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Hybrid Approaches to PAPR, BER, and PSD Optimization in 6G OTFS: Implications for Healthcare
Arun Kumar,Sumit Chakravarthy,Nishant Gaur,Aziz Nanthaamornphong 한국통신학회 2024 Journal of communications and networks Vol.26 No.3
The envisioned smart hospital framework leveraging the sixth-generation (6G) technology aims to enhance healthcare services by ensuring reliable communication across various wireless channel conditions, including both line-of-sight and obstructed paths. However, the traditional orthogonal frequency division multiplexing (OFDM) approach, used in 4G and 5G, struggles with the high Doppler shifts associated with dynamic environments, presenting challenges for burgeoning smart hospital demands. To address this, Orthogonal Time Frequency Space (OTFS) modulation is proposed. The OTFS operates effectively across both stationary and highly mobile channels by manipulating delay and Doppler domains. Nevertheless, a high peak-to-average power ratio (PAPR) remains a critical challenge for OTFS implementation within 6G smart hospitals. Elevated PAPR levels can reduce power amplifier efficiency, causing them to operate outside their ideal linear range and impairing battery performance. They also contribute to signal distortion, increased interference, and suboptimal spectrum utilization, which can undermine wireless communication and data integrity. To mitigate the PAPR issue in OTFS, this work introduces a hybrid algorithm that integrates the benefits of the Riemann matrix optimal phase element-based Partial Transmission Sequence (PTS) and Selective Mapping (SLM), along with A and Mu law complementary algorithms. This study compares the performance of the proposed hybrid algorithm with traditional PAPR reduction techniques by evaluating metrics such as PAPR, bit error rate (BER), and power spectrum density (PSD) within the Rician and Rayleigh fading channels. Simulation outcomes indicate that the hybrid algorithm achieves superior PAPR, BER, and PSD performance with only a marginal increase in complexity when compared with the established methods.
OFDM system with cyclostationary feature detection spectrum sensing
Arun Kumar,NandhaKumar P. 한국통신학회 2019 ICT Express Vol.5 No.1
In Orthogonal Frequency Division Multiplexing OFDM, a cyclic prefix (CP) is applied to reduce the intervention between symbols. The CP results in bandwidth wastage, and the solution to this problem leads to the cognitive radio. In the first part of the work, OFDM with CP is presented and integrated with cyclostationary spectrum sensing. Subsequently, OFDM with cyclostationary spectrum sensing without CP is proposed with the function of the filter at the transmitter and receiver being to utilize the bandwidth that is wasted in the CP phase. The Bit Error Rate BER, signal probability detection, false alarm, and error probability are obtained and analyzed.
Experimental investigations on resilient beam-column end-plate connection with structural fuse
Arunkumar Chandrasekaran,Umamaheswari Nambiappan 국제구조공학회 2023 Steel and Composite Structures, An International J Vol.47 No.3
The steel structure is an assembly of individual structural members joined together by connections. The connections are the focal point to transfer the forces which is susceptible to damage easily. It is challenging to replace the affected connection parts after an earthquake. Hence, steel plates are utilised as a structural fuse that absorbs connection forces and fails first. The objective of the present research is to develop a beam-column end plate connection with single and dual fuse and study the effect of single fuse, dual fuse and combined action of fuse and damper. In this research, seismic resilient beam-column end plate connection is developed in the form of structural fuse. The novel connection consists of one main fuse was placed horizontally and secondary fuse was placed vertically over main fuse. The specimens are fabricated with the variation in number of fuse (single and dual) and position of fuse (beam flange top and bottom). From the fabricated ten specimens five specimens were loaded monotonically and five cyclically. The experimental results are compared with Finite Element Analysis results of Arunkumar and Umamaheswari (2022). The results are critically assessed in the aspect of moment-rotation behaviour, strain in connection components, connection stiffness, energy dissipation characteristics and ductility. While comparing the performance of total five specimens, the connection with fuse exhibited superior performance than the conventional connection. An equation is proposed for the moment of resistance of end-plate connection without and with structural fuse.
Arunkumar, S.,Hou, Tianfeng,Kim, Young-Bae,Choi, Byungchul,Park, Su Han,Jung, Seunghun,Lee, Dong-Weon Elsevier 2017 Sensors and actuators. B Chemical Vol.243 No.-
<P><B>Abstract</B></P> <P>A highly selective and sensitive gas sensing material was prepared by decorating gold (Au) nanoparticles on zinc oxide <I>(ZnO)</I> nanostructure. First, zinc oxide architectures were synthesised through facile one-pot hydrothermal synthesis route by using zinc acetate as the metal precursors, ethanolamine as the organic Lewis base and water as the reaction medium. The versatile zinc oxide architectures such as (i) nanostars <I>(ZNS)</I>, (ii) marigold flower <I>(ZMF)</I>, (iii) nanorods assembled flower <I>(ZNF)</I> and (iv) nanorods <I>(ZNR)</I> were successfully synthesised by the controlled variation of the reaction medium mole ratio. The crystal structure and morphological evaluation of the as prepared material were investigated in detail by several analytical techniques, and the findings are consistent with each other. The carbon monoxide (CO) sensing ability of the as prepared materials was carried out at different sensing temperature (Ts≤300°C) and at different gas concentration (5–1000 <I>ppm</I>). Gas sensing study clearly shows that the sensor responses are found to be morphology and surface area dependent. Among all the zinc oxide nanostructures, nanostars exhibits excellent sensitivity (S<SUB>R</SUB> ∼31 toward 5 <I>ppm</I>) at the optimized sensing temperature of 275°C. Further, to improve the sensing characteristics and to reduce the operating temperature, different wt% of gold nanopartilces were decorated on the surface of zinc oxide nano-stars by solution impregnation technique. Surface decoration of only 3wt% gold nanoparticles incorporated zinc oxide nanostars exhibits enhanced sensing response (S<SUB>R</SUB> ∼15 toward 50 <I>ppm</I>) at 35°C with an excellent response (Γ<I> <SUB>RES</SUB> </I> ∼8s) and recovery (Γ<I> <SUB>REC</SUB> </I> ∼15s) time. Sensor also posses excellent selectivity toward CO compare to other interfering gases such as methanol, ethanol, acetone and hydrogen.</P>
Arunkumar Arumugam,Ramadevi Subramani,Sushmita Bose Nandy,Daniel Terreros,Alok Kumar Dwivedi,Edward Saltzstein,Rajkumar Lakshmanaswamy 생화학분자생물학회 2019 Experimental and molecular medicine Vol.51 No.-
Growth hormone receptor (GHR) plays a vital role in breast cancer chemoresistance and metastasis but the mechanism is not fully understood. We determined if GHR could be a potential therapeutic target for estrogen receptor negative (ER−ve) breast cancer, which are highly chemoresistant and metastatic. GHR was stably knocked down in ER-ve breast cancer cells and its effect on cell proliferation, metastatic behavior, and chemosensitivity to docetaxel (DT) was assessed. Microarray analysis was performed to identify potential GHR downstream targets involved in chemoresistance. GHR and ATP-binding cassette sub-family G member 2 (ABCG2) overexpression and knockdown studies were performed to investigate the mechanism of GHR-induced chemoresistance. Patient-derived xenografts was used to study the effect of GHR and ABCG2. Immunohistochemical data was used to determine the correlation between GHR, pAKT, pmTOR, and ABCG2 expressions. GHR silencing drastically reduced the chemoresistant and metastatic behavior of ER-ve breast cancer cells and also inhibited AKT/mTOR pathway. In contrast, activation, or overexpression of GHR increased chemoresistance and metastasis by increasing the expression and promoter activity, of ABCG2. Inhibition of JAK2/STAT5 signaling repressed GHR-induced ABCG2 promoter activity and expression. Further, ABCG2 knockdown significantly increased the chemosensitivity. Finally, patient-derived xenograft studies revealed the role of GHR in chemoresistance. Overall, these findings demonstrate that targeting GHR could be a novel therapeutic approach to overcome chemoresistance and associated metastasis in aggressive ER-ve breast cancers.
( Arunkumar Shanmugasundaram ),( Dong-su Kim ),( Tian Feng Hou ),( Dong Weon Lee ) 한국센서학회 2020 센서학회지 Vol.29 No.3
In this study, hierarchical mesoporous CuO spheres, ZnO flowers, and heterojunction CuO/ZnO nanostructures were fabricated via a facile hydrothermal method. The as-prepared materials were characterized in detail using various analytical methods such as powder X-ray diffraction, micro Raman spectroscopy, X-ray photoelectron spectroscopy, field-emission scanning electron microscopy, and transmission electron microscopy. The obtained results are consistent with each other. The H2S-sensing characteristics of the sensors fabricated based on the CuO spheres, ZnO flowers, and CuO/ZnO heterojunction were investigated at different temperatures and gas concentrations. The sensor based on ZnO flowers showed a maximum response of ~141 at 225 ℃. The sensor based on CuO spheres exhibited a maximum response of 218 at 175 ℃, whereas the sensor based on the CuO/ZnO nano-heterostructure composite showed a maximum response of 344 at 150 ℃. The detection limit (DL) of the sensor based on the CuO/ZnO heterojunction was ~120 ppb at 150 ℃. The CuO/ZnO sensor showed the maximum response to H<sub>2</sub>S compared with other interfering gases such as ethanol, methanol, and CO, indicating its high selectivity.
Arunkumar, Paulraj,Kim, Yoon Hwa,Im, Won Bin American Chemical Society 2016 The Journal of Physical Chemistry Part C Vol.120 No.8
<P>White-light-emitting Ca4-xF2Si2O7:xCe(3+) phosphor and violet-light emitting oxyfluoride Ca4F2Si2O7 host were synthesized by solid-state reaction. Ca4-xF2Si2O7:xCe(3+) has strong absorption in the near-UV region (370 nm) and shows a broad emission in the range of 390-600 nm centered at 475 nm. Under 315 rim excitation, a narrow blue emission was observed. The Ca4F2Si2O7 host synthesized under the same reduction conditions exhibited-violet emission due to the formation of anion-deficient nonstoichiorrietric Ca4F2-delta Si2O7+delta/2, species. The broad emission of Ca4F2Si2O7:xCe(3+) phosphor is attributed to Ce3+ occupying two crystallographic calcium sites available in the host. A white LED device was fabricated using Ca4F2Si2O7:Ce3+ without any additive phosphor, displaying excellent CIE chromaticity (0.29, 0.35) close to white emission with a color rendering index of 97. These exceptional optical properties of Ca4F2Si2O7:Ce3+ suggest the promising application of the single activator phosphor that could produce white light under near-UV-based LEDs.</P>