Uma Bhattacharya - Academia.edu (original) (raw)

Papers by Uma Bhattacharya

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of Computer Sc. & Engg. WB University of Technology Calcutta 700064, INDIA rchaki@hotmail. com Na... more of Computer Sc. & Engg. WB University of Technology Calcutta 700064, INDIA rchaki@hotmail. com Nabendu Chaki Dept. of Computer Sc. & Engg. University of Calcutta Calcutta 700009, INDIA nabendu@ieee.org Uma Bhattacharya Dept. of Computer Sc. & Tech. ...

Advances in Computing Science — ASIAN 2000, 2000

A new scalable logical topology for multihop optical networks has been presented in this paper ba... more A new scalable logical topology for multihop optical networks has been presented in this paper based on de-Bruijn graph. The de-Bruijn graph having simple routing property is a regular non-scalable logical topology having diameter to be of logarithmic value of number of nodes. The proposed topology adds the advantage of scalability over those in de-Bruijn graph, keeping perturbation in the network to a very low level during insertion of nodes, at the cost of marginal variance in degree of the network.

2012 15th International Conference on Computer and Information Technology (ICCIT), 2012

ABSTRACT Sharing of secret values in MANET is inconsistent and computationally insecure due to it... more ABSTRACT Sharing of secret values in MANET is inconsistent and computationally insecure due to its dynamic nature. Over the years, key generation, encryption and decryption have evolved as important techniques for providing secure routing in MANETs. Many researchers are involved in solving the secret sharing problem. Shamir's proposal is one of the eminent secret sharing schemes. However, this scheme does not include secure key generation. This paper proposes the use of the mathematical theory of Chinese remainder theorem coupled with the commonly used RSA for generating keys. Computational complexity of CRT is less than RSA modular exponentiation scheme. This helps to reduce the computational overhead. Once a secure key has been generated, it has been used for finding a secure route between source and destination. The final route is selected based on the highest weighted trust value of the routes. The three phased approach is aimed to increase the overall performance.

Asian Computing Science Conference, 2000

This paper presents a new logical topology GIADM-net, a generalised IADM network for enhancing th... more This paper presents a new logical topology GIADM-net, a generalised IADM network for enhancing the reliability of optical networks using wavelength division multiplexing. The presence of multiple number of paths of same distance between any two nodes in exchange of reasonable number of hops in the network, ensures a higher degree of reliability compared to other existing topologies in case

Computer Communications, 2005

This paper presents a scalable optimal logical topology scale-net for multi-hop optical networks ... more This paper presents a scalable optimal logical topology scale-net for multi-hop optical networks based on de Bruijn graph, a regular nonscalable one with simple routing strategy. In addition to its scalability property, this new topology maintains the simplicity in routing as in de Bruijn graph while keeping its diameter same throughout the insertion of nodes as that in a de Bruijn graph where the diameter is of logarithmic value of its number of nodes. Also, perturbation in the network is maintained at a very low level, while inserting a node in the network. Simulation results also show a reasonable average hop distance between any source destination pair of the topology developed.

2019 IEEE Region 10 Symposium (TENSYMP), 2019

Huge demand of high bandwidth applications nowadays necessitates the use of data centers (DC) as ... more Huge demand of high bandwidth applications nowadays necessitates the use of data centers (DC) as storage house at the nodes of Elastic optical networks (EON). Huge cost associated with DC limits its usage to some of the nodes in the network. Proper placement of these DCs as well as the requested files residing in these DCs has also crucial importance on network performance such as survivability and provisioning of online requests. In this paper, we propose a novel routing and spectrum allocation (RSA) scheme for dynamic requests in EON when minimum number of DCs are placed in proper positions to maintain survivability which results in reducing spectrum utilization as well as blocking probability. We have formulated an ILP and a heuristic DC-PL for placement of DCs in EON which is followed by another heuristic MDC-RSA to find out route and allocate spectrum for dynamic requests in survivable EON. Outcome of MDC-RSA is analyzed by varying different parameters such as subcarrier capacity, distance-adaptivity/(non-adaptivity), best fit/(first fit) approach and optical reach.

2020 11th International Conference on Computing, Communication and Networking Technologies (ICCCNT), 2020

Spectral fragmentation caused by frequent arrival and departure of random dynamic connections is ... more Spectral fragmentation caused by frequent arrival and departure of random dynamic connections is a major area of concern, which may lead to block even some high prioritized dynamic connection requests in elastic optical network (EON). EONs supporting high bandwidth data traffic may also suffer from huge data loss even if a single link fails. To ensure survivability in elastic optical network, adequate redundancy of network elements is needed, which increases power consumption in the network. In this paper, we have addressed all these problems at a time and propose a novel fragmentation-aware and energy-efficient survivable routing and spectrum allocation scheme (P-EM-RSA) for prioritized traffic in dynamic EONs. Survivability is ensured by applying multipath based approach. By enabling high priority connections with high demand and maintaining survivability, this heuristic shows a remarkable reduction in bandwidth blocking ratio leading to improved spectrum occupation rate with reduced power consumption. Simulation experiments using two well-known topologies justify the result.

2015 Twelfth International Conference on Wireless and Optical Communications Networks (WOCN), 2015

The selection of as few as possible proper nodes for placement of regenerators (RPP) in transluce... more The selection of as few as possible proper nodes for placement of regenerators (RPP) in translucent optical networks is an active area of research. In this paper, we propose a strategy for sparse placement of regenerators in translucent optical networks named as Computation of Locations of Regenerator nodes (CLR). We analyze the effectiveness of our approach for large WDM networks. Simulation results show that our scheme CLR produces remarkable better results in terms of number of sparsely placed regenerator nodes and blocking probability when compared with the existing heuristic. Scheme CLR is also able to provide a route between any source-destination pair and thus solve RRP (Routing with Regenerator Problem) while utilizing lesser number of channels (maximum value) in each optical fiber.

Lecture Notes in Electrical Engineering, 2020

Nowadays, Elastic Optical Network (EON) has attracted a lot of attention due to its efficient spe... more Nowadays, Elastic Optical Network (EON) has attracted a lot of attention due to its efficient spectrum allocation. The popularity of different multicast applications is on the rise and survivability against single link failure has become a crucial issue. Our proposed scheme has considered pre-configured cycles or p-cycles for the protection of multicast sessions. Simulation shows quite good results in terms of blocking probability while ensuring survivability.

2018 International Conference on Signal Processing and Communications (SPCOM), 2018

In this paper, we consider an underlay cognitive radio (CR) multicast network where a secondary n... more In this paper, we consider an underlay cognitive radio (CR) multicast network where a secondary network, comprising of a cognitive base station (CBS) and multiple secondary user (SU) multicast groups, coexist with a primary user (PU) network. The CBS is equipped with multiple antennas, which transmit information to multiple multicast groups over a set of orthogonal PU channels. An exact as well as an asymptotic expression for multicast group outage probability of SUs are derived. Also, the closed form expression for outage probability of PUs, both in absence and presence of interferences from the CBS are analyzed. Furthermore, the optimal multicast group power allocation problem, to minimize the aggregate group outage probability of the CR multicast system is presented. To guarantee QoS of PUs' transmission, a probabilistic outage loss constraint is considered. In high SNR regime, the outage probability minimization problem under outage loss constraint of PUs and average transmit power constraint of the CBS, is shown to be convex in nature. Simulation results are presented to validate the proposed analytical expressions as well as the power allocation scheme. Results demonstrate that the spectral efficiency of the SUs improve significantly with the increase in antenna array size.

Optical Switching and Networking, 2021

IEEE Transactions on Green Communications and Networking, 2021

This paper proposes the design of energy and spectrum efficient, survivable Routing and Spectrum ... more This paper proposes the design of energy and spectrum efficient, survivable Routing and Spectrum Allocation (RSA) scheme for regenerator aware Elastic Optical Network (EON) under static environment. Regenerator(s), after being placed at the intermediate site(s) of the EON, helps in reducing the spectrum required for a traffic demand associated with the connection request, at the expense of its huge power consumption. Any effort to ensure survivability also leads to an increase in power consumption due to provisioning redundancy in EON. All these factors imply a trade-off to exist in between total power consumption and spectrum utilization while the placement of regenerator(s) in EON plays a key role. A two step Integer Linear Programming based model has been formulated to design multipath based survivable RSA while optimizing spectrum requirement and energy consumption in regenerator aware offline EON jointly. E-S-RSM-RSA problem is an NP-hard one and hence intractable in nature. A Heuristic algorithm based on the Non-dominated Sorting Genetic Algorithm addressing this objective has been developed. The heuristic performance is compared with that of the ILP model in terms of spectrum utilization and energy consumption. Simulation results of the heuristic tested on two large-sized topologies also confirm the existing trade-off.

Computer Communications, 2020

In this paper, we propose a novel integrated approach for designing survivable off-line Elastic O... more In this paper, we propose a novel integrated approach for designing survivable off-line Elastic Optical Network (EON) to minimize energy consumption and spectrum requirement. Single link failure recovery is ensured by applying multipath based routing and spectrum allocation (RSA). The RSA problem to minimize spectrum utilization is a NP-Hard one. Integer Linear Programming model is formulated for survivable multipath RSA (SM-ILP) to obtain the optimal solution for a small sized network. As the solution of SM-ILP gets intractable with the growth of the network size, two heuristics based on Greedy Algorithm (SM-GR) and Genetic Algorithm (SM-GA) are also developed to obtain near optimal solution for large-sized networks. Simulation studies have been carried out to evaluate the performance of the heuristics, and the results are compared with that obtained by solving the ILP formulation for small problem size. It is observed that for the considered simulation set up, proposed heuristics provide solution with variation of at most 6.77% for energy consumption and 3.71% for spectrum utilization to the optimal solution. Execution of those heuristics with different parameters on two large-sized networks NSFNET and COST-239 reveals that SM-GA outperforms SM-GR while aiming to minimize spectrum and power consumption jointly as well as spectrum utilization only whereas SM-GR performs better than SM-GA while minimizing power consumption only.

IEEE Access, 2020

Lightpaths in translucent optical networks have to undergo regeneration at certain nodes designat... more Lightpaths in translucent optical networks have to undergo regeneration at certain nodes designated as regeneration sites to maintain its quality of transmission. Regenerating an optical signal necessitates optical-electronic-optical conversion and is thus a costly affair due to use of regeneration resources. Thus minimizing the cost of regeneration in such networks is vital. Minimizing cost of regeneration leads to two different problems; 1) the problem of minimizing the total cost of regeneration for the connections served and 2) the problem of minimizing the cost of regeneration at regeneration sites while serving the connections. The previous works on lightpath establishment in such networks have mostly addressed the first problem. In this paper we study the second problem i.e. the problem of minimizing the cost of regeneration at regeneration sites during dynamic establishment of lightpaths. As the problem is NP-Complete, we propose an Integer Linear Program for small networks and then propose two heuristic routing approaches for large networks. Time complexity analysis shows that our heuristic algorithms run in polynomial time. Extensive simulation experiments reveal that our approaches are not only efficient to address the problem but can also provide better blocking performance when regeneration resources are scarcely deployed at regeneration sites. INDEX TERMS Dynamic routing, minimizing regeneration, regeneration sites, translucent optical networks, wavelength assignment.

Optical Switching and Networking, 2019

The most effective way of providing popular user services such as high-definition television, vid... more The most effective way of providing popular user services such as high-definition television, video conferencing and distributed gaming over the Internet is multicasting. Protecting multicast sessions against single link failure or a fiber cut in the WDM optical backbone is thus vital. Protection schemes involve reserving resources for backup paths that remain idle during normal fault-free operation. It is thus important to design protection or survivability schemes that consume as few extra resources as possible. A number of protection schemes for multicast sessions exist in the literature but only few can provide rapid recovery. In this paper we propose a new offline strategy for ensuring survivability of multicast traffic that can aid rapid recovery from a link failure. Our strategy is designed to achieve significant resource saving while providing recovery speed comparable to 1:1 dedicated path protection. We first propose an Integer Linear Program formulation to solve the problem optimally for small networks and then a heuristic for large networks. Performance comparisons show that our heuristic performs better than two well-known heuristics and also produces near optimal results. Time complexity analysis further shows that our heuristic runs in polynomial time.

Photonic Network Communications, 2017

Since a single fiber carries a huge amount of data in optical WDM networks, a fiber cut even for ... more Since a single fiber carries a huge amount of data in optical WDM networks, a fiber cut even for a brief period is a very serious event. Designing schemes to prevent disruption of user traffic and recovery techniques from failures is thus an important area of research. Since a single fiber cut is the most common type of fault, in this paper we address the problem of protecting all-optical WDM mesh networks from single link failure. Our proposed online protection scheme is an improvement over an existing approach and is not only cost-efficient in terms of network resource consumption but can also provide quick recovery from a link failure. We first provide an ILP formulation for the problem and then propose a heuristic solution iStreams that can provide near-optimal solution in polynomial time. Performance comparisons with some well-known schemes of protection show that our heuristic algorithm can be a better choice for conserving resource while providing quick recovery from a link failure.

International Journal of Parallel, Emergent and Distributed Systems, 2017

ABSTRACT In Optical WDM networks, a single fiber carries enormous amount of data and consequently... more ABSTRACT In Optical WDM networks, a single fiber carries enormous amount of data and consequently designing schemes to prevent the user traffic from disruption and techniques to recover from failures still remains an important area of research. In this paper we address the problem of protecting all-optical WDM mesh networks from single link failure. We propose an offline protection scheme that is not only cost-efficient in terms of network resource consumption but can also provide quick recovery from a link failure. In our scheme, backup paths are combined to reduce cost of protection and to facilitate fast recovery from a failure. We address a critical issue related to selection of backup paths to be combined, which was not addressed earlier. Instead of choosing backup paths for connection requests arbitrary as done in an existing scheme, our scheme is designed to select backup paths in a way that they are suitable for combination and can maximize resource saving as well. We first provide an Integer Linear Program for the problem, and then propose a heuristic eStreams that can provide near optimal solution in polynomial time. Performance comparisons with some well-known schemes show that our protection scheme is definitely an improvement in terms resource conservation while ensuring fast recovery from a link failure. The figure shows how a primary (working) path is protected with the help of a link-disjoint backup path in WDM optical networks. A primary path is used to carry traffic under normal fault free condition. In the event of a link fault (fiber-cut) the traffic is switched over to the backup path. GRAPHICAL ABSTRACT

Tencon 2010 2010 Ieee Region 10 Conference, Nov 1, 2010

Smart Innovation, Systems and Technologies, 2015

The method in which Routing and Wavelength Assignment (RWA) of connection requests is performed i... more The method in which Routing and Wavelength Assignment (RWA) of connection requests is performed in optical WDM networks, can appreciably affect resource consumption. The blocking probability for lightpath requests increases significantly with increase in resource consumption. Thus the method of performing RWA should be such that it minimizes consumption of network resources. RWA in all-optical networks is an NP-Complete problem. This paper proposes six new heuristic algorithms for static RWA in all-optical mesh networks that are not only efficient in terms of resource conservation but can also solve the RWA problem effectively in polynomial time. Comparisons show that the proposed algorithms perform better than some earlier well-known strategies.