Dr.Kalipindi Murali | Jntu Kakinada (original) (raw)

Papers by Dr.Kalipindi Murali

— Our aim is to build an eco-friendly system for the assortment of information from the environme... more — Our aim is to build an eco-friendly system for the assortment of information from the environment. The system must be power-independent with the usage of renewable power bases. As a holdup different resources in power source in the event of critical conditions, other ecological technologies can be used. Our proposed system needs to be power efficient and should be able to accomplish itself without any exterior observation.

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Our aim is to build an eco-friendly system for the assortment of information from the environment... more Our aim is to build an eco-friendly system for the assortment of information from the environment. The system must be power-independent with the usage of renewable power bases. As a holdup different resources in power source in the event of critical conditions, other ecological technologies can be used. Our proposed system needs to be power efficient and should be able to accomplish itself without any exterior observation.

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If alien civilizations do, or did, exist, their technology will impact their environment.... more If alien civilizations do, or did, exist, their technology will impact their environment. However, a very advanced technology might leave more subtle footprints requiring sophisticated scientific methods to uncover. However, indirect evidence for extraterrestrial intelligence could come from any incontrovertible signatures of non-human technology. We must not overlook the possibility that alien technology has impacted our immediate astronomical environment, even Earth itself, but probably a very long time ago. In this paper we take as a case study first and then propose a new approach, how to trace the aliens in any part of the universe just by using Space Astro DNA technology which includes the possibilities of biological, geological and physical traces, and suggest ways that we might search for them. In addition, the DNA sequence can become a tool for other science investigations aboard the station. For example, researchers could use it to examine changes in genetic material or gene expression on orbit rather than waiting for the samples to return to Earth for testing.
Key Words: civilization, extraterrestrial intelligence, DNA.

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Abstract—The number of users and the use of telecommunication systems are increasing rapidly and ... more Abstract—The number of users and the use of telecommunication systems are increasing rapidly and this result in greater demands on energy usage. Based on the extensive Life-cycle assessment (LCA) conducted by various network operators, it is learned that energy consumption in the usage phase of its radio access networks is the most imminent factor relating to impact on athe environment. The amount of CO2 emission is increasing in communication system, in parallel with increase in mobile consumers. And it is also observed that current wireless networks are not energy- efficient, mainly the base stations (BS). This alarming growth in mobile users forces us to use higher data rate mobile broadband. The need for restructuring of existing network architecture, we need to control the systems in every base station. This paper discusses the current energy consumption scenario in base station devices. It also describes innovative and promising method for enhancing the energy-efficiency of the wireless networks and developing solutions that reduce operating costs and effects on the environment.

Index Terms—CO2 emission reduction, Energy efficient wireless network, Green Radio Technology, Power saving in base stations.

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AB S T R A C T: The advancements in mobile communication has given many privileges to the subscri... more AB S T R A C T:
The advancements in mobile communication has given many privileges to the subscribers for instance high speed data connectivity, voice and video applications in economical rates with good quality of services. It offers both LOS and non-LOS wireless communication. Orthogonal frequency division multiple access is used by WiMAX on its physical layer. Orthogonal frequency division multiple access uses adaptive modulation technique on the physical layer of WiMAX and it uses the concept of cyclic prefix that adds additional bits at the transmitter end. The signal is transmitted through the channel and it is received at the receiver end. Then the receiver removes these additional bits in order to minimize the inter symbol interference, to improve the bit error rate and to reduce the power spectrum. In our research work, we investigated the physical layer performance on the basis of bit error rate, signal to noise ratio, power spectral density and error probability. These parameters are discussed in a simple OFDM communication model without the cyclic prefix[1]

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Spectrum sensing is an important function to enable cognitive radios to detect the underutilized ... more Spectrum sensing is an important function to enable cognitive radios to detect the underutilized spectrum licensed to the primary systems and improve the overall spectrum efficiency. Some well-known spectrum sensing techniques are energy detection, matched filter and cyclostationary feature detection that have been proposed for narrowband sensing. In these methods, based on the signal properties, a decision is made to detect presence or absence of a primary user in the considered band. The proposed model for wideband spectrum sensing is illustrated in Figure 2. The analog received signal at the sensing cognitive radio is sampled by the multicoset sampler at a sample rate lower than the Nyquist rate. The sampling reduction ratio is affected by the channel occupancy and multicoset sampling parameters. The outputs of the multicoset sampler are partially shifted using a multirate system, which contains the interpolation, delaying and down sampling stages. Next, the sample correlation matrix is computed from the finite number of obtained data. Finally, the correlation matrix is investigated to discover the position of the active channels by subspace methods. We evaluate this method by computing the probability of detecting signal occupancy in terms of the number of samples and signal to noise ratio (SNR).

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This project addresses the problem of clock synchronization between a base station (BS) and a mob... more This project addresses the problem of clock synchronization between a base station (BS) and a mobile station (MS). A conventional technique for clock synchronization is that the MS clock is derived from the downlink signal originated from a base station. In cellular systems, a base station and mobile stations need to be synchronized before data exchange. Since the base station clock reference is more accurate, a mobile station typically derives its clock reference from the base station. But the carrier frequency offset due to Doppler shift may have harmful effects on the local clock derivation. This project proposes a joint clock and frequency synchronization technique between a base station and a mobile station, which is effective even with Doppler shift. We derive the joint estimation algorithm by analyzing the phase and the amplitude distortion caused by the sampling frequency offset and the carrier frequency offset. Simulation results showing the effectiveness of the proposed algorithm will also be presented.

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The rapid growth of bandwidth demanding wireless technologies has led to the problem of spectrum ... more The rapid growth of bandwidth demanding wireless technologies has led to the problem of spectrum scarcity. However, studies show that licensed spectrum is underutilized. Cognitive radio technology promises a solution to the problem by allowing unlicensed users, access to the licensed bands opportunistically. A prime component of the cognitive radio technology is spectrum sensing. Many spectrum sensing techniques have been developed to sense the presence or not of a licensed user. This paper evaluates the performance of the energy detection based spectrum sensing technique in noisy, fading, jamming, interference environments. Both single user detection and cooperative detection situations were investigated. Closed form solutions for the probabilities of detection and false alarm were derived. The analytical results were varied by numerical computations using Monte Carlo method with MATLAB. The performance of the computationally efficient energy detection (CE-ED) techniques were evaluated by use of Receiver Operating Characteristics (ROC) curves over additive white Gaussian noise (AWGN) and fading (Rayleigh & Nakagami-m) channels. Results show that for single user detection, the energy detection technique performs better in AWGN channel than in the fading channel models. The performance of cooperative detection is better than single user detection in fading environments.

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ABSTRACT: OFDM can be seen as either a modulation technique or a multiplexing technique. One of t... more ABSTRACT:
OFDM can be seen as either a modulation technique or a multiplexing technique. One of the
main reasons to use OFDM is to increase the robustness against frequency selective fading or
narrowband interference. In a single carrier system, a single fade or interferer can cause the
entire link to fail, but in a multicarrier system, only a small percentage of the subcarriers will be
affected. Error correction coding can then be used to correct for the few erroneous subcarriers.
In this paper, channel estimation for Spatial Multiplexing (SM) is investigated
for MIMO-OFDM system. Due to the channel characteristic of the transmission system is always
changed by the time and its importance in wireless transmission to reconstruct the transmitted
signals, the channel needs to be known as well as possible. Pilot symbols are used to gather
knowledge about the channel and try to estimate it. The channel estimation based on the pilot
symbol is called pilot aided channel estimation. In this research, Least Square (LS) method was
chosen for initial channel estimation. By using applicable proposed system design, channel state information is estimated through the use of channel information before in subcarriers with no
pilot symbols. Zero forcing (ZF) algorithms is used to detect and separate the received signal.
Keywords- MIMO, OFDM , pilot symbol, channel estimation, least square, minimum mean
square ,zero forcing.

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ABSTRACT: Recent advances in communication technologies and the proliferation of wireless comput... more ABSTRACT:
Recent advances in communication technologies and the proliferation of wireless computing and
communication devices make the radio spectrum overcrowded. However, experiments from the
Federal Communication Commission (FCC) reveals that the spectrum utilization varies from
15% − 85%. Consequently, Cognitive Radio Networks (CRNs) are proposed to utilize the radio
spectrum opportunistically. Therefore, FCC is currently working on the concept of unlicensed
users “borrowing” spectrum from incumbent license holders temporarily to improve the
spectrum utilization. This concept is called dynamic spectrum access (DSA). Cognitive radios
offer versatile, powerful, and portable wireless transceivers enabling DSA.
For complex computer networks with many tunable parameters and network performance
objectives, the task of selecting the ideal network operating state is difficult. To improve the
performance of these kinds of networks, this research proposes the idea of the cognitive network.
A cognitive network is a network composed of elements that, through learning and reasoning,dynamically adapt to varying network conditions in order to optimize end-to-end performance.
Therefore, a new channel selection strategy is required which cause less harmful interference to
PR nodes and try to maximize the chances that the message is delivered to the neighboring
cognitive radio receivers, thus increasing the data dissemination reachability.
Keywords: Cognitive radio networks, channel selection, dynamic spectrum access networks,
spectrum sensing, cooperation, Receiver Detection, OR and AND rule

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Abstract - In this report the ultra wide band signals are more affected due to EM waves propagate... more Abstract - In this report the ultra wide band signals are more
affected due to EM waves propagated through irregular
shaped bodies such as walls, buildings and hill areas
multipath effects, too. MPCs are analyzed for various cases
with several antenna heights and distances. Path delays (due
to propagation through walls and various paths of direct and
reflected rays) and the ringing (similar to UWB propagation
through wall) can be clearly observed and analyzed. This
paper provides a new proposal where an antenna is used in
(40-60GHz) frequency range to reduce the effect of Multipath
path fading coefficients.
Keywords - UWB, Multipath Fading, EWP

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ABSTRACT: The main aim of the paper is to explain the working of a robot with the use of an Ad-Ho... more ABSTRACT: The main aim of the paper is to explain the working of a robot with the use of an Ad-Hoc network. This paper explains major features of the Ad –Hoc network along with the wheel rotational analysis and the DC motor specifications used for the robot. The microcontroller used here is an aurdino controller. This robot is designed in order for access to areas that are not safe for humans in case of disasters. Ad-Hoc is used instead of infrastructure mode because it moves convenient. Secondly we also wanted to test the robot communication using the Ad-hoc network. A brief description of the dc motor and wheel rotational analysis are given with respective our robot construction. Keyword: Ad-Hoc, capacity, 802.11, traffic density, D C motor, load characteristics, speed control, wheel rotation. * VIJAYA INSTITUE OF TECHNOLOGY FOR WOMEN, ENIKEPADU, VIJAYAWADA. ** Asst Professor of ECE, VIJAYA INSTITUE OF TECHNOLOGY FOR WOMEN, ENIKEPADU, VIJAYAWADA.

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Abstract: OFDM can be seen as either a modulation technique or a multiplexing technique. One of t... more Abstract: OFDM can be seen as either a modulation technique or a multiplexing technique. One of the main reasons to use OFDM is to increase the robustness against frequency selective fading or narrowband interference. In a single carrier system, a single fade or interferer can cause the entire link to fail, but in a multicarrier system, only a small percentage of the subcarriers will be affected. Error correction coding can then be used to correct for the few erroneous subcarriers. Nanotechnologies are providing a new set of tools to the engineering community to design and manufacture devices in a scale ranging from one to a few hundred nanometers. The same nano communication applied for OFDM to provide connection between Nano molecular communication , At this scale, a nano machine is defined as the most basic functional unit, which is able to perform only very simple tasks, such as computing, data storing, sensing and actuation. Nano networks, i.e., the interconnection of nanomachines in networks, will expand the capabilities of single nano-devices by providing them a way to cooperate and share information. The sharing is in between the wireless communication network with Molecular Nano Communication network which indirectly reduces the foliage loss and loss of bandwidth of the signal by trees in wireless environment with approximate information of tree molecules . Keywords- MIMO, OFDM, pilot symbol, nao communication

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Abstract - When a new control strategy of a drive system is formulated, it is often convenient to... more Abstract - When a new control strategy of a drive system is formulated, it is often convenient to study the system performance by simulation before building the prototype. The simulation not only validates the system operation, but also permits optimization of the system performance by iteration of its parameters. Besides control and circuit parameters, the plant parameter variation effect can be studied. Valuable time is thus saved in the development and design of the product and the failure of components of poorly designed systems can be avoided. The simulation program also helps to generate real time controller software codes for downloading to a microprocessor or digital signal processor [2]. Many circuit simulators like PSPICE, EMTP, and MATLAB/SIMULINK incorporated these features. The advantages of simulink over other circuit simulators are the ease in modeling the transients of electrical machines and drives and to include controls in the simulation. To achieve out objectives this efficient simulink software is used. For electrical drives good dynamic performance is mandatory so as to respond to the changes in command speed and torques. So various speed control techniques are being used for real time applications. Here the speed of a dc motor is controlled by using various controllers like PI-controller, Fuzzy controllers. Fuzzy logic and neural network concepts are applied to DC drive system [1]. This project describes application of fuzzy logic controllers for current and speed control loops of DC drive systems. Neural network is employed to linearize the rectifier characteristics in discontinuous conduction mode. Simulation result shows the superiority of proposed controller over fixed parameter PI-controller and best possible fuzzy logic controller can be designed without expert knowledge and extensive tuning of parameters [1]. Keywords: cosine wave crossing method, neural compensation, fuzzy controller, conventional PI- controller, armature reaction, GUI (graphical user interface), feed forward back propagation

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Abstract: The theory of orthogonal designs dates back over a century. Since Radon’s classical res... more Abstract: The theory of orthogonal designs dates back over a century. Since Radon’s classical result implying the set of
dimensions for which real square orthogonal designs exist, several generalizations of real square orthogonal designs have
followed, including generalized real orthogonal designs and complex orthogonal designs, generalized complex orthogonal
designs, and generalized complex linear processing orthogonal designs. Tarokh, Jafarkhani and Calderbank pioneered
using generalized complex orthogonal designs to construct space-time Block codes (STBCs), which are used to transmit
data over wireless channels using multiple transmit antennas. Their work extends Alamouti’s scheme for wireless
communications with two transmit antennas. In this work a construction technique for generalized Complex linear processing
orthogonal designs, is introduced which are p × n matrices X Satisfying XHX = fI, where f is a complex quadratic form, I is
the identity matrix, and X has complex entries. These matrices generalize the familiar notations of orthogonal designs and
generalized complex orthogonal designs. We explain the application of these matrices to space-time block coding for multipleantenna
wireless communications. In particular, the Practical strengths of the space-time block codes constructed using the
proposed technique (i.e. Quasi Orthogonal Space time block codes) are discussed and Interference can also be eliminated.
Keywords: Antenna Diversity, Rayleigh Fading, Space–time Coding, Transmit Diversity, Interference.

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Almost 80 to 90 percent of the radio spectrum is left unutilized at any period of time, while at ... more Almost 80 to 90 percent of the radio spectrum is left unutilized at any period of time, while at the same time some other regions of spectrum experience overcrowding. We consider a dynamic spectrum access system in which Secondary Users (SUs) choose to either acquire dedicated spectrum or to use spectrum-holes (white spaces) which belong to Primary Users (PUs). The tradeoff incorporated in this decision is between immediate yet costly transmission and free but delayed transmission (a consequence of both the possible appearance of PUs and sharing the spectrum holes with multiple SUs). Cognitive radio is a smart radio that can identify the idle frequencies (also termed as spectral holes or white spaces) and allot them for the use of unlicensed secondary users. The basic functionality of a cognitive radio is to sense the spectrum accurately by avoiding any chances for interfering with primary or licensed users. Spectrum sensing can be performed either in cooperative or non-cooperative method. This paper performs Non cooperative spectrum sensing, using search based energy detection technique (SB-ED). The idea is to utilize nodes to convey the signal transmitted from primary user to the fusion center and then estimate the presence or absence of primary activities in the spectrum. Key words: Cognitive Ra

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Index Terms—CO2 emission reduction, Energy efficient wireless network, Green Radio Technology, Power saving in base stations.

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