George Kesidis

Effective bandwidths for multiclass Markov fluids and other ATM sources

The authors show the existence of effective bandwidths for multiclass Markov fluids and other types of sources that are used to model ATM traffic. More precisely, it is shown that when such sources share a buffer with deterministic service rate, a constraint on the tail of the buffer occupancy distribution is a linear constraint on the number of sources. That is, for a small loss probability one can assume that each source transmits at a fixed rate called its effective bandwidth. When traffic parameters are known, effective bandwidths can be calculated and may be used to obtain a circuit-switched style call acceptance and routing algorithm for ATM networks. The important feature of the effective bandwidth of a source is that it is a characteristic of that source and the acceptable loss probability only. Thus, the effective bandwidth of a source does not depend on the number of sources sharing the buffer or the model parameters of other types of sources sharing the buffer. >

Denial-of-service attack-detection techniques

Denial-of-service (DoS) detection techniques - such as activity profiling, change-point detection, and wavelet-based signal analysis - face the considerable challenge of discriminating network-based flooding attacks from sudden increases in legitimate activity or flash events. This survey of techniques and testing results provides insight into our ability to successfully identify DoS flooding attacks. Although each detector shows promise in limited testing, none completely solve the detection problem. Combining various approaches with experienced network operators most likely produce the best results.

Incentive-Based Energy Consumption Scheduling Algorithms for the Smart Grid

In this paper, we study Demand Response (DR) problematics for different levels of information sharing in a smart grid. We propose a dynamic pricing scheme incentivizing consumers to achieve an aggregate load profile suitable for utilities, and study how close they can get to an ideal flat profile depending on how much information they share. When customers can share all their load profiles, we provide a distributed algorithm, set up as a cooperative game between consumers, which significantly reduces the total cost and peak-to-average ratio (PAR) of the system. In the absence of full information sharing (for reasons of privacy), when users have only access to the instantaneous total load on the grid, we provide distributed stochastic strategies that successfully exploit this information to improve the overall load profile. Simulation results confirm that these solutions efficiently benefit from information sharing within the grid and reduce both the total cost and PAR.

Resource management in wide-area ATM networks using effective bandwidths

This paper is principally concerned with resource allocation for connections tolerating statistical quality of service (QoS) guarantees in a public wide-area ATM network. Our aim is to sketch a framework, based on effective bandwidths, for call admission schemes that are sensitive to individual QoS requirements and account for statistical multiplexing. Results approximating the effective bandwidth required by heterogeneous streams sharing buffered links, including results for the packetized generalized processor sharing service discipline, are described. Extensions to networks follow via the concept of decoupling bandwidths, motivated by a study of the input-output properties of queues. Based on these results we claim that networks with sufficient routing diversity will inherently satisfy nodal decoupling. We then discuss on-line methods for estimating the effective bandwidth of connection. Using this type of traffic monitoring we propose an approach to usage parameter control (i.e., policing) for effective bandwidth descriptors. Finally, we suggest how on-line monitoring might be combined with admission control to exploit unknown statistical multiplexing gains and thus increase utilization. >

Equilibria of a noncooperative game for heterogeneous users of an ALOHA network

A noncooperative group of users sharing a channel via ALOHA is considered. Depending on their quality-of-service requirements and willingness to pay, the users will select a desired throughput. The users then participate in a noncooperative game wherein they adjust their transmission-probability parameters in an attempt to attain their desired throughputs. The possible equilibrium points reached by such a community of users are studied.

Dynamic cluster structure for object detection and tracking in wireless ad-hoc sensor networks

Wireless ad-hoc sensor networks are being developed to carry out tasks such as target detection and tracking, environment monitoring, and data collection across the area of deployment. We explore the problem of using sensor networks to detect and track continuous objects, such as wild fire and bio-chemical material. The continuous objects are different from traditional one or many individual targets in that they are continuously distributed across a region and usually occupy a large area. These continuous objects tend to diffuse, increase in size, change in shape, or even split into multiple relatively smaller continuous objects. The fusion and dissemination of local boundary information becomes a very challenging problem. In the paper, we propose a dynamic cluster-based structure to track the movement of boundaries and facilitate the fusion and dissemination of boundary information in a sensor network.

Admission control and routing in ATM networks using inferences from measured buffer occupancy

Addresses the issue of call acceptance and routing in ATM networks. The goal is to design an algorithm that guarantees bounds on the fraction of cells lost by a call. The method proposed for call acceptance and routing does not require models describing the traffic. Each switch estimates the additional fraction of cells that would be lost if new calls were routed through the switch. The routing algorithm uses these estimates. The estimates are obtained by monitoring the switch operations and extrapolating to the situation where more calls are routed through the switch. The extrapolation is justified by a scaling property. To reduce the variance of the estimates, the switches calculate the cell loss that would occur with virtual buffers. A way to choose the sizes of the virtual buffers in order to minimize the variance is discussed. Thus, the switches constantly estimate their spare capacity. Simulations were performed using Markov fluid sources to test the validity of the approach. >

Purposeful mobility for relaying and surveillance in mobile ad hoc sensor networks

We consider a mobile ad hoc sensor network. The mobility of the sensor nodes is designed with the cost of communication and mobility in mind along with consideration of the possible scanning tasks of the nodes. Our mobility algorithm is developed in the context of a distributed system where, for any single mobile node, only local information about associated energy costs is known. We use a distributed simulated annealing framework to govern the motion of the nodes and prove that, in a limiting sense, a global objective function comprising mobility and communication energy costs are minimized. This paper concludes with a simulation study focusing on mobile sensors with dual roles of scanning and relaying higher priority tracking traffic from tracking nodes.

Cyber defense technology networking and evaluation

Creating an experimental infrastructure for developing next-generation information security technologies.

ATM input-buffered switches with the guaranteed-rate property

There is considerable interest in the provision of guaranteed-rate services for IP and ATM networks. Simultaneously, bandwidth demands make input-buffered architectures attractive, and in some cases, necessary. We consider the problem of how to support guaranteed-rate services in a single-stage, input-buffered switch suitable for a LAN switch, an ATM switch or an IP router. Such a switch must be feasible at high transmission speeds, offering both guaranteed-rate performance for CBR channels (e.g. for real-time connections) and best-effort services for traditional data traffic. We consider a switch scheduling mechanism that employs idling hierarchical round-robin (HRR) scheduling and fabric arbitration at the connection-level for guaranteed-rate service using the Slepian-Duguid algorithm. The switch uses cell level arbitration for best-effort service. This overall switch scheduling mechanism is a variation of DECs AN2 design.