This paper presents the results of experiments to study throughput behavior and determine the maximum attainable throughput in an 802.11g wireless LAN under UDP traffic. The focus is on observing the measured throughp...
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ISBN:
(纸本)0769522947
This paper presents the results of experiments to study throughput behavior and determine the maximum attainable throughput in an 802.11g wireless LAN under UDP traffic. The focus is on observing the measured throughput over time when the network is flooded with a continuous stream of UDP data. Whereas previous studies investigate 802.11b/a performance, or use analytical or simulation methods to study 802.11g performance, this study measures the throughput by generating actual 802.11g traffic. In order to study 802.11g behavior exclusively, minimize environmental effects, and keep the network as simple as possible, the experimental setup is restricted to an isolated wireless LAN with a single access point configured for 802.11g operation. The studies show that in almost all cases the observed throughput is well below 50% of the 802.11g maximum data rate of 54 Mbps even under ideal and controlled conditions. Although network card implementation and use of RTS/CTS have a significant impact on throughput, access point distance has little effect. We also give a formula for computing the expected throughput and compare the values it gives with the measured values.
This paper presents a proposed ExRTI architecture which is much more flexible, dynamic, and able to handle mobile devices and also based on authentication mode to provide security. In this new architecture GAIA layer ...
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Wireless sensor networks have emerged recently as an effective way of monitoring remote or inhospitable physical environments. One of the major challenges in devising such networks is how to organize a large amount of...
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ISBN:
(纸本)3540308563
Wireless sensor networks have emerged recently as an effective way of monitoring remote or inhospitable physical environments. One of the major challenges in devising such networks is how to organize a large amount of sensor nodes without the coordination of any centralized access point. Clustering can not only conserve limited system resource, but also serve as an effective self-organization tool. In this paper, we present a distributed clustering algorithm based on adaptive backoff strategy. By adaptively adjusting the wakeup rate of the exponential distribution, a node with higher residual energy is more likely to be elected clusterhead. We also take advantage of the content ion- based channel access method to ensure that clusterheads are well scattered. Simulation experiments illustrate that our algorithm is able to significantly prolong network life compared with the conventional approach.
This paper proposes a novel algorithm combining Fuzzy logic (FL) and Genetic algorithm (GA) for Concurrent Mapping and Localization (CML) of mobile robot. First, CML is formulated as a multidimensional informed search...
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ISBN:
(纸本)0780389123
This paper proposes a novel algorithm combining Fuzzy logic (FL) and Genetic algorithm (GA) for Concurrent Mapping and Localization (CML) of mobile robot. First, CML is formulated as a multidimensional informed search problem. The search is performed to detect a robot pose which can best accommodate the recent sensor scan in the currently available map. A fuzzy set theoretic approach is used to predict a sample based representation of the state space of possible robot poses and a GA is designed to find out the globally optimal solution from the predicted pose space. The GA evaluates the fitness of poses based on the sensory information and drives the generation gradually towards the globally optimal solution even when the fuzzy prediction is inaccurate. The best fit solution as decided by GA offers the most likely continuation of the currently available map. Experiment on synthetic and real data illustrates the robustness of the algorithm.
Here a scheme is presented for key pre-distribution in wireless sensor networks. A transversal design is considered to construct a (v, b, r, k) configuration. Then properly chosen blocks are merged to form sensor node...
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ISBN:
(纸本)3540307060
Here a scheme is presented for key pre-distribution in wireless sensor networks. A transversal design is considered to construct a (v, b, r, k) configuration. Then properly chosen blocks are merged to form sensor nodes such that there is no intra-node common key. The choice of blocks in merging is currently made heuristically in a randomized manner. The scheme is called hybrid as a combinatorial design followed by a heuristic is applied. Detailed analysis is presented regarding the number of nodes, number of keys per nodes and the probability that a link gets affected if certain number of nodes are compromised. It is also argued how the scheme compares favourably with the state of the art proposals. Towards the end we also present a result to find out the lower bound on the number of nodes given a certain combinatorial design.
Mostsensor network research to date has targeted ad hoc wireless networks of closely co-located, resource-constrained, scalar sensor motes. Such work has tended to overlook the potential importance of wide-area senso...
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sensor networks consisting of nodes with limited battery power and wireless communications is among the fastest growing technologies. There are many challenges in implementation of such systems: energy dissipation and...
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ISBN:
(纸本)3540308563
sensor networks consisting of nodes with limited battery power and wireless communications is among the fastest growing technologies. There are many challenges in implementation of such systems: energy dissipation and data gathering being one of them. Gathering sensed information in an energy efficient manner is critical to operate the sensor network for a long period of time. While cluster-based data collection is efficient at energy and bandwidth, it's difficult to ensure balanced energy depletion on all cluster-members after a longtime run. In this paper we propose a new distributed cluster-based data gathering algorithm using PSO to optimize clustering process. The election of cluster-heads need synthetically consider the state information including location and energy reserved about candidates and their neighbors. Our preliminary simulation results show that the proposed algorithm balances the energy dissipation over the whole network thus prolongs the network lifetime.
Amorphous computing promises a novel approach with massively distributedsystems. Research in the field hasn't yet produced any formal methodology for design of such system. Paintable computing architecture provid...
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ISBN:
(纸本)953713802X
Amorphous computing promises a novel approach with massively distributedsystems. Research in the field hasn't yet produced any formal methodology for design of such system. Paintable computing architecture provides an interesting testbed for process self-assembly and together with wireless sensor networks, presents a platform whose goal is to tightly integrate with its environment. Such a platform could combine the best of both technologies while running applications composed of fragments resembling classical software agents capable of mobility. This article presents an introduction to changes that are necessary to have all these similar computing approaches unite.
This paper1 proposes a workflow intelligence and quality improvement framework maximizing the workflow traceability and rediscoverability by analyzing the total sequences of the control-path perspective of a workflow ...
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