Browsing by Author "Sabapathy, S"

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MISO M-Ppm for Integrated-Receiver SWIPT with Pulse Shaping and PSO-Based Beamforming
(Institute of Electrical and Electronics Engineers, 2026-06-12) Vithanage, G. S; Jayakody, D. N.K; Sabapathy, S
Integrated-receiver (IntRx) simultaneous wireless information and power transfer (SWIPT) enables low-power Internet of Things devices by eliminating energy-intensive radio frequency (RF) front-end components at the receiver. This paper investigates a multiple-input single-output (MISO) SWIPT system employing M-ary pulse position modulation (M-PPM), where high-amplitude time-localized pulses exploit rectifier nonlinearity via increased peak-to-average power ratio (PAPR). Transmit beamforming is employed to enhance harvested DC power, and the impact of pulse shaping is analyzed using rectangular and raised-cosine (RC) pulses with varying roll-off factors. Monte Carlo simulations under random channel realizations show that the proposed MISO M-PPM architecture achieves harvested energy gains of up to 37.8% compared to single-antenna transmission. Furthermore, RC pulse shaping consistently outperforms rectangular pulses, with harvested energy increasing with the roll-off factor. To enable beamforming without increasing receiver complexity, a particle swarm optimization (PSO)-based transmit beamforming method is proposed, using received power as the sole fitness metric and requiring no phase estimation at the receiver. Beamforming coherence is characterized by using the standard deviation of received signal phases. An analytical model is developed to estimate the expected number of PSO iterations required to satisfy a target coherence level as a function of swarm size, enabling efficient allocation of computational resources.
Open Access
Multi-User Sparse Vector Coding for eXtreme Ultra-Reliable Low-Latency Communication in Beyond 5G
(Institute of Electrical and Electronics Engineers Inc., 2025-03-14) Sabapathy, S; Maruthu, S; Jayakody, D. N.K
Short A short packet transmission scheme, such as Sparse Vector Coding (SVC), is a primary candidate for achieving ultra-low latency and high-reliability communication (URLLC). This paper proposes a spectral-efficient multi-user SVC (MU-SVC) scheme for achieving next-generation URLLC or eXtreme URLLC (xURLLC) in beyond 5G (B5G) communications. The key idea is to transmit multiple user information within a single sparse vector where the users are segregated into far users (FU) and near users (NU) depending on the distance from the base station. The classification into FU and NU paves way to optimize resource allocation, user fairness, manage interference, ensure reliable communication and quality of service requirements. Firstly, the FU binary data is converted into a sparse vector and secondly, the NU data is modulated and embedded into the non-zero positions of the sparse vector to form an MU-SVC. On transmission, the FU data is obtained through sparse demapping, while the NU adopts symbol detection techniques like the maximum likelihood detector. A new performance metric, called position error rate (PoER), is introduced to study the performance of the FU since it is based on the correct identification of the non-zero positions. Theoretical analyses of PoER and symbol error rate (SER) were carried out for FU and NU, respectively and the results are also validated through Monte-Carlo simulations. Further, the bit error rate, complexity, spectral and latency analyses are performed for MU-SVC and compared with the SVC and enhanced SVC schemes. The simulation results demonstrate an improved spectral efficiency and low latency with high reliability for the proposed MU-SVC scheme, thus, achieving xURLLC with reduced complexity in the multi-user scenario for B5G.