Visibility Region-Based Surface Identification for Near-Field XL-MIMO at THz Frequencies
IEEE Open Journal of the Communications Society, cilt.7, ss.118-137, 2026 (ESCI, Scopus)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 7
- Basım Tarihi: 2026
- Doi Numarası: 10.1109/ojcoms.2025.3648535
- Dergi Adı: IEEE Open Journal of the Communications Society
- Derginin Tarandığı İndeksler: Emerging Sources Citation Index (ESCI), Scopus, Compendex, INSPEC, Directory of Open Access Journals
- Sayfa Sayıları: ss.118-137
- Anahtar Kelimeler: diffuse scattering, Extra-large MIMO (XL-MIMO), power angle profile (PAP), rough surface, smooth surface, specular reflection, visibility region (VR)
- İstanbul Medipol Üniversitesi Adresli: Evet
Özet
The evolution from fifth-generation (5G) networks to sixth-generation (6G) networks demands ultra-high data rates, low latency, and robust connectivity. Terahertz (THz) band offers broad bandwidth but suffers from severe path loss and high blockage sensitivity, making non-line-of-sight (NLoS) links challenging. While large antenna arrays mitigate attenuation, performance still depends on environmental surface interactions. In this context, extremely large-scale multiple-input multiple output (XL-MIMO) systems provide a unique advantage by offering enhanced angular resolution for better characterization of surface interactions. Building on these insights, we propose a visibility region (VR)-based framework for surface identification in near field (NF) THz XL-MIMO systems. By incorporating surface scattering characteristics into VR modeling, we derive power-angle profiles (PAPs) that serve as unique signatures to distinguish smooth, medium, and rough surfaces based on their scattering power behavior and angular spread. Our analysis of VR power across antenna indices highlights how both proximity and surface characteristics affect the ability to identify surfaces. The performance of the proposed framework is evaluated through root mean square error, and probability of detection analyses, with results compared against a conventional scattering-agnostic NF channel. The proposed method also achieves significantly reduced computational complexity, enabling real-time execution while maintaining high estimation accuracy. Furthermore, a Gaussian filter is applied to reduce diffuse scattering fluctuations, making the angular broadening from surfaces more obvious. In addition, capacity analysis is performed under single- and multi-surface scenarios, revealing trade-offs between path loss reduction at close distances and multipath richness due to multiple surfaces. The capacity analysis further demonstrate that the scattering-aware framework achieves higher overall throughput and approaches the analytical upper bound. The results confirm the practicality of the proposed approach and highlight surface characteristics as a critical design parameter for establishing robust NLoS connectivity in NF THz XL-MIMO while maintaining lower complexity.