Bandwidth Metrics Research Articles

Automated Antenna Design via Domain Knowledge-Informed Reinforcement Learning and Imitation Learning

In this study, we propose a novel approach for automating antenna design through the utilization of domain knowledge-informed reinforcement learning (RL) and imitation learning (IL). The proposed method allows the RL agent to learn from its interactions with the environment and to take actions that maximize the reward signal, resulting in the optimal policy. Despite the attractive advantages, the learning process of RL can be challenging and time-consuming, as the agent must explore a vast range of states, actions, and policies. To enhance the efficiency of the design process, we incorporate two key components into the proposed method. Firstly, we utilize domain knowledge, such as the scaling property of antenna, to initialize the antenna parameters. This not only provides interpretability to the design process but also reduces the solution space. Additionally, we employ IL to pretrain the decision-making network within the RL algorithm, which significantly mitigates the data inefficiency issue for RL and reduces the time required to explore feasible solutions. The proposed method has been evaluated using the design of a slot filtering antenna as a case study. Simulation results indicate that the proposed method can achieve the antenna design for different frequencies and bandwidth metrics with at least 50% fewer adjusting steps than the traditional reinforcement learning method, such as deep deterministic policy gradient (DDPG). The combination of RL and IL also results in a considerable performance boost compared to both pure IL and pure RL for antenna designs.

Impact of Multiple Beams on Plan Quality, Linear Energy Transfer Distribution, and Plan Robustness of Intensity Modulated Proton Therapy for Lung Cancer.

The increase of proton beam number might provide higher degrees of freedom in the optimization of intensity-modulated proton therapy planning. In this study, we aimed to quantitatively explore the potential benefits of the increased beam number, including dose volume histogram (DVH), linear energy transfer volume histogram, and DVH bandwidth metrics. Twelve patients with lung cancer are retrospectively selected. Four plans were created based on internal target volume (ITV) robust optimization for each patient using the RayStation treatment planning system. Four plans were generated using different numbers (three, five, seven, and nine) of evenly separated coplanar beams. The three-beam plan was considered as the reference plan. Biologically equivalent doses were calculated using both constant relative biological effectiveness (RBE) and variable RBE models, respectively. To evaluate plan quality, DVH metrics in the target [ITV: D2%, CI, HI] and organs-at-risk [Lung: V5Gy[RBE], V20Gy[RBE], V30Gy[RBE]; Heart D2%; Spinal cord D2%] were calculated using both RBE models. To evaluate LET distributions, LET volume histogram metrics [ITV LETmean and LET2%; Lung LETmean and LET2%; Heart LET2%; Spinal cord LET2%] were quantified. To evaluate plan robustness, the metrics using DVH bandwidth [ITV: D2%, D99%; Lung: V5Gy[RBE], V20Gy[RBE], V30Gy[RBE]; Heart D2%; Spinal cord D2%] were also reported. For plan quality, the increase of proton beam number resulted in fewer target hot spots, improved target dose conformity, improved target dose homogeneity, lower median-dose lung volume, and fewer hot spots in spinal cord. As to LET distributions, target mean LET increased significantly as the beam number increased to seven or more. Lung LET hot spots were significantly reduced with the increase of proton beams. With respect to plan robustness, the robustness of target dose coverage, target hot spots, and low-dose lung volume were improved, while the robustness of heart hot spots became worse as the beam number increased to nine. The robustness of cord hot spots became worse using five and seven beams compared to that using three beams. As the proton beam number increased, plan quality and LET distributions were comparable or significantly improved. The robustness of target dose coverage, target dose hot spots, and low-dose lung volume were significantly improved.

An end-to-end measurement and monitoring technique for the bottleneck link capacity and its available bandwidth

An efficient and accurate measurement technique for the network bandwidths information can be utilized for various areas including the application layer services improvement, congestion control and for the network administration support. For these purposes, we propose an end-to-end measurement and monitoring technique for the bottleneck link capacity and its available bandwidth. This novel technique based on a new packet-pairs scheme figures out and utilizes the path signatures and sampling of the cross traffic density, through which both bandwidth metrics can be obtained from the same measurement data. This feature enables us to measure multi-metrics in a single measurement framework, reducing the probe overhead and the measurement time without causing congestions. We used ns-2 simulations and Internet measurements for the bottleneck link capacity and simulation comparisons for the available bandwidth to evaluate the performance of our proposed methodology. The results showed a high level of accuracy and a short probe time with very low intrusiveness, providing the capability of estimating the dual bandwidth metrics.

Load Balancing Metrics for the SOAJA Framework

The paper describes system and program metrics used for load balancing algorithms for Java program execution in the SOAJA (Service Oriented Adaptative Java Applications) executive environment. This environment aims in maintaining design and execution of large scale computing tasks in complex networked Grid environments. SOAJA services provide means for static and dynamic load balancing with the use of special metrics obtained by Java object observation. SOAJA comprises mechanisms and algorithms for automatic placement and adaptation of application objects, in response to evolution of resource availability. Under control of SOAJA, parallel Java objects can be optimally allocated to Grid nodes before execution and next migrated at runtime to less loaded nodes to maintain the balance of loads of constituent JVMs. SOAJA mechanisms employ computation power metrics based on measurements of the idle time of processor nodes and communication bandwidth metrics for network resources based on statistical assessment of the existing traffic. Due to these mechanisms the granularity of computing and distribution of the application elements on the Grid platform can be optimally controlled.

Networks of Networks: Changing Patterns in Country Bandwidth and Centrality in Global Information Infrastructure, 2002-2010

Linkages between countries have changed significantly as the global information infrastructure has evolved over the past decade. We argue that communication infrastructure and political processes evolve together, and in this study we attempt to measure key structural changes in bandwidth and the centrality of digital nodes in Middle East and North Africa. Using a combination of bandwidth metrics and centrality indicators, we demonstrate how global information infrastructure evolved between 2002 and 2010, and how several countries in the Middle East rose to prominence as good nodes mediating strong intraregional networks.

Fuzzy QoS Based OLSR Network

Quality-of-Service (QoS) routing protocol is developed for mobile Ad Hoc Networks. MANET is a self configuring network of mobile devices connected by wireless links. Each device in the MANET is free to move independently in any direction; therefore, it changes links to other devices frequently. The proposed QoS-based routing in the Optimized Link State Routing (OLSR) protocol relates bandwidth and delay using a fuzzy logic algorithm. The path computations are examined and the reason behind the selection of bandwidth and delay metrics is discussed. The performance of the protocol is investigated by simulation. The results in FQOLSR indicate an improvement in mobile wireless networks compared with the existing QOLSR system.

Characterization of Fixed and Reconfigurable Multi-Core Devices for Application Acceleration

As on-chip transistor counts increase, the computing landscape has shifted to multi- and many-core devices. Computational accelerators have adopted this trend by incorporating both fixed and reconfigurable many-core and multi-core devices. As more, disparate devices enter the market, there is an increasing need for concepts, terminology, and classification techniques to understand the device tradeoffs. Additionally, computational performance, memory performance, and power metrics are needed to objectively compare devices. These metrics will assist application scientists in selecting the appropriate device early in the development cycle. This article presents a hierarchical taxonomy of computing devices, concepts and terminology describing reconfigurability, and computational density and internal memory bandwidth metrics to compare devices.

FPGA-oriented HW/SW implementation of the MPEG-4 video decoder

This paper presents an FPGA-oriented implementation methodology for the MPEG-4 video decoder based on a hardware/software co-design approach. The MPEG-4 decoder is based on MoMuSys optimized reference software combined with new hardware VLSI architectures. New architectures for input demultiplexing, variable length decoding and inverse discrete cosine transform are developed. All software and hardware structures are evaluated in terms of visual quality, computational complexity and memory bandwidth metrics. The presented implementation is compared with an optimized reference software-based solution. Simulation results demonstrate a reduction of decoder complexity, especially speed and memory bandwidth, while maintaining an acceptable quality of decoded sequences. The proposed hardware additions provide 30% speed improvement over software solution, thereby reducing the clock rate required to process full-rate video from 300 MHz down to 213 MHz. The MPEG-4 decoder was functionally tested on a Flextronics FPGA prototyping board.

QOLSR, QoS routing for ad hoc wireless networks using OLSR

AbstractThis paper describes a novel quality‐of‐service (QoS) routing protocol for ad hoc networks based on the OLSR protocol. Our protocol, QOLSR, is designed for wireless networks with stationary or moving nodes, where each node is equipped with 802.11 wireless card. The goal of our protocol is not only to find a route from a source to a destination, but an optimal route that satisfies the end‐to‐end QoS requirement, often given in terms of bandwidth or delay. We present an analytical model to compute the average delay and permissible throughput on links using the IEEE 802.11 medium access protocol and considering correlations and interferences between nodes. This model takes into account packet's collision probability, node's MAC queuing and service times based on the IEEE 802.11 binary exponential backoff algorithm and the events underneath its operation. Afterwards, our protocol assigns weights to individual links based on the average delay and bandwidth metrics of packets over the link. We present a distributed algorithm for multiple QoS requirements to find the source destination optimal paths in terms of bandwidth and delay using the known partial network topology available on each node. However, these optimal paths in partial network topology are not optimal paths in the whole ad hoc network. We show that this problem is due to the heuristic for the selection of MPRs used in OLSR. We propose innovative heuristics for the selection of MPRs based on QoS measurements that allow QOLSR to find optimal paths on the known partial topology having the same bandwidth performances that those on the whole network. The performance evaluation of our protocol in both static and dynamic ad hoc networks is extensively investigated. Mathematical analysis and simulation results show that the QOLSR protocol yields better performance compared to the best‐effort OLSR protocol and significantly improves throughput by using our proposed heuristic. Copyright © 2005 AEIT.

Traffic shaping, bandwidth allocation, and quality assessment for MPEG video distribution over broadband networks

This article provides an overview of residential video delivery systems and presents the applications, benefits, and challenges of using VBR MPEG video encoding in broadband video distribution networks. The network resources required to transmit stored variable-rate MPEG can be reduced by properly analyzing and smoothing the video stream before transmission. A scheduling technique is presented which selects a traffic contract for a pre-encoded MPEG video stream with the criteria of minimizing network resources and maintaining video quality. Several effective bandwidth metrics are discussed and used to model the potential savings in network resources for the shaped streams.