16131402
A mobile agent-based active network architecture
Active networks enable the customization of network functionality without the lengthy standard-mediated committee processes. Most of the works in the literature utilize capsules or active packets as the means to transfer code information across active networks. In this paper, we propose an active network infrastructure based on mobile agent technologies. In our prototype implementation, mobile agents are the building blocks carrying functional customizations, and the active nodes offer software application layers, caled agent servers, to process mobile agent-specific customizations to facilitate network functionality. Both integrated and discrete operational models of network customizations are supported. In addition, for the application-specific protocol development and deployment, an abstract protocol structure and a protocol loading mechanism are presented. Furthermore, we provide an agent management/control mechanism and devise a protocol management/control mechanism. As a result, improved network functionality can be achieved.
20310851
A mobile agent-based active network architecture for intelligent network control
The innovation and evolution of network technologies and services to enhance network functionality have traditionally encountered the problems of backward-compatibility and standardization. To resolve the related issues, active networks have been introduced to enable specific customization of network functionality without the lengthy standard-mediated committee processes. In this paper, we exploit the capability of mobile agent technology to construct an active network architecture. We argue that the mobile agent can be a building block for specific network customizations, and introduction of new network functionality. Both integrated and discrete operational models of network customizations can be supported in our prototype implementation. For the service development and deployment, an abstract service structure and a service loading mechanism are presented. Furthermore, we provide an agent management/control mechanism and devise a service management/control mechanism, which is either not available or incomplete in the other related work. The proposed architecture allows new service introduction, and as a result, achieves improved network functionality.
14906808
Dynamic data broadcasting with traffic awareness
Data dissemination has significantly served as a scalable data delivery mechanism in wireless networks. However, even though the broadcast traffic has the nature of dynamic changes, most previous research efforts were elaborated upon the premise of static workloads and access patterns without having proper traffic awareness. In this paper, we address the existence of client impatience and accordingly devise an online traffic awareness mechanism based on a novel selective deferment and reflection (SDR) technique to estimate the dynamic workloads and access patterns in a granularity of a broadcast cycle. In comparison with prior probing and feedback approaches, our design is of practical usefulness in that it has low complexity and is light-weight without performance degradation. With various dynamic traffic scenarios, the experimental results show that with an increasing/decreasing workload, the real access frequency distribution is bounded by two specific estimated distributions. This fact in turn suggests us to employ a trigonometric tuning method to further enhance the estimation. In addition, we examine that the mean difference between the estimated access frequency distribution and the real one is very small, consequently indicating the feasibility and reliability of our proposed data broadcast mechanism with traffic awareness.
146722
Adaptive dissemination of dynamic information services in an extended data broadcast environment
Considering that most information broadcast services generate data dynamically in practice, we devise in this paper an extended data broadcast mechanism which supports not only the original data broadcast scenario but also the dissemination of dynamic inforamtion services. Furthermore, we design an on-line loan-based slot allocation and feedback technique to tolerate the dynamic changes of broadcast traffic and accordingly perform the adaptation of service classification, bandwidth allocation and broadcast schedule so as to enhance the performance. Our experimental studies show that the extended data broadcast mechanism associated with the loan-based feedback technique is able to achieve a substantial saving in message traffic for dynamic information dissemination in wireless networks.
5668129
A reactive channel model for expediting wireless network simulation
A major problem with leveraging event-driven, packet-level simulation environments, such as ns2[6], J-Sim[1], OpNet[2]), and QualNet[3]), in conducting wireless network simulation is the vast number of events generated, a majority of which are related to signal transmission in the PHY/MAC layers.In this extended abstract, we investigate the operations of signal transmission in the various stages: signal propagation, signal interference, and interaction with the PHY/MAC layers, and identify where events can be reduced without impairing the accuracy. We propose to leverage the MAC/PHY state information, and devise (from the perspective of network simulation) a reactive channel model (RCM) in which nodes explicitly register their interests in receiving certain events according to the MAC/PHY states they are in and the corresponding operations that should be performed. The simulation study indicates that RCM renders an order of magnitude of speed-up without compromising the accuracy of simulation results. An advantage of RCM with respect to the implementation is that there is no need to re-design the channel model for each specific MAC layer, and the modification made in the MAC/PHY layers is quite modest (e.g., a few API changes). This, coupled with the performance gain, suggests that RCM is an attractive, light-weight mechanism for expediting wireless network simulation.
14717474
A Novel Approach to Contention Control in IEEE 802.11e-Operated WLANs
In this paper, we devise, in compliance with the IEEE 802.11e protocol, a novel MAC-centric approach, called MAC contention control (MCC), to maximizing the bandwidth utilization and achieving proportional bandwidth allocation. We first show that approaches based on estimating the number of competing nodes and then setting the contention window size may not converge (and in some cases diverge) because of network dynamics. Then, by studying the optimality condition derived in our prior work, we identify two parameters (referred to as control references) that remain approximately constant when the network operates at the optimal operational point, regardless of the number of competing nodes in each AC. We instrument MCC to measure these control references, compare measurement results to their optimal control reference levels, and adjust the packet dequeuing rate from the interface queues in an additive-increase-multiplicative-decrease (AIMD) fashion and with respect to prespecified bandwidth allocation ratio associated with its AC. In some sense, MCC controls the rate of passing packets from the interface queues to to the MAC access function, and thus practically controls the effective number of competing nodes. We have conducted an extensive simulation study, and demonstrated the superiority of MCC to 802.11e in terms of both the achievable network throughput and the capability of achieving proportional bandwidth allocation. This, coupled with the fact that MCC does not require change in firmware and can be practically deployed, makes MCC a viable approach to contention control in IEEE 802.11e-operated WLANs.
8404805
Fractal Dimensions for Percolation and Phase Transition Models: Theory and New Monte Carlo Calculation Method
8145594
Effects of global interconnect optimizations on performance estimation of deep submicron design
In this paper, we quantify the impact of global interconnect optimization techniques that address such design objectives as delay, peak noise, delay uncertainty due to noise, power, and cost. In doing so, we develop a new system-performance simulation model as a set of studies within the MARCO GSRC Technology Extrapolation (GTX) system. We model a typical point-to-point global interconnect and focus on accurate assessment of both circuit and design technology with respect to such issues as inductance, signal line shielding, dynamic delay, buffer placement uncertainty and repeater staggering. We demonstrate, for example, that optimal wire sizing models need to consider inductive effects-and that use of more accurate (-1,3) worst-case capacitive coupling noise switch factors substantially increases peak noise estimates compared to traditional (0,2) bounds. We also find that optimal repeater sizes are significantly smaller than conventional models would suggest, especially when considering energy-delay issues.
14957395
A statistical performance simulation methodology for VLSI circuits
A statistical performance simulation (SPS) methodology for VLSI circuits is presented. Traditional methods of worst-case corner analysis lack accuracy and Monte-Carlo simulations cannot be applied to VLSI circuits because of their complexity. SPS methodology is accurate because no statistical information about the device parameter variation is lost. It achieves efficiency by analyzing the smaller circuit blocks and generating the performance distribution for the entire circuit. Circuit evaluation at any specified performance level is possible.