804068
Evaluation of RSVP and Mobility-Aware RSVP Using Performance Evaluation Process Algebra
As a resource reservation mechanism, the Resource ReSerVation Protocol (RSVP) faces a lot of challenges when applying it to the wireless and mobile networks. The interworking problems of RSVP and mobility management protocols have been extensively discussed over the last decade. As the solutions of this problem, mobility-aware RSVP schemes that integrate RSVP and micro-mobility management are becoming more and more popular. Therefore, the investigation on how much they improve the performance of the basic RSVP is necessary and useful. Instead of the traditional simulation based approaches, in this paper we introduce a formal performance evaluation formalism, named Performance Evaluation Process Algebra (PEPA), and employ it to investigate the performance of the basic RSVP and mobility-aware RSVP. Important performance metrics such as handover blocking probability and signalling cost are presented.
6690308
PEPA Analysis of MAP Effects in Hierarchical Mobile IPv6
To overcome the drawbacks of the mobile IPv6 protocol on handling local mobility management, IETF proposed the HMIPv6 protocol which introduces an intermediate mobility anchor point (MAP) to hide the movement of a mobile node within a local area. However, the MAP forms a bottleneck in the network since all the traffic destined for its served nodes has to go through it. Most research on HMIPv6 focuses on protocol optimisation, and performance analysis of HMIPv6 is usually simulation-based. In this paper, we employ a performance evaluation formalism named PEPA to investigate the performance tradeoffs of MAPs in HMIPv6. Performance measures such as response time and MAP utilisation are presented.
32096084
Critical Success Factors for Web-Based Organizational IT Training Systems
Over the years, organizational training plays an important role in human resource management in firms and organizations. With the rapidly changing technology and the increasing business demands, organizations especially IT departments have been investing greatly in web-based training. However, a successful web-based training system depends not only on the willingness from management, but also on IT infrastructure and employee acceptance, which is determined by many factors such as the degree of courseware customization and the level of collaboration.In this study, propositions on the critical success factors of a web-based training system were raised and verified in a case-study involving two web-based courses in a large corporate IT department. The case study method is used to contrast between two modules, and demonstrate the critical success factors for the web-based IT training in a corporate environment. Four factors were identified including management involvement and support, courseware customization, level of collaboration and effective and consistent IT infrastructure. The insights gained and lessons learnt from this case study may hold valuable implications for both research and practice.
5494803
Wireless Network Dynamic Topology Routing Protocol Based on Aggregation Tree Model
As the scale of the network increases, especially wireless and mobile networks comes into fashion, the problem of network dynamic topology management turns into a focus topic in the network world. When network information changes, frequent route computing and network state updates can cause computing and traffic overhead, respectively. Therefore, minimum of influence to network structure has been identified as one of the key issues in designing dynamic network routing protocols. A novel protocol, which is based on Aggregation Tree Routing Model (ATRM) as well as an effective ball-and-string algorithm, is introduced in this paper which aims to minimize the alteration of network topology and to speed up the minimum cost route computation. This routing protocol is applicable to all kinds of networks, including Internet, ad hoc and wireless sensor networks. The simulations show that our protocol not only results in significantly lower overhead, but also gives high levels of dynamic network topology management performance while keeping practical.
24647482
En-route Security Monitoring Based on an Incident Detection Algorithm for Commercial Vehicles
This paper presents the development of a real-time system for monitoring the security of commercial vehicles in road networks. Embedded in the security monitoring system is a commercial vehicle tracking and incident detection algorithm which relies on a combination of vehicle telemetry data obtained from Global Positioning Systems and on-board sensors to continuously monitor the route choice and car-following behavior of the driver. The performance of this algorithm has been tested in a microscopic simulation model, on a set of hypothetical scenarios, which included deviations from the approved routes, forced to travel at unreasonably low speeds, or even stopped at unexpected places in the network. The initial results indicate that the proposed system has good potential in detecting abnormal driving behaviors, with 100% detection rate, 6.0 seconds of mean detection time, and less than 0.5% false alarm rate.
22168621
BLAST++ : A Tool for BLASTing Queries in Batches
BLAST is the standard tool that molecular biologists use to search for sequence similarity in genomic (and protein) databases. It employs a brute force approach of comparing a query sequence against every database sequence - for each pair of the sequences to be matched, BLAST searches for short fixed-length word pairs (seeds) in the sequences and then extends them to higher-scoring regions. To search multiple queries, the basic approach is to run BLAST on each of the queries one at a time. This is clearly inefficient and fails to exploit common subsequences that the collection of queries may share. In this paper, we propose a new genome search tool, BLAST++, that allows multiple, say K, queries to be searched against a database concurrently. The design of BLAST++ is based on our observation that the seed searching step of BLAST is a bottleneck that consumes more than 80% of the total response time! BLAST++ essentially treats a collection of queries as a single virtual query so that the seed searching step needs to be performed only once for common subsequences. We implemented BLAST++ as an extension of the NCBI BLAST, and evaluated its performance. Our study shows that the results obtained by BLAST++ are identical to that obtained by executing BLAST on each of the K queries, but the single-process version of BLAST++ completes the processing in a much shorter time, about only 25% of the original single-process version of NCBI BLAST.
6929789
WSN02-2: Adaptive Network Resource Management in IEEE 802.11 Wireless Random Access MAC
Effective and efficient management of wireless network resources is attracting more and more research attention, due to the rapid growing deployment of wireless mesh and ad hoc networks and to the increasing demand for Quality of Service (QoS) support in these networks. This paper proposes an adaptive network resource management scheme in the popular IEEE 802.11 random access MAC by adaptively adjusting the minimum contention window sizes of traffic flows. First, a novel generalized processor sharing (GPS) model is presented for the IEEE 802.11 random access MAC revealing the relationship between the minimum contention window size of a traffic flow and the amount of network resource this flow can receive. Using this GPS MAC model, a feedback control system model for the proposed adaptive network resource management system is developed, by directly extending our previous work in wireline GPS networks. Based on the feedback control system model, adaptive P and adaptive PI controllers are designed, and their performances are studied in simulations. Simulation results show that by using the designed controllers, the proposed adaptive network resource management approach is able to provide guaranteed distinct QoS support to traffic flows.