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Residential gateways play a key role in providing internet access to home consumers. Nowadays, users in the same home with heterogeneous applications share a common gateway. As such, the gateway becomes the bandwidth bottleneck, leading to impairments and negatively affecting users' Quality of Experience (QoE). In the case of delay sensitive applications like video streaming and online gaming, this...
In this paper we propose an SDN-based control plane for the University of Costa Rica. Our campus network faces heavy congestion problems and fails at providing adequate quality of service (QoS). Therefore, we describe a solution that leverages priority-traffic routing to ensure that important services (such as live video streaming) are not as heavily affected by congestion. To this end, we first survey...
With the recent proliferation of the Internet-of-Things (IoT) devices, coupled with the expected massive growth in the deployment of such devices, the 3GPP Specifications continued to evolve to address the performance needs and the cost/complexity reduction requirements of these IoT devices, achieved through the introduction of new features and new User Equipment (UE) categories. These features will...
Security threats in the Internet have been ever increasing, in number, type and means used for attacks. In the face of large-scale attacks, such as DDoS attacks, networks take unacceptable time to respond and mitigate the attacks, resulting in disruption to connections and the losses due to it. In this work, we look into the problem of dynamically mitigating attacks from the perspective of an ISP...
Multipath TCP (MPTCP) has gained great attention by the researchers and network application developers due to its features providing better bandwidth utilization and higher reliability recently. Utilizing MPTCP in the datacenters provides performance gain to the applications. If the underlying network has Software Defined Networking (SDN) architecture, the routing of the MPTCP subflows can be specialized...
Meeting the ever-growing information rate demands has become of utmost importance for optical communication systems. However, it has proven to be a challenging task due to the presence of Kerr effects, which have largely been regarded as a major bottleneck for enhancing the achievable information rates in modern optical communications. In this work, the optimisation and performance of digital nonlinearity...
A lot of research has been proposed to improve network performance in the data center. However, with the development of distributed applications, these applications face a new performance bottleneck since existing solutions almost ignore the application level optimization. The concept of coflow has been proposed which provides a chance for us to optimize network in application level rather than individual...
This paper investigates the resource allocation problem in heterogeneous cognitive radio networks (HCRNs). In this paper, two types of users, i.e., multi-homing and single-network cognitive radio users (CRUs), are considered to coexist in HCRNs. Multi-homing CRUs can access multiple networks simultaneously, while single-network CRUs can be served by only one network at a time. With the aim of maximizing...
In ultra-dense cellular networks, research works on enhancing cell edge performance receive considerable attention. Based on interlaced clustering, we propose a heuristic sparse beamforming strategy to improve the cell edge throughput effectively in distributed antenna systems (DASs). In our scheme, each cluster pattern (CP) is divided into several adaptive cells, where all the remote antenna units...
Virtual reality (VR) applications target high-quality and zero-latency scene navigation to provide users with a full-immersion sensation within a scene. From a network perspective, this requires transmission of the omnidirectional content in its entirety, at a high resolution, which is not always feasible in bandwidth-limited networks. In this work, we propose an optimal transmission strategy for...
Naval surface fleets of the United States and its allies rely on multiple satellite communication systems (SATCOM) for onboard communication with other entities such as ships, shore nodes and hosts from external networks. Current practice is for an onboard ship router to select a particular SATCOM link for each outgoing traffic flow based on a mission-specific routing policy. In this paper we propose...
We designed and optimized a high-speed, low-loss electrodes applied to photodetector array (PDA) using simulating software HFSS. The designed electrodes structure was fabricated and tested. Compared with the electrodes before optimization, the insert loss decreased by 1.1dB at 40GHz and the bandwidth increased by 8GHz.
In this paper a Markov decision process (MDP) model for virtualized content delivery networks is proposed. We use stochastic optimization to assign cloud site resources to each user group. We propose how quality of experience (QoE) can be included in the modeling and optimization. We then present an optimal solution for a constraint-free version of the problem, and show the improvement in accumulated...
The rapid growth of traffic demands has posed challenges and difficulties on both the radio access networks (RANs) and the backhaul links. To stress these problems, caching technology, more specifically, caching user contents at the infrastructures of different RANs is proposed as an effective approach. In this paper, we consider the joint user association and cache content placement problem in cache-enabled...
An ultra-wideband metasurface is designed for suppressing the specular electromagnetic wave reflection or backward radar cross section (RCS). Square ring structure is chosen as the basic meta-atoms. A new physical mechanism based on size adjustment of the basic meta-atoms is proposed for ultrawideband manipulation of electromagnetic (EM) waves. Based on hybrid array pattern synthesis (APS) and particle...
This work presents a new parallel non-speculative implementation of the Unordered Reverse Cuthill-McKee algorithm. Reordering quality (bandwidth reduction) and reordering performance (CPU time) are evaluated in comparison with a serial implementation of the algorithm made available by the state-of-the-art mathematical software library HSL. The bandwidth reductions reached by our parallel RCM were...
The presented study analyses 563 representative benchmark sparse matrices with respect to their partitioning into uniformly-sized blocks. The aim is to minimize memory footprints of matrices. Different block sizes and different ways of storing blocks in memory are considered and statistically evaluated. Memory footprints of partitioned matrices are additionally compared with lower bounds and the CSR...
The Network Functions Virtualization (NFV) paradigm offers network operators benefits in terms of cost efficiency, vendor independence, as well as flexibility and scalability. However, in order to profit most from these features, new challenges in the area of management and orchestration of the virtual network functions (VNFs) need to be addressed.,,In particular, this work deals with the VNF chain...
Scale-out distributed storage systems have recently gained high attentions with the emergence of big data and cloud computing technologies. However, these storage systems sometimes suffer from performance degradation, especially when the communication subsystem is not fully optimized. The problem becomes worse as the network bandwidth and its corresponding traffic increase. In this paper, we first...
Due to energy efficiency, heterogeneous computing is gaining more and more attention. Since FPGA implementations are time consuming, high-level synthesis (HLS) is used to close the productivity gap. OpenCL has become accepted as a good programming model for HLS, due to its portability, good capability of design verification and rich instruction set. This work implements different optimization strategies...
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