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Providing a-priori temporal guarantees is paramount in real-time systems. Although much of the normal operation in such a system is modeled using sporadic tasks, event-driven behavior is modeled using aperiodic jobs. To ensure an acceptable Quality of Service for aperiodic jobs without jeopardizing safety of sporadic tasks, aperiodic servers were introduced. While aperiodic servers periodically reserve...
In this paper a scheme is presented to process 3D ground-penetrating radar reflection data acquired on a surface above a vertical transverse isotropic layered medium. The processing steps first decompose the data into Transverse Electric and Transverse Magnetic modes and up and down going waves, where the two modes are fully separated and can be treated separately in the two following steps. The first...
This paper presents a new multipath delay based algorithm, MPPERT (Multipath Probabilistic Early response TCP), which provides high throughput and efficient load balancing. In all-PERT environment, MPPERT suffers no packet loss and maintains much smaller queue sizes compared to existing MPTCP, making it suitable for real time data transfer. MPPERT is suitable for incremental deployment in a heterogeneous...
XCP is one of the most commonly used protocols in modern congestion control implementations. XCP can provide the available transmission rate to applications. It is well known fact that one of the issues of XCP is that the time-delay of its traditional implementation (TR-XCP) is twice the time-delay of its flow model. This leads to unstable behaviors when controlling the congestion in networks with...
WMN (Wireless Mesh Network) is a useful wireless multi-hop network with tremendous research value. A good routing mechanism for WMN can use the whole bandwidth of the network and can assure the quality of service of traffic. Through simulations we verify that the routing metric ETX (Expected Transmission Count) cannot assure good quality of wireless links. To improve the routing performance, a QoS-assured...
Envisioning to meet the expectations arising from the Future Internet, and specifically to provide efficient Quality of Service (QoS) support for multimedia multi-user sessions, the attempts by the research community have resulted in mechanisms such as Multi-User Aggregated Resource Allocation (MARA). The MARA mechanism adopts an over-provisioning centric strategy to control surplus class-based bandwidth...
The IEEE 802.11 standard does not define any feedback policy for the multicast transport. Hence missing multicast packets are not retransmitted and are definitely lost. In this paper we define the Block Negative-Ack (BNAK) recovery policy. Using our protocol, the multicast source transmits a block of multicast packets followed by a Block NAK Request (BNR). Upon reception of a BNR, a multicast member...
In this study, a high sensitivity CMOS-based Capacitive Micromachined Ultrasonic Transducer (CMUT) is developed. This CMUT device provides high performance for operations with and without DC bias. It is implemented based on the TSMC 0.35µm 2P4M CMOS-MEMS process. The hypothesis is that driven by a commercial pulser, charges were injected into charge traps in CMUT and they were temporarily stored providing...
Design limitations for synthetic aperture radiometer are quantitatively analyzed. Firstly, the image quality of a small scaled system with a few baselines is analyzed. The image quality is getting poorer due to the truncation in the spatial frequency domain while the number of baselines is getting fewer. This is called the lower limit for the design. Secondly, the design limitation for a large scaled...
In the paper we present integer programming (IP) optimization models for flexgrid elastic optical networks (EON). We consider several different basic assumptions regarding flexibility of EON that lead to a variety of IP formulations differing in precision and complexity. As usual, detailed models aiming at precisely describing technological aspects of EON suffer from tractability issues resulting...
Arbitrarily divisible workloads are present in a large class of scientific applications, such as N-body simulations, Monte Carlo simulations, CFD applications, and others. Divisible load theory (DLT) provides a tractable approach to the scheduling of arbitrarily divisible workloads. High performance parallel and distributed systems may operate in an unreliable environment, and a robust system is expected...
P2P live streaming are increasingly popular nowadays. Due to their popularity, these systems may be a target of attacks and opportunistic user behavior. In this paper, we address the pollution attacks in such systems. We present a pollution damage model and also analyze a reputation system as a tool to fight attacks in P2P live streaming systems. The model we propose evidences that attacks are harmful...
The Internet is replacing the traditional telephone network as the ubiquitous network infrastructure. Internet customers are increasing at an exponential rate and will continue to increase in the near future. Among the various Internet services, IPTV VoD (Video on Demand) service is expected to be one of the most popular services. In general, for deploying streamed video service, it is likely to use...
Our focus, in this paper is on the embedding problem which consists on the mapping of Virtual Network (VN) resources onto physical infrastructure network. In relevant literature, number of works have been proposed to solve this challenging problem. However, few proposals have been dedicated to provide backup mapping mechanism for failing physical links. In virtualization environment a failing link...
Data centers consume significant amounts of energy. As severs become more energy efficient with various energy saving techniques, the data center network (DCN) has been accounting for 20% or more of the energy consumed by the entire data center. While DCNs are typically provisioned with full bisection bandwidth, DCN traffic demonstrates fluctuating patterns. The objective of this work is to improve...
Data availability is critical in distributed storage systems, especially when node failures are prevalent in real life. A key requirement is to minimize the amount of data transferred among nodes when recovering the lost or unavailable data of failed nodes. This paper explores recovery solutions based on regenerating codes, which are shown to provide fault-tolerant storage and minimum recovery bandwidth...
Energy efficiency of computing devices has become a dominant area of research interest in recent years. Most previous work has focused on architectural techniques to improve power and energy efficiency, only a few consider saving energy at the algorithmic level. We prove that a region of perfect strong scaling in energy exists for matrix multiplication (classical and Strassen) and the direct n-body...
In the report new weight functions with low side-lobe level, based on convolutions of atomic functions are presented. There are effective algorithms for their computation. To increase coherent gain the window is truncated with an additional one. This approach allows us to obtain windows with good properties. The degree of cut of the function determines the relation between side-lobes and coherent...
In this paper, we consider a cognitive relay network, in which multiple pairs of secondary users (SUs) share the unlicensed spectrum by the overlay mode, and for each SU pair, the two ends exchange data via a common relay node that senses the spectrum and allocates the unused bandwidth. Here, we formulate the spectrum allocation problem as a multi-object auction and introduce the mechanisms of sequential...
In this paper, we present an approach to the design of orthogonal, Doppler tolerant waveforms for diversity waveform radar (e.g. MIMO radar). Previous work has given little consideration to the design of radar waveforms that remain orthogonal when they are received. Our research is focused on: (1) developing sets of waveforms that are orthogonal on both transmit and receive, and (2) ensuring that...
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