Papers by Debasish Chakraborty
WSEAS Transactions on Computers archive, Sep 1, 2008
Many countries are facing an ever-growing need to supply constant care and support for their disa... more Many countries are facing an ever-growing need to supply constant care and support for their disabled and elderly populations. So the importance to remote monitoring is becoming essential for looking after them. With an environment full of smart and cooperating artifacts will at the same time pose great risks to personal privacy. To protect personal information patient's data should be available irrespective of their location, but only to the authorized person. At the same time quality and reliability of transferring data is also important depending on the content of the data and the recipient. In this paper we propose a system where a personalized overlay network will be built in an ad hoc basis and links between different entities will be established according to the social relationship between the person under observation and the people at the other end and the situation of the observed person. The connected links will provide reliability, quality and other required characteristics according to the requirements specified by the members involved. For efficient cost and resource utilization, an on-demand network connection is considered for our proposed context aware ubiquitous healthcare system.
A Study on QoS Constrained Dynamic Multicast Routing in Computer Networks
In wireless network RTS/CTS frame exchange protocol is widely used to avoid packet collisions. Ho... more In wireless network RTS/CTS frame exchange protocol is widely used to avoid packet collisions. However, the protocol lacks the ability to release the reserved but unused channel. For Mobile Ad hoc NETworks (MANET), this often keeps the channel unnecessarily inaccessible, resulting in inefficient channel utilization. In this paper, we propose innovative schemes which can optimize the Medium Access control mechanism by using wasted channel for MANET deployed over IEEE 802.11. The proposed schemes are based on different variations of extra frame transmission method. NAV (Network Allocation Vector) updating scheme is also introduced to provide higher channel efficiency. For further improvement, we combine those schemes with specific parameters. The combination of schemes can achieve throughput more than 40% compared to standard IEEE 802.11 and at the same time compatible with IEEE 802.11.
2003 Symposium on Applications and the Internet Workshops, 2003. Proceedings.
IFIP Advances in Information and Communication Technology, 2010
Access control to resources is one of the most important technologies for supporting human activi... more Access control to resources is one of the most important technologies for supporting human activities in the digital space. To realize the control two schemes were proposed: RBAC (Role-Based Access Control) and TRBAC (Temporal Role-Based Access Control) by adding time constraints and role dependencies to RBAC. However, these methods are not effective for temporal activities such as visitor access because of maintenance costs and inadequacy in safeness. In this paper, we focus on a visitor access control in the real world, by utilizing relationship with users and situations, and propose a novel access control scheme which is effective for temporal activities.
Journal of Information Processing, 2009
Quality of Service (QoS) routing in Mobile Ad hoc NETworks (MANETs) is hard to achieve because th... more Quality of Service (QoS) routing in Mobile Ad hoc NETworks (MANETs) is hard to achieve because the network topology tends to change constantly in a dynamic network. In this paper, we propose an effective QoS routing scheme to satisfy the required service demand and adapt to the dynamic changes in network resources. This novel approach of Application-Level QoS Routing Scheme (ALRS) comprises three significant features: (1) Estimation of consumed bandwidth on each node by using 2-hop neighbors' traffic information, (2) Route construction combined with admission control on each application session with (1), and (3) Route maintenance based on (1) and (2). By using our proposed ALRS scheme the availability of bandwidth is greatly improved for high-load communications, such as multimedia applications. By computer simulation we confirmed that ALRS increases the delivery ratio by up to 50% and decreases delay by less than one-fourth of the existing traditional method.
Mobile Information Systems, 2009
In recent years, wireless technologies and application received great attention. The Medium Acces... more In recent years, wireless technologies and application received great attention. The Medium Access Control (MAC) protocol is the main element that determines the efficiency in sharing the limited communication bandwidth of the wireless channel in wireless local area networks (WLANs). IEEE 802.11 introduced the optional RTS/CTS handshaking mechanism to address the hidden terminal problem as well as to reduces the chance of collision in case of higher node density and traffic. RTS Threshold (RT) determines when RTS/CTS mechanism should be used and proved to be an important parameter for performance characteristics in data transmission. We first investigate to find a meaningful threshold value according to the network situation and determine the impact of using or disengaging the RTS/CTS optional mechanism and dynamically adjust the RTS Threshold to maximize data transmission. The results show a significant improvement over existing CSMA/CA and RTS/CTS schemes. Our adaptive scheme perf...
IPSJ Digital Courier, 2007
The MAC protocol of IEEE 802.11 reduces hidden terminal problem using the RTS/CTS handshaking mec... more The MAC protocol of IEEE 802.11 reduces hidden terminal problem using the RTS/CTS handshaking mechanism. However, it lacks the ability to release or reallocate a channel that was reserved but not used. For Mobile Ad hoc NETworks (MANET), this often keeps the channel unnecessarily inaccessible, resulting in inefficient channel utilization. In this paper, we propose schemes for releasing and reallocating unused channels in MANET deployed over IEEE 802.11. We introduce a Network Allocation Vector (NAV) updating method that can improve the performance of the existing RTS Validation scheme and our proposed Extra Frame Transmission scheme. We then combine these schemes as a further improvement. Through simulations, done in different scenarios with varying networking load and node density, we were able to show that combining these schemes leads to a throughput improvement of up to 40%. In addition, our proposed mechanisms have no compatibility problems.
International Journal of Mobile Network Communications & Telematics, 2012
In this work, we propose a mechanism in which power consumption in a sensor network can be reduce... more In this work, we propose a mechanism in which power consumption in a sensor network can be reduced greatly by taking into account the fairness factors and to increase the probability of nodes for successful packet transmission with lowest possible Signal to Noise Ratio (SNR) in a crowded environment. In other words we propose a high throughput and spectrally efficient network. The power consumption of the network reduces drastically when the clustered approach is adopted, which has been confirmed using the Friss transmission formula. Here, we have used analytical expressions from renewal reward theorem to deduce network throughput, probability of collisions and back-off periods upon collision in a random multiple access environment. Using those expressions we have made an analysis on network throughput, probability of collisions, bandwidth availability per node and estimation of back-off intervals upon collisions. The total number of nodes in the network is kept constant for observational purposes. The number of clusters has been varied to take observation of network throughput, probability of collisions, bandwidth availability per node and estimation of back-off intervals upon collisions. The analytical results obtained show that the power requirement of the network reduces drastically as the number of clusters increases.
Techniques and Applications
The advancement in optical fiber and switching technologies has resulted in new generation high-s... more The advancement in optical fiber and switching technologies has resulted in new generation high-speed networks that can achieve speeds of up to a few gigabits per second. Also, the progress in audio, video and data storage technologies has given rise to new distributed real-time applications. These applications may involve multimedia, which require low endto-end delay. The applications' requirements, such as the end-to-end delay, delay jitter, and loss rate, are expressed as QoS parameters that must be guaranteed. In addition, many of these new applications may involve multiple users, and hence the importance of multicast communication. In this chapter we discuss the basics of multicasting, its routing protocols and algorithms, along with different QoS-based multicast routing.
International Journal of Network Management, 2005
He has been engaged in research on distributed processing systems and flexible intelligent networ... more He has been engaged in research on distributed processing systems and flexible intelligent networks. He is a Fellow of the IEEE, IEICE, IPSJ.
International Journal of Network Management, 2004
The self-similar bursty Internet traffic is usually characterized by the Hurst parameter (H). Suc... more The self-similar bursty Internet traffic is usually characterized by the Hurst parameter (H). Such a process is also seen to possess fractal characteristics in time described by a parameter (b), with multifractals in most cases. We observe that these highly stochastic traffics have fractals in flow density too, described by a fractal dimension (D), also with the possibiliy of multifractals as in the former. This requires another parameter for the description of Internet traffic, besides the usual selfsimilarity parameter b or H and the different simulations or models worked out to understand the Internet traffic to reproduce the characteristics as found in the present work. We also find a notable selfsimilarity feature of the autocorrelations in the data and its aggregates, in all the cases studied.
International Journal of Network Management, 2003
In this paper we propose a QoS-based routing algorithm for dynamic multicasting. The complexity o... more In this paper we propose a QoS-based routing algorithm for dynamic multicasting. The complexity of the problem can be reduced to a simple shortest path problem by applying a Weighted Fair Queuing (WFQ) service discipline. Using a modified Bellman-Ford algorithm, the proposed routing builds a multicast tree, where a node is added to the existing multicast tree without rerouting and satisfying QoS constraints.
Wireless Networks, 2008
Device discovery and connection establishment are fundamental to communication between two Blueto... more Device discovery and connection establishment are fundamental to communication between two Bluetooth (BT) devices. In this paper, we give an analytical model of the time it takes for the master in a piconet to discover one slave. We show that, even in the absence of packet interference, the discovery time can be long in some instances. We have simulated the discovery protocol by actually implementing it to validate the analytical model. By means of simulations, we show how discovery time is affected by (i) the presence of multiple potential slaves, and (ii) changes in the maximum backoff limit. Using simulation studies we observed the effectiveness of two proposed improvements to device discovery, namely, (i) avoiding repetitions of the A and B trains before a train switch, and (ii) eliminating the idea of random backoff, or reducing the backoff limit. We show that discovery time can be reduced by avoiding repetitions of the A and B trains before a train switch. However, complete elimination of the random backoff is not a good idea, as discovery time will be too long when the number of BT devices is large. Instead, choosing a small backoff limit of 250-300 slots is highly effective in reducing discovery time even in the presence of a large number (say, 50) of potential slaves.
The Internet is changing computing more than ever before. As the possibilities and the scopes are... more The Internet is changing computing more than ever before. As the possibilities and the scopes are limitless, so too are the risks and chances of malicious intrusions. Due to the increased connectivity and the vast spectrum of financial possibilities, more and more systems are subject to attack by intruders. One of the commonly used method for intrusion detection is based on anomaly. Network based attacks may occur at various levels, from application to link levels. So the number of potential attackers or intruders are extremely large and thus it is almost impossible to ''profile'' entities and detect intrusions based on anomalies in host-based profiles. Based on meta-information, logical groupings has been made for the alerts that belongs to same logical network, to get a clearer and boarder view of the perpetrators. To reduce the effect of probably insignificant alerts a threshold technique is used.
IEICE Transactions on Communications, 2005
The advent of mobile IP communication has opened up several new areas of mission critical communi... more The advent of mobile IP communication has opened up several new areas of mission critical communication applications. But the bandwidth and reliability constraints coupled with handover latency are posing some hurdles which need to be overcome before real world mobile IP applications, with low tolerance for data loss, can be deployed. In this paper, we analyze the unreliability of existing information collection methods in the real-world MobileIP environment. We focus on this problem and propose a novel network management model that anticipates the wireless mobile entities and uses SNMP. The key idea of this model is the introduction of a store-and-forward type Managed Object (MO). During the period of unreachability between the Manager and the agent, the data is cached at the agent until the connectivity recovers. In our experiment we used a prototype implementation in real-world wireless communication field, and showed the effectiveness of our proposed method.
European Transactions on Telecommunications, 1999
Multimedia applications are becoming increasingly important as networks are now capable to carry ... more Multimedia applications are becoming increasingly important as networks are now capable to carry continuous media traffic, such as voice and video, to the end user. Most of the multimedia applications need multicast support too. In dynamic multicasting, destination nodes can join and leave the group during the communication period. Total or partial rerouting can optimize the tree cost to some extent. But rerouting for optimization is complex as cell‐ordering at ATM switches has to be preserved. Optimum Steiner tree is NP‐complete and therefore the present problem too. We propose a heuristic centralized routing algorithm, which optimize the total cost of the Steiner tree over the whole session period, where information about the joining and leaving of participants are available, at the time s/he actually joins. With this algorithm, the average hop‐length from source to destination has also reduced considerably. The efficiency of our algorithm and comparison with other proposed algori...
Proceedings of the …, 2008
As more and more people living by their own, the importance to remote monitoring is becoming esse... more As more and more people living by their own, the importance to remote monitoring is becoming essential for looking after them. But protecting personal privacy is going to be a prime concern as patient's data should be available irrespective of their location, but only to the authorized person. We need to consider the social relationship between the monitored person and those who are responsible for taking care for that person. At the same time quality and reliability of transferring data is also important depending on the content of the data and the recipient. In this paper we propose a system where an overlay network will be built in an ad hoc basis and links between different entities will be established according to the social relationship between the person under observation and the people at the other end and the situation of the observed person. The connected links will provide reliability, quality and other required characteristics according to the requirements specified by the members involved. For efficient cost and resource utilization, an on-demand network connection is considered for our proposed context aware ubiquitous healthcare system.
Journal of Information Processing, 2009
Recently, P2P networks have been evolving rapidly. Efficient authentication of P2P network nodes ... more Recently, P2P networks have been evolving rapidly. Efficient authentication of P2P network nodes remains a difficult task. As described herein, we propose an authentication method called Hash-based Distributed Authentication Method (HDAM), which realizes a decentralized efficient mutual authentication mechanism for each pair of nodes in a P2P network. It performs distributed management of public keys using Web of Trust and a Distributed Hash Table. The scheme markedly reduces both the memory size requirement and the overhead of communication data sent by the nodes. Simulation results show that HDAM can reduce the required memory size by up to 95%. Furthermore, the results show that HDAM is more scalable than the conventional method: the communication overhead of HDAM is O(log p).
22nd International Conference on Advanced Information Networking and Applications (aina 2008), 2008
Wireless network is an essential and integral part of the ubiquitous environment. For efficient a... more Wireless network is an essential and integral part of the ubiquitous environment. For efficient access control, two different transmission schemes are used: The Basic Carrier Sensing Multiple Access with Collision Avoidance (CSMA/CA) and Request-To-Send/ Clear-To-Send (RTS/CTS) handshaking. The RTS/CTS handshaking addresses the hidden terminal problem as well as reduces the chance of collision in case of higher node density and traffic. However, in networks with low density, basic scheme would lead to higher throughput due to its less overhead. Efficient switching between these two schemes is imperative to maximize the throughput. We have first investigated to find a meaningful threshold value according to the network situation. The proposed algorithm then dynamically adjusts RTS Threshold according to the packet delivery ratio, which is an indicator of network traffic and shows a significant improvement over existing CSMA/CA and RTS/CTS schemes. Our adaptive scheme performed even better when data rates increases. We verify our proposed scheme with extensive network simulation using ns-2.
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Papers by Debasish Chakraborty