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Due to the robust construction of AC drives, the majority of industries use AC drives. Low maintenance cost, Low power loss, easy to use and simple arrangement for starting the motor are the advantages due to which it is widely used in the industries. But the AC drives are constant speed drives and its speed can not be controlled smoothly over a wide range and operation in either direction. Direct Current (DC) motor is also an important drive configuration which is widely used in many applications. It is used in wide range of power and speed. The ease of access and good performance of the DC motor decides the growth of its use in the number of applications. There are many conventional methods available for controlling the speed of the DC motor, modern methods include high-speed switching power devices. The power switching devices provide accuracy and precision to speed control of the DC motor. The most efficient method for controlling the speed of DC motor is PWM control, it is very easy as well as cost efficient method. It is done by using the microcontroller which removes bulkiness of the system and provides increased reliability and flexibility to the control. When the load on the DC motor increases then it's current requirement also increases. For high current, the normal H-bridge configuration is not efficient as it gets heated up and then burns. The design of high current bearing H-bridge configuration or motor driver and generation of PWM and programs for the microcontroller are discussed in detail in this research paper. [ABSTRACT FROM AUTHOR]

Differential Bio-potential Amplifier is used to measuring the bio-impedance of the living things, like human body. The value of bio-impedance of body is very low on scale. To enhance it in a readable for this amplifier is used. It increases the value to bio-impedance up to very high on a scale. So measurement of bio-impedance correctly is a difficult task. It requires very precision circuitry to calculate it and enhance it. To enhance the performance of the circuitry high input impedance and high CMRR is required. In this paper an approach of using TLV2474 opamp in place of conventionally used op-amp. In proposed circuit has been shown to have better performance than all other input impedance & CMRR used in past research works. [ABSTRACT FROM AUTHOR]

A Wireless sensor network (WSN) has important applications such as remote environmental monitoring and target tracking. This has been enabled by the availability, particularly in recent years, of sensors that are smaller in size and intelligent. These sensors are equipped with wireless interfaces with which they can communicate with one another to form a network. Wireless sensor networks consist of sensor nodes with sensing and communication capabilities. As sensor nodes are generally battery-powered devices, the critical aspects to face concern how to reduce the energy consumption of nodes, so that the network life time can be increased to reasonable times. In this paper, we first describe the energy consumption for components of a typical sensor node and discuss the main directions to energy saving methods in wireless sensor networks. Then we present a systematic and comprehensive taxonomy of the energy optimization methods in wireless sensor networks. The main goal of energy optimization methods is to gather and aggregate data in an energy efficient manner so that network lifetime is enhanced. We conclude with possible future research directions. [ABSTRACT FROM AUTHOR]

The paper presents analytical and experimental results of a turbo equalizer based on MAP algorithm, including an assessment of its performance by means of computer simulation. Capitalizing on the tremendous performance gains of turbo codes and the turbo decoding algorithm, turbo equalization is an iterative equalization and decoding technique that can achieve equally impressive performance gains for communication system that sends digital data over channels that require equalization, i.e. those which suffer from intersymbol interference(ISI).In this paper, we discuss the turbo equalization approach to coded data transmission over ISI channels, with an emphasis on the basic ideas and some of the practical details. The above practices are just some steps to find out the best equalization technique that should be employed in the process so that at the receiving side we get a signal which is very nearly a replica of the transmitted signal. This clearly reflects that the BER is minimized. Simulation results are included. [ABSTRACT FROM AUTHOR]

The paper presents design and analysis of orthogonal space time block codes which provide a new concept for transmission over Rayleigh fading channels using multiple transmit antennas and single receive antenna. Data is encoded using an orthogonal space-time block code, and the encoded data is split into n streams which are simultaneously transmitted using n transmit antennas. In the structure, the noise added by the channel is considered as additive white Gaussian noise. The system performance is evaluated using the Maximum likelihood (ML) decoding. Numerical and simulation results show that orthogonal space time block codes exhibits significant performance improvement over Alamouti STBC, especially in interference limited conditions. [ABSTRACT FROM AUTHOR]

The issue of energy saving is significant since in a battery-operated wireless node, the battery energy is finite and a node can only transmit a finite number of bits. To extend the life span of a node in wireless sensor networks, an energy-efficient communication technique is mandatory so that energy expenditure is minimized, and at the same time, it satisfies the given throughput and delay necessities. In this context, we analyze the performance of cooperative Multiple-Input Multiple-Output (MIMO)-based communication in wireless sensor networks. In this paper, we analyze the communication method to reduce the total delay and total energy expenditure required to send specified quantity of bits. This energy efficiency investigation of MIMO scheme is broadened to individual single antenna nodes that collaborate to form multiple antenna transmitters or receivers. It is also seen that over some distance ranges, cooperative MIMO broadcast and reception can simultaneously achieve both energy savings and delay reduction. Simulations show that with proper design, cooperative MIMO-based communication is more faster and energy-efficient as compared to non-cooperative approach e.g., Single-Input Single-Output (SISO) for larger distances and prolong sensor network lifetime. [ABSTRACT FROM AUTHOR]

Space diversity technique is an attractive solution for improving quality in wireless links. The objectives of this paper are to investigate the impact of bit error rate on the number of users and the SNR for space time block coded MIMO Rayleigh fading channels. Diversity is a technique used to combat multipath-fading. Space Diversity is a technique in which multiple numbers of antennas are used at transmitter and receiver side. As far as detection techniques are concerned, we have used two detection techniques (a) joint minimum mean square error (JMMSE) (b) maximal receive ratio combining (MRRC). Furthermore, the usage of higher order diversity schemes not only provides the superior performance over lower order schemes, but also offers an opportunity for the service provider to accommodate more number of users. Simulation results are included. [ABSTRACT FROM AUTHOR]

This paper analyzes the performance of space time equalizer in multiple transmittermultiple receiver (MIMO) wireless communication system by combining it with Minimum Mean Square Error (MMSE) Equalizer. A comparison of various space diversity techniques is shown and it is found that 2 × 2 diversity gives better Bit Error Rate (BER) performance with respect to no diversity, transmit diversity and receiver diversity. It is also verified that the MMSE equalizer can operate better than other linear and nonlinear equalizers. The parameters of space time equalizer are optimized according to the MMSE criterion to reduce the effect of noise, Intersymbol Interference (ISI), and Multi-Access Interference (MAI) while at the same time maintaining moderate complexity. The system performance is evaluated using the Gaussian approximation. Numerical and simulation results showed that the MMSE-MIMO exhibited significant performance improvement over the standard space-time coded system, especially in interference limited conditions. [ABSTRACT FROM AUTHOR]