Journal Articles

Permanent URI for this collectionhttps://idr.nitk.ac.in/handle/123456789/19884

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Author: search.filters.author.Chaturvedi, A.Subject: search.filters.subject.Fading channels

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    Geometry-based stochastic channel modeling of a semi-urban environment using simultaneously transmitting and reflecting reconfigurable intelligentsurface
    (Elsevier B.V., 2024) Rashmi, H.; Chaturvedi, A.; D'Souza, J.
    Simultaneously 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 (UR/UT) 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.
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    Ergodic Capacity and Outage Probability Analysis for Multiple Intelligent Reflecting Surface Assisted Wireless Networks
    (Springer, 2024) DhruvaKumar, T.; Chaturvedi, A.
    Due to location-specific geometrical properties and time-dependent vehicular traffic, many urban area segments exhibit diverse fading patterns. This research examines the ergodic capacity and outage probability estimate for these segments. Several Intelligent Reflecting Surface (IRS) panels installed on roadside infrastructure are present in these geographical regions. Various application scenarios are examined when the receiver is exposed to reflected and direct Line-of-Sight links, which are defined by ?-? shadowed fading. An approximation analysis of the studied ?-? shadowed fading channel via Nakagami-m fading model and an exact study of the impact of ?-? shadowed fading on the ergodic capacity and outage probability of the wireless link are presented using Monte Carlo simulation. In order to confirm the effectiveness of IRS panel deployment, one of the governing factors is the average signal-to-noise ratio. When accounting for the dynamics of the vehicle traffic, an improved ergodic capacity and outage probability estimate show the value of placing IRS panels at any point within the examined geographic segments. © The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2025.
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    Analysis of symbol error probability in GFDM under generalized ????? channels: An approach based on probability density function for beyond 5G wireless applications
    (Elsevier GmbH, 2025) Bodempudi, N.S.P.; Chaturvedi, A.; Rashmi, R.; Kulkarni, M.
    Generalized Frequency Division Multiplexing (GFDM) is a flexible multicarrier modulation scheme tailored to meet the diverse requirements of 5G and beyond (B5G) wireless systems. It provides flexibility to select subsymbols, subcarriers, and pulse-shaping filters, making it suitable for various B5G communication needs. Moreover, GFDM includes orthogonal frequency division multiplexing (OFDM) and single carrier frequency domain equalization (SC-FDE) as special cases. Since fading conditions greatly affect communication reliability, this paper derives a closed-form expression for the symbol error probability/symbol error rate (SEP/SER) of GFDM using M-QAM and M-PSK in generalized ????? fading channels. The study examines how fading parameters (?,?,?), pulse-shaping filters, roll-off factor, and subsymbol count influence SER performance. Results show these factors have a significant impact on error probability. This comprehensive analysis provides important insights for evaluating GFDM performance under complex fading scenarios, making it a valuable reference for GFDM system design for B5G wireless applications. © 2025