Non-Reciprocal Dynamic Metasurface Antenna: Practical Multiport-Network Modeling and Optimization for Multi-User Interference Resilience

Shuai S. A. Yuan, Jean Tapie, Bahman Amrahi, Viktar Asadchy, Philipp del Hougne

Channel reciprocity fundamentally limits full-duplex (FD) base stations due to multi-user co-channel interference. We examine the potential of deploying a non-reciprocal dynamic metasurface antenna (NR-DMA) at the base station to overcome this limitation. Our NR-DMA architecture connects a single circulator to three feed ports of a multi-feed DMA with strong mutual coupling (MC) between its seven feeds and 96 1-bit-programmable meta-elements. We model our system with multiport network theory, using experimentally estimated proxy parameters of a fabricated 19-GHz DMA and the measured circulator response. Our NR-DMA's reconfigurability is captured by a diagonal tunable scattering matrix, showing that non-reciprocal DMAs and RISs need not require a "beyond-diagonal" tunable scattering matrix. We jointly optimize the DMA state, analog feed weights, circulator-port assignment, and circulation direction. Our optimized NR-DMA realizes distinct forward and reverse channel responses. In our interference-limited high-SNR case study, the NR-DMA improves the FD sum rate by about 60% over a reciprocal DMA benchmark. Comparisons with proxy objectives and MC-unaware optimization show that end-to-end FD optimization and MC-aware modeling are both essential.