Researcher:
Akhtar, Nabeel

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Master Student

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Nabeel

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Akhtar

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Akhtar, Nabeel

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2012 - 20154

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Researcher Of Publications: search.filters.isAuthorOfPublication.acd58e66-a580-4927-9fa7-94eb71d744cd

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    VANET topology characteristics under realistic mobility and channel models
    (Institute of Electrical and Electronics Engineers (IEEE), 2013) N/A; Department of Computer Engineering; Department of Electrical and Electronics Engineering; Akhtar, Nabeel; Özkasap, Öznur; Ergen, Sinem Çöleri; Master Student; Faculty Member; Faculty Member; Department of Computer Engineering; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; College of Engineering; College of Engineering; N/A; 113507; 7211
    Developing real-time safety and non-safety applications for vehicular ad hoc networks (VANET) requires understanding the dynamics of the network topology characteristics since these dynamics determine both the performance of routing protocols and the feasibility of an application over VANET. Using various key metrics of interest including node degree, number of clusters, link duration and link quality, we provide a realistic analysis of the VANET topology characteristics. In this analysis, we integrate real-world road topology and real-time data extracted from Freeway Performance Measurement System database into the microscopic mobility model in order to generate realistic traffic flows along the highway. Moreover, we use more realistic, recently proposed, obstacle-based channel model and compare the performance of this sophisticated model to the most commonly used more simplistic channel models including unit disc and log-normal shadowing model. Our investigation on the key system metrics reveal that largely used unit disc model fails to realistically model communication channel, while parameters of simplistic models like log normal can be adjusted to match the corresponding system metrics of more complex and hard to implement obstacle based model.
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    Analysis of distributed algorithms for density estimation in VANETs
    (Ieee, 2012) N/A; Department of Electrical and Electronics Engineering; Department of Computer Engineering; Akhtar, Nabeel; Ergen, Sinem Çöleri; Özkasap, Öznur; Master Student; Faculty Member; Faculty Member; Department of Electrical and Electronics Engineering; Department of Computer Engineering; Graduate School of Sciences and Engineering; College of Engineering; College of Engineering; N/A; 7211; 113507
    Vehicle density is an important system metric used in monitoring road traffic conditions. Most of the existing methods for vehicular density estimation require either building an infrastructure, such as pressure pads, inductive loop detector, roadside radar, cameras and wireless sensors, or using a centralized approach based on counting the number of vehicles in a particular geographical location via clustering or grouping mechanisms. These techniques however suffer from low reliability and limited coverage as well as high deployment and maintenance cost. In this paper, we propose fully distributed and infrastructure-free mechanisms for the density estimation in vehicular ad hoc networks. Unlike previous distributed approaches, that either rely on group formation, or on vehicle flow and speed information to calculate density, our study is inspired by the mechanisms proposed for system size estimation in peer-to-peer networks. We adapted and implemented three fully distributed algorithms, namely Sample & Collide, Hop Sampling and Gossip-based Aggregation. The extensive simulations of these algorithms at different vehicle traffic densities and area sizes for both highways and urban areas reveal that Hop Sampling provides the highest accuracy in least convergence time and introduces least overhead on the network, but at the cost of higher load on the initiator node.
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    Analysis of distributed algorithms for density estimation in VANETs (poster)
    (IEEE-Inst Electrical Electronics Engineers Inc, 2012) N/A; Department of Computer Engineering; Department of Electrical and Electronics Engineering; N/A; Özkasap, Öznur; Ergen, Sinem Çöleri; Akhtar, Nabeel; Faculty Member; Faculty Member; Master Student; Department of Computer Engineering; Department of Electrical and Electronics Engineering; College of Engineering; College of Engineering; Graduate School of Sciences and Engineering; 113507; 7211; N/A
    Vehicle density is an important system metric used in monitoring road traffic conditions. Most of the existing methods for vehicular density estimation require either building an infrastructure, such as pressure pads, inductive loop detector, roadside radar, cameras and wireless sensors, or using a centralized approach based on counting the number of vehicles in a particular geographical location via clustering or grouping mechanisms. These techniques however suffer from low reliability and limited coverage as well as high deployment and maintenance cost. In this paper, we propose fully distributed and infrastructure-free mechanisms for the density estimation in vehicular ad hoc networks. Unlike previous distributed approaches, that either rely on group formation, or on vehicle flow and speed information to calculate density, our study is inspired by the mechanisms proposed for system size estimation in peer-to-peer networks. We adapted and implemented three fully distributed algorithms, namely Sample & Collide, Hop Sampling and Gossip-based Aggregation. The extensive simulations of these algorithms at different vehicle traffic densities and area sizes for both highways and urban areas reveal that Hop Sampling provides the highest accuracy in least convergence time and introduces least overhead on the network, but at the cost of higher load on the initiator node.
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    PublicationMetadata only
    Vehicle mobility and communication channel models for realistic and efficient highway vanet simulation
    (Institute of Electrical and Electronics Engineers (IEEE), 2015) N/A; Department of Electrical and Electronics Engineering; Department of Computer Engineering; Akhtar, Nabeel; Ergen, Sinem Çöleri; Özkasap, Öznur; Master Student; Faculty Member; Faculty Member; Department of Electrical and Electronics Engineering; Department of Computer Engineering; Graduate School of Sciences and Engineering; College of Engineering; College of Engineering; N/A; 7211; 113507
    Developing real-time safety and nonsafety applications for vehicular ad hoc networks (VANETs) requires understanding of the dynamics of the network topology characteristics since these dynamics determine both the performance of routing protocols and the feasibility of an application over VANETs. Using various key metrics of interest, including node degree, neighbor distribution, number of clusters, and link duration, we provide a realistic analysis of the VANET topology characteristics over time and space for a highway scenario. In this analysis, we integrate real-world road topology and real-time data extracted from the freeway Performance Measurement System (PeMS) database into a microscopic mobility model to generate realistic traffic flows along the highway. Moreover, we use a more realistic, recently proposed, obstacle-based channel model and compare the performance of this sophisticated model to the most commonly used and more simplistic channel models, including unit disk and lognormal shadowing models. Our investigation on the key metrics reveals that both lognormal and unit disk models fail to provide realistic VANET topology characteristics. We therefore propose a matching mechanism to tune the parameters of the lognormal model according to the vehicle density and a correlation model to take into account the evolution of the link characteristics over time. The proposed method has been demonstrated to provide a good match with the computationally expensive and difficult-to-implement obstacle-based model. The parameters of the proposed model have been validated to depend only on the vehicle traffic density based on the real data of four different highways in California.