On Placement of LAA / LTE-U Base Stations in the Presence of Wi-Fi

Recently, the use of LTE in unlicensed has gained a lot of attention to improve the data rate and satisfy the increasing user demand. Use of unlicensed spectrum is allowed with restricted transmission power hence mostly LAA/LTE-U nodes are Femto cells and mostly will be used to improve the indoor data rates. In future, the LAA nodes will get deployed inside residential apartment complexes and office buildings to provide high data rates for indoor User Equipment (UEs). The UEs with high Signal-to-Interference plus Noise Ratio (SINR) experience good throughput, but the SINR decreases significantly if building walls and other obstacles are present in the communication path. The coverage difference of licensed and unlicensed spectrum provides different SINR so, efficient placement of LAA Femtos in buildings with consideration of interference from other LAA Femto nodes, Wi-Fi Access Points (APs) and Macro Base Stations (BSs) is very crucial for attaining desirable SINR for the indoor UEs. In this paper, we have considered obstructions (walls, floors) and interference from Macro, Femto BSs, and Wi-Fi APs. Our goal is to find the optimal number of Femtos with minimum SINR requirements in the unlicensed band, and next thing is to achieve good SINR in all sub-regions in licensed band as well. To do this, we formulated an optimization model (MinLF) to find the minimum number of LAA/LTE-U Femtos along with its positions in indoor scenarios which resulted in Mixed Integer Linear Programming (MILP) optimization problem. Further, to maximize minimum SINR in the licensed spectrum, we formulated MinLPow model to find the optimal power of each located Femto inside the building which is Mixed Integer Non-Linear Programming (MINLP). MinLF formulation is solved using GAMS CPLEX optimization solver. After getting positions of Femtos, we solved MinLPow formulation using Genetic Algorithm. Finally, the efficiency of proposed formulation model is shown with sufficient simulation study

On placement and efficient resource allocation of LAA/LTE-U base stations in HetNet

LTE operation in unlicensed spectrum is considered as a promising solution to meet the increase in user data demand. Licensed Assisted Access (LAA), and duty cycled LTE-U are two options for LTE to operate in the unlicensed band for fair sharing of unlicensed spectrum with IEEE 802.11 (Wi-Fi). Due to restriction on the transmission power in the unlicensed band, LAA/LTE-U Base Stations (BSs) will get deployed mostly inside residential and office buildings to provide high data rates for indoor User Equipments (UEs). In an indoor scenario, walls and other obstacles in the communication path along with co-tier and cross-tier interferences decrease the Signal-to-Interference plus Noise Ratio (SINR) significantly which results in throughput decrease. Hence, an optimal placement of LAA BSs is essential. As the available bandwidth in the unlicensed spectrum is more compared to the licensed spectrum, an efficient resource allocation is also necessary for ensuring minimum throughput for the indoor UEs. In this paper, our goal is to find the optimal number of LAA/LTE-U BSs with minimum throughput guarantee inside the building using licensed and unlicensed bands. To do this, we formulate an optimization model (MinLAA) for LAA BSs placement which is Mixed Integer Non-Linear Programming (MINLP) problem. So, we propose a heuristic algorithm to find the minimum number of LAA/LTE-U BSs such that all the users inside the building get minimum guaranteed throughput

On Placement of LAA/LTE-U Base Stations in Heterogeneous Wireless Networks

Recently, the use of LTE in the unlicensed spectrum has gained a lot of attention to address bandwidth crunch. Due to restriction on the transmission power in the unlicensed spectrum, LTE-U/LAA cells will get deployed mostly inside residential and office buildings to provide high data rates for indoor User Equipments (UEs). The UEs with high Signal-to-Interference plus Noise Ratio (SINR) experience good throughput, but the SINR decreases significantly due to walls and other obstacles that are present in the communication path. The coverage difference of licensed and unlicensed spectrum leads to different SINRs so, efficient placement of LAA Base Stations (BSs) inside the buildings is very crucial for attaining desirable SINR for the indoor UEs. Our primary objective is to find the optimal number of LAA/LTE-U BSs with minimum SINR requirements in the unlicensed band, and the secondary objective is to maximize the minimum SINR inside the building in the licensed band with power control. To do this, we formulate an optimization model (MinLF) to find the minimum number of LAA/LTE-U BSs along with their positions in indoor scenarios which resulted in Mixed Integer Linear Programming (MILP) problem. Further, to maximize the minimum SINR in the licensed spectrum, we formulate MinLPower model to find the optimal transmission power of each LTE-U/LAA cell inside the building which resulted in Mixed Integer Non-Linear Programming (MINLP) problem. Our proposed models achieve optimal placement with a maximum energy saving of 88% compared to the maximum power scheme

Screening of Plant Extracts against a Vector of Arboviruses, Aedes aegypti (Linnaeus) (Diptera: Culicidae)

Aedes aegypti is a vector mosquito of dengue haemorrhagic fever, chikungunya, yellow fever, zika, filariasis and other viral infectious disease-causing pathogens. We tested ethanol extracts of the six plant species viz., Cassia fistula, Curcuma amada, Manilkara zapota, Momordica charantia, Sansevieria trifasciata and Solanum indicum at dosages of 25, 50, 75 and 100% for their larvicidal effect against the third instar larva of A. aegypti. We observed maximum larval mortality and minimum LC50, LC90, and LC99 in C. amada (LC50 = 0.14, LC90 = 9.28 and LC99 = 277.97) among the tested plant extracts. All the extracts caused moderate to high larval mortality, and hence, these plant extracts could be a substitute source for A. aegypti control as they comprise a potential source of bioactive chemicals and generally free from toxicants. Applications of these natural derivatives in A. aegypti control could reduce the cost of control methods and environmental contamination

Kinematic and Mechanical Profile of the Self-Actuation of Thermosalient Crystal Twins of 1,2,4,5-Tetrabromobenzene: A Molecular Crystalline Analogue of a Bimetallic Strip

A paradigm shift from hard to flexible, organic-based optoelectronics requires fast and reversible mechanical response from actuating materials that are used for conversion of heat or light into mechanical motion. As the limits in the response times of polymer-based actuating materials are reached, which are inherent to the less-than-optimal coupling between the light/heat and mechanical energy in them, a conceptually new approach to mechanical actuation is required to leapfrog the performance of organic actuators. Herein, we explore single crystals of 1,2,4,5-tetrabromobenzene (TBB) as actuating elements and establish relations between their kinematic profile and mechanical properties. Centimeter-size acicular crystals of TBB are the only naturally twinned crystals out of about a dozen known materials that exhibit the <i>thermosalient effect</i>an extremely rare and visually impressive crystal locomotion. When taken over a phase transition, crystals of this material store mechanical strain and are rapidly self-actuated to sudden jumps to release the internal strain, leaping up to several centimeters. To establish the structural basis for this colossal crystal motility, we investigated the mechanical profile of the crystals from macroscale, in response to externally induced deformation under microscope, to nanoscale, by using nanoindentation. Kinematic analysis based on high-speed recordings of over 200 twinned TBB crystals exposed to directional or nondirectional heating unraveled that the crystal locomotion is a kinematically complex phenomenon that includes at least six kinematic effects. The nanoscale tests confirm the highly elastic nature, with an elastic deformation recovery (60%) that is far superior to those of molecular crystals reported earlier. This property appears to be critical for accumulation of stress required for crystal jumping. Twinned crystals of TBB exposed to moderate directional heating behave as all-organic analogue of a bimetallic strip, where the lattice misfit between the two crystal components drives reversible deformation of the crystal

SARS-CoV-2 seroprevalence among the general population and healthcare workers in India, December 2020–January 2021

Background: Earlier serosurveys in India revealed seroprevalence of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) of 0.73% in May–June 2020 and 7.1% in August–September 2020. A third serosurvey was conducted between December 2020 and January 2021 to estimate the seroprevalence of SARS-CoV-2 infection among the general population and healthcare workers (HCWs) in India. Methods: The third serosurvey was conducted in the same 70 districts as the first and second serosurveys. For each district, at least 400 individuals aged ≥10 years from the general population and 100 HCWs from subdistrict-level health facilities were enrolled. Serum samples from the general population were tested for the presence of immunoglobulin G (IgG) antibodies against the nucleocapsid (N) and spike (S1-RBD) proteins of SARS-CoV-2, whereas serum samples from HCWs were tested for anti-S1-RBD. Weighted seroprevalence adjusted for assay characteristics was estimated. Results: Of the 28,598 serum samples from the general population, 4585 (16%) had IgG antibodies against the N protein, 6647 (23.2%) had IgG antibodies against the S1-RBD protein, and 7436 (26%) had IgG antibodies against either the N protein or the S1-RBD protein. Weighted and assay-characteristic-adjusted seroprevalence against either of the antibodies was 24.1% [95% confidence interval (CI) 23.0–25.3%]. Among 7385 HCWs, the seroprevalence of anti-S1-RBD IgG antibodies was 25.6% (95% CI 23.5–27.8%). Conclusions: Nearly one in four individuals aged ≥10 years from the general population as well as HCWs in India had been exposed to SARS-CoV-2 by December 2020