Ioannis Stavrakakis | National and Kapodistrian University of Athens (original) (raw)

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Papers by Ioannis Stavrakakis

Networking, 2000

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Lecture Notes in Computer Science, 2001

ABSTRACT In this paper a multi-state rate adaptation scheme for rate adaptable continuous media (... more ABSTRACT In this paper a multi-state rate adaptation scheme for rate adaptable continuous media (CM) sources is presented; the network bandwidth availability information is assumed to be communicated to the source only indirectly, through a notification of the packet losses. The developed scheme is capable of detecting and responding well to static (due to access bandwidth limitations) and long-term (due to initiation/termination of CM flows) bandwidth availability, as well as locking the rate of a CM flow to an appropriate value. Its performance is compared with that under a classic Additive Increase Multiplicative Decrease algorithm and its shown to perform better in terms of a number of relevant metrics, such as packet losses, oscillatory behavior, and fairness.

Lecture Notes in Computer Science, 2000

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Proceedings of the Second International Workshop on Mobile Opportunistic Networking - MobiOpp '10, 2010

Random walk-based approaches are suitable for information dissemination in mobile and opportunist... more Random walk-based approaches are suitable for information dissemination in mobile and opportunistic environments that are inherently dynamic and typically large-scale. Multiple random walkers have been proposed in the recent past as a suitable mechanism to significantly reduce termination time when covering a network topology. In this paper, the multiple random walkers mechanism is studied and analyzed under a different and novel perspective that allows for further understanding of network coverage when employing multiple random walkers in a network. Given that under this mechanism the number of movements is significantly increased (proportional to the number of random walkers)and sometimes not as effective as expected due to frequent revisits that do not improve coverage as shown in this paper -a replication mechanism is introduced that is capable of reducing the number of movements by reducing initial revisits. Simulation results considering geometric random graph topologies -which are suitable for modeling mobile environments -are also presented supporting the analytical findings and shedding more light on various aspects of both the aforementioned mechanisms.

International Journal of Digital & Analog Communication Systems, 1992

ABSTRACT

Data Communications and Their Performance, 1993

Abstract A discrete-time system of two queues served according to distinct policies is studied in... more Abstract A discrete-time system of two queues served according to distinct policies is studied in this paper: one queue receives 1-limited service; the other is served according to some policy from the introduced class of (state dependent) policies S. Class S contains traditional ...

This paper presents a exible tra c model which is capable of describing tra c dynamics on a varie... more This paper presents a exible tra c model which is capable of describing tra c dynamics on a variety of time-scales associated with broadband packet networks such as ATM. The model is applied to the study of Non-Deterministic Periodic (NDP) sources as well as Variable Bit Rate (VBR) video sources in which cells are delivered at a sub-frame level referred to as a slice. An e cient numerical technique is presented for the study of a nite-capacity multiplexer under an input process determined by the superposition of N of the proposed tra c models. Numerical results support the assertion that the time-scales at which variations in a cell arrival stream occur have a signi cant impact on multiplexer performance, thereby illustrating the relevance of the proposed modeling and analytical techniques.

Random Walks have been proposed for information dissemination/discovery in Wireless Sensor Networ... more Random Walks have been proposed for information dissemination/discovery in Wireless Sensor Networks. In this work we propose the Random Walk with Jumps model as an improvement on the Random Walk without Jumps for sparse graphs. Our proposal features the incorporation of 'jumps' (with random direction and length) in the otherwise simple random walk movement throughout the graph of sensor nodes. Our proposal is tested via simulations and is shown to outperform the Random Walk without Jumps both in the average number of steps required to partially cover the network and in the overall energy consumption of the nodes in the network.

Our paper approaches the parking assistance service in urban environments as an instance of servi... more Our paper approaches the parking assistance service in urban environments as an instance of service provision in non-cooperative network environments. We propose normative abstractions for the way drivers pursue parking space and the way they respond to partial or complete information for parking demand and supply as well as specific pricing policies on public and private parking facilities. The drivers are viewed as strategic agents who make rational decisions attempting to minimize the cost of the acquired parking spot. We formulate the resulting games as resource selection games and derive their equilibria under different expressions of uncertainty about the overall parking demand. The efficiency of the equilibrium states is compared against the optimal assignment that could be determined by a centralized entity and conditions are derived for minimizing the related price of anarchy value. Our results provide useful hints for the pricing and practical management of on-street and private parking resources. More importantly, they exemplify counterintuitive less-is-more effects about the way information availability modulates the service cost, which underpin general competitive service provision settings and contribute to the better understanding of effective information mechanisms.

We summarize undertaken and ongoing work on the direct and exclusive use of mobile phone traces f... more We summarize undertaken and ongoing work on the direct and exclusive use of mobile phone traces for assessing the performance of different opportunistic forwarding schemes. Our methods draw on graph-expansion techniques and circumvent the need for more custom simulation software packages. They address a wide range of opportunistic dissemination schemes including controlled flooding and socioaware protocol variants. We outline the general approach and exemplify it with an assessment of centrality metrics as drivers of data dissemination decisions. Finally, we report results on the benefits of identifying community structure out of the similarity of interests across the opportunistic network and discuss their implications for tracebased evaluation.

Proceedings of GLOBECOM'96. 1996 IEEE Global Telecommunications Conference, 1996

Abstract A queueing model is developed and analyzed to evaluate the performance of a simple rate ... more Abstract A queueing model is developed and analyzed to evaluate the performance of a simple rate control scheme in the presence of propagation delays (in ATM networks). Unlike previous discrete-time studies of adaptive rate control, the arrival processes are assumed ...

Proceedings of INFOCOM'95, 1995

Traffic streams---originally shaped to comply withdesired traffic descriptors---may suffer substa... more Traffic streams---originally shaped to comply withdesired traffic descriptors---may suffer substantial distortionwithin an ATM network due to statistical multiplexing.As a consequence, traffic re-shaping withinthe network may be necessary. In this work the modificationof a tagged traffic stream due to a series of multiplexingoperations is studied. The standard FCFSservice policy, as well as a peak-rate enforcing multiplexingdiscipline, are considered. Tagged cell delay,jitter

[Conference Record] SUPERCOMM/ICC '92 Discovering a New World of Communications, 1992

Abstract The distributed queue dual bus (DQDB) medium access protocol has been adopted as a metro... more Abstract The distributed queue dual bus (DQDB) medium access protocol has been adopted as a metropolitan area network (MAN) standard. The performance of the DQDB protocol is analyzed under underloaded operation. No bandwidth balancing mechanism is assumed ...

Seamless Interconnection for Universal Services. Global Telecommunications Conference. GLOBECOM'99. (Cat. No.99CH37042), 1999

... to avoid ei-PI 1 PI. *This work is part of Zoe Antoniou's Ph.D. research while with Nort... more ... to avoid ei-PI 1 PI. *This work is part of Zoe Antoniou's Ph.D. research while with Northeastern University and has been supported by the National Science Foundation under Grant NCR 9628116. Ioannis Stavrakakis Department ...

1994 IEEE GLOBECOM. Communications: The Global Bridge, 1994

In this paper, a dual-class queueing system is formulated and applied to study the e ects of cell... more In this paper, a dual-class queueing system is formulated and applied to study the e ects of cell spacing within the network premises as a means of controlling networkinduced delay jitter. The adopted service policy regulates the tra c class of interest by enforcing a predetermined peak output rate. Probability distributions for delay and jitter of the regulated tra c class are derived by analyzing the system in discrete time. While maintaining a high degree of simplicity, the proposed policy is shown to provide improved jitter performance for the regulated tra c class over the First-In First-Out (FIFO) service policy.

IEEE Transactions on Communications, 1994

A discrete-time queueing system operating under a two-level, consistent priority service policy i... more A discrete-time queueing system operating under a two-level, consistent priority service policy is studied. The consistency of the policy guarantees that no low priority customer will be served before a previously (or simultaneously) arrived high priority one. Unlike the well known head of the line priority policy (which is consistent), the considered policy provides for limited service to low priority

IEEE INFOCOM, 1990

The queueing behavior of a statistical multiplexer with a finite number of input lines is studied... more The queueing behavior of a statistical multiplexer with a finite number of input lines is studied. Each input line is assumed to deliver fixed-length packets of information according to a generally distributed process whose parameters depend on the state of an underlying finite-state Markov chain associated with each of the input lines. A method for the derivation of the moments

Networking, 2000

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Lecture Notes in Computer Science, 2001

ABSTRACT In this paper a multi-state rate adaptation scheme for rate adaptable continuous media (... more ABSTRACT In this paper a multi-state rate adaptation scheme for rate adaptable continuous media (CM) sources is presented; the network bandwidth availability information is assumed to be communicated to the source only indirectly, through a notification of the packet losses. The developed scheme is capable of detecting and responding well to static (due to access bandwidth limitations) and long-term (due to initiation/termination of CM flows) bandwidth availability, as well as locking the rate of a CM flow to an appropriate value. Its performance is compared with that under a classic Additive Increase Multiplicative Decrease algorithm and its shown to perform better in terms of a number of relevant metrics, such as packet losses, oscillatory behavior, and fairness.

Lecture Notes in Computer Science, 2000

RefDoc Refdoc est un service / is powered by. ...

Proceedings of the Second International Workshop on Mobile Opportunistic Networking - MobiOpp '10, 2010

Random walk-based approaches are suitable for information dissemination in mobile and opportunist... more Random walk-based approaches are suitable for information dissemination in mobile and opportunistic environments that are inherently dynamic and typically large-scale. Multiple random walkers have been proposed in the recent past as a suitable mechanism to significantly reduce termination time when covering a network topology. In this paper, the multiple random walkers mechanism is studied and analyzed under a different and novel perspective that allows for further understanding of network coverage when employing multiple random walkers in a network. Given that under this mechanism the number of movements is significantly increased (proportional to the number of random walkers)and sometimes not as effective as expected due to frequent revisits that do not improve coverage as shown in this paper -a replication mechanism is introduced that is capable of reducing the number of movements by reducing initial revisits. Simulation results considering geometric random graph topologies -which are suitable for modeling mobile environments -are also presented supporting the analytical findings and shedding more light on various aspects of both the aforementioned mechanisms.

International Journal of Digital & Analog Communication Systems, 1992

ABSTRACT

Data Communications and Their Performance, 1993

Abstract A discrete-time system of two queues served according to distinct policies is studied in... more Abstract A discrete-time system of two queues served according to distinct policies is studied in this paper: one queue receives 1-limited service; the other is served according to some policy from the introduced class of (state dependent) policies S. Class S contains traditional ...

This paper presents a exible tra c model which is capable of describing tra c dynamics on a varie... more This paper presents a exible tra c model which is capable of describing tra c dynamics on a variety of time-scales associated with broadband packet networks such as ATM. The model is applied to the study of Non-Deterministic Periodic (NDP) sources as well as Variable Bit Rate (VBR) video sources in which cells are delivered at a sub-frame level referred to as a slice. An e cient numerical technique is presented for the study of a nite-capacity multiplexer under an input process determined by the superposition of N of the proposed tra c models. Numerical results support the assertion that the time-scales at which variations in a cell arrival stream occur have a signi cant impact on multiplexer performance, thereby illustrating the relevance of the proposed modeling and analytical techniques.

Random Walks have been proposed for information dissemination/discovery in Wireless Sensor Networ... more Random Walks have been proposed for information dissemination/discovery in Wireless Sensor Networks. In this work we propose the Random Walk with Jumps model as an improvement on the Random Walk without Jumps for sparse graphs. Our proposal features the incorporation of 'jumps' (with random direction and length) in the otherwise simple random walk movement throughout the graph of sensor nodes. Our proposal is tested via simulations and is shown to outperform the Random Walk without Jumps both in the average number of steps required to partially cover the network and in the overall energy consumption of the nodes in the network.

Our paper approaches the parking assistance service in urban environments as an instance of servi... more Our paper approaches the parking assistance service in urban environments as an instance of service provision in non-cooperative network environments. We propose normative abstractions for the way drivers pursue parking space and the way they respond to partial or complete information for parking demand and supply as well as specific pricing policies on public and private parking facilities. The drivers are viewed as strategic agents who make rational decisions attempting to minimize the cost of the acquired parking spot. We formulate the resulting games as resource selection games and derive their equilibria under different expressions of uncertainty about the overall parking demand. The efficiency of the equilibrium states is compared against the optimal assignment that could be determined by a centralized entity and conditions are derived for minimizing the related price of anarchy value. Our results provide useful hints for the pricing and practical management of on-street and private parking resources. More importantly, they exemplify counterintuitive less-is-more effects about the way information availability modulates the service cost, which underpin general competitive service provision settings and contribute to the better understanding of effective information mechanisms.

We summarize undertaken and ongoing work on the direct and exclusive use of mobile phone traces f... more We summarize undertaken and ongoing work on the direct and exclusive use of mobile phone traces for assessing the performance of different opportunistic forwarding schemes. Our methods draw on graph-expansion techniques and circumvent the need for more custom simulation software packages. They address a wide range of opportunistic dissemination schemes including controlled flooding and socioaware protocol variants. We outline the general approach and exemplify it with an assessment of centrality metrics as drivers of data dissemination decisions. Finally, we report results on the benefits of identifying community structure out of the similarity of interests across the opportunistic network and discuss their implications for tracebased evaluation.

Proceedings of GLOBECOM'96. 1996 IEEE Global Telecommunications Conference, 1996

Abstract A queueing model is developed and analyzed to evaluate the performance of a simple rate ... more Abstract A queueing model is developed and analyzed to evaluate the performance of a simple rate control scheme in the presence of propagation delays (in ATM networks). Unlike previous discrete-time studies of adaptive rate control, the arrival processes are assumed ...

Proceedings of INFOCOM'95, 1995

Traffic streams---originally shaped to comply withdesired traffic descriptors---may suffer substa... more Traffic streams---originally shaped to comply withdesired traffic descriptors---may suffer substantial distortionwithin an ATM network due to statistical multiplexing.As a consequence, traffic re-shaping withinthe network may be necessary. In this work the modificationof a tagged traffic stream due to a series of multiplexingoperations is studied. The standard FCFSservice policy, as well as a peak-rate enforcing multiplexingdiscipline, are considered. Tagged cell delay,jitter

[Conference Record] SUPERCOMM/ICC '92 Discovering a New World of Communications, 1992

Abstract The distributed queue dual bus (DQDB) medium access protocol has been adopted as a metro... more Abstract The distributed queue dual bus (DQDB) medium access protocol has been adopted as a metropolitan area network (MAN) standard. The performance of the DQDB protocol is analyzed under underloaded operation. No bandwidth balancing mechanism is assumed ...

Seamless Interconnection for Universal Services. Global Telecommunications Conference. GLOBECOM'99. (Cat. No.99CH37042), 1999

... to avoid ei-PI 1 PI. *This work is part of Zoe Antoniou's Ph.D. research while with Nort... more ... to avoid ei-PI 1 PI. *This work is part of Zoe Antoniou's Ph.D. research while with Northeastern University and has been supported by the National Science Foundation under Grant NCR 9628116. Ioannis Stavrakakis Department ...

1994 IEEE GLOBECOM. Communications: The Global Bridge, 1994

In this paper, a dual-class queueing system is formulated and applied to study the e ects of cell... more In this paper, a dual-class queueing system is formulated and applied to study the e ects of cell spacing within the network premises as a means of controlling networkinduced delay jitter. The adopted service policy regulates the tra c class of interest by enforcing a predetermined peak output rate. Probability distributions for delay and jitter of the regulated tra c class are derived by analyzing the system in discrete time. While maintaining a high degree of simplicity, the proposed policy is shown to provide improved jitter performance for the regulated tra c class over the First-In First-Out (FIFO) service policy.

IEEE Transactions on Communications, 1994

A discrete-time queueing system operating under a two-level, consistent priority service policy i... more A discrete-time queueing system operating under a two-level, consistent priority service policy is studied. The consistency of the policy guarantees that no low priority customer will be served before a previously (or simultaneously) arrived high priority one. Unlike the well known head of the line priority policy (which is consistent), the considered policy provides for limited service to low priority

IEEE INFOCOM, 1990

The queueing behavior of a statistical multiplexer with a finite number of input lines is studied... more The queueing behavior of a statistical multiplexer with a finite number of input lines is studied. Each input line is assumed to deliver fixed-length packets of information according to a generally distributed process whose parameters depend on the state of an underlying finite-state Markov chain associated with each of the input lines. A method for the derivation of the moments