In this letter, we investigate the problem of actuator scheduling for networked control systems. Given a stochastic linear system with a number of actuators, we consider the case that one actuator is activated at each time. This problem... more
In this letter, we investigate the problem of actuator scheduling for networked control systems. Given a stochastic linear system with a number of actuators, we consider the case that one actuator is activated at each time. This problem is combinatorial in nature and NP hard to solve. We propose a convex relaxation to the actuator scheduling problem, and use its solution as a reference to design an algorithm for solving the original scheduling problem. Using dynamic programming arguments, we provide a suboptimality bound of our proposed algorithm. Furthermore, we show that our framework can be extended to incorporate multiple actuators scheduling at each time and actuation costs. A simulation example is provided, which shows that our proposed method outperforms a random selection approach and a greedy selection approach.
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Abstract—Two approximate techniques for analyzing the window size distribution of TCP flows sharing a RED-like bottleneck queue are pre-sented. Both methods presented first use a fixed point algorithm to ob-tain the mean window sizes of... more
Abstract—Two approximate techniques for analyzing the window size distribution of TCP flows sharing a RED-like bottleneck queue are pre-sented. Both methods presented first use a fixed point algorithm to ob-tain the mean window sizes of the flows, and the mean queue length in the bottleneck buffer. The simpler of the two methods then uses the ‘square root formula ’ for TCP; the other method is more complicated. More of-ten than not, the simpler method is slightly more accurate; this is proba-bly due to the fact that window sizes of the different flows are negatively correlated. Keywords—TCP, multiple, distribution, RED, queues. I.
— The paper describes how the use of ‘drop-biasing’, a tech-nique to control the distribution of the gap between consecutive packet losses in random drop queues (such as RED) can be used to reduce the variabil-ity of the queue occupancy... more
— The paper describes how the use of ‘drop-biasing’, a tech-nique to control the distribution of the gap between consecutive packet losses in random drop queues (such as RED) can be used to reduce the variabil-ity of the queue occupancy with TCP traffic. Reducing the variance of the queue occupancy reduces delay jitter for buffered packets, as well as decreases the likelihood of buffer underflow. We find that modifying the packet drop probabilities to ensure a minimum separation between con-secutive packet drops serves to decrease the variability in the queue occu-pancy. This is really achieved as a result of the increased negative corre-lation among the congestion windows of the constituent TCP flows. Such negative correlation explains why the use of simple drop-biasing strategies can reduce the queue variability without increasing the likelihood of bursts of packet losses. The results of our investigations have relevance for the de-sign and deployment of RED-like algorithms for co...
Abstract: In this paper, we address the multicast routing problem for mobile ad hoc networks (MANETs). We present the Source Grouped Flooding approach to achieve multicast in MANETs. The protocol creates multiple multicast routes between... more
Abstract: In this paper, we address the multicast routing problem for mobile ad hoc networks (MANETs). We present the Source Grouped Flooding approach to achieve multicast in MANETs. The protocol creates multiple multicast routes between the source and group members based on hop count distance constraints. We also propose a probabilistic data forwarding mechanism to achieve efficient data dissemination. The protocol aims to achieve the robustness of flooding and data distribution efficiency of tree based protocols. Simulation results verify performance. I.
Isr develops, applies and teaches advanced methodologies of design and analysis to solve complex, hierarchical, heterogeneous and dynamic problems of engineering technology and systems for industry and government. Isr is a permanent... more
Isr develops, applies and teaches advanced methodologies of design and analysis to solve complex, hierarchical, heterogeneous and dynamic problems of engineering technology and systems for industry and government. Isr is a permanent institute of the university of maryland, within the a. James clark school of engineering. It is a graduated national science foundation engineering research center.
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Several challenging optimization problems arise while considering the deployment of the space-air-ground integrated networks (SAGINs), among which the optimal satellite gateway deployment problem is of significant importance. Moreover,... more
Several challenging optimization problems arise while considering the deployment of the space-air-ground integrated networks (SAGINs), among which the optimal satellite gateway deployment problem is of significant importance. Moreover, with the increasing interest in the software-defined integration of 5G networks and satellites, the existence of an effective scheme for optimal placement of SDN controllers is essential. In this paper, we discuss the interrelation between the two problems above and propose suitable methods to solve them under various network design criteria. We first provide a MILP model for solving the joint problem, and then motivate the decomposition of the model into two disjoint MILPs. We then show that the resulting problems can be modeled as the optimization of submodular set functions and can be solved efficiently with provable optimality gaps.
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Connected and automated vehicles (CAVs) have seen a rapid surge in interest over the past few years. A lot of focus is being placed on improving the efficiency and robustness of transportation systems by leveraging the sensors and... more
Connected and automated vehicles (CAVs) have seen a rapid surge in interest over the past few years. A lot of focus is being placed on improving the efficiency and robustness of transportation systems by leveraging the sensors and capabilities of CAVs. However, the integration of CAVs into existing traffic infrastructure would give rise to certain issues that must be addressed before the CAVs can be seen ubiquitously on public roads. Since the highway networks are considered permanent investments that are expensive to build and maintain, the priority is to improve the efficiency of the current traffic system. This chapter explores the integration of two of the most common traffic management strategies, namely, ramp metering (RM) and route guidance (RG), into existing highway networks with human-driven vehicles (HDVs). The introduction of CAVs to public roads will engender issues pertaining to safe interactions between CAVs and HDVs. The later part of the chapter addresses the specif...
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Research supported by the Army Research Office under MURI award W911NF-08-1-0238 and by the National Science Foundation under grant CNS1018346.
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Svetlana Radosavac is now with DoCoMo Communications Laboratories USA, Inc.
We study the stability of linear time invariant distributed consensus dynamics in the presence of multiple propagation and processing delays. We employ fixed point theory (FPT) methods and derive sufficient conditions for asymptotic... more
We study the stability of linear time invariant distributed consensus dynamics in the presence of multiple propagation and processing delays. We employ fixed point theory (FPT) methods and derive sufficient conditions for asymptotic convergence to a common value while the emphasis is given in estimating the rate of convergence. We argue that this approach is novel in the field of networked dynamics as it is also flexible and thus capable of analyzing a wide variety of consensus based algorithms for which conventional Lyapunov methods are either too restrictive or unsuccessful.
The widespread adoption of Network Function Virtualization (NFV) poses significant dataplane scalability limitations in datacenters (DC), as switches will be required to maintain a large amount of forwarding state for service chaining.... more
The widespread adoption of Network Function Virtualization (NFV) poses significant dataplane scalability limitations in datacenters (DC), as switches will be required to maintain a large amount of forwarding state for service chaining. This problem is exacerbated by the small Forwarding Information Base (FIB) of commodity switches, which are typically deployed in NFV infrastructures.To mitigate this problem, we present a routing fabric that combines source routing with pathlet switching in order to (i) achieve state reduction and (ii) provide support for longer paths, hence, meeting the increased hop-count requirement of service chains. Coupling the proposed source routing fabric with a service chain embedding method, we achieve significant gains in terms of FIB consumption, request acceptance, and revenue generation.
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Research Interests: Engineering, Computer Science, Satellite Communication, Wireless Network, Network evolution, and 11 moreQuality of Service, Bandwidth Allocation, Sensor Network, Dynamic Bandwidth Allocation, Community Networks, Secure Communication, Network Topology, Constellation, Space Missions, Time varying, and Propagation delay
Research Interests: Engineering, Geography, Computer Science, Computer Network, Security Requirements, and 11 moreMobile Robot, Data Integrity, User authentication, Space Missions, Satellite Network, Process Capability, Sensor nodes, MESSAGE AUTHENTICATION CODE(MAC), Authentication Protocol, Public Key, and Message Authentication Code
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Research Interests: Computer Science, Wireless Systems, Fading Channel, User eXperience, Computer Network, and 11 moreWireless Network, Quality of Service, System Simulation, Service Differentiation, Multimedia Traffic, System performance, Non Real time, Base station, Cellular system, Opportunistic scheduling, and Discrete time
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System integration is the elephant in the china store of large-scale cyber–physical system (CPS) design. It would be hard to find any other technology that is more undervalued scientifically and at the same time has bigger impact on the... more
System integration is the elephant in the china store of large-scale cyber–physical system (CPS) design. It would be hard to find any other technology that is more undervalued scientifically and at the same time has bigger impact on the presence and future of engineered systems. The unique challenges in CPS integration emerge from the heterogeneity of components and interactions. This