Optimal Power Allocation for Channel Estimation in MIMO-OFDM System with Per-Subcarrier Transmit Antenna Selection

A novel hybrid channel estimator is proposed for multiple-input multiple-output orthogonal frequency- division multiplexing (MIMO-OFDM) system with per-subcarrier transmit antenna selection having optimal power allocation among subcarriers. In practice, antenna selection information is transmitted through a binary symmetric control channel with a crossover probability. Linear minimum mean-square error (LMMSE) technique is optimal technique for channel estimation in MIMO-OFDM system. Though LMMSE estimator performs well at low signal to noise ratio (SNR), in the presence of antenna-to-subcarrier-assignment error (ATSA), it introduces irreducible error at high SNR. We have proved that relaxed MMSE (RMMSE) estimator overcomes the performance degradation at high SNR. The proposed hybrid estimator combines the benefits of LMMSE at low SNR and RMMSE estimator at high SNR. The vector mean square error (MSE) expression is modified as scalar expression so that an optimal power allocation can be performed. The convex optimization problem is formulated and solved to allocate optimal power to subcarriers minimizing the MSE, subject to transmit sum power constraint. Further, an analytical expression for SNR threshold at which the hybrid estimator is to be switched from LMMSE to RMMSE is derived. The simulation results show that the proposed hybrid estimator gives robust performance, irrespective of ATSA error

Fast Implementation of Transmit Beamforming for Colocated MIMO Radar

Multiple-input Multiple-output (MIMO) radars benefit from spatial and waveform diversities to improve the performance potential. Phased array radars transmit scaled versions of a single waveform thereby limiting the transmit degrees of freedom to one. However MIMO radars transmit diverse waveforms from different transmit array elements thereby increasing the degrees of freedom to form flexible transmit beampatterns. The transmit beampattern of a colocated MIMO radar depends on the zero-lag correlation matrix of different transmit waveforms. Many solutions have been developed for designing the signal correlation matrix to achieve a desired transmit beampattern based on optimization algorithms in the literature. In this paper, a fast algorithm for designing the correlation matrix of the transmit waveforms is developed that allows the next generation radars to form flexible beampatterns in real-time. An efficient method for sidelobe control with negligible increase in mainlobe width is also presented

Molecular characterization of Azotobacter spp. nifH gene Isolated from marine source

The nifH gene sequence of the nitrogen-fixing bacterium Azotobacter spp. was determined with the use of polymerase chain reaction (PCR). The Azotobacter species was isolated from marine source in two different seasons. They were cultivated under laboratory conditions using Nitrogen free Azotobacter specific medium. We observed that they were present in both seasons. The phylogenetic tree revealed that our isolated Azotobacter spp. was distantly related to uncultivated and uncultured organisms. Theydid not form any branch with other Azotobacter spp. in the data bas

Mono-chloro-substituted m-dinitrobenzene compound as cathode materials magnesium battery

The performance of mono-chloro-substituted m-dinitrobenzene compounds in magnesium battery is reported here. While the operating voltage is improved, the current efficiency is lowered by the chloro-substituents. The influence is explained taking into account inductive and mesomeric effects of the substituent

ANTIMICROBIAL ACTIVITY OF PANCHACAVYA AGAINST URINARY TRACK INFECTION

Objective: The present study analyzes the antibacterial activity of the natural product. Panchagavya is a term used in Ayurveda to describe five important substances obtained from cow namely Urine, Dung, Milk, Ghee Curd and the natural product of honey. Methods: The sample used as a different concentration of agar well diffusion technique. Results: Among the natural products, honey/100 µl given the maximum zone of inhibition against Staphylococcus aureus (33 mm), Pseudomonas spp. (31 mm), followed by Klebsiella spp. (28 mm)and Escherichia coli (28 mm). The crude extract of Lactobacillussp. (buttermilk and curd) showed the considerable zone of inhibition in all the four isolates such as Pseudomonas spp. Klebsiella spp. followed by Staphylococcus aureus and Escherichia coli. There is a considerable zone of inhibition for cow dung was observed only in Staphylococcus aureus. Among the natural products honey, milk, buttermilk was effective. Conclusion: All urine samples were aseptically inoculated on Eosine Methylene Blue agar (EMB), MacConkey Agar and Blood agar and incubated

Study of effectiveness, tolerability and safety of intravenous iron sucrose in iron deficiency anaemia in postnatal women

Background: Iron deficiency anaemia is the most common type of reversible anemia encountered during pregnancy and postpartum period. The present study was done with the objective to find out the efficacy and safety of intravenous iron sucrose in the treatment of iron deficiency anaemia in the postpartum period.Methods: Fifty (50) postnatal patients both after vaginal and caesarean section with iron deficiency anaemia within the first 48 hours with haemoglobin percentage between 6 g/dl and 8g/dl were studied prospectively at the Institute of Obstetrics and Gynaecology, Madras Medical College, Chennai. The patients were given 100 mg of elemental iron diluted in 100 ml of 0.9% normal saline and infused over 15 minutes every alternate day (not more than 3 days in a week) until the required dosage is infused. The blood samples of all the patients were collected and analyzed for haemoglobin (g/dl), hematocrit, mean corpuscular volume (MCV), serum iron, total iron binding capacity (TIBC) and compared before and after therapy.Results: The mean age group of the patients was 24.94 years. Majority of the patients were multipara (68%) and belongs to the class V socio economic status (84%). All the blood parameters were increased significantly (p=0.000) when compared from baseline values to end of the treatment. Mean raise in haemoglobin% after 30 days of treatment was 3.60. Average raise in the mean hematocrit was 8.73. The mean difference in the mean corpuscular volume, total iron binding capacity and the percent saturation was 129.77, 13.55, was 22.26 respectively.Conclusions: Our data confirm that the intravenous iron sucrose was very effective, well tolerated and safe than other forms of iron preparations for treating iron deficiency anaemia in postnatal women