Cooperative communication can achieve spatial diversity gains,and consequently combats signal fading due to multipath propagation in wireless networks powerfully.A novel complex field network-coded cooperation（CFNCC...Cooperative communication can achieve spatial diversity gains,and consequently combats signal fading due to multipath propagation in wireless networks powerfully.A novel complex field network-coded cooperation（CFNCC） scheme based on multi-user detection for the multiple unicast transmission is proposed.Theoretic analysis and simulation results demonstrate that,compared with the conventional cooperation（CC） scheme and network-coded cooperation（NCC） scheme,CFNCC would obtain higher network throughput and consumes less time slots.Moreover,a further investigation is made for the symbol error probability（SEP） performance of CFNCC scheme,and SEPs of CFNCC scheme are compared with those of NCC scheme in various scenarios for different signal to noise ratio（SNR） values.展开更多
Multi-user detection (MUD) based on multirate transmission in code division multiple access (CDMA) system is discussed. Under the requirement of signal interference ratio (SIR) detection at base station and framework ...Multi-user detection (MUD) based on multirate transmission in code division multiple access (CDMA) system is discussed. Under the requirement of signal interference ratio (SIR) detection at base station and framework with parallel interference cancellation, a supervision decision algorithm based on pre-decision of probabilistic data association (PDA) and hard decision is proposed. The detection performance is analyzed and simulation is implemented to show that the supervision decision algorithm improves the detection performance effectively.展开更多
A study on the zero-forcing beamforming （ZFBF） scheme with antenna selection at user terminals in downlink multi-antenna multi-user systems is presented. Simulation results show that the proposed ZFBF scheme with re...A study on the zero-forcing beamforming （ZFBF） scheme with antenna selection at user terminals in downlink multi-antenna multi-user systems is presented. Simulation results show that the proposed ZFBF scheme with receiver antenna selection （ZFBF-AS） achieves considerable throughput improvement over the ZFBF scheme with single receiver antenna. The results also show that, with multi-user diversity, the ZFBF-AS scheme approaches the throughput performance of the ZFBF scheme using all receiver antennas （ZFBF-WO-AS） when the base station adopts semi-orthogonal user selection （SUS） algorithm, and achieves larger throughput when the base station adopts the Round-robin scheduling algorithm. Compared with ZFBF-WO-AS, the proposed ZFBF-AS scheme can reduce the cost of user equipments and the channel state information requirement at the transmitter （CSIT） as well as the multiuser scheduling complexity at the transmitter.展开更多
A power allocation scheme for multi-user multiple-input multiple-output orthogonal frequency division multiplexing （MI- MO-OFDM） systems with channel state information （CSI） on transmitter and receiver is pressed....A power allocation scheme for multi-user multiple-input multiple-output orthogonal frequency division multiplexing （MI- MO-OFDM） systems with channel state information （CSI） on transmitter and receiver is pressed. Multi-user lower allocation can be decoupled into single user lower allocation throughout null space mapping of multi-user channel and lower allocation can be performed throughout spatial-spectral water-filling for per user.To deal with more users in system and fading correlation,scheduling is oerformed to maintain the gain of power allocation.The proposed scheme can substantially improve system＇s spectral efficiency with low complexity.Simulation results validate the accuracy of theoretic analyses.展开更多
The syndrome a posteriori probability of the log-likelihood ratio of intercepted codewords is used to develop an algorithm that recognizes the polar code length and generator matrix of the underlying polar code.Based ...The syndrome a posteriori probability of the log-likelihood ratio of intercepted codewords is used to develop an algorithm that recognizes the polar code length and generator matrix of the underlying polar code.Based on the encoding structure,three theorems are proved,two related to the relationship between the length and rate of the polar code,and one related to the relationship between frozen-bit positions,information-bit positions,and codewords.With these three theorems,polar codes can be quickly reconstruced.In addition,to detect the dual vectors of codewords,the statistical characteristics of the log-likelihood ratio are analyzed,and then the information-and frozen-bit positions are distinguished based on the minimumerror decision criterion.The bit rate is obtained.The correctness of the theorems and effectiveness of the proposed algorithm are validated through simulations.The proposed algorithm exhibits robustness to noise and a reasonable computational complexity.展开更多
The aim of this paper is to simulate and study the early moments of the reactive ballistics of a large caliber projectile fired from a gun,combining 0D and 2D axisymmetric Computational Fluid Dynamics(CFD)approaches.F...The aim of this paper is to simulate and study the early moments of the reactive ballistics of a large caliber projectile fired from a gun,combining 0D and 2D axisymmetric Computational Fluid Dynamics(CFD)approaches.First,the methodology is introduced with the development of an interior ballistics(IB)lumped parameter code(LPC),integrating an original image processing method for calculating the specific regression of propellant grains that compose the gun propellant.The ONERA CFD code CEDRE,equipped with a Dynamic Mesh Technique(DMT),is then used in conjunction with the developed LPC to build a dedicated methodology to calculate IB.First results obtained on the AGARD gun and 40 mm gun test cases are in a good agreement with the existing literature.CEDRE is also used to calculate inter-mediate ballistics(first milliseconds of free flight of the projectile)with a multispecies and reactive approach either starting from the gun muzzle plane or directly following IB.In the latter case,an inverse problem involving a Latin hypercube sampling method is used to find a gun propellant configuration that allows the projectile to reach a given exit velocity and base pressure when IB ends.The methodology developed in this work makes it possible to study the flame front of the intermediate flash and depressurization that occurs in a base bleed(BB)channel at the gun muzzle.Average pressure variations in the BB channel during depressurization are in good agreement with literature.展开更多
由于自由曲面灵活的空间布局和设计自由度,使光学系统的结构得到了简化,像质得到了提高。本文通过设计实例详细介绍了在光学设计软件CODE V中运用用户自定义面型UDS(user defined surface)的功能和计算机动态链接库DLL(dynam ic link li...由于自由曲面灵活的空间布局和设计自由度,使光学系统的结构得到了简化,像质得到了提高。本文通过设计实例详细介绍了在光学设计软件CODE V中运用用户自定义面型UDS(user defined surface)的功能和计算机动态链接库DLL(dynam ic link library)软件技术设计含有自由曲面光学系统的方法。通过利用此方法设计了球面和锥面光学系统,验证了其准确性和可靠性。并且利用此项技术设计了含有自由曲面的光学系统,使光学系统达到了质量轻、体积小的设计目标。此项技术扩充了CODE V软件的功能,有效地拓宽了CODE V计算复杂面型的能力。展开更多
基金supported by the National Natural Science Foundation of China(6104000561001126+5 种基金61271262)the China Postdoctoral Science Foundation Funded Project(201104916382012T50789)the Natural Science Foundation of Shannxi Province of China(2011JQ8036)the Special Fund for Basic Scientific Research of Central Colleges (CHD2012ZD005)the Research Fund of Zhejiang University of Technology(20100244)
文摘Cooperative communication can achieve spatial diversity gains,and consequently combats signal fading due to multipath propagation in wireless networks powerfully.A novel complex field network-coded cooperation（CFNCC） scheme based on multi-user detection for the multiple unicast transmission is proposed.Theoretic analysis and simulation results demonstrate that,compared with the conventional cooperation（CC） scheme and network-coded cooperation（NCC） scheme,CFNCC would obtain higher network throughput and consumes less time slots.Moreover,a further investigation is made for the symbol error probability（SEP） performance of CFNCC scheme,and SEPs of CFNCC scheme are compared with those of NCC scheme in various scenarios for different signal to noise ratio（SNR） values.
文摘Multi-user detection (MUD) based on multirate transmission in code division multiple access (CDMA) system is discussed. Under the requirement of signal interference ratio (SIR) detection at base station and framework with parallel interference cancellation, a supervision decision algorithm based on pre-decision of probabilistic data association (PDA) and hard decision is proposed. The detection performance is analyzed and simulation is implemented to show that the supervision decision algorithm improves the detection performance effectively.
基金supported by the National Natural Science Foundation of China (60496314)the National High Technology Research and Development Program of China (2006AA01Z266).
文摘A study on the zero-forcing beamforming （ZFBF） scheme with antenna selection at user terminals in downlink multi-antenna multi-user systems is presented. Simulation results show that the proposed ZFBF scheme with receiver antenna selection （ZFBF-AS） achieves considerable throughput improvement over the ZFBF scheme with single receiver antenna. The results also show that, with multi-user diversity, the ZFBF-AS scheme approaches the throughput performance of the ZFBF scheme using all receiver antennas （ZFBF-WO-AS） when the base station adopts semi-orthogonal user selection （SUS） algorithm, and achieves larger throughput when the base station adopts the Round-robin scheduling algorithm. Compared with ZFBF-WO-AS, the proposed ZFBF-AS scheme can reduce the cost of user equipments and the channel state information requirement at the transmitter （CSIT） as well as the multiuser scheduling complexity at the transmitter.
基金This project was supported bythe National Natural Science Foundation of China (60272079) the National High Technol-ogy Research and Development Plan Project of China (2001AA123014) .
文摘A power allocation scheme for multi-user multiple-input multiple-output orthogonal frequency division multiplexing （MI- MO-OFDM） systems with channel state information （CSI） on transmitter and receiver is pressed. Multi-user lower allocation can be decoupled into single user lower allocation throughout null space mapping of multi-user channel and lower allocation can be performed throughout spatial-spectral water-filling for per user.To deal with more users in system and fading correlation,scheduling is oerformed to maintain the gain of power allocation.The proposed scheme can substantially improve system＇s spectral efficiency with low complexity.Simulation results validate the accuracy of theoretic analyses.
基金supported by the National Natural Science Foundation of China(62371465)Taishan Scholar Project of Shandong Province(ts201511020)the Chinese National Key Laboratory of Science and Technology on Information System Security(6142111190404).
文摘The syndrome a posteriori probability of the log-likelihood ratio of intercepted codewords is used to develop an algorithm that recognizes the polar code length and generator matrix of the underlying polar code.Based on the encoding structure,three theorems are proved,two related to the relationship between the length and rate of the polar code,and one related to the relationship between frozen-bit positions,information-bit positions,and codewords.With these three theorems,polar codes can be quickly reconstruced.In addition,to detect the dual vectors of codewords,the statistical characteristics of the log-likelihood ratio are analyzed,and then the information-and frozen-bit positions are distinguished based on the minimumerror decision criterion.The bit rate is obtained.The correctness of the theorems and effectiveness of the proposed algorithm are validated through simulations.The proposed algorithm exhibits robustness to noise and a reasonable computational complexity.
基金the French Defense Innovation Agency (AID)the French Procurement Agency for Armament (DGA)ONERA's scientific direction for funding and supporting the present work
文摘The aim of this paper is to simulate and study the early moments of the reactive ballistics of a large caliber projectile fired from a gun,combining 0D and 2D axisymmetric Computational Fluid Dynamics(CFD)approaches.First,the methodology is introduced with the development of an interior ballistics(IB)lumped parameter code(LPC),integrating an original image processing method for calculating the specific regression of propellant grains that compose the gun propellant.The ONERA CFD code CEDRE,equipped with a Dynamic Mesh Technique(DMT),is then used in conjunction with the developed LPC to build a dedicated methodology to calculate IB.First results obtained on the AGARD gun and 40 mm gun test cases are in a good agreement with the existing literature.CEDRE is also used to calculate inter-mediate ballistics(first milliseconds of free flight of the projectile)with a multispecies and reactive approach either starting from the gun muzzle plane or directly following IB.In the latter case,an inverse problem involving a Latin hypercube sampling method is used to find a gun propellant configuration that allows the projectile to reach a given exit velocity and base pressure when IB ends.The methodology developed in this work makes it possible to study the flame front of the intermediate flash and depressurization that occurs in a base bleed(BB)channel at the gun muzzle.Average pressure variations in the BB channel during depressurization are in good agreement with literature.
文摘由于自由曲面灵活的空间布局和设计自由度,使光学系统的结构得到了简化,像质得到了提高。本文通过设计实例详细介绍了在光学设计软件CODE V中运用用户自定义面型UDS(user defined surface)的功能和计算机动态链接库DLL(dynam ic link library)软件技术设计含有自由曲面光学系统的方法。通过利用此方法设计了球面和锥面光学系统,验证了其准确性和可靠性。并且利用此项技术设计了含有自由曲面的光学系统,使光学系统达到了质量轻、体积小的设计目标。此项技术扩充了CODE V软件的功能,有效地拓宽了CODE V计算复杂面型的能力。
