Browsing by Author "Talat, Samer T."

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Adaptive link maintenance in cognitive radio within equivalent and nonequivalent channel bandwidths
(2008)
Talat, Samer T.
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Wang, Li-Chun
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電信工程研究所
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Institute of Communications Engineering
Cognitive radio requires sophisticated techniques in spectrum sensing and spectrum analysis to enhance spectrum decision functionality. Generally, it is recognized that if a Primary user (PU) appears in the spectrum band occupied by secondary user (SU). SU should vacate the current spectrum band and move to the available spectrum immediately. However, this kind of spectrum change can decrease the total throughput of SU. The alternative method is to make the SU wait until the PU has left the spectrum band and then transmit again. In this paper, we propose an efficient spectrum allocation scheme which dynamically makes the best choice for the SU within equivalent and nonequivalent channel bandwidths to improve its throughput. This dynamic link maintenance algorithm determines the SU highest channel priority index before transmitting again. Specifically, the SU's stay in the current channel if it has the highest throughput priority index achieved; otherwise, the SU selects the sensed channel with the highest priority index.
An Integrated, Virtualized Joint Edge and Fog Computing System with Multi-RAT Convergence
(2018-01-01)
Rapone, Damiano
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Quasso, Roberto
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Chundrigar, Shahzoob Bilal
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Talat, Samer T.
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Cominardi, Luca
Notably, developing an innovative architectural network paradigm is essential to address the technical challenging of 5G applications' requirements in a unified platform. Forthcoming applications will provide a wide range of networking, computing and storage capabilities closer to the endusers. In this context, the 5G-PPP Phase two project named "5G-CORAL: A 5G Convergent Virtualized Radio Access Network Living at the Edge" aims at identifying and experimentally validating which are the key technology innovations allowing for the development of a convergent 5G multi-RAT access based on a virtualized Edge and Fog architecture being scalable, flexible and interoperable with other domains including transport, core network and distant Clouds. In 5G-CORAL, an architecture is proposed based on ETSI MEC and ETSI NFV frameworks in a unified platform. Then, a set of exemplary use cases benefiting from Edge and Fog networks in near proximity of the end-user are proposed for demonstration on top of connected car, shopping mall and high-speed train platforms.
Delay-bandwidth product approach for unequal-width load balancing spectrum decisions in cognitive radio networks
(2015-10-01)
Talat, Samer T.
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Wang, Li-Chun
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電機資訊學士班
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Undergraduate Honors Program of Electrical Engineering and Computer Science
A cognitive radio (CR) system scans a wide spectrum to find available channels. One of the key challenges in using these temporarily available spectrums is that bandwidths of the available spectrums are not equal. In addition, the issue of competition for a single channel by many secondary users must be resolved. This paper develops a load balancing spectrum decision scheme for CR networks with unequal-bandwidth, using the concept of the delay bandwidth (DB) product to select suitable unequal-width channels. Compared with other existing unequal bandwidth spectrum decision schemes, the proposed DB-based spectrum decision can improve the overall system throughput by up to 40 % in our simulation results.
Load-Balancing Spectrum Decision for Cognitive Radio Networks with Unequal-Width Channels
(2012-01-01)
Talat, Samer T.
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Wang, Li-Chun
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
A cognitive radio (CR) system scans the wide spectrum to find available spectrum. One of key challenges in using these temporarily available spectrums is that the bandwidth of the available spectrum are not equally wide. The other challenge for spectrum decision scheme in CR systems is that many secondary users (SUs) may choose the same channel simultaneously, resulting in channel contention. In this paper, we develop a load balancing spectrum decision scheme for unequal-bandwidth CR networks. We apply the concept of the delay bandwidth (DB) product to select a suitable channel for each user among many unequal-width channels. Compared with other existing unequal bandwidth spectrum decision schemes, our simulation results show that the proposed DB-based spectrum decision can improve the overall system throughput up to 40% in the considered case.
QoS-guaranteed Channel Selection Scheme for Cognitive Radio Networks With Variable Channel Bandwidths
(2009)
Talat, Samer T.
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Wang, Li-Chun
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電信工程研究所
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Institute of Communications Engineering
Cognitive radio (CR) network allows fast deployment of wireless technologies to utilize spectrum channels, all with minimal impact on existing primary users. Another challenge in CR networks is the spectrum handoff issue when the primary user (PU) appears in the spectrum band being used by the secondary user (SU). In this paper, unlike the existing spectrum handoff schemes suitable for fixed channel bandwidth, we introduce the concept of the delay bandwidth product (DBP) to prioritize the channels with variable bandwidths. The delay in the proposed DBP index is defined as the difference of the maximum tolerable delay of the SU and the average occupation time of the PU. Based on the DBP index for the variable bandwidth channels, the SU selects the optimal channel and bandwidth that can deliver the highest throughput and guarantee its QoS requirement. Compared with other existing spectrum handoff schemes, the proposed DBP-based spectrum handoff can achieve 100% to 200% higher throughput subject to the delay requirements for supporting voice and web browsing services.
Spectrum Decision for Cognitive Radio Networks With Various-Bandwidth Channels
(2016)
Talat, Samer T.
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Wang, Chung-Wei
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Wang, Li-Chun
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電機工程學系
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Department of Electrical and Computer Engineering
Cognitive radio (CR) systems can enhance the licensed spectrum efficiency by finding and allocating the under-utilized channels of the primary users to the secondary users. After scanning a wide range of spectrum. A general CR system needs to utilize all the available channels of various bandwidths. Whenever the active primary users appear, the secondary users shall return the borrowed channels, causing interruption even during a transmission period. The behavior of changing the operating channels is called hopping mode in this paper. In this paper we propose an improved preemptive resume priority (PRP) M/G/1 queueing network model for such a general CR system, aiming to characterize the impacts of hopping-mode behaviors and various bandwidth on the delay performance of the secondary users. We further propose a probability-based various-bandwidth channel selection scheme to reduce the overall system time for the hopping-mode secondary users with multiple interruptions, where the overall system time is defined as the sum of transmission time and waiting time. Our analytical results, validated by simulations, show that the proposed probability-based various-bandwidth channel selection scheme can improve the overall system time by 20% compared to the existing methods.