1,721,301 research outputs found
Space-time coding with receive combiner bank for multiple-input-multiple-output system under multi-user cochannel interference
No full text[[abstract]]Space-time coding with receive combiner bank (STC-RCB), in which a bank of receive combiners is added before the space-time decoder for interference-plus-noise suppression, is proposed. Without loss of generality, the author consider space-time block code (STBC) to be the representative of STC and study the performance for (STBC-RCB). The author derive the output signal to interference-plus-noise ratio (SINR) (of the space-time decoder) for STBC-RCB under multi-user cochannel interference. By regarding STBC as a special case of STBC-RCB, the author also derive the output SINR for STBC under multi-user cochannel interference. Simulation results show that the output SINR of STBC-RCB can be much larger than that of STBC, also, they show that STBC-RCB can adopt the appropriate receive combining strategy in the RCB to further improve the performance.[[note]]SC
Identification and characterization of an organic solvent tolerance gene in Helicobacter pylori.
No full textAssessment of the parcel model in evaporating turbulent diluted sprays within a Large-Eddy-Simulation approach
Full text linkThe parcel concept has been exploited in the Eulerian-Lagrangian framework to alleviate the computational cost of tracking an enormous number of particles/droplets in the perspective of dispersed two-phase flows. In this work, with fully systematic analysis, we present a numerical investigation of the reliability of this parcel approach in turbulent flows bearing evaporating droplets. To fulfil this task, we address Large-eddy Simulations (LESs) of a turbulent diluted acetone jet-spray in conjunction with two filtering widths and various numbers of parcels, in which the latter is achieved by reducing the ensemble of all physical droplets with a coarsening factor varying from 0(1) to 0(1000), i.e. parcel ratio (PR). By comparing different realizations of parcel in LESs against that with PR = 1, as well as a fully resolved Direct Numerical Simulation (DNS), our numerical results demonstrate the robustness of the parcel concept only when the ratio between the computational and physical droplets is carefully implemented, depending on the grid spacing. In particular, a significant underestimation of the evaporation process is anticipatable if the parcel ratio exceeds a specific threshold which is much larger in the case of a coarse mesh than a fine one. We propose that the appropriate parcel ratio should be of the order of the filtering width and the dissipative length ratio, thus of the same order as the coarsening factor of the Eulerian mesh spacing with respect to the reference DNS
Centralized and distributed joint dual transmitter receiver diversity and power control for wireless networks
No full text[[abstract]]Centralized and distributed algorithms, which aim to derive the optimal feasible power and weight for joint dual transmitter receiver diversity and power control, are proposed in this paper. We first show that the optimal feasible power and weight can be obtained by executing the centralized algorithm. Then we propose the distributed algorithm that simulates the operation of the centralized algorithm and iteratively adjusts the power and weight of each individual. It is shown that the power and weight obtained from the distributed algorithm converge to the optimal feasible power and weight, and simulation results also coincide with this fact. Furthermore, we also found that the centralized algorithm outperforms the previous approach in the average power level per user and the probability of feasibility. (C) 2007 Elsevier B.V. All rights reserved.[[note]]SC
Distributed rate assignment for multicarrier multi-cell networks
No full text[[abstract]]A distributed rate assignment is proposed for the multicarrier multi-cell networks. It assigns the data rate for each subchannel in a distributed manner and needs not measure the channel gains. We show that the aggregate rate can be increased by increasing the number of iterations in this assignment.[[note]]SC
Centralized and distributed power control algorithms for multimedia CDMA networks
No full text[[abstract]]We study in this paper both centralized and distributed transmitter power control algorithms for multimedia CDMA networks. In our study, users can have different data rates as well as different quality of service (QoS) requirements characterized by bit energy-to-interference ratios. For centralized power control, we derive an optimum power assignment which can be obtained by solving a set of linear equations. For distributed power control (DPC), we study the fully distributed power control (FDPC) algorithm. We modify the FDPC algorithm so that it can be used in a multi-service environment. We prove that, as long as there are solutions of power levels for all users to meet their QoS requirements, the FDPC algorithm can always find one. A quasi-centralized power control algorithm with partial link gain measurements is proposed to speed up the process in finding a feasible power set. In the algorithm, a base station measures the link gains for all mobiles connected to it. Numerical results show that quasi-centralized power control can find a feasible power set much faster than distributed power control. Copyright (C) 2005 John Wiley Sons, Ltd.[[note]]SC
Rate adaptation with joint receive diversity and power control for cognitive radio networks
No full text[[abstract]]A joint receive diversity and power control (JRDPC) algorithm is proposed for cognitive radio networks. By this algorithm, the quality of service for the primary user can be ensured and the secondary user (SU) can make its signal-to-interference-plus-noise ratio (SINR) converge to the SINR requirement. To realize rate adaptation, we propose the rate adaptation algorithm that works with the proposed JRDPC algorithm. We assume that there is a throughput requirement (which is determined by the transmission rate and the SINR), and the proposed rate adaptation algorithm aims to adapt SUs transmission rate to the SINR so that SUs adapted transmission rate can meet the throughput requirement. Simulation results show that compared to rate adaptation without joint receive diversity and power control, the proposed rate adaptation algorithm increases SUs probability of feasibility (for making SUs adapted transmission rate meet the throughput requirement). (C) 2011 Elsevier B.V. All rights reserved.[[note]]SC
SINR Feedback Based Rate Control for Dual-Antenna-Array Multi-Cellular Networks with Cochannel Interference
No full text[[abstract]]We propose in this paper a dual-antenna-array (with transmitter antenna array and receiver antenna array) architecture, where the antenna elements are divided into several antenna element sets and each traffic channel is transmitted over an antenna element set, to realize the multiple traffic channels set up by a user. A SINR feedback based algorithm, which can regulate the transmission rate by iteratively adjusting the power on each traffic channel, is proposed to execute the rate control for the proposed dual-antenna-array architecture under cochannel interference. It is shown that the proposed algorithm can make the throughput meet the throughput requirement or achieve the weighted bandwidth sharing for certain fairness. In addition, we further propose a traffic channel configuration algorithm to help the SINR feedback based algorithm find the optimal traffic channel configuration that can meet the throughput requirement for each traffic channel or results in the maximal total throughput for each user.[[note]]SC
Receive-combining-aided MIMO system
No full text[[abstract]]A receive-combining-aided MIMO system, in which multiple combiners are added before the decoder (or detector) for noise suppression, is proposed to improve the effective SNR and the symbol error rate. We apply the concept of the receive combining to STBC to establish receive-combining-aided STBC (RC-STBC) and derive the effective SNR for this scheme. Simulation results show that RC-STBC has larger effective SNR than STBC, also, they show that RC-STBC can have lower symbol error rate than STBC at low input SNR or in the high-order modulation scheme. (C) 2013 The Franklin Institute. Published by Elsevier Ltd. All rights reserved.[[note]]SC
Ratioed power and rate control for CDMA wireless networks
No full text[[abstract]]We propose in this paper the ratioed power and rate control (RPRC) algorithm to satisfy the requirements of both the data rate and the signal quality. During the execution of the RPRC algorithm, only the representative user in each cell adjusts its power level according to certain distributed power control algorithm, and the ratio of the power level for the non-representative user to that for the representative user is kept constant. When the RPRC algorithm is finished, the power levels for all users remain unchanged and the transmission rate is determined by the available rate. We show that the RPRC algorithm can be used for allocating the bandwidth of each cell and achieving the required rate of each user. Furthermore, simulation results reveal that the RPRC algorithm results in larger throughput and finds a feasible power set faster than the other algorithm. Copyright (C) 2008 John Wiley & Sons, Ltd.[[note]]SC
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