Electrical Engineering

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Shiv Nadar University

This letter presents a small-scale wireless distributed cooperative secure-communication network (WDCSN) design using a novel spectral graph FIR filter to achieve desired secrecy capacity at the intended receiver in the presence of single and multiple eavesdroppers. An undirected weighted graph \mathcal {G} (V, \mathcal {E}, W), with relays, eavesdroppers, source, and destination are as nodes (V), and circularly symmetric complex Gaussian random variables as edge weights (W) are considered to represent the WDCSN. A graph Laplacian is used as a graph shift operator to design the proposed filter. Filter coefficients are calculated by using the least squared error as a criterion. Simulations are conducted for a two-way WDCSN to achieve the desired secrecy capacity using different graph structures considered for WDCSN. The proposed filter design's performance is quantified by using the secrecy outage probability metric. The results show that desired secrecy capacity with SOP of 10^{-2} is achievable using the proposed methodology, irrespective of graph structures with variable complexity. An SOP performance gain of (60\!-\!80) \% is achieved over the SOP reported in the literature. © 2017 IEEE.

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(SoE) School of Engineering

IEEE Sensors Letters

A Small-Scale Wireless Distributed Cooperative Secure Communication Network Design Using Graph FIR Filters

This work presents the designing of 3D uniform circular array using eight exponential flare slot Vivaldi antenna elements that resonates in the frequency range of 3.68 to 5 GHz for generation of Orbital Angular Momentum (OAM) radio waves. Eight exponential flare slot Vivaldi antenna elements are placed in circular manner that form cylindrical arrangement. These elements are connected to a single coaxial cable at its center through a power divider network. All elements of circular array are fed with uniform amplitude and phase, to make progressive phase difference 0° for OAM mode 0. Similarly progressive phase difference -45° for OAM mode -1, and progressive phase difference 45° for OAM mode -1 has been simulated and results are presented. A prototype for the OAM (mode 0) in the above frequency range is fabricated and measured. The hardware results obtained through testing of the array provide are closer to the simulated results. For OAM mode 0, four-element antenna array is also simulated to check the mode purity and results are discussed with 8-element antenna array. The beam divergence of proposed high capacity OAM antenna can be utilized in EVs and HEVs. © 2021 IEEE.

2021 International Conference on Sustainable Energy and Future Electric Transportation, SeFet 2021

Exponential Flare Slot Vivaldi OAM Antenna for near Field Communication in EVs and HEVs

Graph learning from the brain signals deals with capturing the changes in functional relationship between the brain regions during mental active and relaxed states. This paper investigates different graph learning techniques, namely geometry, signal similarity, and Graphical LASSO based methods for the classification of mental task from electroencephalogram (EEG) signals. Graph spectral energy based metric using Graph Signal Processing (GSP) technique is presented to classify mental active state from relaxed state. A binary KNN classifier is used to analyse each graph learning technique on publicly available Keirn and Aunon mental task EEG database. Performance of different graphs is then analysed and compared using classification Accuracy and F-Score. © 2021 IEEE.

Proceedings of the 2021 IEEE 18th India Council International Conference, INDICON 2021

Evaluating Different Graph Learning Techniques for Mental Task EEG Signal Classification

The enhanced capacity-Achieving non-orthogonal multiple access (NOMA) systems suffer from detection errors due to the interference of various users in the uplink (UL) scenario. Successive interference cancellation (SIC) errors propagation and reception of signals from multiple antennas result in inter-user interference (IUI) and inter-Antenna interference (IAI), respectively. Dirty paper coding (DPC) mitigates the IAI by diagonalizing the channel matrix, whereas SIC reduces the IUI by using the back-substitution method. This paper analyses the UL NOMA-MIMO system's performance by proposing a joint DPC-OSIC detector with known channel state information (CSI). QR-based OSIC reduces the IUI while applying all the constellations to the lowest channel gain user. The proposed joint DPC-OSIC is analyzed over a joint DPC-ZF and DPC-ML performance. Simulation results validate that the proposed detector achieves near maximum likelihood (ML) performance with relatively low complexity. © 2021 IEEE.

IEEE Region 10 Annual International Conference, Proceedings/TENCON

Performance of Uplink NOMA-MIMO System with Joint DPC-OSIC Detector

Bias Temperature Instability (BTI) is one of the most crucial reliability issues in modern CMOS technology. It leads to shift in device parameters, which eventually affect circuit performance. SRAM is a widely used circuit which occupies a considerable area in microprocessors. Hence it is important to understand the impact of BTI on performance/stability of SRAM. As device degradation due to BTI depends on gate activity, SRAM performance strongly depends on the data stored in the cell. In this paper, the gate activity is incorporated by activity factor ‘α’ which takes into account the various data patterns stored in the cell. Although many studies have reported the impact of BTI on SRAM performance, none focused on the worst degradation scenario. Our analysis with varying activity factor ‘α’ provides an opportunity to identify the data pattern for worst case degradation. Shift in threshold voltage due to BTI is modelled according to continuous and non-continuous applied gate bias, using physics-based compact model. Process variability is incorporated using Monte Carlo (MC) simulations and worst-case degradation at distribution tail is identified. In this paper, we consolidate various SRAM performance metrics from literature over the last three decades and demonstrate the impact of BTI and process variability with activity factor ‘α’ on these metrics. © 2020 Elsevier B.V.

Integration

Analysis of SRAM metrics for data dependent BTI degradation and process variability

In this manuscript, higher-order Orbital Angular Momentum (OAM) modes and parameters affecting vortex in the radiation pattern have been studied. A uniform circular array resonating at 10 GHz frequency is formed using eight identical rectangular patch antennas. Three uniform circular arrays are analyzed, simulated, and fabricated for OAM modes 0, +1, and-1 respectively. The higher-order OAM modes ±2, ±3, and ±4 are simulated and their effects on radiation and phase pattern are discussed. The effect of number of antenna elements and radius of the circular array on the phase purity of higher order OAM modes is presented. The results of simulated radiation patterns and phase front are well satisfying the generation of OAM modes. The measured results show a close agreement with the simulated result. © 2020, Iran University of Science and Technology. All rights reserved.

Iranian Journal of Electrical and Electronic Engineering

Study on generation of higher order orbital angular momentum modes and parameters affecting the vortex

This paper presents an alternate design for a conventional 3dB Branch line coupler (Quadrature Coupler) for C Band applications. The proposed coupler is designed for 5.2GHz. The proposed coupler has parallel-coupled lines at the port of conventional 3dB coupler with slotted ground plane. The novel design of the coupler allows 82.6\% of bandwidth improvement with DC(Direct Current) isolation. The designs have been simulated and fabricated on FR4 dielectric substrate and measured using Vector Network Analyzer. Simulated and fabricated results of the S-parameters are presented. © 2020 IEEE.

2020 7th International Conference on Signal Processing and Integrated Networks, SPIN 2020

Quadrature coupler with enhanced coupling bandwidth and DC isolation for C-band applications

This paper presents an unconventional design for a circular rat race coupler operating at 5 GHz frequency. The size of the novel design implemented is 21.68mm x 15.72mm. The unconventional design of the coupler allows 40\% reduction in the size of the coupler as compared with the conventional rat race coupler without compromising on performance. Measured and simulated results of the S-parameters are provided. © 2020 IEEE.

Compact horse shoe shape rat-race coupler

This paper presents a design of a four-port, dual-band uniform circular array (UCA) to generate three orthogonal Orbital Angular Momentum (OAM) modes (OAM mode 0, +1 and-1) at two different frequency 2.45 GHz (ISM band/WLAN) and 5.4 GHz (WLAN). The proposed antenna is designed with the help of four 50-Ohm microstrip line radiator (MLR) having an annular slot on the ground plane. The effect of variation of the physical design parameters (like the length of 50-Ohm MLR, the radius of annular slot and annular slot width) on reflection coefficient and the radiation pattern is shown and discussed. © 2020 IEEE.

Dual-band triple mode OAM generation using annular slot microstrip radiator

In this paper, a compact multiband CPW-fed monopole antenna is proposed. The designed antenna has a simple structure, which consists of a rectangular radiating patch with two symmetrically structured meandered line slots on both sides and a CPW-fed 50 Ω microstrip line. The designed antenna occupies only 23 × 23 mm2 size on a FR-4 substrate sheet which makes it a good candidate for wireless mobile communications. Triple-band functionality is realized by making slots on patch to form a meandered strip on both sides of the rectangular radiating patch. These triple bands are suitable for Bluetooth, WiMAX, and WLAN applications, which are operating at 2.4 GHz, 3.5 GHz, and 5.5 GHz, respectively. The fabricated and characterized antenna prototype is having a good omnidirectional and directional radiation pattern in both H-plane and E-plane for the specified bands, respectively. © 2019, Shiraz University.