Sushanta Karmakar

Indian Institute of Technology Guwahati, Gauhāti, Assam, India

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Publications (21)6.23 Total impact

  • Sandip Chakraborty, Ramesh Singh, Sushanta Karmakar
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    ABSTRACT: Distributed systems such as the peer-to-peer and the content management systems have to deal with large volume of data stored in several participating nodes. In a distributed environment, concurrent node joins and node leaves impose new design challenges to effectively manage the structure of the system. Deterministic 1–2 skip list is an efficient structure to manage the topology of an overlay network. However, the existing works on distributed deterministic 1–2 skip list [(S. Mandal, S. Chakraborty, and S. Karmakar, Deterministic 1–2 skip list in distributed system. in Proceedings of the 2nd IEEE International Conference on Parallel Distributed and Grid Computing, IEEE, 2012, pp. 296–301.)] in a decentralised environment do not support concurrency, where multiple parallel join and leave operations may be executed simultaneously. This paper presents a set of algorithms for achieving concurrency in a distributed deterministic 1–2 skip list. The properties and the correctness of the proposed algorithms are analysed theoretically. The proposed set of distributed algorithms for search, join and leave operations has message complexity similar to the centralised versions of the algorithms.
    International Journal of Parallel Emergent and Distributed Systems 10/2014;
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    ABSTRACT: Sink based spanning tree topologies are effectively used in convergecast applications for efficient packet delivery with minimum forwarding delay, eliminating packet loss or duplicate packet delivery. For tree based convergecast, this paper theoretically shows that there is a trade-off between the topology architecture and the network traffic load. Depending on this trade-off, a hierarchical topology adaptation scheme is proposed for the tree based convergecast to improve overall application performances. The effectiveness of the proposed scheme is analyzed using simulation results.
    29th ACM Symposium On Applied Computing, Dependable and Adaptive Distributed Systems Track (ACM SAC - DADS), Gyeongju, Korea,; 03/2014
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    ABSTRACT: Wireless sensor networks have grown significant attentions among researchers for providing a flexible and low-cost framework to design an architecture for Intelligent Transport Systems. The inherent challenges in distribution and management of sensor networks along the road require an application-specific protocol support for the network connectivity, the sensing coverage, the reliable data forwarding, and the network lifetime improvement. This paper introduces the concept of $k$-strip length coverage along the road, which ensures a better sensing coverage for the detection of moving vehicles compared with the conventional barrier coverage and full area coverage, in terms of the availability of sufficient information for statistical processing and the number of sensors required to be active. To extend the network lifetime, every sensor follows a sleep–wakeup schedule maintaining the network connectivity and the $k$-strip length coverage. This scheduling problem is modeled as a graph optimization, the NP-hardness of which motivates to design a centralized heuristic, providing an approximate solution. As a sensor network is inherently distributed in nature, properties of the centralized heuristic are explored to design a per-node solution based on local information. Performance of the proposed scheme is analyzed through simulation results.
    IEEE Transactions on Intelligent Transportation Systems 03/2014; · 2.47 Impact Factor
  • Source
    Sushanta Karmakar, Subhrendu Chattopadhyay
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    ABSTRACT: Consider a distributed system with n processors, which receive triggers from the outside world. The Distributed Trigger Counting (DTC) problem is to raise an alarm if the number of triggers over the sys- tem reaches w, which is an user specified input. DTC is used as a primitive operation in many applications, such as distributed monitoring, global snapshot etc. In this paper, we propose an algorithm for the DTC problem in a ring topology with a message complexity of O(n2 log(w/n)) and each node in the system receives O(n log(w/n)) number of messages. We also discuss about the possible tuning of the algorithm which results better complexities.
    The 37th Australasian Computer Science Conference (ACSC 2014), Auckland, New Zealand; 01/2014
  • Ad Hoc Networks 08/2013; 11(6):1796-1819. · 1.94 Impact Factor
  • 18th IEEE Computer Society International Symposium on Computers and Communications (IEEE ISCC 2013); 07/2013
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    ABSTRACT: The lifetime of sensor network depends on the efficient utilization of resource-constrained sensor nodes. Several MAC protocols like DMAC and its variants have been proposed to save critical sensor resources through sleep-wakeup scheduling over data gathering tree. For applications where data aggregation is not possible, the sleep duration decreases gradually from the leaves to the root of the data gathering tree. This results early failure of sensor nodes near the sink, and affects network connectivity and coverage. Deploying redundant sensors can solve this problem where a faulty node is replaced by a redundant node to maintain network connectivity and coverage. However, the amount of redundancy depends on the node failure pattern, and thus more number of redundant nodes required to be deployed near the sink. This paper proposes a gradient based sensor deployment scheme for energy-efficient data gathering exploring the trade-off among connectivity, coverage, fault-tolerance and redundancy. The density of deployment is estimated based on the distance of a node from the sink while dealing with connectivity, coverage and fault-tolerance. The effectiveness of the proposed scheme has been analyzed both theoretically and with the help of simulation.
    IEEE 9th International Wireless Communications and Mobile Computing Conference (IEEE IWCMC 2013); 07/2013
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    ABSTRACT: Data gathering or converge cast is one of the most popular applications of road side sensor network where the data sensed from the road are accumulated in the road side gateways or sinks for traffic monitoring purpose. The required delay sensitivity and reliability of the application as well as the scarcity of sensor resources make the task challenging. In this paper, a novel tree based data gathering scheme has been proposed exploiting the strip like structure of the road network. Sensor nodes are distributed in several virtual blocks along the road and a converge cast tree is constructed selecting one active node from each block. Implementation of efficient scheduling assures both the coverage and critical power savings of sensor nodes. The network connectivity is guaranteed throughout by the proposed tree maintenance module that handles the sensor node joining and leaving events. Simulation results show that the tree maintenance overhead in terms of both delay and control message communication is nominal.
    27th IEEE International Conference on Advanced Information Networking and Applications (IEEE AINA-2013); 03/2013
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    ABSTRACT: Data management in the peer-to-peer system is a challenging task due to the random distribution of data among several participating peers. Efficient data structures like distributed hash tables (DHT) and its variants are designed and implemented to reduce the complexity of data management in such environment. However, DHT has its limitations in supporting range queries and its variants like distributed segment trees often perform poorly when the number of peers is high. Further, distributed lists and distributed balanced trees require significant amount of time for stabilizing after a new peer joins or a peer leaves. In this paper, a new distributed data structure called deterministic 1–2 skip list is introduced as an alternate solution for data management in the peer-to-peer systems. A deterministic skip list can be viewed as an alternate of a balanced tree, where the semantic locality of each key is preserved. Thus it can support the range queries as well as the single shot queries. This paper proposes three main operations on this data structure - searching data based on keys, insertion when a new peer joins, and deletion when a peer leaves. The correctness of the proposed operations are analyzed using theoretical arguments and mathematical proofs. The proposed scheme is simulated using NS-2.34 network simulator, and the efficiency of the scheme has been compared with DHT, DST, distributed list and distributed tree based data management.
    Peer-to-Peer Networking and Applications 01/2013; · 0.37 Impact Factor
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    ABSTRACT: The changes in environmental parameters may demand switching between underlying topologies for better performance of distributed message passing applications. Arbitrary topology switching using distributed tree construction may lead to loss or redundancy in delivery of application messages. In this work, a set of algorithms has been proposed for dynamic switching between two spanning trees to offer better adaptivity towards the environment for different applications. Here, two extreme cases of spanning trees, a Breadth First Search (BFS) tree and a Depth First Search (DFS) tree, rooted at the core node, have been considered for switching. The core node initiates the switching and all other nodes cooperatively change their parents on the fly maintaining the DFS or BFS properties as required. However, the application remains transparent to the switching that assures the availability of the system at any instance of time. Simulation results show that each application message is delivered correctly to the destination without any loss or redundancy. The proposed scheme is scalable and the control message overhead for switching is linear with respect to the number of edges in the communication graph. Furthermore, there is no control message overhead to assure the delivery of application messages at the time of switching.
    Journal of Network and Systems Management 01/2013; · 0.44 Impact Factor
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    ABSTRACT: Searching data efficiently in distributed applications like peer-to-peer system is a challenging task due to the random distribution of data among several participating nodes. Efficient data structures are designed and implemented to reduce the complexity of data searching in such an environment. In this paper a data structure called deterministic 1-2 skip list has been proposed as a solution for search problems in distributed environment. The data structure has three main operations viz. search, insert, and delete. The detailed description of the insertion, deletion and search operations are given in this paper. It is found that the message complexity of the insertion, deletion and search algorithm is O(log n) where n is the total number of nodes in the skip-list.
    2nd IEEE International Conference on Parallel, Distributed and Grid Computing (PDGC 2012); 12/2012
  • 13th IEEE/IFIP Network Operations and Management Symposium (NOMS 2012); 04/2012
  • 2nd International Conference on Computer and Communication Technology; 09/2011
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    ABSTRACT: Query driven Broadcast through wireless sensor nodes also leads to the domain of event driven converge cast. A query-response based application in Wireless Sensor Networks(WSN) demands the correct delivery of data message at each sensor node. A Breadth-First Search(BFS) tree rooted at the base station offers shortest path traversal for each data message which utilizes the sensor resources efficiently. Resource constrained sensor nodes are highly prone to sudden crash. So the application demands a quick and smart approach to repair the tree when a node dies. In this paper a novel scheme has been proposed to locally repair the tree with constant round of message transmissions. Each node piggybacks a few bytes of extra information along with each query and response messages. Based on these piggybacked values each node calculates its alternate parent. When a parent node fails, its children can contact their respective alternate parents immediately to establish an alternate path to the root. Reduced communication cost in terms of extra message transmissions saves battery power at each node. Efficient query-response message handler ensures the correct delivery of messages. Fast repairing offers good Quality of Service(QoS). Simulation result shows that no message is lost except the one holding by the crashed node.
    Proceedings of the 2011 14th IEEE International Conference on Computational Science and Engineering; 08/2011
  • Suchetana Chakraborty, Sushanta Karmakar
    Advances in Computing and Communications - First International Conference, ACC 2011, Kochi, India, July 22-24, 2011. Proceedings; 01/2011
  • Sushanta Karmakar, Arobinda Gupta
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    ABSTRACT: Adaptation is a desirable requirement in a distributed system as it helps the system to perform efficiently under different environments. For many problems, more than one protocol exists, such that one protocol performs better in one environment while the other performs better in another. In such cases, adaptive distributed systems can be designed by dynamically switching between the protocols as the environment changes. Distributed protocol switching is also important for performance enhancement, or fault-tolerance of a distributed system. In this work, we illustrate distributed protocol switching by providing a distributed algorithm for adaptive broadcast that dynamically switches from a BFS tree to a DFS tree. The proposed switching algorithm can also handle arbitrary crash failures. It ensures that switching eventually terminates in spite of failures and the desired tree (DFS tree) results as the output. We also investigate the properties that can be guaranteed on the delivery of broadcast messages under specific failure conditions. We show that under no failure, each broadcast message is eventually correctly delivered to all the nodes in spite of switching. Under arbitrary crash fault, we ensure that switching eventually terminates with the desired tree as the broadcast topology. We also investigate the specific delivery guarantees that can be provided when a single crash fault happens, both during switching and when no switching is in progress.
    Journal of Parallel and Distributed Computing 09/2010; 70:889-906. · 1.01 Impact Factor
  • Sushanta Karmakar, Arobinda Gupta
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    ABSTRACT: Switching between protocols based on environment is an elegant idea of enabling adaptation in distributed systems. Also self-stabilizing algorithms have been proposed as a mechanism to handle transient failures in distributed systems. In this work we illustrate self-stabilizing distributed protocol switching by proposing a self-stabilizing algorithm for dynamically switching between a BFS tree and a DFS tree. At low network load, the BFS tree may be used for broadcasting messages since it also minimizes delay. At higher network load, the DFS tree may be used to reduce the load on any one node. Both trees are rooted at the common broadcast source. Different properties relating to the delivery of broadcast messages under different failure conditions are investigated.
    Distributed Computing and Networking, 9th International Conference, ICDCN 2008, Kolkata, India, January 5-8, 2008.; 01/2008
  • Ankur Jain, Sushanta Karmakar, Arobinda Gupta
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    ABSTRACT: Switching between protocols based on environment is an elegant idea of enabling adaptation in distributed systems. In this paper, we give one approach of switching between two connected dominating set (CDS) construction protocols, one suitable for low load and the other suitable for higher load. In this method, the two connected dominating sets are computed in advance and switching is done between the two precomputed outputs. In addition, some CDS of the network is always maintained when switching is in progress.
    03/2007: pages 88-93;
  • Sushanta Karmakar, Arobinda Gupta
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    ABSTRACT: Adaptation is a desirable requirement in a distributed system. For many problems, there exists more than one protocol such that one protocol performs better in one environment while the other performs better in another. In such cases, adaptive distributed systems can be designed by dynamically switching between the protocols as the environment changes. In this work, we present distributed algorithms to switch from a BFS tree to a DFS tree and from a DFS tree to a BFS tree. For low network load, a BFS tree is a better choice for broadcast since it also minimizes delay, whereas for higher network load, a DFS tree may be more suitable to reduce the load on any one node. The proposed switching algorithms can handle arbitrary crash failures. They ensure that switching eventually completes in spite of failures with the desired tree as the output. Also, all messages are correctly broadcast in the absence of failures even in the presence of switching.
    High Performance Computing - HiPC 2007, 14th International Conference, Goa, India, December 18-21, 2007, Proceedings; 01/2007
  • Sushanta Karmakar, Arobinda Gupta
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    ABSTRACT: Adaptation is a desirable requirement in a distributed system since it helps the system to perform gracefully under different scenarios. There are many adaptive algorithms for different problems. However the techniques are often application specific. In many distributed systems it may happen that the same problem has multiple protocols, each of which performs differently under different environments. In such cases adaptation can be achieved by dynamically switching between them as the environment changes. In this paper we illustrate the idea of designing adaptive distributed system using protocol switching by presenting an adaptive broadcast protocol that uses either a BFS tree or a DFS tree depending on the load of the system, both trees being rooted at the broadcast source. At low load a BFS tree is used as it reduces the broadcast delay (since the distance of any node from the root is always minimum in a BFS tree) while still keeping the load on any one node low. However at higher load a DFS tree is used to reduce the load on any one node since the degree of a node in a DFS tree is generally lower than that in a BFS tree. So the broadcast adapts to the network load by dynamically switching between a BFS tree and a DFS tree. In the proposed scheme, the switching is done by a middleware layered below the broadcast protocol. This separates the adaptation from the application and no change is needed in the application. We also ensure the application layer property that every broadcast message is correctly delivered to all the nodes, including messages sent when the switching is in progress. We assume the asynchronous model of distributed system with reliable but non-FIFO channels. Also it is assumed that no failure occurs during the switching. The message complexity of the algorithm that switches to a DFS tree is O(|E|) and is presented in the next section. The algorithm that switches to a BFS tree needs O(|V||E|) messages and is omitted in this paper due to lack of space.
    Proceedings of the 2007 ACM Symposium on Applied Computing (SAC), Seoul, Korea, March 11-15, 2007; 01/2007