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
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
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 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
随着互联网技术的发展以及社交网络的扩大,网络平台已经成为人们获取信息的一个重要途径。标签的引入提升了信息分类及检索效率。同时,标签推荐系统的出现不仅方便了用户输入标签,还提高了标签的质量。传统的标签推荐算法通常只考虑标...随着互联网技术的发展以及社交网络的扩大,网络平台已经成为人们获取信息的一个重要途径。标签的引入提升了信息分类及检索效率。同时,标签推荐系统的出现不仅方便了用户输入标签,还提高了标签的质量。传统的标签推荐算法通常只考虑标签和项目两个主体,而忽略了用户在选择标签时个人意图所起到的重要作用。由于在标签推荐系统中标签最终由用户确定,因此用户的偏好在标签推荐中起着关键作用。为此,引入用户作为主体,并结合用户发布的历史帖子的先后顺序,将标签推荐任务建模为更加符合真实场景的序列标签推荐任务。提出了一种基于MLP的序列标签推荐方法(MLP for Sequential Tag Recommendation, MLP4STR),该方法显式地建模用户偏好用于引导整体标签推荐。MLP4STR采用一种跨特征对齐的MLP序列特征提取框架,将文本和标签的特征对齐,获取用户的历史帖子信息和历史标签信息中隐含的用户动态兴趣。最后,结合帖子内容和用户偏好进行标签推荐。在4个真实世界的数据集上得到的实验结果表明,MLP4STR能够有效地学习序列标签推荐中的用户历史行为序列的信息,其中,评价指标F1@5较最优的对比算法有显著提升。展开更多
为解决在双可重构智能超表面(Reconfigurable Intelligent Surface,RIS)系统中获取高维信道状态信息(Channel State Information,CSI)的挑战,提出了一种基于混合张量分解的多链路联合信道估计算法。首先,通过设计导频传输机制,将单反射...为解决在双可重构智能超表面(Reconfigurable Intelligent Surface,RIS)系统中获取高维信道状态信息(Channel State Information,CSI)的挑战,提出了一种基于混合张量分解的多链路联合信道估计算法。首先,通过设计导频传输机制,将单反射链路和双反射链路的接收信号分别建模为平行因子模型和平行因子塔克(Tucker)张量模型,将信道估计问题转化为混合张量因子矩阵的拟合问题。然后,考虑到多条链路之间共享的CSI,采用一种基于交替最小二乘迭代算法来分解混合张量,以有效估计出因子矩阵。最后,通过对该混合张量进行唯一性分析,与传统的Khatri-Rao分解方法相比,所提方法具备更为灵活的参数设计特点。仿真实验结果表明,该方法能够在训练块数小于RIS单元数的情况下有效估计反射链路CSI。展开更多
本文研究了基于1-比特模数转换器(Analog to Digital Converters,ADCs)的大规模多输入多输出(Multiple Input Multiple Output,MIMO)系统上行链路的多用户频率同步问题,其中多个单天线用户与配置大规模天线阵列的基站采用正交频分复用(O...本文研究了基于1-比特模数转换器(Analog to Digital Converters,ADCs)的大规模多输入多输出(Multiple Input Multiple Output,MIMO)系统上行链路的多用户频率同步问题,其中多个单天线用户与配置大规模天线阵列的基站采用正交频分复用(Orthogonal Frequency Division Multiplexing,OFDM)技术进行通信.针对多用户角度不重叠的场景,本文利用接收波束成形网络进行多用户干扰消除,从混叠的多用户信号中提取出目标用户的信息,进而对载波频偏(Carrier Frequency Offset,CFO)进行估计.其次,考虑1-比特ADC导致的量化噪声对系统性能的影响,理论推导了基站接收端处的信噪比(Signal-Noise Ratio,SNR).为了提升系统的性能,基于理论SNR对波束成形网络进行了优化设计.最后,计算机仿真结果显示了所提出的频偏估计算法与其他现有算法相比具有更好的性能.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.
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.
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.
文摘随着互联网技术的发展以及社交网络的扩大,网络平台已经成为人们获取信息的一个重要途径。标签的引入提升了信息分类及检索效率。同时,标签推荐系统的出现不仅方便了用户输入标签,还提高了标签的质量。传统的标签推荐算法通常只考虑标签和项目两个主体,而忽略了用户在选择标签时个人意图所起到的重要作用。由于在标签推荐系统中标签最终由用户确定,因此用户的偏好在标签推荐中起着关键作用。为此,引入用户作为主体,并结合用户发布的历史帖子的先后顺序,将标签推荐任务建模为更加符合真实场景的序列标签推荐任务。提出了一种基于MLP的序列标签推荐方法(MLP for Sequential Tag Recommendation, MLP4STR),该方法显式地建模用户偏好用于引导整体标签推荐。MLP4STR采用一种跨特征对齐的MLP序列特征提取框架,将文本和标签的特征对齐,获取用户的历史帖子信息和历史标签信息中隐含的用户动态兴趣。最后,结合帖子内容和用户偏好进行标签推荐。在4个真实世界的数据集上得到的实验结果表明,MLP4STR能够有效地学习序列标签推荐中的用户历史行为序列的信息,其中,评价指标F1@5较最优的对比算法有显著提升。
文摘为解决在双可重构智能超表面(Reconfigurable Intelligent Surface,RIS)系统中获取高维信道状态信息(Channel State Information,CSI)的挑战,提出了一种基于混合张量分解的多链路联合信道估计算法。首先,通过设计导频传输机制,将单反射链路和双反射链路的接收信号分别建模为平行因子模型和平行因子塔克(Tucker)张量模型,将信道估计问题转化为混合张量因子矩阵的拟合问题。然后,考虑到多条链路之间共享的CSI,采用一种基于交替最小二乘迭代算法来分解混合张量,以有效估计出因子矩阵。最后,通过对该混合张量进行唯一性分析,与传统的Khatri-Rao分解方法相比,所提方法具备更为灵活的参数设计特点。仿真实验结果表明,该方法能够在训练块数小于RIS单元数的情况下有效估计反射链路CSI。
文摘本文研究了基于1-比特模数转换器(Analog to Digital Converters,ADCs)的大规模多输入多输出(Multiple Input Multiple Output,MIMO)系统上行链路的多用户频率同步问题,其中多个单天线用户与配置大规模天线阵列的基站采用正交频分复用(Orthogonal Frequency Division Multiplexing,OFDM)技术进行通信.针对多用户角度不重叠的场景,本文利用接收波束成形网络进行多用户干扰消除,从混叠的多用户信号中提取出目标用户的信息,进而对载波频偏(Carrier Frequency Offset,CFO)进行估计.其次,考虑1-比特ADC导致的量化噪声对系统性能的影响,理论推导了基站接收端处的信噪比(Signal-Noise Ratio,SNR).为了提升系统的性能,基于理论SNR对波束成形网络进行了优化设计.最后,计算机仿真结果显示了所提出的频偏估计算法与其他现有算法相比具有更好的性能.
