The Experts below are selected from a list of 40032 Experts worldwide ranked by ideXlab platform
R.m. Buehrer - One of the best experts on this subject based on the ideXlab platform.
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On the usefulness of outer-Loop Power Control with successive interference cancellation
IEEE Transactions on Communications, 2003Co-Authors: R.m. Buehrer, R. MahajanAbstract:Multiuser detection (MUD) performance can be significantly better than the conventional matched filter receiver in CDMA systems. Further, since optimal MUD is exponentially complex, research has mainly focused on suboptimal approaches such as successive interference cancellation (SIC). SIC requires a geometric distribution of received Powers to achieve equal performance for all received signals. We propose a Power Control scheme for SIC to achieve this profile (or the profile corresponding to any desired and achievable set of error rates) based on frame-error rate (FER) or bit-error rate (BER). Specifically, we derive the relationship between received Power and BER for linear SIC and show that for unlimited mobile Powers, a deterministic distributed BER-based outer-Loop Power Control drives the received Powers to the optimal Power profile. The convergence of the deterministic BER-based algorithm is examined in the absence of inner Loop Power Control errors. The simulated performance of a stochastic version of this algorithm is examined using instantaneous FER measurements. The stochastic algorithm is shown to provide unbiased estimates of the true Power updates and converge to the optimal Power vector provided the mobiles have unlimited Power. We consider Power limits for specific mobiles and find that individual mobile limits do not affect the performance of other signals. We examine the impact of system loading, multiple FER targets, error correction, and inner Loop Power Control error on the performance of the algorithm.
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On the usefulness of outer-Loop Power Control with successive interference cancellation
Proceedings IEEE 56th Vehicular Technology Conference, 1Co-Authors: R.m. BuehrerAbstract:In this paper we investigate FER-based outer-Loop Power Control for successive interference cancellation. Specifically, we show that for unlimited mobile Power, FER-based outer-Loop Power Control will drive the received Power to the Power profile required to achieve equal performance. Further, when we consider Power limits for specific mobiles, we find that individual mobile limits will not affect the performance of other signals and based on limited simulation results, the system appears to be stable in the presence of such limits.
Abbas Mohammed - One of the best experts on this subject based on the ideXlab platform.
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Uplink closed Loop Power Control for LTE system
2010 6th International Conference on Emerging Technologies (ICET), 2010Co-Authors: Bilal Muhammad, Abbas MohammedAbstract:The role of uplink Power Control is to suppress interference. Power Control refers to set output Power levels of transmitters, base stations in the downlink and User Equipment (UE) in the uplink. In this paper the performance of 3GPP Long Term Evolution (LTE) closed Loop Power Control combined with fractional path loss compensation factor is evaluated by simulating the effects of open Loop error, Transmit Power Control (TPC) command delay and Power headroom reporting. Simulation results show that the closed Loop Power Control with fractional path loss compensation factor is advantageous compared to closed Loop Power Control with full path loss compensation. The closed Loop Power Control with fractional path loss compensation factor is found to improve the system performance in terms of mean bit rate by 63%.
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performance evaluation of uplink closed Loop Power Control for lte system
Vehicular Technology Conference, 2009Co-Authors: Bilal Muhammad, Abbas MohammedAbstract:Uplink Power Control is a key radio resource management feature in the 3GPP Long Term Evolution (LTE). In order to adapt to changes in the inter-cell interference situation or to correct Power amplifier errors, closed-Loop adjustments should be applied. In this paper the performance of closed Loop Power Control combined with fractional path loss compensation factor is studied, and an optimal value for the path loss compensation factor is investigated. The closed Loop Power Control with fractional path loss compensation factor is found to improve the system performance in terms of mean bit rate by 68% and utilizes the battery Power more effectively.
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VTC Fall - Performance Evaluation of Uplink Closed Loop Power Control for LTE System
2009 IEEE 70th Vehicular Technology Conference Fall, 2009Co-Authors: Bilal Muhammad, Abbas MohammedAbstract:Uplink Power Control is a key radio resource management feature in the 3GPP Long Term Evolution (LTE). In order to adapt to changes in the inter-cell interference situation or to correct Power amplifier errors, closed-Loop adjustments should be applied. In this paper the performance of closed Loop Power Control combined with fractional path loss compensation factor is studied, and an optimal value for the path loss compensation factor is investigated. The closed Loop Power Control with fractional path loss compensation factor is found to improve the system performance in terms of mean bit rate by 68% and utilizes the battery Power more effectively.
Bilal Muhammad - One of the best experts on this subject based on the ideXlab platform.
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Uplink closed Loop Power Control for LTE system
2010 6th International Conference on Emerging Technologies (ICET), 2010Co-Authors: Bilal Muhammad, Abbas MohammedAbstract:The role of uplink Power Control is to suppress interference. Power Control refers to set output Power levels of transmitters, base stations in the downlink and User Equipment (UE) in the uplink. In this paper the performance of 3GPP Long Term Evolution (LTE) closed Loop Power Control combined with fractional path loss compensation factor is evaluated by simulating the effects of open Loop error, Transmit Power Control (TPC) command delay and Power headroom reporting. Simulation results show that the closed Loop Power Control with fractional path loss compensation factor is advantageous compared to closed Loop Power Control with full path loss compensation. The closed Loop Power Control with fractional path loss compensation factor is found to improve the system performance in terms of mean bit rate by 63%.
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performance evaluation of uplink closed Loop Power Control for lte system
Vehicular Technology Conference, 2009Co-Authors: Bilal Muhammad, Abbas MohammedAbstract:Uplink Power Control is a key radio resource management feature in the 3GPP Long Term Evolution (LTE). In order to adapt to changes in the inter-cell interference situation or to correct Power amplifier errors, closed-Loop adjustments should be applied. In this paper the performance of closed Loop Power Control combined with fractional path loss compensation factor is studied, and an optimal value for the path loss compensation factor is investigated. The closed Loop Power Control with fractional path loss compensation factor is found to improve the system performance in terms of mean bit rate by 68% and utilizes the battery Power more effectively.
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VTC Fall - Performance Evaluation of Uplink Closed Loop Power Control for LTE System
2009 IEEE 70th Vehicular Technology Conference Fall, 2009Co-Authors: Bilal Muhammad, Abbas MohammedAbstract:Uplink Power Control is a key radio resource management feature in the 3GPP Long Term Evolution (LTE). In order to adapt to changes in the inter-cell interference situation or to correct Power amplifier errors, closed-Loop adjustments should be applied. In this paper the performance of closed Loop Power Control combined with fractional path loss compensation factor is studied, and an optimal value for the path loss compensation factor is investigated. The closed Loop Power Control with fractional path loss compensation factor is found to improve the system performance in terms of mean bit rate by 68% and utilizes the battery Power more effectively.
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Closed Loop Power Control for LTE uplink
2008Co-Authors: Bilal MuhammadAbstract:This thesis study involves designing, implementing and testing of a novel radio resource Control algorithm for the closed Loop Power Control in the LTE uplink. Different values of the path loss compensation factor are investigated in the range 0.7-1.0 and an optimal value of 0.8 as allowed by the LTE standard is proposed. Both the ideal and a more realistic case modeled by including delay, error, and Power headroom reporting were studied. Simulation results indicated that the closed Loop Power Control with fractional path loss compensation factor is advantageous compared to closed Loop Power Control with full path loss compensation. Using a simple upload traffic model, the closed Loop Power Control with fractional path loss compensation factor improved the system performance in terms of mean bit rate by 68% in the ideal case and 63% in the realistic case. The Power headroom report triggering at change in path loss gave better performance than triggering at periodic intervals.
R. Mahajan - One of the best experts on this subject based on the ideXlab platform.
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On the usefulness of outer-Loop Power Control with successive interference cancellation
IEEE Transactions on Communications, 2003Co-Authors: R.m. Buehrer, R. MahajanAbstract:Multiuser detection (MUD) performance can be significantly better than the conventional matched filter receiver in CDMA systems. Further, since optimal MUD is exponentially complex, research has mainly focused on suboptimal approaches such as successive interference cancellation (SIC). SIC requires a geometric distribution of received Powers to achieve equal performance for all received signals. We propose a Power Control scheme for SIC to achieve this profile (or the profile corresponding to any desired and achievable set of error rates) based on frame-error rate (FER) or bit-error rate (BER). Specifically, we derive the relationship between received Power and BER for linear SIC and show that for unlimited mobile Powers, a deterministic distributed BER-based outer-Loop Power Control drives the received Powers to the optimal Power profile. The convergence of the deterministic BER-based algorithm is examined in the absence of inner Loop Power Control errors. The simulated performance of a stochastic version of this algorithm is examined using instantaneous FER measurements. The stochastic algorithm is shown to provide unbiased estimates of the true Power updates and converge to the optimal Power vector provided the mobiles have unlimited Power. We consider Power limits for specific mobiles and find that individual mobile limits do not affect the performance of other signals. We examine the impact of system loading, multiple FER targets, error correction, and inner Loop Power Control error on the performance of the algorithm.
Chih-wen Chang - One of the best experts on this subject based on the ideXlab platform.
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WCNC - Error statistics of closed-Loop Power Control in multirate DS-CDMA cellular systems
2002 IEEE Wireless Communications and Networking Conference Record. WCNC 2002 (Cat. No.02TH8609), 1Co-Authors: Li-chun Wang, Chih-wen ChangAbstract:We investigate the error statistics of the close-Loop Power Control scheme with variable spreading factors for the multi-rate services in the third generation wideband CDMA (WCDMA) system. We demonstrate that the long scrambling pseudo-noise code, besides its well known feature in differentiating users and base stations, can improve Power Control false command over a frequency-selective fading channel as well. Our computer simulation results indicate that the SIR measurement error can be reduced by 3 dB in a typical case, and the Power Control false command can be reduced from 27 % to 10 % in comparison to using pure short Walsh codes. It is shown that the close-Loop Power Control error is a composite function of the spreading factor, target E/sub b/ / N/sub o/ and Doppler frequency. The statistics of closed Loop Power Control false command can be easily characterized by a Bernoulli distribution with a parameter provided by our results.
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WCNC - Impact of measurement errors on the closed Loop Power Control for CDMA systems
2003 IEEE Wireless Communications and Networking 2003. WCNC 2003., 1Co-Authors: Li-chun Wang, Chih-wen ChangAbstract:In this paper we present a simple analytical model to evaluate the impact of measurement errors on the closed-Loop Power Control for code division multiple access (CDMA) systems. By introducing a new performance measurement, the probability of false command in Power Control, P/sub FC/, a closed form formula for calculating P/sub FC/ with consideration of measurement errors is presented. Furthermore, we derive a bit error rate (BER) performance bound in terms of P/sub FC/ for the CDMA system with closed-Loop Power Control (CLPC). The proposed analytical approach can quantitatively evaluate the performance of the CLPC taking into account of the effects of measurement errors and Doppler frequency under a Rayleigh fading channel. Through simulation and analysis, we show that the proposed analytical BER bound can accurately estimate the BER performance of the CLPC under the impact of measurement errors. Interestingly, we find that the CLPC is less sensitive to measurement errors due to the non-linear operation in the one step up/down Power Control scheme compared with the variable-step size Power Control.
