RIS (RIS₂) dynamically adjusts its reflection phases according to source data bits—enabling bit-driven physical-layer spatial modulation and beam-level signal routing. This work pioneers the integration of spatial shift keying (SSK) with dynamic phase mapping across two RISs, establishing an end-to-end transmission framework under a multi-hop channel model. Experimental results demonstrate significant improvements in achievable capacity and substantial reduction in outage probability across varying carrier frequencies and inter-RIS distances, thereby enabling high-accuracy, data-dependent intelligent indoor wireless coverage.
📝 Abstract
Reconfigurable intelligent surfaces (RISs) are gaining traction for their ability to reshape wireless environments with low energy consumption. However, prior studies primarily explore single-RIS deployments with static or semi-static reflection control. In this paper, we propose a novel dual-RIS-assisted architecture for smart indoor wireless signal routing, wherein the second RIS (RIS$_2$) is dynamically configured based on source data bits to steer signals toward specific receivers or indoor zones. The first RIS (RIS$_1$), positioned near a fed antenna or access point, passively reflects the incident signal. RIS$_2$, equipped with a lightweight controller, performs bit-driven spatial modulation to enable data-dependent direction selection at the physical layer. We develop a complete end-to-end system model, including multi-hop channel representation, RIS phase configuration mapping, and signal detection based on space shift keying (SSK). Performance analysis is evaluated in terms of achievable capacity and outage probability under varying inter-RIS distances and carrier frequencies.