The Experts below are selected from a list of 24225 Experts worldwide ranked by ideXlab platform
Hean Teik Chuah - One of the best experts on this subject based on the ideXlab platform.
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Received Signal statistics in DS-CDMA channels with flat Rayleigh fading and fast closed-loop Power control
IEEE Transactions on Communications, 2003Co-Authors: Moh Lim Sim, Hean Teik ChuahAbstract:The statistics of Received Signal Power at the receiver in a cellular direct-sequence code-division multiple-access (DS-CDMA) system with flat Rayleigh fading and fast closed-loop Power control mechanism are studied. A simple model for the fast closed-loop Power control mechanism is proposed to ease the analysis. The probability density function (pdf) of the Received Signal Power is derived by taking into consideration the updating frequency of Power control mechanism, maximum allowable transmitted Power, and Doppler frequency of the fading channel. The pdf derived can be used to study the performance of a reverse-link DS-CDMA system with noncoherent M-ary orthogonal modulation. The result shows that when optimum maximum allowable transmitted Power is used, system capacity can be substantially increased for typical normalized Doppler frequency in cellular communication.
Zhi Chen - One of the best experts on this subject based on the ideXlab platform.
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intelligent reflecting surface assisted millimeter wave communications joint active and passive precoding design
IEEE Transactions on Vehicular Technology, 2020Co-Authors: Peilan Wang, Jun Fang, Xiaojun Yuan, Zhi ChenAbstract:Millimeter wave (MmWave) communications is capable of supporting multi-gigabit wireless access thanks to its abundant spectrum resource. However, severe path loss and high directivity make it vulnerable to blockage events, which can be frequent in indoor and dense urban environments. To address this issue, in this paper, we introduce intelligent reflecting surface (IRS) as a new technology to provide effective reflected paths to enhance the coverage of mmWave Signals. In this framework, we study joint active and passive precoding design for IRS-assisted mmWave systems, where multiple IRSs are deployed to assist the data transmission from a base station (BS) to a single-antenna receiver. Our objective is to maximize the Received Signal Power by jointly optimizing the BS's transmit precoding vector and IRSs’ phase shift coefficients. Although such an optimization problem is generally non-convex, we show that, by exploiting some important characteristics of mmWave channels, an optimal closed-form solution can be derived for the single IRS case and a near-optimal analytical solution can be obtained for the multi-IRS case. Our analysis reveals that the Received Signal Power increases quadratically with the number of reflecting elements for both the single IRS and multi-IRS cases. Simulation results are included to verify the optimality and near-optimality of our proposed solutions. Results also show that IRSs can help create effective virtual line-of-sight (LOS) paths and thus substantially improve robustness against blockages in mmWave communications.
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intelligent reflecting surface assisted millimeter wave communications joint active and passive precoding design
arXiv: Signal Processing, 2019Co-Authors: Peilan Wang, Zhi Chen, Jun Fang, Xiaojun Yuan, Huiping DuanAbstract:Millimeter wave (MmWave) communications is capable of supporting multi-gigabit wireless access thanks to its abundant spectrum resource. However, the severe path loss and high directivity make it vulnerable to blockage events, which can be frequent in indoor and dense urban environments. To address this issue, in this paper, we introduce intelligent reflecting surface (IRS) as a new technology to provide effective reflected paths to enhance coverage of mmWave Signals. In this framework, we study joint active and passive precoding design for IRS-assisted mmWave systems, where multiple IRSs are deployed to assist the data transmission from a base station (BS) to a single-antenna receiver. Our objective is to maximize the Received Signal Power by jointly optimizing the transmit precoding vector at the BS and the phase shift parameters used by IRSs for passive beamforming. Although such an optimization problem is generally non-convex, we show that, by exploiting some important characteristics of mmWave channels, an optimal closed-form solution can be derived for the single IRS case and a near-optimal analytical solution can be obtained for the multi-IRS case. Our analysis reveals that the Received Signal Power increases quadratically with the number of reflecting elements for both the single IRS and multi-IRS cases. Simulation results are included to verify the optimality and near-optimality of our proposed solutions. Results also show that IRSs can help create effective virtual LOS paths and thus substantially improve robustness against blockages in mmWave communications.
Peilan Wang - One of the best experts on this subject based on the ideXlab platform.
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intelligent reflecting surface assisted millimeter wave communications joint active and passive precoding design
IEEE Transactions on Vehicular Technology, 2020Co-Authors: Peilan Wang, Jun Fang, Xiaojun Yuan, Zhi ChenAbstract:Millimeter wave (MmWave) communications is capable of supporting multi-gigabit wireless access thanks to its abundant spectrum resource. However, severe path loss and high directivity make it vulnerable to blockage events, which can be frequent in indoor and dense urban environments. To address this issue, in this paper, we introduce intelligent reflecting surface (IRS) as a new technology to provide effective reflected paths to enhance the coverage of mmWave Signals. In this framework, we study joint active and passive precoding design for IRS-assisted mmWave systems, where multiple IRSs are deployed to assist the data transmission from a base station (BS) to a single-antenna receiver. Our objective is to maximize the Received Signal Power by jointly optimizing the BS's transmit precoding vector and IRSs’ phase shift coefficients. Although such an optimization problem is generally non-convex, we show that, by exploiting some important characteristics of mmWave channels, an optimal closed-form solution can be derived for the single IRS case and a near-optimal analytical solution can be obtained for the multi-IRS case. Our analysis reveals that the Received Signal Power increases quadratically with the number of reflecting elements for both the single IRS and multi-IRS cases. Simulation results are included to verify the optimality and near-optimality of our proposed solutions. Results also show that IRSs can help create effective virtual line-of-sight (LOS) paths and thus substantially improve robustness against blockages in mmWave communications.
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intelligent reflecting surface assisted millimeter wave communications joint active and passive precoding design
arXiv: Signal Processing, 2019Co-Authors: Peilan Wang, Zhi Chen, Jun Fang, Xiaojun Yuan, Huiping DuanAbstract:Millimeter wave (MmWave) communications is capable of supporting multi-gigabit wireless access thanks to its abundant spectrum resource. However, the severe path loss and high directivity make it vulnerable to blockage events, which can be frequent in indoor and dense urban environments. To address this issue, in this paper, we introduce intelligent reflecting surface (IRS) as a new technology to provide effective reflected paths to enhance coverage of mmWave Signals. In this framework, we study joint active and passive precoding design for IRS-assisted mmWave systems, where multiple IRSs are deployed to assist the data transmission from a base station (BS) to a single-antenna receiver. Our objective is to maximize the Received Signal Power by jointly optimizing the transmit precoding vector at the BS and the phase shift parameters used by IRSs for passive beamforming. Although such an optimization problem is generally non-convex, we show that, by exploiting some important characteristics of mmWave channels, an optimal closed-form solution can be derived for the single IRS case and a near-optimal analytical solution can be obtained for the multi-IRS case. Our analysis reveals that the Received Signal Power increases quadratically with the number of reflecting elements for both the single IRS and multi-IRS cases. Simulation results are included to verify the optimality and near-optimality of our proposed solutions. Results also show that IRSs can help create effective virtual LOS paths and thus substantially improve robustness against blockages in mmWave communications.
Wei Xiang - One of the best experts on this subject based on the ideXlab platform.
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Downlink small-cell base station cooperation strategy in fractal small-cell networks
2017 IEEE Global Communications Conference GLOBECOM 2017 - Proceedings, 2018Co-Authors: Fen Bin, Xi Aohu Ge, Jiaqi Chen, Wei XiangAbstract:Coordinated multipoint (CoMP) communications are considered for the fifth-generation (5G) small-cell networks as a tool to improve the high data rates and the cell-edge throughput. The average achievable rates of the small-cell base stations (SBS) cooperation strategies with distance and Received Signal Power constraints are respectively derived for the fractal small-cell networks based on the anisotropic path loss model. Simulation results are presented to show that the average achievable rate with the Received Signal Power constraint is larger than the rate with a distance constraint considering the same number of cooperative SBSs. The average achievable rate with distance constraint decreases with the increase of the intensity of SBSs when the anisotropic path loss model is considered. What's more, the network energy efficiency of fractal smallcell networks adopting the SBS cooperation strategy with the Received Signal Power constraint is analyzed. The network energy efficiency decreases with the increase of the intensity of SBSs which indicates a challenge on the deployment design for fractal small-cell networks.
Moh Lim Sim - One of the best experts on this subject based on the ideXlab platform.
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Received Signal statistics in DS-CDMA channels with flat Rayleigh fading and fast closed-loop Power control
IEEE Transactions on Communications, 2003Co-Authors: Moh Lim Sim, Hean Teik ChuahAbstract:The statistics of Received Signal Power at the receiver in a cellular direct-sequence code-division multiple-access (DS-CDMA) system with flat Rayleigh fading and fast closed-loop Power control mechanism are studied. A simple model for the fast closed-loop Power control mechanism is proposed to ease the analysis. The probability density function (pdf) of the Received Signal Power is derived by taking into consideration the updating frequency of Power control mechanism, maximum allowable transmitted Power, and Doppler frequency of the fading channel. The pdf derived can be used to study the performance of a reverse-link DS-CDMA system with noncoherent M-ary orthogonal modulation. The result shows that when optimum maximum allowable transmitted Power is used, system capacity can be substantially increased for typical normalized Doppler frequency in cellular communication.
