15454854
TCP Quick-Adjust by Utilizing Explicit Link Characteristic Information
This paper investigates the utilization of explicit bottleneck link characteristic information in order to enhance TCP behaviors. We propose the TCP Quick-Adjust algorithm as an extension of TCP Quick-Start, to allow end nodes to quickly adjust their sending rate for ongoing connections according to the reported bottleneck link bandwidth. Our scheme is considered to be especially suitable to use in a mobile operator's controlled network domain, where it is possible to provide a subscribed mobile node with reasonably accurate access link and path information. The link characteristic information is piggybacked in IP mobility signaling in this paper. Using simulations, we show that TCP Quick-Adjust provides good performance in terms of link capacity utilization in the scenarios where vertical handovers can happen between two links with very different characteristics.
19257985
Proactive care-of address test for route optimization in FMIPv6
This paper proposes a practical scheme to run the care-of address test (part of the Return Routability test for Mobile IPv6 route optimization) in a proactive way in the context of the Fast Handovers for Mobile IPv6 (FMIPv6) protocol, so that the latency (normally one round-trip time between a mobile node and its correspondent node) caused by the care-of address test after movements can be removed or reduced. Proactive care-of address test can make the Return Rroutability protocol more suitable for delay sensitive applications especially when it is applied in conjunction with other Return Routability optimization schemes.
39781945
Spectral decomposition approach for transient analysis of multi-server discrete-time queues
Previous work by the authors (See Proceedings Conf. on Information Sciences and Systems, Baltimore, USA, 1990) where the spectral decomposition method was used for the transient analysis of a single-server queue is generalized. For the arrival process a general discrete-time Markovian batch arrival process is assumed, where the batch size distribution of the arrivals in successive slots is governed by a N-state discrete-time Markov chain. It is shown that once the N eigenvalues of the probability generating matrix of the arrival process are obtained, the complete solution in the transform domain may be given. Using the complex analysis technique and Cauchy's integral formula, an efficient numerical method is presented for the calculation of a few performance measures. The numerical method is generalized to the situations where the superpositions of a number of independent arrival sources are fed to the queue. It is shown that the numerical complexity are fed to the queue. It is shown that the numerical complexity of obtaining the transient solution in this case can be substantially reduced by using an approach based on the Kronecker product.<<ETX>>
5054397
The transient solution of time-dependent M/M/1 queues
The transient behavior of time-dependent M/M/1 queues is studied. The boundary probability function pi /sub 0/(t), which is the probability that the queue is empty at time t, is shown with analyticity arguments to satisfy a Volterra-type integral equation. The boundary integral equation is derived, and a numerical algorithm is used to solve the integral equation and to find the expected queue size from pi /sub 0/(t). The approach can be applied to many other types of time-dependent queues. Examples are given. >
24760638
Performance study of Markov modulated fluid flow models with priority traffic
The steady-state performance of generic high-speed queuing system with priority traffic is studied, using the Markov modulated fluid models. the focus is on systems with traffic partitioned into two priorities according to a splitting factor alpha , so that low priority traffic can be discarded when congestion occurs. The results are used to further study issues of congestion control with priority traffic. In particular, the expected values, waiting times, variances of the buffer contents, and tail distributions are evaluated. It is found that the waiting time is more sensitive to changes of alpha than the buffer contents. This shows that for time-constrained traffic, the priority assignment is important for properly balancing the tradeoff between packet loss and delays. This model can be considered as a direct extension of the fluid-flow model to include priorities.<<ETX>>
20173388
Spectral Decomposition Approach for Transient Analysis of Multi-Server Discrete-Time Queues
Abstract Discrete time queueing systems are extensively used in modeling the ATM environment at the cell level. This paper examines the transient behavior of a discrete time FCFS multiple server queue. For the arrival process we assume a general discrete time Markovian batch arrival process, where the batch size distribution of the arrivals in successive slots is governed by a finite state discrete time Markov chain. We show that once the spectral decomposition of the “probability generating matrix” of the arrival process is obtained, the complete solution in the transform domain may be given. Using the complex analysis technique and Cauchy's integral formula, we present an efficient numerical method for the numerical calculation of a few performance measures of interest, namely transient probability of queue being empty, and the mean of the queue length distribution. We also generalize our numerical method in the situations where the superposition of a number of independent arrival sources are fed to the queue. It is shown that the numerical complexity of obtaining the transient solution in this case can be substantially reduced by using the approach based on the Kronecker product. The finite buffer case is also analyzed.
3732345
Name Disambiguation Using Atomic Clusters
Name ambiguity is a critical problem in many applications, in particular in the online bibliography systems, such as DBLP and CiteSeer. Previously, several clustering based methods have been proposed although, the problem still presents to be a big challenge for both research and industry communities. In this paper, we present a complementary study to the problem from another point of view. We propose an approach of finding atomic clusters to improve the performance of existing clustering-based methods. We conducted experiments on a dataset from a real-world system: Arnetminer.org. Experiments results show that significant improvements can be obtained by using the proposed atomic clusters finding approach (about +8% and +27% improvements depending on different clustering methods).
13353635
Research group on digital government in North America: developing a comparative and transnational agenda
This poster describes the second year's progress of the research group on Comparative and Transnational Digital Government in North America. This group was formed in 2007 to advance electronic government research across geographic and political boundaries in the region, with the support of the National Science Foundation Digital Government Research Program and the home institutions of the members in Canada, Mexico, and the United States. During the second year of activities, the group members joined their expertise and interests in two face-to-face meetings in Canada. During the second year of work, group members advanced research proposals and developed preliminary products on two topical areas as well as a first draft of a Research Agenda for North America. The group members will continue the discussion of this research agenda in Cholula, Mexico as part of the activities of the 10th Annual International Conference on Digital Government Research (dg.o 2009).
32231750
A Hybrid Restoration Scheme Based on Threshold Reaction Time in Optical Burst-Switched Networks
Optical Burst-Switched (OBS) networks usually employ one-way reservation by sending a burst control packet (BCP) with a specific offset time, before transmitting each data burst frame (BDF). Therefore, a fiber link failure may lead to loss of several BDFs as the ingress nodes sending these BDFs remain unaware of the failed link till they receive the failure indication signal (FIS). In this paper, we propose a hybrid restoration scheme, wherein we employ a novel combination of sub-path as well as path restoration schemes. In particular, the upstream node preceding the failed link employs sub-path restoration as soon as it detects the failure. Thereafter, when the source ingress node receives the FIS message, it (source ingress node) takes over the responsibility and employs path restoration. However, sub-path restoration is exercised by the upstream node only if the remaining time intervals left for the yet-to-arrive BDFs (for which BCPs have already left the upstream node) are less than a minimum time interval (called as threshold reaction time). Performance of the proposed scheme is evaluated through extensive computer simulation using OPNET. Our results indicate that the proposed restoration scheme significantly reduces burst losses due to link failure and, thus, outperforms the existing restoration schemes.
11446949
Composite Evaluation of Replacing Small Generation Units with Large Ones in the Electricity Sector in China
This paper applies two methods to evaluate the economic effects of the policy of "replacing small units with large ones (RSWL)," one is Discounted Cash Flow (DCF) method which performs a technology economic analysis both from the financial and the economic perspectives, the other one is to use the Real Option theory to study the lagging investment problem of the big unit. Through an illustrative example, three alternatives of replacing 200 MW units with 600 MW units are compared. The sensitivity analysis is made to evaluate the impact of uncertain factors on the financial and economic indicators of the execution of RSWL. The environmental costs are also taken into account in the comparison and analysis. The proposed methods can aid the decision-making in the implementation of the policy of RSWL from a wider perspective and it can be used to evaluate the economic benefits and costs of the RSWL projects.
495478
Optimized routing for fault management in optical burst-switched WDM networks
Optical burst switching (OBS) is a promising technique for supporting high-capacity, bursty data traffic over optical wavelength-division-multiplexed (WDM) networks. An optical link failure may result in a huge amount of data (and revenue) loss, and it has been an important survivability concern in optical networks. In this paper, we study the fault- management issues related with a link failure in an OBS network. We propose to use pre-planned global rerouting to balance network load and to reroute bursts after a link fails. We apply optimization techniques to pre-plan explicit backup routes for failure scenarios. Our objective is to achieve optimal load balancing both before and after a failure such that the network state can still remain stable with minimum burst-loss probability when a failure occurs. We apply the pre-planned normal and backup routing tables to an OBS network, and study the network performance after a failure occur using illustrative numerical examples. The results show that the average burst-loss probability can be significantly reduced by 60% - from an average of 0.10 to 0.04 (when the normalized link load is less than 0.5) using globally-rerouted backup routes, when compared with the scheme without global rerouting. We also observe that the burst-loss probability is reduced by 43% - from an average of 0.07 to 0.04 (when the link load is less than 0.5) if the rerouting is done using optimization techniques, when compared with shortest-path routing.for Fault Management