Divya R - Academia.edu (original) (raw)

Papers by Divya R

— An antenna is one of the main element used in both transmitter and receiver of a communication ... more — An antenna is one of the main element used in both transmitter and receiver of a communication system. Antenna helps in transmitting signals to space and receiving signals from space. It is the end component of the transmitter and starts component of the receiver. Therefore it is very important to study about antenna for designing a system. If there is any mistake occurs while selecting an antenna it will lead to the unreliability of the whole system. To design or select a suitable antenna its types and features should be analyzed, that's why this paper includes some types and features for antenna selection in a communication system. This paper simply summarizes an overview of antennae.

Mitigation of nonlinearity is very important factor as it influences the performance of a visible... more Mitigation of nonlinearity is very important factor as it influences the performance of a visible light communication (VLC) system. In this paper several nonlinearities and limitations of VLC systems are analyzed as a review study and detailing about some previous papers to develop a new logic as well as researching for VLC systems and future scopes to make a VLC system reliable. Nonlinearity is discussed and mainly focused in this paper as a main limitation of VLC. This paper discusses about a mitigation technique which is already proposed with micro light emitting diodes (LED) in cooperation with multiple access schemes here mainly CDMA is considered. Nonlinearity limits the performance in terms of bit error rate as well as error vector magnitude. Nonlinearity mitigation methods are proposed earlier but that system designs are not suitable for indoor and industrial applications, because such design required additional circuits, which make the system high cost and complex. This paper can be considered as a literature survey or a case study to analyze VLC and a search for new scopes in VLC.

— Antenna is a main element used in both transmitter and receiver of a communication system. Ante... more — Antenna is a main element used in both transmitter and receiver of a communication system. Antenna helps in transmitting signals to space and receiving signals from space. It is the end component of transmitter and start component of receiver. Therefore it is very important to study about antenna for designing a system. If there is any mistake occurs while selecting an antenna it will leads to the unreliability of whole system. To design or select a suitable antenna its types and features should be analyzed, that's why this paper includes some types and features for antenna selection in communication system. This paper simply summarizes an overview of antennae.

Underwater communication is one of the unique and challenging fields in communication engineering... more Underwater communication is one of the unique and challenging fields in communication engineering in the case of both designing and communication. But it is very necessary to study on UWC as major portion of earth contains sea water. UWC has many scopes in various areas like Radar, Sonar, oceanography, UWIoT, etc. UWC mainly of three types through optical fiber, RF waves, and acoustic waves. Communication with acoustic waves use low decibel sound waves and have long transmission range than others. This paper explains about some acoustic waves communication within underwater. Mainly different areas and applications in UWC with acoustic waves are explained as a literature work.

Polymer based electronic devices have vast potential for future electronics development as it has... more Polymer based electronic devices have vast potential for future electronics development as it has many advantages over conventional inorganic semiconductor based systems, interms of manufacturing, cost, weight, flexibility, and especially the ability to integrate a wide variety of functions on a single platform. Polymer electronics is a unique micro-device technology utilizing plastic diodes, transistors, sensors, light-emitting devices, and photovoltaics among others. Usually the polymer materials can be synthesized chemically, electrochemically and in plasmas. Structural order can be varied from purely amorphous to highly crystalline. Substrate shapes can range from fibers to films. It means that organic materials have more degrees of freedom to work with than inorganic semiconductors. This paper deals with some detailed study about an advanced alternative to conventional inorganic fabrication materials.

— To design a reliable wireless system, its energy efficiency is an essential factor. As MIMO sys... more — To design a reliable wireless system, its energy efficiency is an essential factor. As MIMO system has to suffer from fading, interferences and noises, the system should design in such a way that to compensate these problems. So interference alignment is included with MIMO interfering broadcast channel. This paper deals with the energy efficiency maximization of MIMO-IFBC system. When the energy efficiency is maximized, as it depends on power, the capacity of the system increases and thus the data rate also increases and cancels or minimizes interferences. Here the EE is compared and optimized for two SNR regions, that is, for high SNR and moderate SNR. For high SNR singular value decomposition is used with water filling power adaptation algorithm and EE is optimized. The optimization of EE and power allocation is easy to implement as noise and interference is less. In the case of high SNR the power is high and noise is low so EE can maximize using power allocation algorithms most commonly used is water filling algorithm. For moderate SNR regions, the power is less so by using DPC algorithm the distorted or low power signal at receiver can be boosted so power can increased and thereby EE get maximized. This paper focused mainly on the EE optimization of moderate SNR regions, and thereby a reliable MIMO-IFBC system with interference alignment for medium SNR is proposed.

In networking technology, wireless is the term used to describe any network where there is no phy... more In networking technology, wireless is the term used to describe any network where there is no physical wired connection between sender and receiver, but rather the network by radio waves or micro waves to maintain communications. The evolution of technology specially in mobile technology is the most and fast developing, that era starts from 1G in 1980s and it is replaced by a continuous emerging of next generations. To compensate the drawbacks of each previous generation next generation with lot of new applications is introduced. Now it is fourth generation that is 4G, beyond 4G now researches are going on about 5G and it will come into existence by 2020s. In the near future, i.e., beyond 4G, some of the prime objectives or demands that need to be addressed are increased capacity, improved data rate, decreased latency, and better quality of service. To meet these demands, drastic improvements need to be made in cellular network architecture. This paper presents the results of a detailed survey on the fifth generation (5G) cellular network architecture and some of the key emerging technologies that are helpful in improving the architecture and meeting the demands of users. A detailed survey is included regarding all wireless generations especially concentrated on 5G by research groups and institutions are detailed in this paper.

Thesis Chapters by Divya R

Underwater communication is one of the challenging fields in communication engineering with wired... more Underwater communication is one of the challenging fields in communication engineering with wired and wireless communication. In underwater communication there are several possibilities for mitigating terrestrial communication limitations. Familiar methods for underwater communication are using radio waves, optical fibers and acoustic waves. Limitation of short distance range of communication with RF and fiber, low frequency sound waves are used here as the medium and also acoustic waves are capable of withstanding ambient noises and vibrations in water.
This project intend to the design of an underwater acoustic communication system. For an underwater communication cost is not a factor for initial deployment of the system as the frequent maintenance is not practically possible. To design a reliable communication system the main aims are long distance, secure and accurate. Here such a system is selected as existing system and it is analyzed. An amplifier and forward relay assisted system is considered as the existing system to study about underwater acoustic communication system in detail for designing a reliable system. One of the specialty of this paper is it covers almost all fields in communication engineering, especially signal processing, wireless communication, estimation and detection, etc.
The main focus of this paper is sparse channel estimation and equalization with AF relaying for underwater cooperative systems based on OFDM. For the channel estimation Matching Pursuit (MP) algorithm is used in combination with maximum a posteriori probability (MAP) based SAGE technique. This algorithm is low complex for good performance channel estimation and it will provide a better symbol error rate and can overcome the mismatching effects of Doppler shift. In simulation results for CGM-MP-SAGE algorithm, Doppler effects and multipath system for BPSK modulation are analyzed in terms of SER performance and average MSE based on SNR values. This system has a poor reliability in terms of practical implementation. Thus a new system is proposed to compensate the drawbacks and for practical implementation. Some reliable approaches can be used by including different ideas such as compress and forward relay can be used to increase the data rate and avoiding error, instead of AF relaying. For frequency and time analyzing pilot based estimation with PN sequence can be used.
In addition to this for providing high diversity MIMO system can be integrated. Zero force equalizer can be provided and adaptive filter is used for equalization, here RLS filter is used to avoid interferences. For the removal of channel error and burst error, a channel encoder and interleaver is used respectively. More important a fast converging estimation technique is used instead of MAP is MMSE. Minimum mean square error estimation is used, as it is suitable for practical deployment in underwater with excellent SNR performance results than MP-SAGE algorithm.
As UWAC system has to suffer from fading, interferences and noises, the system should design in such a way that to compensate these problems. So interference alignment is included to improve capacity, power allocation is provided with SVD and DPC algorithms for separate SNR regions. When the energy efficiency is maximized, the capacity of the system increases. For high SNR singular value decomposition is used with water filling power adaptation algorithm and EE is optimized. The optimization of EE and power allocation is easy to implement as noise and interference is less.
For moderate SNR regions, the power is less so by using DPC algorithm the distorted or low power signal at receiver can be boosted so power can increased and thereby energy efficiency get maximized. This work introduces a design for reliable underwater communication system using acoustic waves is implementing with CGM-MP-MMSE estimation and the capacity of the system is improving for variable SNR regions with SVD and DPC algorithms.

For an underwater communication cost is not a factor for initial deployment of the system as the ... more For an underwater communication cost is not a factor for initial deployment of the system as the frequent maintenance is not practically possible. To design a reliable underwater communication system the main aims are long distance, secure and accurate. Some reliable approaches can be implemented by including different ideas such as compress and forward relay can be used to increase the data rate instead of AF relaying, as it is commonly used in previous researches, for frequency and time analyzing pilot based estimation with PN sequence can be used. In addition to this for providing high diversity MIMO system can be integrated. Zero force equalizer can be provided and adaptive filter is used for equalization, here RLS filter is used to avoid interferences. For the removal of channel error and burst error, a channel encoder and interleaver is used respectively. More important a fast converging estimation technique is used instead of MAP is MMSE. Minimum mean square error estimation is used, as it is suitable for practical deployment in underwater. Thus a reliable design for UWAC for practical implementation is proposed and its performance exhibits excellent simulation results.

— Underwater communication is one of the unique and challenging fields in communication engineeri... more — Underwater communication is one of the unique and challenging fields in communication engineering in the case of both designing and communication. Previous papers explained about different views in acoustic based underwater communication. Communication with acoustic waves is suitable type of wireless transmission with sound waves underwater. This paper explains about SER and MSE analysis of AF relay based cooperative underwater communication based on CGM-MP-SAGE algorithm. Here in this paper it summarizes estimation and equalization with SAGE algorithm of acoustic waves through underwater. This is a review paper to analyze the error rate performance and reliability of UWAC with respect to the SNR for different signal parameters, mainly MP, perfect CSI and MP SAGE algorithms, Doppler rates, resolution factors, multipath with variable lengths and pilot spacing based on BPSK modulated OFDM signals.

— underwater communication is one of the unique and challenging fields in communication engineeri... more — underwater communication is one of the unique and challenging fields in communication engineering in the case of both designing and communication. Previous papers explained about different views in acoustic based underwater communication. Communication with acoustic waves is suitable type of wireless transmission with sound waves underwater. This paper explains about different underwater acoustic communication approaches. Here in this paper it summarizes different estimation, equalization and transmission criteria of acoustic waves through underwater. This is a review paper to combine different approaches in UWAC as a summary work.

This work presents the development of a robotic wheelchair that can be commanded by users. It pro... more This work presents the development of a robotic wheelchair that can be commanded by users. It provides flexibility to choose different modalities to command the wheelchair, in addition to be suitable for people with different levels of disabilities like partially paralyzed, by birth disabilities, accidental injuries etc. Users can command and control the wheelchair based on their head movements. Also, the user can control some home appliances. As a trial, we work on the lighting system in a room that is ON and OFF mechanism of a light. The wheelchair can also operate like an auto-guided vehicle, with the help of obstacle sensors, which detects the obstacles in front of it, and it either stops or takes deviation. A main door detection section is provided with a magnetic sensor in the wheelchair and a magnet fixed at the main door for safety and then the wheelchair stops. A security as well as a safety alarm is provided in the device, which beeps when the device may hit somewhere or an emergency situation occurs. Head movements are used for both moving the device and for controlling directions of the device. This device is capable of lighting the room by eye movements.

Conference Presentations by Divya R

Mitigation of nonlinearity is very important as it influences the performance of a visible light ... more Mitigation of nonlinearity is very important as it influences the performance of a visible light communication (VLC) system. In this paper a mitigation technique is proposed with micro light emitting diodes (LED) in cooperation with multiple access schemes here mainly CDMA is used. Nonlinearity limits the performance in terms of bit error rate as well as error vector magnitude. Nonlinearity mitigation methods are proposed earlier but that system designs are not suitable for indoor and industrial applications, because such design required additional circuits, which make the system high cost and complex. This paper deals with multi user scenario with multiple access technique instead of point to point VLC systems. Here a CDMA transmission scheme which can support variable data rate for multi user is proposed. To enable linear transmission with wider modulation bandwidth and variable data rate micro LED array devices are used. Conventional CDMA scheme does not take the nonlinearity of the LED into account so a new CDMA architecture with micro LED array is proposed and also provides multiple access as well as variable data rate with no nonlinear impairments. To achieve the variable data rate spreading codes are combined to a new spreading code with lower chip rate. The proposed system is a robust VLC system which is proved by simulations and laboratory experiments.

Its a seminar paper presentation on mitigation methods of nonlinearity by comparing previous meth... more Its a seminar paper presentation on mitigation methods of nonlinearity by comparing previous methods for a VLC system.
This paper combines a CDMA technique to mitigate LED nonlinearity in VLC.