PAPR Reduction in SLM–OFDM System Using Lehmer Sequence Without Explicit Side Information

Selected mapping (SLM) is one of the promising techniques used for peak-to-average power ratio (PAPR) reduction in orthogonal frequency division multiplexing (OFDM) system. One of the major drawbacks in this technique is that, the transmitter is forced to transmit more amount of side information (SI) bits in order to recover the original data at the receiver, which leads to data rate loss and inefficient transmission. In this paper, a new phase sequence generation method using Lehmer Random Number Generator (LRNG) called Lehmer sequence is proposed for SLM technique. Using the periodicity property of this sequence, the SI bits are embedded within the transmitted data block for 16-PSK modulation, which ensures that SI bits are not explicitly sent. The simulation results show that the proposed SLM (PSLM) provides a slight improvement in PAPR reduction without compromising the bit error rate (BER) for higher values of an expansion factor when compared to conventional SLM (CSLM).

     

Effect of Preparation Conditions on Magnetic and Dielectric Properties of Y2MMnO6 (M = Co,Ni)

Herein we report the structure, magnetic and dielectric properties of Y₂CoMnO₆ (YCMO) and Y₂NiMnO₆ (YNMO) prepared under various conditions. On annealing in inert atmosphere, YCMO sample shows a partial decomposition while YNMO remains unaffected. Both YCMO and YNMO samples show paramagnetic to ferromagnetic transition around 80 K, but only the magnetic properties of YCMO samples depend on the preparation conditions. YCMO samples show antiferromagnetic ground state in zero field and a metamagnetic transition at relatively low field (~2 T). Differences in the annealing environment do not destroy the initial antiparallel spin order in YCMO, but affect the critical fields of metamagnetic transition. The field‐dependent magnetic properties indicated soft ferromagnetic nature of YNMO samples. The dielectric measurements show distinct frequency and temperature‐dependent features in YCMO samples compared to YNMO samples. A large relative permittivity with ε? of about 10⁴ is observed in both O₂ and air‐annealed YCMO samples. Multiple dielectric relaxations are observed in all the annealed YCMO and YNMO samples.     

Random variability modeling and its impact on scaled CMOS circuits

Random variations have been regarded as one of the major barriers on CMOS scaling. Compact models that physically capture these effects are crucial to bridge the process technology with design optimization. In this paper, 3-D atomistic simulations are performed to investigate fundamental variations in a scaled CMOS device, including random dopant fluctuation (RDF), line-edge roughness (LER), and oxide thickness fluctuation (OTF). By understanding the underlying physics and analyzing simulation results, compact models for random threshold (V _th ) variations are developed. The models are scalable with device specifications, enabling quantitative analysis of circuit performance variability in future technology nodes. Using representative circuits, such as the inverter chain and SRAM cell, key insights are extracted on the trend of variability, as well as the implications on robust design.     

Studies on structural,magnetic, and DC electrical resistivity properties of Co0.5M0.37Cu0.13Fe2O4 (M = Ni,Zn and Mg) ferrite nanoparticle systems

Ferrite nanoparticles of the composition Co_0.5M_0.37Cu_0.13Fe₂O₄ (M?=?Ni, Zn, and Mg) have been synthesized using sol-gel auto combustion method. Structural properties are investigated using powder X-ray diffraction technique and the results showed a pure spinel crystal structures of the synthesized materials with lattice parameters in the range of 8.3331–8.4793?Å. Crystallite sizes are calculated using the Scherrer’s formula and the results are found to be in the range of 62.22–82.41?nm. The surface texture and morphological nature of the samples are studied by scanning electron microscopy which depicted clear crystalline nature of the materials. Characteristic vibrational states prevailing in the samples are studied using room temperature Fourier transform infrared spectroscopy. A two-probe DC electrical resistivity measurement of the samples showed a high resistive nature. Room temperature vibrating sample magnetometer measurements revealed the magnetic properties of the samples.