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As wireless local area networks gain popularity from network access providers and customers, supporting multimedia applications becomes a crucial yet unresolved challenge. The need to maintain quality-of-service in the presence of bandwidth limitations, increasing traffic volume and user mobility entails radical rethinking in resource management design in WLANs. The unique capabilities of wireless sensor networks constitute a promising research direction to tackle these issues. In this paper, we present a new sensor-based resource management architecture for enhanced QoS provisioning and handoff management in WLANs. Through theoretical analysis and simulations, we show that the framework can maximize bandwidth utilization while satisfying applications’ QoS requirements and significantly reduce handoff latency.  相似文献
2.
Multihop wireless mesh networks are an attractive solution for providing last-mile connectivity. However, the shared nature of the transmission medium makes it challenging to fully exploit these networks. In an attempt to improve the radio resource utilization, several routing metrics have been specifically designed for wireless mesh networks. However none of these routing metrics efficiently tackles interference issues. Moreover, although some evaluations have been conducted to assess the performance of these metrics in some contrived scenarios, no overall comparison has been performed. The contributions of this paper are consequently twofold. First, we propose a new routing metric, Interference-Aware Routing metric (IAR), specifically designed for WMNs. IAR uses MAC-level information to measure the share of the channel that each link is able to utilize effectively. As a result, paths that exhibit the least interference will be selected to route the data traffic. Then we evaluate the performance of IAR against some of the most popular routing metrics currently used in wireless mesh networks: Hop Count, Blocking Metric, Expected Transmission Count (ETX), Expected Transmission Time (ETT), Modified ETX (mETX), Network Allocation Vector Count (NAVC) and Metric of Interference and Channel-Switching (MIC). We show under various simulation scenarios that IAR performs the best in terms of end-to-end delay and packet loss, and provides the fairest resource utilization.  相似文献
3.
Wireless sensor networks rely on the cooperative effort of the densely deployed sensor nodes to report the detected events. As a result, sensor observations are highly correlated in the space domain. Typically, multiple sensor nodes may report the same event. Consequently, redundant information may be transmitted by the different sensor nodes, leading thus to unnecessary energy wastage. In this paper, we investigate the relationship between the spatial correlation and the number of reporting nodes by developing a new analytical model based on the theoretical framework of the CC-MAC (correlation-based collaborative medium access control) protocol (Vuran and Akyildiz in IEEE/ACM Trans Netw 14(2): 316–32912006). We show that the reporting task can be delegated to a small subset of sensor nodes without transgressing the distortion constraint. Building on this result, a simple spatial correlation medium access control protocol is then proposed to achieve further energy conservation and faster reporting latency than CC-MAC.  相似文献
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This paper introduces a 3-level multiagent architecture for QoS control in WATM. The ultimate aim of the proposed architecture is to provide a self-regulating network congestion control management by means of global network state awareness and agent interactions. The agents dynamically manage the buffer space at the level of a switch and interact to reduce the cell loss ratio while guaranteeing a bounded transit delay. We particularly address video transmission over UBR services using a per-VP queuing approach and an adaptive cell discarding congestion control scheme. Furthermore, a dynamic reconfiguration of the agents is performed during handoffs in order to continue meeting user end-to-end QoS requirements. The handoff delay absorption is also addressed. This revised version was published online in June 2006 with corrections to the Cover Date.  相似文献
5.
Active Networks is a modern network approach in which pieces of code can be downloaded and executed on network devices, affecting in this way their behavior. This approach alters the philosophy of a computer network, makes it resemble to a distributed system and affects not only network protocols, services or applications, but also high-level mechanisms and procedures. One of the affected procedures is the development and testing of new protocols. By exploiting active network properties the development of a network protocol can be simplified to software development. Expensive and time-consuming hardware implementations are avoided, while the code can be developed, shared and tested by individual researchers. Testing can be performed on actual conditions instead of using inaccurate simulations. Early implementations of the protocol, which can be modified easily while the protocol evolves, can be used to obtain useful feedback. This paper describes our experiences of developing and testing of some of theietf cops family protocols in an Active Environment.  相似文献
6.
Wireless sensor networks are composed of energy constrained nodes embedding limited transmission, processing and sensing capabilities. The main research efforts in this area sought to prolong the network lifetime by reducing energy consumption of network operations. Data gathering mechanisms such as clustering have been shown to achieve significant energy savings. However, such benefits can be obtained only if neighboring clusters operate on different frequencies (channels). As the salient characteristics of wireless sensor networks favor a distributed approach, we analyze the performance of several distributed frequency assignment algorithms with a focus on energy consumption. In this context, we find that a heuristic may achieve better results than backtracking-based algorithms.  相似文献
7.
MapReduce has become a popular model for large‐scale data processing in recent years. Many works on MapReduce scheduling (e.g., load balancing and deadline‐aware scheduling) have emphasized the importance of predicting workload received by individual reducers. However, because the input characteristics and user‐specified map function of a given job are unknown to the MapReduce framework before the job starts, accurately predicting workload of reducers can be a difficult challenge. To address this challenge, we present ROUTE, a run‐time robust reducer workload estimation technique for MapReduce. ROUTE progressively samples the partition size of the early completed mappers, allowing ROUTE to perform estimation at run time yet fulfilling the accuracy requirement specified by users. Moreover, by using robust estimation and bootstrapping resampling techniques, ROUTE can achieve high applicability to a wide variety of applications. Through experiments using both real and synthetic data on an 11‐node Hadoop cluster, we show ROUTE can achieve high accuracy with error rate no more than 10.92% and an improvement of 40.6% in terms of error rate while compared with the state‐of‐the‐art solution. Besides, through simulations using synthetic data, we show that ROUTE is robust to a variety of skewed distributions. Finally, we apply ROUTE to existing load balancing and deadline‐aware scheduling frameworks and show ROUTE significantly improves the performance of these frameworks. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献
8.
Intrusion detection systems (IDSs) are designed to monitor a networked environment and generate alerts whenever abnormal activities are detected. The number of these alerts can be very large, making their evaluation by security analysts a difficult task. Management is complicated by the need to configure the different components of alert evaluation systems. In addition, IDS alert management techniques, such as clustering and correlation, suffer from involving unrelated alerts in their processes and consequently provide results that are inaccurate and difficult to manage. Thus the tuning of an IDS alert management system in order to provide optimal results remains a major challenge, which is further complicated by the large spectrum of potential attacks the system can be subject to. This paper considers the specification and configuration issues of FuzMet, a novel IDS alert management system which employs several metrics and a fuzzy‐logic based approach for scoring and prioritizing alerts. In addition, it features an alert rescoring technique that leads to a further reduction in the number of alerts. Comparative results between SNORT scores and FuzMet alert prioritization onto a real attack dataset are presented, along with a simulation‐based investigation of the optimal configuration of FuzMet. The results prove the enhanced intrusion detection accuracy brought by our system. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献
9.
Flexibility and efficiency are the prime requirements for any P2P search mechanism. Existing P2P systems do not provide satisfactory solution for achieving these two conflicting goals. Unstructured search protocols (as adopted in Gnutella and FastTrack) provide search flexibility but exhibit poor performance characteristics. Structured search techniques (mostly Distributed Hash Table (DHT)-based), on the other hand, can efficiently route queries but support exact-match semantic only. In this paper we have defined Distributed Pattern Matching (DPM) problem and have presented a novel P2P architecture, named Distributed Pattern Matching System (DPMS), as a solution. Possible application areas of DPM include P2P search, service discovery and P2P databases. In DPMS, advertised patterns are replicated and aggregated by the peers, organized in a lattice-like hierarchy. Replication Improves availability and resilience to peer failure, and aggregation reduces storage overhead. An advertised pattern can be discovered using any subset of its 1-bits. Search complexity in DPMS is logarithmic to the total number of peers in the system. Advertisement overhead and guarantee on search completeness is comparable to that of DHT-based systems. We have presented mathematical analysis and simulation results to demonstrate the effectiveness of DPMS  相似文献
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