Faculty Publications

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Comparative Study of Power Optimization Technique for M2M Communication Node Under 5G (NR)
(Springer Science and Business Media Deutschland GmbH, 2023) Sharma, V.; Arya, R.K.; Kumar, S.; Pandey, K.
The direct Fourier transform-spread OFDM (DFT-s-OFDM) and cyclic prefix orthogonal frequency division multiplexing (CP-OFDM) are used for the end-to-end data transmission to support the 5G services and backward compatibility. Improving battery life has always been an important concern in 5G machine-to-machine (M2M) communication nodes. Efficient utilization of power amplifiers (PA) and inferior peak-to-average power ratio (PAPR) is helpful to achieve enhanced battery life. Filter bank multi-carrier (FBMC) multiplexing is an alternative to CP-OFDM that offers low PAPR with the benefits of CP removal. Another way to get low PAPR is single carrier OFDM (SC-FDMA). The transmission requirements between these services are different, which presents a challenge for waveform adaptability to PAPR issues. The DFT-s-OFDM technique is one of the choices to overcome the PAPR that is used in uplink scenarios. Apart from PAPR reduction, DFT-s-OFDM provides optimal use of nonlinear power amplifiers. In addition to PAPR analysis, spectral efficiency is also compared in the simulation results. Using parameters that adjust the cost of spectral efficiency, DFT-s-OFDM provides the extent of improvement in PAPR performance and bit error rate over traditional CP-OFDM, SC-FDMA, and FBMC against the noisy channel. Â© 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.
A 2.71-pA/√Hz ultra-low noise, 70-dB dynamic range CMOS transimpedance amplifier with incorporated microstrip line techniques over extended bandwidth
(John Wiley and Sons Ltd, 2023) Gorre, P.; Vignesh, R.; Kumar, S.; Song, H.; Roy, G.M.
Recent advancements in the area of telemedicine have focused on remote patient monitoring services as a new frontier in medical applications. The present work reports a 65-nm complementary metal–oxide–semiconductor (CMOS)-based transimpedance amplifier (TIA) in an optical radar system for non-contact patient monitoring. A T-shaped microstrip line (MSL) integrated with variable gain common source TIA using MSL peaking technique and off-chip post-amplification integration is a newly proposed architecture to achieve a ultra-low noise, high dynamic range (DR) and high figure of merit over broadband than a traditional TIAs. First, the integrated T-shaped MSL develops an additional resonant frequency that resonates with a photodiode capacitance improving the bandwidth performance at higher Q values. Second, the shunt MSL peaking technique that introduces an additional conjugate pole-pair that cancels the effect of input capacitance helps to further improve the bandwidth of the TIA. Finally, an active feedback concept achieves a wide linear dynamic range enabling high TIA detectability. The proposed TIA realizes an impedance bandwidth of 770 MHz ranging from 7.12 to 7.89 GHz with a transimpedance gain of 105.1 dBΩ and ultra-low input-referred noise (IRN) density of 2.71 pA/√Hz. A high linear DR of 70 dB is achieved by employing a variable gain control scheme with a low group delay variation of 0.81 ns. The proposed work demonstrates a 1-Gb/s data rate while a bit-error rate less than 10−12 is achieved. The TIA consumes a power of 0.82 mW under the supply voltage of 1.2 V. © 2022 John Wiley & Sons Ltd.
Adaptive DFT-s-OFDM employed novel multi layered scheme for reduction of PAPR for mMTC node in 5G (NR)
(Elsevier B.V., 2023) Sharma, V.; Arya, R.K.; Kumar, S.
In 5G New Radio, The DFT-s-OFDM is a promising multiplexing technique for enhancing the average power of subcarriers to reduce the overall peak-to-average power ratio (PAPR). The peak of subcarrier is too high then the impact of DFT-s-OFDM is quite inferior. An Adaptive DFT-s-OFDM employed multilayered novel mechanism has been proposed in this research article to reduce the PAPR. The extent of sub-band is varied in accordance with predefined threshold value to enhance average power, meanwhile clipping is applied to shape the peak value of subcarrier. The clipping technique reduced the subcarrier's peak power. The proposed approach has the greater impact in order to enhance the efficiency of non-linear Power Amplifier (PA). The PAPR is suppressed by the multilayered strategy in two ways. The first is the numerator element, which is the reduction of peak power by clipping operation, and the second is the denominator element, which is the improvement of average power through K-point DFT sub-band. The superior time–frequency localization of DFT-s-OFDM across uplink transmissions reduces the requirement for difficult node-to-node synchronization, which is potentially used by the mMTC nodes. The proposed adaptive DFT-s-OFDM modulation scheme performs better than conventional OFDM modulation, which is approximately 24% more effective at 6 dB. © 2023 Elsevier B.V.

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