Rashmi, H.Chaturvedi, A.D'Souza, J.2026-02-032024Physical Communication, 2024, 67, , pp. -18744907https://doi.org/10.1016/j.phycom.2024.102527https://idr.nitk.ac.in/handle/123456789/20783Simultaneously Transmitting and Reflecting (STAR) Reconfigurable Intelligent Surface (RIS) demonstrates the ability to split incoming electromagnetic beams to transmit and reflect signals in a concurrent manner. Thus, compared to conventional RIS, service area coverage is extended on deploying STAR-RIS. This paper presents a geometry-based stochastic channel model (GBSM) of STAR-RIS-assisted outdoor wireless channel. For the considered semi-urban environment, STAR-RIS operates in energy-splitting mode. Channel between a base station (BS) and users (U<inf>R</inf>/U<inf>T</inf>) located on the reflect/transmit (R/T) side of STAR-RIS is characterised using a GBSM. An elliptical model incorporates the inevitable presence of scatterers in the considered semi-urban segment. Statistical properties of the wireless channel under test are analysed using space–time cross-correlation function (ST-CCF) and temporal auto-correlation function (ACF). Further, to gain holistic insight about the wireless channel behaviour, normalised Doppler power spectral density (ND-PSD) is estimated for semi-urban segment having three distinct underlying hypothesis as: (i) Wireless channel is governed by Rayleigh fading model, (ii) Wireless Channel is equipped with conventional RIS and (iii) STAR-RIS is an integral part of the considered wireless channel. Simulation results confirm that STAR-RIS performs at par with RIS, however, facilitating an additional degree of coverage. It is observed that temporal ACF and ST-CCF improves with an increase in the number of elements in STAR-RIS. © 2024 Elsevier B.V.Channel estimationFading channelsPower spectral densityTime difference of arrivalAuto correlationDoppler power spectral densityEllipticalsEnergy splitting protocolEnergy splittingsGeometry-basedReconfigurableSimultaneously transmitting and reflecting-reconfigurable intelligent surfaceSpace-time cross correlationStochasticsStochastic models