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Now showing 1 - 10 of 11

Design of Downlink Synchronization for Millimeter Wave Cellular System Based on Multipath Division Multiple Access
(2020-09-01)
Chiu, Kang-Lun
;
Shen, Pai-Hsiang
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Lin, Bing-Ru
;
Hsiao, Wei-Han
;
Jou, Shyh-Jye Jerry
This work focuses on the design of downlink receiver for future generation cellular systems. In the multipath division multiple access (MDMA) system, the initial synchronization process includes timing and carrier frequency synchronization as well as home cell search. For the proposed system, the user data is transmitted in time domain and the cell search is based on control signals transmitted in frequency domain simultaneously. Firstly, this paper presents a novel architecture for the joint detection and estimation of both the coarse symbol boundary and the fractional carrier frequency offset based on cyclic prefix in time domain. Secondly, a robust integer carrier frequency offset detection is performed with the primary control tone in frequency domain. Moreover, the position of the secondary control tones is used to obtain the cell ID. Finally, the preamble sequence carried by the secondary control tones is used to detect frame header through differential detection. The simulation results show the proposed synchronization algorithms can achieve detection failure rate less than 1% and the normalized residual carrier frequency offset is less than 5% under the interference of user data. Furthermore, a hardware design targeted at 200 Mbps per-user data rate is realized with memory arbiter to share memory.
Enabling Mobile Service Continuity Across Orchestrated Edge Networks
(2020-07-01)
Abdullaziz, Osamah Ibrahiem
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Wang, Li-Chun
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Chundrigar, Shahzoob Bilal
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Huang, Kuei-Li
;
電機工程學系
Edge networking has become an important technology for providing low-latency services to end users. However, deploying an edge network does not guarantee continuous service for mobile users. Mobility can cause frequent interruptions and network delays as users leave the initial serving edge. In this paper, we propose a solution to provide transparent service continuity for mobile users in large-scale WiFi networks. The contribution of this work has three parts. First, we propose ARNAB architecture to achieve mobile service continuity. The term ARNAB means rabbit in Arabic, which represents an Architecture for Transparent Service Continuity via Double-tier Migration. The first tier migrates user connectivity, while the second tier migrates user containerized applications. ARNAB provides mobile services just like rabbits hop through the WiFi infrastructure. Second, we identify the root-causes for prolonged container migration downtime. Finally, we enhance the container migration scheme by improving system response time. Our experimental results show that the downtime of ARNAB container migration solution is 50% shorter than that of the state-of-the-art migration.
Communication and Computing Cost Optimization of Meshed Hierarchical NFV Datacenters
(2020-01-01)
Kar, Binayak
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Wu, Eric Hsiao-Kuang
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Lin, Ying-Dar
;
資訊工程學系
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Department of Computer Science
Telecommunication carriers of 5G-MEC are re-architecting their central offices and mobile base stations as datacenters with network function virtualization (NFV) technology. These datacenters (DCs) are known as edge datacenters that help network operators speed deployment and reduce costs. Previously, the use of NFV was limited to within a datacenter (DC) known as intra-DC. Recently, many studies have been conducted into the use of NFV across DCs, i.e., inter-DC. However, these NFV inter-DC architectures have limited communication between DCs with either horizontal or vertical connectivity. In this paper, we propose a generic architecture of such edge NFV datacenters with both horizontal and vertical connectivity, and demonstrate the consequences of both vertical and horizontal connectivity between DCs in terms of communication and computing costs. We formulate a cost optimization problem with latency and capacity as constraints by estimating the traffic dispatch rate between DCs. We propose a vertical-horizontal communication (VHC) heuristic solution to the NP-hard problem. Compared to horizontal connectivity, our results show that vertical connectivity helps to reduce computing costs by 10-30 & x0025;. However, both vertical and horizontal communications together can help to reduce such costs by 20-30 & x0025; compared to only vertical communication.
A Two-Directional BigData Sorting Architecture on FPGAs
(2020-01-01)
Lai, Bo-Cheng
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Chen, Chun-Yen
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Hsin, Yi-Da
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Lin, Bo-Yen
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電子工程學系及電子研究所
Sorting is pivotal data analytics and becomes challenging with intensive computation on drastically growing data volume. Sorting on FPGA has shown superior throughput, but the limited in-system memory causes vast data transferring to/from external storage when handling a large dataset. We propose a two-directional sorting (2DSort) architecture which sorts data sequences on both horizontal and vertical directions. 2DSort significantly reduces the costly data transmission by tracking the data on FPGA and writes back the data to external storage when the final sorting position is determined. 2DSort shows average 38.5 percent runtime enhancement in comparison to state-of-the-art bigdata sorting engine on FPGA.
Smoothed Graphic User Interaction on Smartphones With Motion Prediction
(2020-04-01)
Lin, Ying-Dar
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Chu, Edward T-H
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Chang, Evan
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Lai, Yuan-Cheng
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資訊工程學系
The smoothness of human-smartphone interaction directly influences users experience and affects their purchase decisions. A commonly used method to improve user interaction of smartphones is to optimize the CPU scheduler. However, optimizing the CPU scheduler requires a modification of operating system. In addition, the improvement of the smoothness of human-smartphone interaction may be limited because the display subsystem is not optimized. Therefore, in this paper, we design a motion prediction queuing system, named MPQS, to improve the smoothness of human-smartphone interaction. For this, we use the information of vector, speed, movement, provided by the queuing mechanism of Android, to predict the movement of user-smartphone interaction. Based on the prediction, we then utilize available execution time between frames to perform image processing. We conducted a set of experiments on beagleboard-xM to evaluate the performance of MPQS. Our experiment results show that the proposed method can reduce the number of jank by up to 21.75%.
Storage-Aware Algorithms for Dilution and Mixture Preparation With Flow-Based Lab-on-Chip
(2020-04-01)
Bhattacharjee, Sukanta
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Wille, Robert
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Huang, Juinn-Dar
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Bhattacharya, Bhargab B.
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電子工程學系及電子研究所
Lab-on-chip (LoC) technology has emerged as one of the major driving forces behind the recent surge in biochemical protocol automation. Dilution and mixture preparation with fluids in a desired ratio, constitute basic steps in sample preparation for which several LoC-based architectures and algorithms are known. The optimization of cost and time for such protocols requires proper sequencing of fluidic mix-and-split steps, and storage-units for holding intermediate-fluids to be reused in the later steps. However, practical design constraints often limit the amount of on-chip storage in microfluidic LoC architectures and thus can badly affect the performance of the algorithms. Consequently, results generated by previous work may not be useful (in the case they require more storage-units than available) or more expensive than necessary (in the case when storage-units are available but not used, e.g., to further reduce the number of mix/split operations or reactant-cost). In this paper, we propose new algorithms for dilution and mixing with continuous-flow-based LoCs that explicitly take care of storage constraints while optimizing reactant-cost and time of sample preparation. We present a symbolic formulation of the problem that captures the degree of freedom in algorithmic steps satisfying the specified storage constraints. Solvers based on Boolean satisfiability are used to achieve the optimization goals. The experimental results show the efficiency and effectiveness of the solution as well as a variety of applications where the proposed methods would prove beneficial.
Workload and Capacity Optimization for Cloud-Edge Computing Systems with Vertical and Horizontal Offloading
(2020-03-01)
Thai, Minh-Tuan
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Lin, Ying-Dar
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Lai, Yuan-Cheng
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Chien, Hsu-Tung
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交大名義發表
A collaborative integration between cloud and edge computing is proposed to be able to exploit the advantages of both technologies. However, most of the existing studies have only considered two-tier cloud-edge computing systems which merely support vertical offloading between local edge nodes and remote cloud servers. This paper thus proposes a generic architecture of cloud-edge computing with the aim of providing both vertical and horizontal offloading between service nodes. To investigate the effectiveness of the design for different operational scenarios, we formulate it as a workload and capacity optimization problem with the objective of minimizing the system computation and communication costs. Because such a mixed-integer nonlinear programming (MINLP) problem is NP-hard, we further develop an approximation algorithm which applies a branch-and-bound method to obtain optimal solutions iteratively. Experimental results show that such a cloud-edge computing architecture can significantly reduce total system costs by about 34%, compared to traditional designs which only support vertical offloading. Our results also indicate that, to accommodate the same number of input workloads, a heterogeneous service allocation scenario requires about a 23% higher system costs than a homogeneous scenario.
Three-Stage DRX Scheduling for Joint Downlink Transmission in C-RAN
(2020-02-01)
Liang, Jia-Ming
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Hsu, Ching-Kuo
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Chen, Jen-Jee
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Wu, Kun-Ru
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Tseng, Yu-Chee
Cloud-RAN (C-RAN) is a promising network architecture to provide 5G broadband services. In C-RAN, the base stations (BSs) are separated as the computation entities (i.e., Baseband Units (BBUs)) and the radio entities (i.e., Remote Radio Heads (RRHs)), where the BBUs are put in a centralized cloud to realize centrally control and the RRH are left at cell sites for signal transmission. With C-RAN, multiple collaborative cells can transmit data to user equipments (UEs) by Joint Transmission (JT) technology to improve network efficiency. On the other hand, 3GPP standard has defined the Discontinuous Reception (DRX) mechanism, which allows UEs to turn off their radio interfaces periodically to save their energy. However, how to cooperate DRX with JT under the C-RAN architecture is still an open issue. Therefore, this letter studies how to optimize UEs' DRX parameters while considering their quality-of-service (QoS) in C-RAN with JT. To solve this problem, we propose an energy-efficient JT scheduling scheme. The main idea of our scheme is to well pair UEs and BSs with the consideration of joint transmission quality and then optimizes DRX parameters to further save energy. Extensive simulation results show that our scheme can improve system throughput, well utilize resource and save UEs' energy consumption.
MmWave UAV Networks With Multi-Cell Association: Performance Limit and Optimization
(2019-12-01)
Liu, Chun-Hung
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Ho, Kai-Hsiang
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Wu, Jwo-Yuh
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電信工程研究所
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Institute of Communications Engineering
This paper aims to exploit the fundamental limits on the downlink coverage and spatial throughput performances of a cellular network comprised of a tier of unmanned aerial vehicle (UAV) base stations (BSs) using the millimeter wave (mmWave) band and a tier of ground BSs using the ultra high frequency (UHF) band. To reduce handover signaling overhead, the ground BSs take charge of control signaling delivery whereas the UAVs are in charge of payload data transmission so that users need to be simultaneously associated with a ground BS and a UAV in this network with a control-data plane-split architecture. We first propose a three-dimensional (3D) location distribution model of the UAVs using stochastic geometry which is able to generally characterize the positions of the UAVs in the sky. Using this 3D distribution model of UAVs, two performance metrics, i.e., multi-cell coverage probability and volume spectral efficiency, are proposed. Their explicit low-complexity expressions are derived and their upper limits are found when each of the UAVs and ground BSs is equipped with a massive antenna array. We further show that the multi-cell coverage probability and the volume spectral efficiency can be maximized by optimally deploying and positioning the UAVs in the sky and thereby their fundamental maximal limits are found. These important analytical findings are validated by numerical simulations.
End-to-End Slicing as a Service with Computing and Communication Resource Allocation for Multi-Tenant 5G Systems
(2019-10-01)
Chien, Hsu-Tung
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Lin, Ying-Dar
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Lai, Chia-Lin
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Wang, Chien-Ting
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交大名義發表
5G services, such as Ultra-reliable and Low Latency Communications, Massive Machine Type Communications and Enhanced Mobile Broadband, support low (or ultra-low) latency, a huge number of connections, and high bandwidth. Typically, 5G platforms are shared by multiple tenants, where each tenant has different service deployment requirements and thus requires different amounts of resources from the lower tier (i.e., radio access network and mobile edge) and upper tier (i.e., transport network and central office) of the 5G architecture. Consequently, slicing is a key technology in 5G networks for providing scalability and flexibility in allocating the 5G resources with appropriate isolation. This study proposes an Endto- End Slicing as a Service framework for slicing both computing and communication resources across the full 2-tier multi-access edge computing architecture. The framework is implemented using open source tools. It is shown that the framework successfully isolates the 5G resources, which are computing and communication, between slices (slicing isolation effect ratio equals 1) and ensures that resources of the deployed slices are merely sufficient to meet the latency requirements of the tenants. Moreover, the experiments show that URLLC and mMTC services require more than 70 percent of the needed computing and communication resources be provided by the edge and RAN in order to satisfy their tighter latency requirements. Overall, the results suggest a central to edge resource allocation ratio of 9:1, 3:7, and 1:9 for the eMBB, URLLC, mMTC applications, respectively. Therefore,

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