Existing routing protocols for Wireless Mesh Networks (WMNs) are generally optimized with statistical link measures, while not addressing on the intrinsic uncertainty of wireless links. We show evidence that, with the...
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ISBN:
(纸本)9781424459889
Existing routing protocols for Wireless Mesh Networks (WMNs) are generally optimized with statistical link measures, while not addressing on the intrinsic uncertainty of wireless links. We show evidence that, with the transient link uncertainties at PHY and MAC layers, a pseudo-deterministic routing protocol that relies on average or historic statistics can hardly explore the full potentials of a multi-hop wireless mesh. We study optimal WMN routing using probing-based online anypath forwarding, with explicit consideration of transient link uncertainties. We show the underlying connection between WMN routing and the classic Canadian Traveller Problem (CTP) [1]. Inspired by a stochastic recoverable version of CTP (SRCTP), we develop a practical SRCTP-based online routing algorithm under link uncertainties. We study how dynamic next hop selection can be done with low cost, and derive a systematic selection order for minimizing transmission delay. We conduct simulation studies to verify the effectiveness of the SRCTP algorithms under diverse network configurations. In particular, compared to deterministic routing, reduction of end-to-end delay (51:15∼73:02%) and improvement on packet delivery ratio (99:76%) are observed.
We present a modular evolutionary framework, coined CASE for "complex adaptive system evolver", to automate the modeling and analysis of agent-based simulations (ABSs). The field of agent-based modeling is r...
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We present a modular evolutionary framework, coined CASE for "complex adaptive system evolver", to automate the modeling and analysis of agent-based simulations (ABSs). The field of agent-based modeling is rapidly growing due to its capabilities to expose the emerging complex phenomena occurring in a wide range of natural and artificial systems such as biological cells, societies, battlefields, stock markets, etc. Nevertheless, studying agent-based simulations is a complicated, interdisciplinary and time-consuming process. Indeed, a large number of simulation parameters has to be considered to identify and fully understand the conditions leading to the emerging phenomena of interest. To tackle this difficulty, the study of ABSs is thus typically conducted in an iterative manner, where each iteration includes the successive and manual modeling of ABSs and analysis of simulation outcomes. To automate this iterative and time-consuming process, we propose CASE, a platform-independent framework capable of evolving ABSs to exhibit the desired emerging behaviors. Through this evolutionary approach, the examination, i.e., the modeling, execution and analysis, of ABSs is automated. This process automation significantly facilitates the examination of complex systems using ABSs. In this paper, we present in detail this modular evolutionary framework which is illustrated with an example experiment. In this experiment, CASE is utilized for Automated Red Teaming, a simulation-based vulnerability assessment technique commonly employed by defense analysts. The aim of this paper is to introduce this flexible computational framework which may potentially benefit related fields involving agent-based simulations such as the gaming or financial industries.
In distributed virtual environments (DVEs), maintaining a consistent view of the virtual world among all users is a primary task. Due to the resource limitations such as network capacity and computational power, the c...
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In distributed virtual environments (DVEs), maintaining a consistent view of the virtual world among all users is a primary task. Due to the resource limitations such as network capacity and computational power, the consistency of the virtual world cannot be guaranteed sometimes. In this paper, we try to address this problem in client-server-based DVEs by considering server side network capacity limitation. We look at the position update packets from client to server and show the impact of packet loss due to server side network capacity limitation on the consistency of the virtual world. We assume clients use Dead Reckoning (DR) models to control position updates. In order to adapt client updates with the server side network capacity to avoid update packet loss, two server assistant DR threshold tuning policies for different updating schemas are proposed in this paper. The proposed tuning polices are validated to have good performance by simulation results.
An Interest Management (IM) mechanism eliminates irrelevant status updates transmitted in Networked Virtual Environments (NVE). However, IM itself involves both computation and communication overhead, of which the lat...
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An Interest Management (IM) mechanism eliminates irrelevant status updates transmitted in Networked Virtual Environments (NVE). However, IM itself involves both computation and communication overhead, of which the latter is the focus of this paper. Traditionally, there are area-based and cell-based IM mechanisms. This paper proposes a hybrid IM mechanism for peer-to-peer NVEs, that utilizes the cell-based mechanism to reduce Area-Of-Interest (AOI) updates in the area-based mechanism so as to reduce its communication overhead. To compare the new mechanism with the two traditional approaches, a multiplayer game scenario is simulated. The performance results show that, compared to the traditional mechanisms, the hybrid mechanism reduces the upload bandwidth consumption by more than 25.28 percent, reduces the overhead ratio from more than 67.54 percent to only 25.17 percent, and allows more than 5000 players in the Internet to join the same game with today's network upload bandwidth.
The news filtering and summarization (NFAS) system can automatically recognize Web news pages, retrieve each news page's title and news content, and extract key phrases. This extraction method substantially outper...
Existing routing protocols for Wireless Mesh Networks (WMNs) are generally optimized with statistical link measures, while not addressing on the intrinsic uncertainty of wireless links. We show evidence that, with the...
详细信息
Existing routing protocols for Wireless Mesh Networks (WMNs) are generally optimized with statistical link measures, while not addressing on the intrinsic uncertainty of wireless links. We show evidence that, with the transient link uncertainties at PHY and MAC layers, a pseudo-deterministic routing protocol that relies on average or historic statistics can hardly explore the full potentials of a multi-hop wireless mesh. We study optimal WMN routing using probing-based online anypath forwarding, with explicit consideration of transient link uncertainties. We show the underlying connection between WMN routing and the classic Canadian Traveller Problem (CTP). Inspired by a stochastic recoverable version of CTP (SRCTP), we develop a practical SRCTP-based online routing algorithm under link uncertainties. We study how dynamic next hop selection can be done with low cost, and derive a systematic selection order for minimizing transmission delay. We conduct simulation studies to verify the effectiveness of the SRCTP algorithms under diverse network configurations. In particular, compared to deterministic routing, reduction of end-to-end delay (51.15~73.02%) and improvement on packet delivery ratio (99.76%) are observed.
Event traces are helpful in understanding the performance behavior of parallel applications since they allow the indepth analysis of communication and synchronization patterns. However, the absence of synchronized clo...
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Event traces are helpful in understanding the performance behavior of parallel applications since they allow the in-depth analysis of communication and synchronization patterns. However, the absence of synchronized cl...
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Event traces are helpful in understanding the performance behavior of parallel applications since they allow the in-depth analysis of communication and synchronization patterns. However, the absence of synchronized clocks on most cluster systems may render the analysis ineffective because inaccurate relative event timings may misrepresent the logical event order and lead to errors when quantifying the impact of certain behaviors or confuse the users of time-line visualization tools by showing messages flowing backward in time. In our earlier work, we have developed a scalable algorithm that eliminates inconsistent inter-process timings postmortem in traces of pure MPI applications. Since hybrid programming, the combination of MPI and OpenMP in a single application, is becoming more popular on clusters in response to rising numbers of cores per chip and widening shared-memory nodes, we present an extended version of the algorithm that in addition to message-passing event semantics also preserves and restores shared-memory event semantics.
Massively Multiplayer Online Games (MMOGs) gradually become one of the most popular internet applications. Traditional client-server architecture is widely used in MMOGs’ deployment, but its scalability and maintenan...
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