[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"doc-detail-85361-en":3,"doc-seo-85361-105":29,"detail-sidebar-cat-0-en-105":89},{"code":4,"msg":5,"data":6},0,"success",{"doc_id":7,"user_id":8,"nickname":9,"user_avatar":10,"doc_module":4,"category_id":11,"category_name":12,"doc_title":13,"doc_description":14,"doc_content":15,"file_id":16,"file_url":17,"file_type":18,"file_size":19,"view_count":4,"is_deleted":4,"is_public":20,"is_downloadable":20,"audit_status":20,"page_count":21,"language":22,"language_code":23,"site_id":24,"html_lang":23,"table_of_contents":25,"faqs":26,"seo_title":13,"seo_description":14,"update_tm":27,"read_time":28},85361,7971461741311,"Ophelia","https://ap-avatar.wpscdn.com/avatar/74000253aff267980c6?x-image-process=image/resize,m_fixed,w_180,h_180&k=1779345379180704826",8,"Research & Report","Visibility-Region Coupling in XL-MIMO AGV Fleets: Triple-Role Modeling and Masked Beamforming","Extremely large-scale multiple-input multiple-output (XL-MIMO) supports automated guided vehicle (AGV) fleets in smart port terminals, but metallic containers create spatial non-stationarity where each AGV is seen only by a subset of the array, its visibility region (VR). The work models each AGV as a user, a metallic scatterer, and a physical blocker, yielding coupled user channels and VRs. It proposes a VR-coupled channel model and a masked weighted WMMSE downlink beamforming framework that enforces VR constraints while reducing complexity, achieving over threefold sum-rate gains in realistic simulations.","This work has been submitted to the IEEE for possible publication. Copyright may be transferred without notice, after which this version may no longer be accessible.  \n1  \nVisibility-Region Coupling in XL-MIMO AGV Fleets: Triple-Role Modeling and Masked  \nBeamforming  \nChanghao He, Xiaojuan Zhang, Senior Member, IEEE  \narXiv :2607 . 1 178 1v 1 [ cs .IT] 13 Jul 2026  \nAbstract—Extremely large-scale multiple-input multipleoutput (XL-MIMO) is a promising technology for supporting automated guided vehicle (AGV) fleets in smart port terminals. However, the metallic container environment induces spatial non-stationarity, whereby each AGV is visible to only a subset of the array, referred to as its visibility region (VR). Unlike existing XL-MIMO models that assume user-independent VRs, we show that each AGV simultaneously acts as a communication user, a metallic scatterer, and a blocker, resulting in coupled user channels and VRs. We formulate this triple-role effect through a VR-coupled channel model and develop a VR-aware downlink beamforming framework based on masked weighted minimum mean-square error (WMMSE), where the masking operation exactly enforces VR support constraints while significantly reducing computational complexity. Simulation results in a realistic smart port scenario demonstrate more thana threefold sum-rate improvement over VR-unaware baselines, with the gains becoming increasingly pronounced as fleet density increases.  \nIndex Terms—XL-MIMO, visibility region, spatial nonstationarity, AGV, channel modeling, smart port.  \nI. INTRODUCTION  \nMODERN automated container terminals rely on fleets of  \nautomated guided vehicles (AGVs) that require ultrareliable and low-latency wireless connectivity for real-time coordination and navigation [1] . Extremely large multipleinput multiple-output (XL-MIMO) systems, equipped with hundreds of antenna elements over large apertures, provide the array and multiplexing gains needed to support dense AGV deployments [2] . Owing to the large array aperture, however, users operate in the radiative near-field and experience spatially non-stationary channels, where each user is visible to only a subset of the array, referred to as its visibility region (VR) [2], [3] .  \nContainer terminals further complicate wireless propagation. Dense metallic container stacks create severe blockage and strong specular reflections, resulting in highly locationdependent propagation characteristics [4] . Existing studies have investigated VR modeling [3], energy-efficient transmission under spatial non-stationarity [5], sub-array selection [6], VR detection [7], and modular XL-MIMO architectures [8] . Nevertheless, these works generally assume user-independent  \nC. H. He is with King Abdullah University of Science and Technology (KAUST), Saudi Arabia ([changhao.he@kaust.edu.sa](changhao.he@kaust.edu.sa)). X. J. Zhang is with the Institute of Advanced Intelligence and Computing, Agency for Science, Technology and Research (A*STAR IAIC), Singapore ([xiaojuanzhang@ieee.org](xiaojuanzhang@ieee.org)). Corresponding author: X. J. Zhang.  \npropagation and treat VRs as static or independently varying across users.  \nA distinctive characteristic of AGV fleets is that every AGV simultaneously acts as a communication user, a metallic scatterer generating additional reflection paths, and a physical blocker that may obstruct propagation for neighboring AGVs [9] . Consequently, the channel and VR of one AGV depend not only on its own position but also on the locations of surrounding AGVs, giving rise to dynamic inter-user VR coupling that is absent from conventional XL-MIMO channel models. Exploiting this coupling is therefore essential for efficient resource allocation in dense AGV networks.  \nThe main contributions of this letter are as follows.  \n• We develop a near-field spatially non-stationary channel model that decomposes the NLoS channel into static container-induced and dynamic AGV-induced components. Based on","cbCaijAhiBBnOLYM","https://ap.wps.com/l/cbCaijAhiBBnOLYM","pdf",398437,1,4,"English","en",105,"# Introduction\n# System Model and Triple-Role Coupling\n## VR-Coupled Near-Field Channel","[{\"question\":\"What is the visibility region (VR) problem in XL-MIMO for AGV fleets?\",\"answer\":\"In smart port terminals, metallic container environments cause spatial non-stationary channels, so each AGV can only be visible to a subset of the array elements, defined as its visibility region (VR).\"},{\"question\":\"How does the proposed triple-role effect change the channel modeling?\",\"answer\":\"Each AGV simultaneously acts as a communication user, a metallic scatterer generating additional reflection paths, and a blocker that can shadow links for neighboring AGVs, making both channels and VRs inter-dependent.\"},{\"question\":\"What is the main idea behind VR-aware masked WMMSE downlink beamforming?\",\"answer\":\"The method formulates VR constraints directly through a masking operation while solving a VR-constrained weighted minimum mean-square error (WMMSE) beamforming problem, enforcing VR support and reducing computational complexity compared with VR-unaware baselines.\"}]",1784202777,10,{"code":4,"msg":30,"data":31},"ok",{"site_id":24,"language":23,"slug":32,"title":13,"keywords":33,"description":14,"schema_data":34,"social_meta":84,"head_meta":86,"extra_data":88,"updated_unix":27},"visibility-region-coupling-in-xl-mimo-agv-fleets-triple-role-modeling-and-masked-beamforming","",{"@graph":35,"@context":83},[36,52,66],{"@type":37,"itemListElement":38},"BreadcrumbList",[39,43,47,50],{"item":40,"name":41,"@type":42,"position":20},"https://docshare.wps.com","Home","ListItem",{"item":44,"name":45,"@type":42,"position":46},"https://docshare.wps.com/document/","Document",2,{"item":48,"name":12,"@type":42,"position":49},"https://docshare.wps.com/document/research-report/",3,{"item":51,"name":13,"@type":42,"position":21},"https://docshare.wps.com/document/visibility-region-coupling-in-xl-mimo-agv-fleets-triple-role-modeling-and-masked-beamforming/85361/",{"url":51,"name":13,"@type":53,"author":54,"headline":13,"publisher":56,"fileFormat":59,"inLanguage":23,"description":14,"dateModified":60,"datePublished":60,"encodingFormat":59,"isAccessibleForFree":61,"interactionStatistic":62},"DigitalDocument",{"name":9,"@type":55},"Person",{"url":40,"name":57,"@type":58},"DocShare","Organization","application/pdf","2026-07-16",true,{"@type":63,"interactionType":64,"userInteractionCount":4},"InteractionCounter",{"@type":65},"ViewAction",{"@type":67,"mainEntity":68},"FAQPage",[69,75,79],{"name":70,"@type":71,"acceptedAnswer":72},"What is the visibility region (VR) problem in XL-MIMO for AGV fleets?","Question",{"text":73,"@type":74},"In smart port terminals, metallic container environments cause spatial non-stationary channels, so each AGV can only be visible to a subset of the array elements, defined as its visibility region (VR).","Answer",{"name":76,"@type":71,"acceptedAnswer":77},"How does the proposed triple-role effect change the channel modeling?",{"text":78,"@type":74},"Each AGV simultaneously acts as a communication user, a metallic scatterer generating additional reflection paths, and a blocker that can shadow links for neighboring AGVs, making both channels and VRs inter-dependent.",{"name":80,"@type":71,"acceptedAnswer":81},"What is the main idea behind VR-aware masked WMMSE downlink beamforming?",{"text":82,"@type":74},"The method formulates VR constraints directly through a masking operation while solving a VR-constrained weighted minimum mean-square error (WMMSE) beamforming problem, enforcing VR 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