Department of Computer Science and Information Systems
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Item QoS-aware data dissemination for dense urban regions in vehicular ad hoc networks(Springer, 2014-12) Dua, AmitWith an evolution of 5G and related technologies, there is a need of high data rate transfer between different communication objects such as vehicles, sensor nodes, or mesh clients connected to the Internet to maintain Quality of Service (QoS) at various levels. As vehicles in Vehicular Ad Hoc Networks (VANETs) are mainly used for safety related applications, so there is a need of an efficient QoS-aware data dissemination for various applications in different regions especially in dense urban regions where congestion is one of the major issues. Hence, to address this issue, in this paper, we propose a new mechanism to maintain QoS for data dissemination among the different vehicles in VANETs. An intelligent forwarding mechanism is used by newly defined metric which assigns weights to the different routing paths from source to destination. Separate algorithms are designed for route construction, and maintenance in the proposed scheme. The performance of the proposed scheme is studied by extensive simulations with respect to various metrics such as delay incurred, percentage of active links, and load on the network. The results obtained show that the proposed scheme is better than the other state-of-the-art existing schemes in the literature.Item Game theoretic approach for real-time data dissemination and offloading in vehicular ad hoc networks(Springer, 2016-06) Dua, AmitDue to high velocity of the vehicles, data dissemination and mobile data offloading are most difficult tasks to be performed in vehicular ad hoc networks (VANETs). In recent years, due to an exponential increase in the data generated from various sources such as smart devices, gadgets, and actuators, there arises a need of usage of an efficient communication infrastructure to handle the aforementioned issues. Most of the earlier solutions reported in the literature for data offloading problem have used the cellular communication, which may be congested in handing a large number of requests from community of users. This may result a performance bottleneck in terms of call drops and data dissemination to the other vehicles in the VANET environment. Also, these schemes lack a comprehensive approach of data dissemination to meet the quality of service (QoS) in real time. Hence, to overcome this problem, some of the mobile data can be disseminated using the existing vehicular infrastructure and Wi-Fi access points (APs). In this paper, we propose a new schedule based on game theoretic approach where the APs and vehicles act as players in a game and compete for offloading the cellular data. The proposed scheme is based on the selection of the best vehicle or AP based on the utility of the players (vehicles and APs) in the game. The utility of vehicle and AP is decided based on the parameters such as distance, velocity, connectivity to destination, bandwidth, and area of the network. A novel algorithm has been designed using the proposed game theoretic approach for handling mobile data offloading and data dissemination. The proposed solution not only successfully offloads the data but also maintains QoS with respect to the parameters such as end-to-end delay, message progress, and message dissemination speed. Results obtained confirm the superiority of the proposal in comparison with the other existing schemes. Specifically, the proposed scheme achieves improvement of 4.16 and 20.5 % in message progress, 18.91 and 4.75 % in extra messages generated, 11.26 and 54.94 % in message dissemination speed, and 78.71 and 87.94 % in end-to-end delay in sparse network as compared to GyTAR and GPCR, respectively.Item Cross layer adaptive congestion control for best-effort traffic of IEEE 802.11e in mobile ad hoc networks(IEEE, 2016) Gudino, Lucy J.The dominance of multimedia traffic over the Internet, coupled with the rising number of applications of MANETs, has made Quality of Service (QoS) a major concern. The IEEE 802.11e standard enhanced distributed channel access(EDCA) has been proposed as an enhancement of 802.11 standard, which provides QoS at MAC layer with a service differentiation scheme for high priority traffic. But IEEE 802.11e has not adequately addressed the issue of handling best effort traffic data flows through contention-based networks which in turn results in TCP performance degradation. To enhance the best effort traffic performance in 802.11e with high-quality of service to maximize the system throughput, we propose a novel scheme called, Adaptive Best Effort Traffic Scheduler for EDCA(ABET-EDCA). In this scheme, TCP packets get prioritized by dynamically adapting to contention window parameters. In addition to this, traffic class monitors the MAC queue and computes TXOP limits value at runtime. This results in reduced delay and loss factor. Additionally, we incorporate the cross layer approach by exploiting the physical and MAC layer information to initiate corrective measures at the Transport and Network layer to enhance best effort traffic performance. The simulation conducted shows the significant improvement in TCP performance in terms of goodput, delay and throughput even under high loads compared to EDCA.Item QoS based multipath routing in MANET: A cross layer approach(IEEE, 2017) Gudino, Lucy J.MANET is a network of mobile nodes which is infrastructure-less, self-configuring and are gaining popularity in recent times due to the ease of deployment. Applications such as audio/video conferencing require very stringent and inflexible Quality of Service (QoS) in data delivery. To provide QoS in Routing in MANET is a challenging issue because of the dynamic nature of nodes and limited node energy. In this paper, we proposed a QoS aware weight based on demand Multipath Routing protocol (QMR) to enhance Quality of Service (QoS). QMR is based on cross-layer design, which cooperate in sharing network-status information within different layers of protocol while maintaining the layers' separation to improve overall network performance. In QMR, the weight of the link is decided by multiple QoS factors like signal strength, and residual energy. The maximum aggregated weight decided by these factors helps to choose the most optimal route which is stable and energy efficient between source and destination. The proposed protocol offers an increased lifetime of nodes, better throughput, low packet delay and high packet delivery ratio in different mobile environments.Item A Cross-Layer Delay-Aware Node Disjoint Multipath Routing Algorithm for Mobile Ad Hoc Networks(AIRCJJ, 2014) Gudino, Lucy J.Mobile Ad Hoc Networks (MANETS) require reliable routing and Quality of Service(QoS) mechanism to support diverse applications with varying and stringent requirements. Routing protocols such as AODV, AOMDV, DSR and OLSR use minimum hop count as the metric for path selection, hence are not suitable for delay sensitive real time applications. To support such applications delay constrained routing protocols are employed. These Protocols makes path selection based on the delay over the discovered links during routing discovery and routing table calculations. We propose a variation of a node-disjoint Multipath QoS Routing protocol called Cross Layer Delay aware Node Disjoint Multipath AODV (CLDM-AODV) based on delay constraint. It employs cross-layer communications between MAC and routing layers to achieve link and channel-awareness. It regularly updates the path status in terms of lowest delay incurred at each intermediate node. Performance of the proposed protocol is compared with single path AODV and NDMR protocols. Proposed CLDM-AODV is superior in terms of better packet delivery and reduced overhead between intermediate nodes.Item Fuzzy-Based Querying Approach for Multidimensional Big Data Quality Assessment(2017) K., Pradheep KumarThis paper is intended to design a fuzzy based approach to assess standards and quality of big data. It also serves as a platform to organizations that intend to migrate their existing database environment to big data environment. Data is assessed using a multidimensional approach based on quality factors like accuracy, completeness, reliability, usability, etc. These factors are analysed by constructing decision trees to identify the quality aspects which need to be improved. In this work fuzzy queries have been designed. The queries are grouped as sets namely Excellent, Optimal, Fair and Hybrid. Based on the fuzzy data sets formed and the query compatibility index, a query set is chosen. A data set that has a very high degree of membership is assigned a fair query set. A data set with a medium degree of membership is assigned a optimal query set. A data set that has a lesser degree of membership is assigned a Excellent query set. A data set which needs a combination of queries of all the above is assigned a hybrid query set. The fuzzy query based approach reduces the query compatibility index by 36%, compared to a normal query set approach.Item PRIME: A partial path establishment based handover management technique for QoS support in WiMAX based wireless mesh networks(Elsevier, 2015-06) Lakshmi, L.R.In this paper, we propose a novel handover management technique called PaRtIal path establishment based handover Management tEchnique (PRIME) for WiMAX based wireless mesh networks (WMNs). Different from the currently existing methods for WiMAX networks, PRIME addresses handover management in WiMAX WMNs deployed with distributed scheduling. In these networks, to continue the quality of service (QoS) constrained flows to a mobile node (MN) after its handover, a new path with the required bandwidth and which passes through its new base station (BS) needs to be established as quickly as possible. To address that issue, PRIME handles re-routing and scheduling issues of a handing over MN together. To provide lossless and seamless service, PRIME tries to establish new path(s) in the wireless mesh with the required bandwidth to the MN before it enters into the coverage area of the new BS. The present paper proposes a novel crossover node based partial path establishment algorithm to establish new path(s) which support QoS requirements of handoff calls. To analyze the performance of PRIME, the present paper proposes a multi-dimensional Markov model. Unlike previous models which analyze the performance of wireless networks, our proposed model represents nodes in terms of the number of transmission and reception available slots. The theoretical upper and lower bounds on the call dropping probabilities of handoff calls are obtained. To study the performance advantages of PRIME, we devise another handover management method called RFPHMT which does not use the concept of crossover base station in the new path establishment of a handing over node. The performance of PRIME and RFPHMT are compared in terms of call dropping probabilities and call setup delays. PRIME shows superior performance than RFPHMT. For a random topology, at a high call arrival rate of 1/2000 (calls/milliseconds), the handover call dropping probability of PRIME is 40% less than that of RFPHMT. The call dropping probabilities of PRIME with the simulations are always within the theoretical bounds which proves that the obtained bounds are close to the real call dropping probabilities.Item A Dynamic Backup Path Management Method for TDMA Based WiMAX Client WMNs(Springer, 2016-02) Lakshmi, L.R.This paper proposes a backup path management method for time division multiple access (TDMA) based client wireless mesh networks (WMNs). In a TDMA based client WMN, as links/nodes fail or as nodes perform handover and as flows enter and leave the network, the paths between various nodes change as well as the bandwidth available along these paths. In these networks, to support the quality of service requirements of flows, backup paths with the required bandwidth need to be established dynamically. Some methods are proposed in the literature to establish backup paths which handle link/node failures and node handover in ad hoc networks, but none of these methods can provide backup paths with the required bandwidth dynamically. To address that issue, the present paper proposes a backup path management method which is adaptive to both topological changes and traffic changes in a network. Each node along the current path between a source and a destination finds backup paths with the required bandwidth in order to handle failure of the link to its downstream node and its own failure or handover. Nodes use twohop neighborhood information and slots status information of two-hop neighbors to establish backup paths. We prove that the number of backup paths available when a node N searches for backup paths to handle its own failure are more than the number of backup paths available when some other node searches for the backup paths for the failure of node N. Performance of the proposed method is compared with the performance of a naive path management (NPM) method in which always the source establishes backup paths whenever a link/node fails or a node performs handover, and also with the performance of a backup path management method proposed in the literature. The proposed method significantly outperforms the NPM method and the method selected from the literature. For example, when the speed of the mobile nodes is 50 m/s, the packet delivery ratio with the proposed method is 63 % more than the NPM method and 35 % more than the method selected from the literature.Item Adaptive Zone Size Selection Method for IEEE 802.16j Mobile Multihop Relay Networks(Springer, 2017-08) Lakshmi, L.R.IEEE 802.16j relay networks are capable of extending the coverage areas of IEEE 802.16 networks and can support the data rate requirements of users at cell edges. In these networks, each frame is divided into various zones to facilitate data transmission between various types of nodes. As the link qualities in the network change, accordingly the zone sizes should also change to support the Quality of Service (QoS) requirements of flows and to avoid bandwidth wastage. To address this issue, in this paper, we propose an adaptive zone size selection method for IEEE 802.16j networks. With this method, zone sizes of scheduling nodes are adaptively changed in accordance with their changing link qualities. As the link qualities degrade, the scheduling nodes may not be able to support the QoS requirements of flows due to the lack of free bandwidth availability in the corresponding zones. To handle this issue with less control overhead, we propose a cross-zone bandwidth allocation method. A zone size reselection method is also proposed to handle the situations where the cross-zone bandwidth allocation is not possible. Performance of the proposed method is compared with the performance of a fixed zone size selection method and a zone size selection method proposed in the literature. The proposed method shows significantly better performance than the other two methods in terms of traffic admittance, bandwidth utilization, and satisfaction ratios of flows.Item Fair Scheduling of Concurrent Transmissions in Directional Antenna Based WPANs/WLANs(IEEE, 2018) Lakshmi, L.R.With their capability to support high data rates, millimeter-Wave (mmWave) communications are evolving as a promising and potential technology to support high data rate applications in short range networks. This paper addresses the problem of fair scheduling in mmWave wireless personal and local area networks (WPANs/WLANs) to support applications with varying quality of service (QoS) requirements. To ensure fairness while exploiting the spatial reuse facilitated by directional antennas, concurrent transmission scheduling in mmWave WPANs/WLANs is formulated as a multi-objective optimization problem. Two heuristic schedulers are developed to obtain a schedule in real-time. These schedulers first satisfy the minimum QoS requirements of as many flows as possible, and then, allocate the remaining bandwidth to various flows while ensuring long-term and short-term fairness among the flows. Results from extensive simulations conducted in a dense mmWave WPAN show that the proposed fair schedulers provide better fairness and throughput, compared to existing methods