研究了基于下行无线信息和能量协同传输(simultaneous wireless-information and power-transfer,SWIPT)大规模多输入单输出(multiple-input and single-output,MISO)系统的吞吐率优化问题.该系统为时分双工(time division duplex,TDD)...研究了基于下行无线信息和能量协同传输(simultaneous wireless-information and power-transfer,SWIPT)大规模多输入单输出(multiple-input and single-output,MISO)系统的吞吐率优化问题.该系统为时分双工(time division duplex,TDD)模式,同时移动站采用先收集后传输的协议.在下行信噪比(signal-to-noise ratio,SNR)和移动站的传输功率约束下,为实现上行吞吐率的最大化,对功率分配系数和下行传输时间进行了联合优化,由于该问题为非凸优化问题,采用基于拉格朗日乘子的梯度算法进行优化.最后,通过与单独优化下行传输时间算法的比较,验证了该联合优化算法的优越性.展开更多
Two efficient and low complexity multiuser scheduling algorithms are proposed for the uplink multi- ple-input multiple-output systems in this paper. Conventionally, the exhaustive search algorithm （ESA） can give the...Two efficient and low complexity multiuser scheduling algorithms are proposed for the uplink multi- ple-input multiple-output systems in this paper. Conventionally, the exhaustive search algorithm （ESA） can give the optimal performance; however, it is complexity prohibitive for practical implementation. Aiming at re- ducing the complexity while keeping the achievable sum rate performance, two heuristic algorithms are proposed for the multiuser scheduling problems： the improved genetic algorithm and simplified norm-based greedy algo- rithm. Moreover, we also consider the heterogeneity scenario where a modified grouping-based user selection al- gorithm is given to guarantee the user＇ s fairness. Specifically, the asymptotic behavior of the norm-based greed- y algorithm is given when each user is equipped with one antenna. Numerical examples demonstrate the superi- ority of our proposed schedulin~ and ~rouoin~ algorithms.展开更多
This paper represents a comparative performance evaluation of different diversity combining techniques for a SIMO-OFDM （single-input-multiple-output orthogonal frequency division multiplexing） system over Rayleigh f...This paper represents a comparative performance evaluation of different diversity combining techniques for a SIMO-OFDM （single-input-multiple-output orthogonal frequency division multiplexing） system over Rayleigh fading channel. OFDM is a key technique for achieving high data rates and spectral efficiency requirements for wireless communication systems. But in scattering environment, the system performances are severely degraded by the effects of multipath fading and inter-symbol interference. In wireless communication systems, antenna diversity is an important technique to combat multipath fading in order to improve the system performance and increase the channel capacity. In this paper, the performance of different diversity combining techniques-SC （selection combining）, EGC （equal gain combining） and MRC （maximal ratio combining） has been analyzed and compared in terms of SNR （signal to noise ratio） and BER （bit error rate） probability. The simulation results show that the maximal ratio combining technique provides maximum performance improvement relative to all other combining schemes by maximizing the SNR of SIMO-OFDM system at the combiner output. The analytic expressions of error probability and effective bit energy to noise ratio correlated with BPSK （binary phase shift keying） modulation have been derived and formulated for N-branch SC, EGC and MRC schemes. The BER characteristics for all three combining techniques are simulated in MATLAB （matrix laboratory） tool box for varying bit energy to noise ratio. Our results also derives that SNR can be improved if the number of receiving antenna is increased, which in turn reduces BER over a Rayleigh fading channel.展开更多
The failure modes and effects analysis （FMEA） is widely applied in manufacturing industries in various phases of the product life cycle to evaluate the system, its design and processes for failures that can occur. T...The failure modes and effects analysis （FMEA） is widely applied in manufacturing industries in various phases of the product life cycle to evaluate the system, its design and processes for failures that can occur. The FMEA team often demonstrates different opinions and these different types of opinions are very difficult to incorporate into the FMEA by the traditional risk priority number model. In this paper, for each of the Occurrence, Severity and Detectivity parameters a fuzzy set is defined and the opinion of each FMEA team members is considered. These opinions are considered simultaneously with weights that are given to each individual based on their skills and experience levels. In addition, the opinion of the costumer is considered for each of the FMEA parameters. Then, the Risk Priority Numbers （RPN） is calculated using a Multi Input Single Output （MISO） fuzzy expert system. The proposed model is applied for prioritizing the failures of Peugeot 206 Engine assembly line in IKCo （Iran Khodro Company）.展开更多
文摘研究了基于下行无线信息和能量协同传输(simultaneous wireless-information and power-transfer,SWIPT)大规模多输入单输出(multiple-input and single-output,MISO)系统的吞吐率优化问题.该系统为时分双工(time division duplex,TDD)模式,同时移动站采用先收集后传输的协议.在下行信噪比(signal-to-noise ratio,SNR)和移动站的传输功率约束下,为实现上行吞吐率的最大化,对功率分配系数和下行传输时间进行了联合优化,由于该问题为非凸优化问题,采用基于拉格朗日乘子的梯度算法进行优化.最后,通过与单独优化下行传输时间算法的比较,验证了该联合优化算法的优越性.
基金Sponsored by the Technology Specific Project(Grant No. 2010ZX03002-003-01)
文摘Two efficient and low complexity multiuser scheduling algorithms are proposed for the uplink multi- ple-input multiple-output systems in this paper. Conventionally, the exhaustive search algorithm （ESA） can give the optimal performance; however, it is complexity prohibitive for practical implementation. Aiming at re- ducing the complexity while keeping the achievable sum rate performance, two heuristic algorithms are proposed for the multiuser scheduling problems： the improved genetic algorithm and simplified norm-based greedy algo- rithm. Moreover, we also consider the heterogeneity scenario where a modified grouping-based user selection al- gorithm is given to guarantee the user＇ s fairness. Specifically, the asymptotic behavior of the norm-based greed- y algorithm is given when each user is equipped with one antenna. Numerical examples demonstrate the superi- ority of our proposed schedulin~ and ~rouoin~ algorithms.
文摘This paper represents a comparative performance evaluation of different diversity combining techniques for a SIMO-OFDM （single-input-multiple-output orthogonal frequency division multiplexing） system over Rayleigh fading channel. OFDM is a key technique for achieving high data rates and spectral efficiency requirements for wireless communication systems. But in scattering environment, the system performances are severely degraded by the effects of multipath fading and inter-symbol interference. In wireless communication systems, antenna diversity is an important technique to combat multipath fading in order to improve the system performance and increase the channel capacity. In this paper, the performance of different diversity combining techniques-SC （selection combining）, EGC （equal gain combining） and MRC （maximal ratio combining） has been analyzed and compared in terms of SNR （signal to noise ratio） and BER （bit error rate） probability. The simulation results show that the maximal ratio combining technique provides maximum performance improvement relative to all other combining schemes by maximizing the SNR of SIMO-OFDM system at the combiner output. The analytic expressions of error probability and effective bit energy to noise ratio correlated with BPSK （binary phase shift keying） modulation have been derived and formulated for N-branch SC, EGC and MRC schemes. The BER characteristics for all three combining techniques are simulated in MATLAB （matrix laboratory） tool box for varying bit energy to noise ratio. Our results also derives that SNR can be improved if the number of receiving antenna is increased, which in turn reduces BER over a Rayleigh fading channel.
文摘The failure modes and effects analysis （FMEA） is widely applied in manufacturing industries in various phases of the product life cycle to evaluate the system, its design and processes for failures that can occur. The FMEA team often demonstrates different opinions and these different types of opinions are very difficult to incorporate into the FMEA by the traditional risk priority number model. In this paper, for each of the Occurrence, Severity and Detectivity parameters a fuzzy set is defined and the opinion of each FMEA team members is considered. These opinions are considered simultaneously with weights that are given to each individual based on their skills and experience levels. In addition, the opinion of the costumer is considered for each of the FMEA parameters. Then, the Risk Priority Numbers （RPN） is calculated using a Multi Input Single Output （MISO） fuzzy expert system. The proposed model is applied for prioritizing the failures of Peugeot 206 Engine assembly line in IKCo （Iran Khodro Company）.
