Spatial Coordination of Electromagnetic Communication Infrastructure, AI Technology Attention and Regional E-commerce Development: Evidence from China

The digital economy rests on a physical substrate that is entirely electromagnetic: every transaction it records travels either as a guided optical wave in the fiber transport network or as a free-space radio wave across the mobile access link. These two layers obey different physics and therefore different deployment economics, yet regional studies of digital-economy development collapse them into a single infrastructure variable. This paper builds a three-system coupling coordination framework linking electromagnetic communication infrastructure, public attention to artificial intelligence (AI), and regional e-commerce development across 31 Chinese provinces from 2012 to 2022. The infrastructure system is resolved into a guided-wave layer, measured by long-haul optical cable route length, route density per square kilometer and broadband access ports, and a free-space layer, measured by mobile switching capacity, its areal density and mobile telephone penetration, because path-loss-limited areal coverage and length-proportional transport scale differently with provincial geography. Subsystem levels are obtained by entropy-weighted TOPSIS and combined through a coupling coordination model generalized to n = 3. A binding-constraint diagnostic then identifies, for each province and year, whether the electromagnetic layer rather than demand limits coordination, and whether the constraint originates in transport or in access. Coordination rises from 0.293 to 0.448 and is spatially clustered in every year, with Moran's I falling from 0.418 to 0.296 while remaining significant at the 1% level; relative dispersion narrows, and inter-regional differences supply about 71% of what remains. The binding subsystem migrates from demand to physical capacity: the electromagnetic layer binds in no province in 2012 but in 14 of 31 by 2022, and 82% of constrained observations are access-limited, concentrated in provinces that are systematically larger in area and more thinly settled.