The Experts below are selected from a list of 3549 Experts worldwide ranked by ideXlab platform
Tony Q. S. Quek - One of the best experts on this subject based on the ideXlab platform.
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ICC Workshops - UAV-Assisted Uplink Transmission for Ultra-Reliable and Low-Latency Communications
2018 IEEE International Conference on Communications Workshops (ICC Workshops), 2018Co-Authors: Tony Q. S. Quek, Chenyang Yang, Yonghui LiAbstract:In this work, we investigate the potential of using unmanned aerial vehicles (UAVs) in supporting ultra- reliable and low-latency communications (URLLC). The key idea is to leverage better link qualities provided by high possibility of line-of-sight (LoS) links in UAV communication systems. We first characterize the latency, the reliability and the network availability of UAV communication systems. We show that the probability of the existing of LoS links and the network availability are strictly concave in terms of the distance between the user and the UAV. Then, given the density of UAVs, we optimize the altitude of UAV and Bandwidth allocation for minimizing the required Total Bandwidth of URLLC. Numerical results show that increasing the density of UAVs can remarkably reduce the Total Bandwidth required by URLLC in suburban areas. It is also shown that, in urban areas, using a single ground-to-air wireless link is not sufficient for ensuring the QoS and the network availability of URLLC, implying the needs of deploying multiple ground-to-air or ground-to-ground wireless links in order to support URLLC.
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Joint Uplink and Downlink Resource Configuration for Ultra-reliable and Low-latency Communications
IEEE Transactions on Communications, 2018Co-Authors: Changyang She, Chenyang Yang, Tony Q. S. QuekAbstract:Supporting ultra-reliable and low-latency communications (URLLC) is one of the major goals for the fifth-generation cellular networks. Since spectrum usage efficiency is always a concern, and large Bandwidth is required for ensuring stringent quality-of-service (QoS), we minimize the Total Bandwidth under the QoS constraints of URLLC. We first propose a packet delivery mechanism for URLLC. To reduce the required Bandwidth for ensuring queueing delay, we consider a statistical multiplexing queueing mode, where the packets to be sent to different devices are waiting in one queue at the base station, and broadcast mode is adopted in downlink transmission. In this way, downlink Bandwidth is shared among packets of multiple devices. In uplink transmission, different subchannels are allocated to different devices to avoid strong interference. Then, we jointly optimize uplink and downlink Bandwidth configuration and delay components to minimize the Total Bandwidth required to guarantee the overall packet loss and end-to-end delay, which includes uplink and downlink transmission delays, queueing delay and backhaul delay. We propose a two-step method to find the optimal solution. Simulation and numerical results validate our analysis and show remarkable performance gain by jointly optimizing uplink and downlink configuration.
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UAV-Assisted uplink transmission for ultra-reliable and low-latency communications
2018 IEEE International Conference on Communications Workshops ICC Workshops 2018 - Proceedings, 2018Co-Authors: Changyang She, Chenxi Liu, Tony Q. S. Quek, Chenyang Yang, Yonghui LiAbstract:In this work, we investigate the potential of using unmanned aerial vehicles (UAVs) in supporting ultra-reliable and low-latency communications (URLLC). The key idea is to leverage better link qualities provided by high possibility of line-of-sight (LoS) links in UAV communication systems. We first characterize the latency, the reliability and the network availability of UAV communication systems. We show that the probability of the existing of LoS links and the network availability are strictly concave in terms of the distance between the user and the UAV. Then, given the density of UAVs, we optimize the altitude of UAV and Bandwidth allocation for minimizing the required Total Bandwidth of URLLC. Numerical results show that increasing the density of UAVs can remarkably reduce the Total Bandwidth required by URLLC in suburban areas. It is also shown that, in urban areas, using a single ground-to-air wireless link is not sufficient for ensuring the QoS and the network availability of URLLC, implying the needs of deploying multiple ground-to-air or ground-to-ground wireless links in order to support URLLC.
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GLOBECOM Workshops - Uplink Transmission Design with Massive Machine Type Devices in Tactile Internet
2016 IEEE Globecom Workshops (GC Wkshps), 2016Co-Authors: Chenyang Yang, Tony Q. S. QuekAbstract:In this work, we study how to design uplink transmission with massive machine type devices in tactile internet, where ultra-short delay and ultra- high reliability are required. To characterize the transmission reliability constraint, we employ a two- state transmission model based on the achievable rate with finite blocklength channel codes. If the channel gain exceeds a threshold, a short packet can be transmitted with a small error probability; otherwise there is a packet loss. To exploit frequency diversity, we assign multiple subchannels to each active device, from which the device selects a subchannel with channel gain exceeding the threshold for transmission. To show the Total Bandwidth required to ensure the reliability, we optimize the number of subchannels and Bandwidth of each subchannel and the threshold for each device to minimize the Total Bandwidth of the system with a given number of antennas at the base station. Numerical results show that with 1000 devices in one cell, the required Bandwidth of the optimized policy is acceptable even for prevalent cellular systems. Furthermore, we show that by increasing antennas at the BS, frequency diversity becomes unnecessary, and the required Bandwidth is reduced.
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Uplink Transmission Design with Massive Machine Type Devices in Tactile Internet
arXiv: Information Theory, 2016Co-Authors: Chenyang Yang, Tony Q. S. QuekAbstract:In this work, we study how to design uplink transmission with massive machine type devices in tactile internet, where ultra-short delay and ultra-high reliability are required. To characterize the transmission reliability constraint, we employ a two-state transmission model based on the achievable rate with finite blocklength channel codes. If the channel gain exceeds a threshold, a short packet can be transmitted with a small error probability; otherwise there is a packet loss. To exploit frequency diversity, we assign multiple subchannels to each active device, from which the device selects a subchannel with channel gain exceeding the threshold for transmission. To show the Total Bandwidth required to ensure the reliability, we optimize the number of subchannels and Bandwidth of each subchannel and the threshold for each device to minimize the Total Bandwidth of the system with a given number of antennas at the base station. Numerical results show that with 1000 devices in one cell, the required Bandwidth of the optimized policy is acceptable even for prevalent cellular systems. Furthermore, we show that by increasing antennas at the BS, frequency diversity becomes unnecessary, and the required Bandwidth is reduced.
Chenyang Yang - One of the best experts on this subject based on the ideXlab platform.
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ICC Workshops - UAV-Assisted Uplink Transmission for Ultra-Reliable and Low-Latency Communications
2018 IEEE International Conference on Communications Workshops (ICC Workshops), 2018Co-Authors: Tony Q. S. Quek, Chenyang Yang, Yonghui LiAbstract:In this work, we investigate the potential of using unmanned aerial vehicles (UAVs) in supporting ultra- reliable and low-latency communications (URLLC). The key idea is to leverage better link qualities provided by high possibility of line-of-sight (LoS) links in UAV communication systems. We first characterize the latency, the reliability and the network availability of UAV communication systems. We show that the probability of the existing of LoS links and the network availability are strictly concave in terms of the distance between the user and the UAV. Then, given the density of UAVs, we optimize the altitude of UAV and Bandwidth allocation for minimizing the required Total Bandwidth of URLLC. Numerical results show that increasing the density of UAVs can remarkably reduce the Total Bandwidth required by URLLC in suburban areas. It is also shown that, in urban areas, using a single ground-to-air wireless link is not sufficient for ensuring the QoS and the network availability of URLLC, implying the needs of deploying multiple ground-to-air or ground-to-ground wireless links in order to support URLLC.
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Joint Uplink and Downlink Resource Configuration for Ultra-reliable and Low-latency Communications
IEEE Transactions on Communications, 2018Co-Authors: Changyang She, Chenyang Yang, Tony Q. S. QuekAbstract:Supporting ultra-reliable and low-latency communications (URLLC) is one of the major goals for the fifth-generation cellular networks. Since spectrum usage efficiency is always a concern, and large Bandwidth is required for ensuring stringent quality-of-service (QoS), we minimize the Total Bandwidth under the QoS constraints of URLLC. We first propose a packet delivery mechanism for URLLC. To reduce the required Bandwidth for ensuring queueing delay, we consider a statistical multiplexing queueing mode, where the packets to be sent to different devices are waiting in one queue at the base station, and broadcast mode is adopted in downlink transmission. In this way, downlink Bandwidth is shared among packets of multiple devices. In uplink transmission, different subchannels are allocated to different devices to avoid strong interference. Then, we jointly optimize uplink and downlink Bandwidth configuration and delay components to minimize the Total Bandwidth required to guarantee the overall packet loss and end-to-end delay, which includes uplink and downlink transmission delays, queueing delay and backhaul delay. We propose a two-step method to find the optimal solution. Simulation and numerical results validate our analysis and show remarkable performance gain by jointly optimizing uplink and downlink configuration.
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UAV-Assisted uplink transmission for ultra-reliable and low-latency communications
2018 IEEE International Conference on Communications Workshops ICC Workshops 2018 - Proceedings, 2018Co-Authors: Changyang She, Chenxi Liu, Tony Q. S. Quek, Chenyang Yang, Yonghui LiAbstract:In this work, we investigate the potential of using unmanned aerial vehicles (UAVs) in supporting ultra-reliable and low-latency communications (URLLC). The key idea is to leverage better link qualities provided by high possibility of line-of-sight (LoS) links in UAV communication systems. We first characterize the latency, the reliability and the network availability of UAV communication systems. We show that the probability of the existing of LoS links and the network availability are strictly concave in terms of the distance between the user and the UAV. Then, given the density of UAVs, we optimize the altitude of UAV and Bandwidth allocation for minimizing the required Total Bandwidth of URLLC. Numerical results show that increasing the density of UAVs can remarkably reduce the Total Bandwidth required by URLLC in suburban areas. It is also shown that, in urban areas, using a single ground-to-air wireless link is not sufficient for ensuring the QoS and the network availability of URLLC, implying the needs of deploying multiple ground-to-air or ground-to-ground wireless links in order to support URLLC.
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GLOBECOM Workshops - Uplink Transmission Design with Massive Machine Type Devices in Tactile Internet
2016 IEEE Globecom Workshops (GC Wkshps), 2016Co-Authors: Chenyang Yang, Tony Q. S. QuekAbstract:In this work, we study how to design uplink transmission with massive machine type devices in tactile internet, where ultra-short delay and ultra- high reliability are required. To characterize the transmission reliability constraint, we employ a two- state transmission model based on the achievable rate with finite blocklength channel codes. If the channel gain exceeds a threshold, a short packet can be transmitted with a small error probability; otherwise there is a packet loss. To exploit frequency diversity, we assign multiple subchannels to each active device, from which the device selects a subchannel with channel gain exceeding the threshold for transmission. To show the Total Bandwidth required to ensure the reliability, we optimize the number of subchannels and Bandwidth of each subchannel and the threshold for each device to minimize the Total Bandwidth of the system with a given number of antennas at the base station. Numerical results show that with 1000 devices in one cell, the required Bandwidth of the optimized policy is acceptable even for prevalent cellular systems. Furthermore, we show that by increasing antennas at the BS, frequency diversity becomes unnecessary, and the required Bandwidth is reduced.
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Uplink Transmission Design with Massive Machine Type Devices in Tactile Internet
arXiv: Information Theory, 2016Co-Authors: Chenyang Yang, Tony Q. S. QuekAbstract:In this work, we study how to design uplink transmission with massive machine type devices in tactile internet, where ultra-short delay and ultra-high reliability are required. To characterize the transmission reliability constraint, we employ a two-state transmission model based on the achievable rate with finite blocklength channel codes. If the channel gain exceeds a threshold, a short packet can be transmitted with a small error probability; otherwise there is a packet loss. To exploit frequency diversity, we assign multiple subchannels to each active device, from which the device selects a subchannel with channel gain exceeding the threshold for transmission. To show the Total Bandwidth required to ensure the reliability, we optimize the number of subchannels and Bandwidth of each subchannel and the threshold for each device to minimize the Total Bandwidth of the system with a given number of antennas at the base station. Numerical results show that with 1000 devices in one cell, the required Bandwidth of the optimized policy is acceptable even for prevalent cellular systems. Furthermore, we show that by increasing antennas at the BS, frequency diversity becomes unnecessary, and the required Bandwidth is reduced.
Changyang She - One of the best experts on this subject based on the ideXlab platform.
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Joint Uplink and Downlink Resource Configuration for Ultra-reliable and Low-latency Communications
IEEE Transactions on Communications, 2018Co-Authors: Changyang She, Chenyang Yang, Tony Q. S. QuekAbstract:Supporting ultra-reliable and low-latency communications (URLLC) is one of the major goals for the fifth-generation cellular networks. Since spectrum usage efficiency is always a concern, and large Bandwidth is required for ensuring stringent quality-of-service (QoS), we minimize the Total Bandwidth under the QoS constraints of URLLC. We first propose a packet delivery mechanism for URLLC. To reduce the required Bandwidth for ensuring queueing delay, we consider a statistical multiplexing queueing mode, where the packets to be sent to different devices are waiting in one queue at the base station, and broadcast mode is adopted in downlink transmission. In this way, downlink Bandwidth is shared among packets of multiple devices. In uplink transmission, different subchannels are allocated to different devices to avoid strong interference. Then, we jointly optimize uplink and downlink Bandwidth configuration and delay components to minimize the Total Bandwidth required to guarantee the overall packet loss and end-to-end delay, which includes uplink and downlink transmission delays, queueing delay and backhaul delay. We propose a two-step method to find the optimal solution. Simulation and numerical results validate our analysis and show remarkable performance gain by jointly optimizing uplink and downlink configuration.
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UAV-Assisted uplink transmission for ultra-reliable and low-latency communications
2018 IEEE International Conference on Communications Workshops ICC Workshops 2018 - Proceedings, 2018Co-Authors: Changyang She, Chenxi Liu, Tony Q. S. Quek, Chenyang Yang, Yonghui LiAbstract:In this work, we investigate the potential of using unmanned aerial vehicles (UAVs) in supporting ultra-reliable and low-latency communications (URLLC). The key idea is to leverage better link qualities provided by high possibility of line-of-sight (LoS) links in UAV communication systems. We first characterize the latency, the reliability and the network availability of UAV communication systems. We show that the probability of the existing of LoS links and the network availability are strictly concave in terms of the distance between the user and the UAV. Then, given the density of UAVs, we optimize the altitude of UAV and Bandwidth allocation for minimizing the required Total Bandwidth of URLLC. Numerical results show that increasing the density of UAVs can remarkably reduce the Total Bandwidth required by URLLC in suburban areas. It is also shown that, in urban areas, using a single ground-to-air wireless link is not sufficient for ensuring the QoS and the network availability of URLLC, implying the needs of deploying multiple ground-to-air or ground-to-ground wireless links in order to support URLLC.
Takahiro Numai - One of the best experts on this subject based on the ideXlab platform.
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Reduction of four-wave-mixing noises in FDM optical fiber transmission systems in unequally spaced frequency allocations using base units
Optics Communications, 2013Co-Authors: Tatsuya Nishio, Takahiro NumaiAbstract:Abstract The purpose of this paper is to reduce four-wave-mixing (FWM) noises with narrow Total Bandwidth in frequency-division-multiplexing optical fiber transmission systems. In this work, unequally spaced (US) frequency allocations using base units (BUs), which have US frequency allocations, are proposed, and dependence of the Total Bandwidth and FWM noises on the allocation of the BUs is investigated. When the frequency separations of the channels in the BUs are ascending arithmetic progressions, the lowest power penalty is obtained for the combination of the BUs with ascending Bandwidths.
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dependence of Total Bandwidth and four wave mixing noises in fdm optical fiber transmission systems on the number of base units
Optics Communications, 2013Co-Authors: Tatsuya Nishio, Takahiro NumaiAbstract:Abstract The purpose of this paper is to reduce the Total Bandwidth and four-wave-mixing (FWM) noises in frequency-division-multiplexing optical fiber transmission systems. In this work, dependence of the Total Bandwidth and FWM noises on the number of base units in the unequally spaced – repeated unequally spaced frequency allocations is investigated. Here, a frequency allocation of a base unit is different from that of another base unit. Among the frequency allocations where the number of the base units is 1–5, the frequency allocation with 5 base units shows the best results: the narrowest Total Bandwidth of 3740 GHz and the lowest power penalty.
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Theoretical Analysis of Frequency Allocations in FDM Lightwave Transmission Systems
Journal of Lightwave Technology, 2008Co-Authors: Y. Nagatani, J. Onishi, S. Kojima, Takahiro NumaiAbstract:In long-haul frequency-division-multiplexing (FDM) lightwave transmission systems, transmission characteristics are degraded by four-wave mixing (FWM) in optical fibers. To date, equally spaced (ES), unequally spaced (US), and repeated unequally spaced (RUS) allocations have been demonstrated in FDM lightwave transmission systems. It has been already revealed theoretically and experimentally that optical power of FWM light with fFWM = fi for RUS is lower than that for ES, and a Total Bandwidth of signal light for RUS is comparable to that for US, where fFWM is a frequency of FWM light and /< is a frequency of signal light with a channel index i. Moreover, it has been shown that equally spaced RUS (ERUS), unequally spaced RUS (URUS), and paired RUS with combined base units have lower FWM noises than RUS with a single base unit. In this paper, paired URUS is proposed as modified URUS and theoretically analyzed. Efficiency of FWM light and a Total Bandwidth of signal light for paired URUS are compared with those for URUS. As a result, it is found that the efficiency of FWM light with fFWM = fi for paired URUS is lower than that for URUS, and the Total Bandwidth of signal light for paired URUS is slightly narrower than that for URUS. Bit error rate and power penalty for paired URUS are also lower than those for URUS at a modulation speed of 10 Gb/s. Therefore, it is concluded that paired URUS is superior to URUS in FDM lightwave transmission systems.
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Analysis of repeated unequally spaced channels for FDM lightwave systems
Journal of Lightwave Technology, 2000Co-Authors: Takahiro Numai, O. KubotaAbstract:In long-haul optical frequency-division-multiplexing (FDM) systems, transmission characteristics are degraded by four-wave mixing (FWM). To overcome this problem, repeated unequally spaced (RUS) channels have been recently proposed as a new frequency allocation. In this paper, frequency distribution and intensity of generated FWM lights, and a Total Bandwidth of signal lights of RUS channels are compared with those of already known equally spaced (ES) and unequally spaced (US) channels. It is found that intensities of generated FWM lights of RUS are less than those of ES when the number of channels and a Total Bandwidth of signals are common in both channels. It is also revealed that RUS has a narrower Total Bandwidth than US when the number of channels and the minimum channel spacing are common in both channels. Since RUS simultaneously satisfies a low FWM light intensity and a narrow signal Bandwidth, it is considered that RUS is suitable for FDM lightwave transmission systems.
Nobuyuki Yamasaki - One of the best experts on this subject based on the ideXlab platform.
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scheduling aperiodic tasks using Total Bandwidth server on multiprocessors
Embedded and Ubiquitous Computing, 2008Co-Authors: S Kato, Nobuyuki YamasakiAbstract:This paper presents real-time scheduling techniques for reducing the response time of aperiodic tasks scheduled with real-time periodic tasks on multiprocessor systems. Two problems are addressed in this paper: (i) the scheduling of aperiodic tasks that can be dispatched to any processors when they arrive, and (ii) the scheduling of aperiodic tasks that must be executed on particular processors on which they arrive. In order to improve the responsiveness to both types of aperiodic tasks, efficient dispatching and migration algorithms are designed based on the Earliest Deadline First (EDF) algorithm and the Total Bandwidth Server (TBS) algorithm. The effectiveness of the designed algorithms is evaluated through simulation studies.
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EUC (1) - Scheduling Aperiodic Tasks Using Total Bandwidth Server on Multiprocessors
2008 IEEE IFIP International Conference on Embedded and Ubiquitous Computing, 2008Co-Authors: S Kato, Nobuyuki YamasakiAbstract:This paper presents real-time scheduling techniques for reducing the response time of aperiodic tasks scheduled with real-time periodic tasks on multiprocessor systems. Two problems are addressed in this paper: (i) the scheduling of aperiodic tasks that can be dispatched to any processors when they arrive, and (ii) the scheduling of aperiodic tasks that must be executed on particular processors on which they arrive. In order to improve the responsiveness to both types of aperiodic tasks, efficient dispatching and migration algorithms are designed based on the Earliest Deadline First (EDF) algorithm and the Total Bandwidth Server (TBS) algorithm. The effectiveness of the designed algorithms is evaluated through simulation studies.
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Feedback-Controlled Server for Scheduling Aperiodic Tasks
World Academy of Science Engineering and Technology International Journal of Computer Electrical Automation Control and Information Engineering, 2007Co-Authors: S Kato, Nobuyuki YamasakiAbstract:This paper proposes a scheduling scheme using feedback control to reduce the response time of aperiodic tasks with soft real-time constraints. We design an algorithm based on the proposed scheduling scheme and Total Bandwidth Server (TBS) that is a conventional server technique for scheduling aperiodic tasks. We then describe the feedback controller of the algorithm and give the control parameter tuning methods. The simulation study demonstrates that the algorithm can reduce the mean response time up to 26% compared to TBS in exchange for slight deadline misses. Keywords—Real-Time Systems, Aperiodic Task Scheduling, Feedback-Control Scheduling, Total Bandwidth Server
