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A. Sangeetha

Bio: A. Sangeetha is an academic researcher from VIT University. The author has contributed to research in topics: Wavelength-division multiplexing & Dispersion (optics). The author has an hindex of 6, co-authored 22 publications receiving 106 citations.

Papers
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01 Jan 2009
TL;DR: In this article, the authors analyzed the wavelength assignment problem in optical WDM networks and compared the first-fit algorithm with the random algorithm in terms of blocking probability and number of links.
Abstract: This paper analyses the wavelength assignment problem in optical WDM networks. First, the random wavelength assignment algorithm is compared with the first-fit wavelength assignment algorithm, later, the sparse wavelength conversion case is compared with no wavelength conversion and full wavelength conversion cases. These comparisons are done on the basis of blocking probability and number of links; numbers of channels are kept constant whereas the response is calculated by varying the load per link (in Erlangs). The blocking probability in case of random algorithm is always greater than first-fit wavelength assignment algorithm. The blocking probability is minimum in case of wavelength conversion, whereas in case of no conversion, the first-fit algorithm has better results as compared to that of random wavelength assignment algorithm.

20 citations

Proceedings ArticleDOI
13 Dec 2007
TL;DR: The experimental results demonstrate the efficiency of the proposed scheme, which fulfills the strict requirements concerning alterations of satellite images, and provides a third level DWT decomposition of the satellite image by choosing a region of interest and embedding the watermark in the same.
Abstract: Digital watermarking has been proposed to increase the digital data security, confidentiality and integrity. Satellite image watermarking is a special category of image watermarking in the sense that the images have special requirements. Particularly, watermarked satellite images should not differ perceptually from the the original counterparts, because the purpose of taking the image must not be violated. This paper provides a third level DWT decomposition of the satellite image by choosing a region of interest and embedding the watermark in the same. The reason for choosing a region of interest is an area which contains important information and must be sent through media without any distortions and attacks. Image quality is checked out with a number of widely used metrics such as PSNR, normalized correlation and JPEG compression. The experimental results demonstrate the efficiency of the proposed scheme, which fulfills the strict requirements concerning alterations of satellite images.

14 citations

Proceedings ArticleDOI
01 Apr 2017
TL;DR: The range requirements and ideal choice of laser for indoor usage of RoF systems have been identified and a novel architecture has been proposed for indoor application, which provides several important benefits in terms of design, installation, and operation of the systems used.
Abstract: Radio over Fiber (RoF) Systems have the unique characteristic of featuring both a fiber optic link and a free space radio path. It finds extensive use in the indoor wireless market. The range requirements and ideal choice of laser for indoor usage of RoF systems have been identified in this paper. A novel architecture has been proposed for indoor application, which provides several important benefits in terms of design, installation, and operation of the systems used. This architecture is very much useful in meeting the increasing demands of user bandwidth. In this network, a central station (CS) was connected to numerous Radio Access Points (RAP) using an optical fiber to facilitate indoor connection. The indoor RF front end consisted of the following-a photodiode, a bandpass filter, a power amplifier and an antenna operating in the 2.4 GHz frequency band. S-parameter measured data from factory data sheets were used for modeling the RF front end components. Indoor picocells were used having power capacity lower than 1 Watt (30 dBm) and a service range of about 100 metres. The operating gain of the system was calculated with the aforementioned configuration.

13 citations

Journal ArticleDOI
TL;DR: A new code proposed is Dynamically Cyclic Shift (DCS) code to assess the execution of SAC-OCDMA network and the reduction of Multiple Access Interference (MAI) and the correlation values lies between 0 and 1, for the developed DCS code.
Abstract: In this paper, a new method is presented to calculate the execution of Spectral Amplitude Coding Optical Code Division Multiple Access (SAC-OCDMA) network. A new code proposed is Dynamically Cyclic Shift (DCS) code to assess the execution of the network. Bit error rate is the parameter of performance studied. A Dynamically Cyclic Shift (DCS) algorithm is used at the transmitter section and a detection technique called AND-Subtraction technique is used at the receiver. The most astonishing aspect in the detection techniques the reduction of Multiple Access Interference (MAI) and the correlation values lies between 0 and 1, for the developed DCS code. SAC-OCDMA network is more consideration in view of their capacity to totally avoid multiple access obstruction by utilizing code successions with settled in phase cross correlation (λ c ). The performance is calculated using the Signal to Noise Ratio (SNR) and the experiment is simulated at 8 Gb/s for a link length of 15 km using optisystem TM ver.12 simulation software from optiwave. The BER obtained is 4.66 × 10 -17 using DCS code.

10 citations

01 Jan 2009
TL;DR: In this paper, a comprehensive simulation on the optimization of the management of the non linear effects in long-haul light wave systems has been carried out by chirped RZ format as the format has significant advantages over the RZ and NRZ modulation formats in WDM systems.
Abstract: A comprehensive simulation on the optimization of the management of the non linear effects in long haul light wave systems has been carried out by chirped RZ format as the format has significant advantages over the RZ and NRZ modulation formats in WDM systems We have tried to demonstrate that a system reach of long-haul light wave link could be significantly improved by optimizing the dispersion map in transmission path and pre-chirping input pulses. Input powers were reduced to provide quasi-linear regime. There is a need for the optimization of the length of compensation fiber on both terminal sides to maximize the effect for channel away from zero-dispersion wavelength.

8 citations


Cited by
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Journal ArticleDOI
TL;DR: A cognitive engineering design study is presented that examines the effect of the distance of analogical design stimuli on design solution generation, and places those findings in context of results from the literature.
Abstract: This work lends insight into the meaning and impact of “near” and “far” analogies. A cognitive engineering design study is presented that examines the effect of the distance of analogical design stimuli on design solution generation, and places those findings in context of results from the literature. The work ultimately sheds new light on the impact of analogies in the design process and the significance of their distance from a design problem. In this work, the design repository from which analogical stimuli are chosen is the U.S. patent database, a natural choice, as it is one of the largest and easily accessed catalogued databases of inventions. The “near” and “far” analogical stimuli for this study were chosen based on a structure of patents, created using a combination of Latent Semantic Analysis and a Bayesian based algorithm for discovering structural form, resulting in clusters of patents connected by their relative similarity. The findings of this engineering design study are contextualized with the findings of recent work in design by analogy, by mapping the analogical stimuli used in the earlier work into similar structures along with the patents used in the current study. Doing so allows the discovery of a relationship between all of the stimuli and their relative distance from the design problem. The results confirm that “near” and “far” are relative terms, and depend on the characteristics of the potential stimuli. Further, although the literature has shown that “far” analogical stimuli are more likely to lead to the generation innovative solutions with novel characteristics, there is such a thing as too far. That is, if the stimuli are too distant, they then can become harmful to the design process. Importantly, as well, the data mapping approach to identify analogies works, and is able to impact the effectiveness of the design process. This work has implications not only in the area of finding inspirational designs to use for design by analogy processes in practice, but also for synthesis, or perhaps even unification, of future studies in the field of design by analogy.

222 citations

Journal ArticleDOI
07 Mar 2019-Sensors
TL;DR: A system prespective of VLC is given along with the survey on existing literature and potential challenges toward the implementation and integration of V LC.
Abstract: Visible light communication (VLC) is a new paradigm that could revolutionise the future of wireless communication. In VLC, information is transmitted through modulating the visible light spectrum (400–700 nm) that is used for illumination. Analytical and experimental work has shown the potential of VLC to provide high-speed data communication with the added advantage of improved energy efficiency and communication security/privacy. VLC is still in the early phase of research. There are fewer review articles published on this topic mostly addressing the physical layer research. Unlike other reviews, this article gives a system prespective of VLC along with the survey on existing literature and potential challenges toward the implementation and integration of VLC.

140 citations

Journal ArticleDOI
TL;DR: Methodical analysis of task scheduling in cloud and grid computing is presented based on swarm intelligence and bio-inspired techniques and will enable the readers to decide suitable approach for suggesting better schemes for scheduling user’s application.
Abstract: Heterogeneous distributed computing systems are the emerging for executing scientific and computationally intensive applications. Cloud computing in this context describes a paradigm to deliver the resource-like computing and storage on-demand basis using pay-per-use model. These resources are managed by data centers and dynamically provisioned to the users based on their availability, demand and quality parameters required to be satisfied. The task scheduling onto the distributed and virtual resources is a main concern which can affect the performance of the system. In the literature, a lot of work has been done by considering cost and makespan as the affecting parameters for scheduling the dependent tasks. Prior work has discussed the various challenges affecting the performance of dependent task scheduling but did not consider storage cost, failure rate-related challenges. This paper accomplishes a review of using meta-heuristics techniques for scheduling tasks in cloud computing. We presented the taxonomy and comparative review on these algorithms. Methodical analysis of task scheduling in cloud and grid computing is presented based on swarm intelligence and bio-inspired techniques. This work will enable the readers to decide suitable approach for suggesting better schemes for scheduling user’s application. Future research issues have also been suggested in this research work.

114 citations

Journal ArticleDOI
TL;DR: The results of experimentally testing a new method for extracting functional analogies from general data sources, such as patent databases, to assist designers in systematically seeking and identifying analogies are presented.
Abstract: Design-by-analogy is a growing field of study and practice, due to its power to augment and extend traditional concept generation methods by expanding the set of generated ideas using similarity relationships from solutions to analogous problems. This paper presents the results of experimentally testing a new method for extracting functional analogies from general data sources, such as patent databases, to assist designers in systematically seeking and identifying analogies. In summary, the approach produces significantly improved results on the novelty of solutions generated and no significant change in the total quantity of solutions generated. Computationally, this design-by-analogy facilitation methodology uses a novel functional vector space representation to quantify the functional similarity between represented design problems and, in this case, patent descriptions of products. The mapping of the patents into the functional analogous words enables the generation of functionally relevant novel ideas that can be customized in various ways. Overall, this approach provides functionally relevant novel sources of design-by-analogy inspiration to designers and design teams.

99 citations

01 Jan 2009
TL;DR: This paper gives a tutorial overview of OFDM highlighting the aspects that are likely to be important in optical applications and the constraints imposed by single mode optical fiber, multimode optical fiber and optical wireless.
Abstract: Orthogonal frequency division multiplexing (OFDM) is a modulation technique which is now used in most new and emerging broadband wired and wireless communication systems because it is an effective solution to intersymbol interference caused by a dispersive channel. Very recently a number of researchers have shown that OFDM is also a promising technology for optical communications. This paper gives a tutorial overview of OFDM highlighting the aspects that are likely to be important in optical applications. To achieve good performance in optical systems OFDM must be adapted in various ways. The constraints imposed by single mode optical fiber, multimode optical fiber and optical wireless are discussed and the new forms of optical OFDM which have been developed are outlined. The main drawbacks of OFDM are its high peak to average power ratio and its sensitivity to phase noise and frequency offset. The impairments that these cause are described and their implications for optical systems discussed.

96 citations