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Subrat Kar
IIT Delhi, Electrical Engineering, Faculty Member
- Computer Networks, Wildlife Conservation, Human-wildlife conflicts, Embedded Systems, Photonics, WDM Optical Networks, and 16 moreElectrical Engineering, Optical Fiber Communications, Satellite Communications, UMTS 3G SYSTEMS, Location Based Services, optical CDMA, Four Wave Mixing, Optical Networks, Traffic Models, Body Condition Score, Atmospheric Channel, Non-linear Effects, Performacellular Mobile Systems, WDM star networks, Optical Amplifier Placement, and Four-Wave Mixingedit
ABSTRACT Ubiquitous sensing applications often involve the sensor based data collection with a large coverage in space in and time. From a return on investment perspective the value of information needs to be attractive with the cost of... more
ABSTRACT Ubiquitous sensing applications often involve the sensor based data collection with a large coverage in space in and time. From a return on investment perspective the value of information needs to be attractive with the cost of infrastructure to acquire it. The role of participative sensing and human centric sensing has been widely explored for collecting and analyzing data for use in social science, environmental and health applications. The wide availability of smart phones integrated with variety of sensors is becoming platform for people to document a neighborhood, gather evidence, study behaviors and is accelerating the pace of exploration in new application areas. Many of the current applications involve the monitoring of public spaces involving the participation of citizen in general. Participative surveillance is an application that can bring substantial social benefit. There are many challenges in effectively deploying such applications. It includes the privacy issues, trustworthiness of the data, human factors that affect the quality of sensing, variability of devices, enrolling and motivating participants, and a sustainable business model. Further it should be supported with a sound framework for deployment where the participant has control over data, transparency in data handling and intuitive user interface supporting multi-modal interactions. This presentation will discuss the above aspects with a few illustrative use case scenarios.
—We present Pratham, an embedded platform with programmable wireless communication range and Over-The-Air programming capability. It is a new design for wireless node hardware aimed at creating a class of heterogeneous sensor networks... more
—We present Pratham, an embedded platform with programmable wireless communication range and Over-The-Air programming capability. It is a new design for wireless node hardware aimed at creating a class of heterogeneous sensor networks which bridge the gap between ultra-low power short range and high power long range wireless sensor nodes, while maintaining ease of use and robustness of software. The wireless link created by Pratham nodes is characterised for throughput, quality and power profiles for elementary operations. The supported Over-The-Air programming process is modelled as a Colored Petri Net to analyse its performance. Typical network lifetimes are discussed and the effect of post-deployment remote programming on the life of the node is calculated.
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Research Interests: Artificial Intelligence, Information Security, Access Control, Trusted Computing, Computer Security, and 22 moreUltrasound, Digital imaging, Database Management Systems, Digital, Humans, Information Systems Security, Health Services, Computer Systems, Great Plains, Security Policy, Information Infrastructure, Clinical Sciences, Computer User Interface Design, Health Care System, Computer communication networks, Radiology Information Systems, Boolean Satisfiability, Department of Defense, System Evaluation, Digital Image, X ray Computed Tomography, and Magnetic resonance image
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It is a common story that weapons of policemen are stolen. A result of this is the use of these weapons for various crimes. It is not uncommon to see these weapons of law enforcement being used to break the law instead. The problem is... more
It is a common story that weapons of policemen are stolen. A result of this is the use of these weapons for various crimes. It is not uncommon to see these weapons of law enforcement being used to break the law instead. The problem is that the pistols do not recognize their ...
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ABSTRACT Programmable embedded systems which are configured through a cable for operation, typically are inaccessible for reprogramming after deployment. Cheaper systems tend to be deployed in large numbers like Wireless Sensor Network... more
ABSTRACT Programmable embedded systems which are configured through a cable for operation, typically are inaccessible for reprogramming after deployment. Cheaper systems tend to be deployed in large numbers like Wireless Sensor Network (WSN) nodes forming a mesh network. In such cases, a reconfiguration or upgrade of firmware is difficult. A wireless channel for programming with broadcasting features addresses the problem. The design and implementation of add-on modules for Over The Air (OTA) programming of low-power resource-constrained embedded programmable devices is proposed. The design is based on an ATmega8 microcontroller (Atmel) based embedded circuit along with a TelosB node and can be easily extended to other systems. The programming procedure is implemented over an RF channel between the module attached to the programming terminal and the target devices to be programmed simultaneously - the key advantage with our design. IEEE 802.15.4 is used as the underlying protocol for our design making it platform independent. Link power characterization is done by performing Received Signal Strength Indication (RSSI) profiling at the receiver node. The applications of the protocol for a wireless mesh network are discussed and the effect of the programmer-target distance on the programming reliability is evaluated.
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Atmospheric effects can deteriorate the intensity of the received signal and increases the bit error rate (BER). However, the use of error correcting codes in FSO system can mitigate the effect of turbulence and helps in improving the... more
Atmospheric effects can deteriorate the intensity of the received signal and increases the bit error rate (BER). However, the use of error correcting codes in FSO system can mitigate the effect of turbulence and helps in improving the system performance. In this paper, ...
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ABSTRACT We propose a solution for efficiently transforming video data over a delay tolerant network. We extract and transport only relevant features from the video frame at a minimal computational cost using low cost COTS embedded... more
ABSTRACT We propose a solution for efficiently transforming video data over a delay tolerant network. We extract and transport only relevant features from the video frame at a minimal computational cost using low cost COTS embedded environment.
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Abstract This paper gives a detailed overview of the inter-satellite links used in free space optical (FSO) communication. FSO communication uses laser technology to send and receive data. For the modulation of message signal, OOK and... more
Abstract This paper gives a detailed overview of the inter-satellite links used in free space optical (FSO) communication. FSO communication uses laser technology to send and receive data. For the modulation of message signal, OOK and 8-PPM schemes are used. ...
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ABSTRACT The IP Multimedia Subsystem (IMS) is envisioned as a solution for the next generation multimedia rich communication. The 3rd Generation Partnership Project (3GPP) has chosen Session Initiation Protocol (SIP) as signaling protocol... more
ABSTRACT The IP Multimedia Subsystem (IMS) is envisioned as a solution for the next generation multimedia rich communication. The 3rd Generation Partnership Project (3GPP) has chosen Session Initiation Protocol (SIP) as signaling protocol for IMS. The main cause of performance degradation in SIP network is the overload. SIP does not provide sufficient mechanism to handle this problem. In this paper, we propose a hierarchical modeling for performance evaluation of the network for both normal and overload conditions. An analytical model is developed using cut-off priority queueing for a SIP server and the Generalized Stochastic Petri Nets (GSPN) technique is used to study the performance of the complete network. The proposed model is suitable for handling two different types of signaling traffic and protects them from overloading against each-other. Based on our performance analysis, it is observed that the system reduces retransmissions of SIP messages, thereby reducing congestion and increasing throughput.
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ABSTRACT Targeted use of low noise ROADMs and Raman amplifiers provide increased network capacity for minimal additional equipment. For Raman amplifiers with frequency granularities of 50GHz and 12.5GHz, 19.5Tbps and 30Tbps extra network... more
ABSTRACT Targeted use of low noise ROADMs and Raman amplifiers provide increased network capacity for minimal additional equipment. For Raman amplifiers with frequency granularities of 50GHz and 12.5GHz, 19.5Tbps and 30Tbps extra network capacity is available for BT’s core network
ABSTRACT The core network traffic has been increasing with the evolution of multimedia applications, rise in cloud computing and data centres. This has lead to wide heterogeneity of demands of more than 100Gbps which the current fixed... more
ABSTRACT The core network traffic has been increasing with the evolution of multimedia applications, rise in cloud computing and data centres. This has lead to wide heterogeneity of demands of more than 100Gbps which the current fixed grid network cannot handle. This paper focuses on the concept of Superchannel in the Flexgrid Network Paradigm and its ability to handle demands beyond 100Gbps. We show the advantages of operating at the OSNR limit with reduced Link Margin(LM) and compare the increase in network capacity at 0.1 Cumulative Blocking Probability (CBP) by using frequency granularities (FG) 50GHz and 12.5 GHz respectively. Operating at 100Gbps with FG of 12.5GHz the network capacity increases as much as 105% compared to using FG of 50GHz. Finally, we show that this capacity advantage decreases to 20% as the traffic demand increases to 1000Gbps at 0dB margin.
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ABSTRACT Graded precision localization is the process by which mobile heterogeneous sensor nodes localize themselves to varying levels of precision, even though they co-exist and operate in a common framework. Some nodes may only need to... more
ABSTRACT Graded precision localization is the process by which mobile heterogeneous sensor nodes localize themselves to varying levels of precision, even though they co-exist and operate in a common framework. Some nodes may only need to compute their approximate location at infrequent intervals. Others may need to be continuously and precisely localized. Since GPS is not available indoors, we need to provision a generic ubiquitous localization infrastructure that services specific localization requirements of each mobile sensor node on a best-available-information basis. We assume that each mobile node has an associated user module that gets localized. For implementing graded-precision localization in indoor spaces, we propose a modular architecture for the user module, site-specific deployment strategies, and a framework for evaluating localization performance. The user module architecture is realized using an Android phone and a Cricket sensor node. We report our experimental and simulation results for various operational scenarios.
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ABSTRACT Wireless sensor networks are finding application in heterogeneous scenarios with varied deployment constraints and consumer requirements. Effective instrumentation, visualization, archival, analysis, and third-party notification... more
ABSTRACT Wireless sensor networks are finding application in heterogeneous scenarios with varied deployment constraints and consumer requirements. Effective instrumentation, visualization, archival, analysis, and third-party notification are the cornerstones of any sensor network deployment. Unfortunately, the manifestation of these generalized needs can differ widely between deployments leading to creation of multiple specialized applications. We present RAPIDSNAP-a flexible, generic and scriptable rapid sensor network application deployment framework that can be quickly customized to realize end-user centric sensor network deployments. Algorithms for routing, clustering and localization have been implemented on sensor nodes and integrated with RAPIDSNAP. Along with standard components for control and visualization, RAPIDSNAP allows each deployment specific extension to be captured in a JavaScript based script called a Rapidapp. RAPIDSNAP acts as an execution platform for Rapidapps and an abstraction layer for them to transparently communicate with nodes in the network.
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ABSTRACT Optical networks are now evolving due to the high bit rate demands of multimedia applications and internet services. These applications demand high bandwidth and the current fixed grid network can no longer work for data rate of... more
ABSTRACT Optical networks are now evolving due to the high bit rate demands of multimedia applications and internet services. These applications demand high bandwidth and the current fixed grid network can no longer work for data rate of 400Gbps or higher. This paper focuses on Link Margin (LM) and its effect on the spectrum saving for the demand of 100Gbps and 1000Gbps in a point to point optical link. Optical Signal to Noise Ratio (OSNR) threshold values are calculated for various Link Margins to achieve a BER of 10−3 for all M-ary modulation. Minimum amount of optical spectrum is allocated using the calculated OSNR threshold. Under good LM conditions, for demand of 100Gbps and 1000Gbps optical spectrum saving up to 7500Km and 1000Km is possible. Finally, we highlight the advantages of Flexgrid over Fixed grid and how it can achieve the above savings.
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ABSTRACT Wisekar - the WIreless SEnsor Knowledge ARchive is presented. It is a centralized web repository for collection, management and distribution of events from sensor-enabled devices towards realization of the Internet of Things... more
ABSTRACT Wisekar - the WIreless SEnsor Knowledge ARchive is presented. It is a centralized web repository for collection, management and distribution of events from sensor-enabled devices towards realization of the Internet of Things (IOT). Wisekar offers flexible multimodal event contribution methods adapted to a variety of user skill and requirement levels. Along with rich visualization capabilities, it is versatile in terms of its ability to extend and decorate events with XML based meta-data and images. This allows enforcement of rigorous standards-compliant formats like the Open Geospatial Consortium (OGC) defined SensorML and TransducerML.
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We show how dynamically adjustable modulation formats can be used to reduce link margins in flexgrid networks, reverting to lower order QAM due to reduced OSNR, if ageing occurs. Spectral savings amount to as much as 63% gain in capacity... more
We show how dynamically adjustable modulation formats can be used to reduce link margins in flexgrid networks, reverting to lower order QAM due to reduced OSNR, if ageing occurs. Spectral savings amount to as much as 63% gain in capacity across a network using 64QAM with a fine frequency granularity of 6.25 GHz, with variable baud rate transponder. Further, a fixed baud rate, demand multiplexed transponder with adaptive modulation has been suggested. These transponders provide twice as much network capacity as compared to widely used fixed baud rate transponders operating at fixed grid of 50 GHz.
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ABSTRACT We evaluate the capacity of a free space optical link under the influence of various atmospheric conditions and turbulence levels. Also the effect of aperture averaging on the capacity is investigated. Results show that in... more
ABSTRACT We evaluate the capacity of a free space optical link under the influence of various atmospheric conditions and turbulence levels. Also the effect of aperture averaging on the capacity is investigated. Results show that in weather conditions such as fog and haze, the capacity decreases significantly. Increasing the receiver aperture causes an increase in the capacity but the rate at which the capacity increases reduces with larger diameters and finally the capacity saturates.
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ABSTRACT We evaluate the performance of a free space optical link using an array of direct detection receivers in terms of the bit error rate (BER) under the influence of various atmospheric conditions and turbulence strengths. The... more
ABSTRACT We evaluate the performance of a free space optical link using an array of direct detection receivers in terms of the bit error rate (BER) under the influence of various atmospheric conditions and turbulence strengths. The expression for BER is derived by modeling the turbulence as a gamma-gamma distribution. The effect of weather conditions is incorporated using Beer-Lambert's law. Results show that increasing the number of detectors reduces the BER as expected. In addition, the diversity gain increases with the increasing turbulence strength but remains almost constant for a fixed value of the turbulence strength and the number of detectors over various atmospheric conditions such as very clear air, drizzle, haze, fog, and so forth.
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Apoptosis has been implicated in the pathophysiology of Parkinson's disease... more
Apoptosis has been implicated in the pathophysiology of Parkinson's disease (PD). Components of signaling pathways that initiate cell death are highly concentrated in vulnerable substantia nigra (SN) neurons and may therefore contribute to the relentless demise of dopamine cells. Here, we report the distribution and organizational pattern of the pro-apoptotic protein BAX in the parkinsonian brain. Coronal sections (60 microm) of SN material from control and PD patients showed identical expression of BAX-immunoreactivity (IR) in all cases examined. Neurons positive for BAX-IR exhibited a discrete cytoplasmic and dendritic labeling that was conspicuously interspersed with previously unrecognized axonal spheroid-like inclusions. Direct comparisons revealed a difference in the aggregation of BAX-rich inclusions, with the parkinsonian brain containing more SN inclusions than control cases. BAX expression by midbrain neurons was confirmed by immunoblot analysis on SN extracts showing a specific band of approximately 21kDa, which is consistent with the known molecular weight of native BAX. These results suggest that apoptosis or programmed cell death may play an indirect role in idiopathic PD.
Research Interests: Cognitive Science, Immunohistochemistry, Apoptosis, Western blotting, Dopamine, and 17 moreBrain, Humans, Female, Male, Cell Death, Substantia nigra, Programmed cell death, Neurons, Human Brain, Aged, Degeneration, Molecular weight, Brain Chemistry, Inclusions, Neurosciences, Parkinson Disease, and Case Control Studies
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Institute of Technical Education and Research ITER, SOA University, Bhubaneshwar on 13 Aug 2011
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IIIT, Bhubaneshwar on 12 Aug 2011 1430- 1600 - a 1 1/2- hour talk for faculty
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Seminar on Next Generation Networks – Implementations and Implications, Telecom Regulatory Authority of India, New Delhi, 25- 26 Aug 2011
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Seminar on Regulatory Framework for Emerging Telecom Environment, Telecom Regulatory Authority of India (TRAI), New Delhi, 6- 8 Sep
2011
2011
{Subrat Kar}, SOA,
Bhubaneshwar 25 Jan 2012 – 3 hour talk for faculty and students
Bhubaneshwar 25 Jan 2012 – 3 hour talk for faculty and students
Students who are already in engineering institutes often have questions like "What next after BTech/MTech ?" “Is a PhD needed for engineers ?” "Should I go abroad or stay in India ?" "Are Internships necessary ?" "Which engineering jobs... more
Students who are already in engineering institutes often have questions like "What next after BTech/MTech ?" “Is a PhD needed for engineers ?” "Should I go abroad or stay in India ?" "Are Internships necessary ?" "Which engineering jobs should I choose ?" "Management or Engineering ?" "Is coaching a must for GATE?"
What does a Class 12 student typically feel about Engineering ? What are the factors that drive a student towards engineering careers ? How does one choose / which engineering is good for one ? What should influence your choice ? Jobs,... more
What does a Class 12 student typically feel about Engineering ?
What are the factors that drive a student towards engineering careers ?
How does one choose / which engineering is good for one ?
What should influence your choice ? Jobs, career, interest ?
How to excel in engineering / having fun while doing it ?
Options for a engineering undergraduate ?
What are the factors that drive a student towards engineering careers ?
How does one choose / which engineering is good for one ?
What should influence your choice ? Jobs, career, interest ?
How to excel in engineering / having fun while doing it ?
Options for a engineering undergraduate ?
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Fourth International Training College on Optical Fibers and Lasers, International Centre for Theoretical Physics, Trieste, Italy, Jan 1993
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PEC (now PECUT), WOC- 2007, Dec 14, 2007