The distributed antenna system （DAS） is considered as a promising architecture for future wireless access. This paper describes the uplink of a power-controlled circular-layout DAS （CL-DAS） with minimum mean-squar...The distributed antenna system （DAS） is considered as a promising architecture for future wireless access. This paper describes the uplink of a power-controlled circular-layout DAS （CL-DAS） with minimum mean-square error （MMSE） receivers. Results from random matrix theory are used to show that for such a DAS, the per-user sum rate and the total transmit power both converge as the number of users and antennas goes to infinity with a constant ratio of antennas to users. The relationship between the asymptotic per-user sum rate and the asymptotic total transmit power is given for all possible values of the radius of the circle on which antennas are placed. This rate-power relationship is then used to find the optimal radius. With this optimal radius, the CL-DAS is proved to offer a significant gain compared with a traditional co-located antenna system. Simulation results demonstrate the validity of the analysis and the superiority of the DAS.展开更多
The small-cell technology is promising for spectral-efficiency enhancement. However, it usually requires a huge amount of energy consumption. In this paper, queue state information and channel state information are jo...The small-cell technology is promising for spectral-efficiency enhancement. However, it usually requires a huge amount of energy consumption. In this paper, queue state information and channel state information are jointly utilized to minimize the time average of overall energy consumption for a multi-carrier small-cell network, where the inter-cell interference is an intractable problem. Based on the Lyapunov optimization theory, the problem could be solved by dynamically optimizing the problem of user assignment, carrier allocation and power allocation in each time slot. As the optimization problem is NP-hard, we propose a heuristic iteration algorithm to solve it. Numerical results verify that the heuristic algorithm offers an approximate performance as the brute-force algorithm. Moreover, it could bring down the overall energy consumption to different degrees according to the variation of traffic load. Meanwhile, it could achieve the same sum rate as the algorithm which focuses on maximizing system sum rate.展开更多
针对多输入多输出(MIMO)系统获取信道信息过程中存在估计误差、反馈延迟等问题,为了提高低信噪比(SNR)时的系统性能,提出了一种基于权值可调的稳健干扰对齐算法。首先,在理想信道的基础上考虑信道误差的影响重新构建系统模型;然后,采用...针对多输入多输出(MIMO)系统获取信道信息过程中存在估计误差、反馈延迟等问题,为了提高低信噪比(SNR)时的系统性能,提出了一种基于权值可调的稳健干扰对齐算法。首先,在理想信道的基础上考虑信道误差的影响重新构建系统模型;然后,采用矩阵投影技术对接收端的信号空间进行分解,分成期望信号子空间与干扰信号子空间两部分;其次,考虑期望信号和干扰信号之间的相互影响,把两者泄漏到相应的子空间的功率加权和作为目标函数运用迭代思想计算出预编码和干扰抑制矩阵;最后,利用计算出的预编码和干扰抑制矩阵推导出存在信道误差的和速率表达式。仿真结果表明与稳健最小干扰泄漏算法相比,在信噪比为10 d B、信道误差方差取值0.05时,系统的频谱效率提升了25%,能量效率提升了38%,因此所提算法在低信噪比时可以有效地提升系统性能。展开更多
基金Supported by the National Natural Science Foundation of China (No. 90204001)
文摘The distributed antenna system （DAS） is considered as a promising architecture for future wireless access. This paper describes the uplink of a power-controlled circular-layout DAS （CL-DAS） with minimum mean-square error （MMSE） receivers. Results from random matrix theory are used to show that for such a DAS, the per-user sum rate and the total transmit power both converge as the number of users and antennas goes to infinity with a constant ratio of antennas to users. The relationship between the asymptotic per-user sum rate and the asymptotic total transmit power is given for all possible values of the radius of the circle on which antennas are placed. This rate-power relationship is then used to find the optimal radius. With this optimal radius, the CL-DAS is proved to offer a significant gain compared with a traditional co-located antenna system. Simulation results demonstrate the validity of the analysis and the superiority of the DAS.
基金partially supported by National Basic Research Program of China (2013CB329002)National Natural Science Foundation of China (61631013)+6 种基金The National High Technology Research and Development Program of China(2014AA01A703)Science Fund for Creative Research Groups of NSFC (61321061)National Major Project (2017ZX03001011)International Science and Technology Cooperation Program (2014DFT10320)National Science Foundation of China (61701457 \& 61771286)Tsinghua-Qualcomm Joint Research ProgramHuawei Innovation Research Program
文摘The small-cell technology is promising for spectral-efficiency enhancement. However, it usually requires a huge amount of energy consumption. In this paper, queue state information and channel state information are jointly utilized to minimize the time average of overall energy consumption for a multi-carrier small-cell network, where the inter-cell interference is an intractable problem. Based on the Lyapunov optimization theory, the problem could be solved by dynamically optimizing the problem of user assignment, carrier allocation and power allocation in each time slot. As the optimization problem is NP-hard, we propose a heuristic iteration algorithm to solve it. Numerical results verify that the heuristic algorithm offers an approximate performance as the brute-force algorithm. Moreover, it could bring down the overall energy consumption to different degrees according to the variation of traffic load. Meanwhile, it could achieve the same sum rate as the algorithm which focuses on maximizing system sum rate.
文摘针对多输入多输出(MIMO)系统获取信道信息过程中存在估计误差、反馈延迟等问题,为了提高低信噪比(SNR)时的系统性能,提出了一种基于权值可调的稳健干扰对齐算法。首先,在理想信道的基础上考虑信道误差的影响重新构建系统模型;然后,采用矩阵投影技术对接收端的信号空间进行分解,分成期望信号子空间与干扰信号子空间两部分;其次,考虑期望信号和干扰信号之间的相互影响,把两者泄漏到相应的子空间的功率加权和作为目标函数运用迭代思想计算出预编码和干扰抑制矩阵;最后,利用计算出的预编码和干扰抑制矩阵推导出存在信道误差的和速率表达式。仿真结果表明与稳健最小干扰泄漏算法相比,在信噪比为10 d B、信道误差方差取值0.05时,系统的频谱效率提升了25%,能量效率提升了38%,因此所提算法在低信噪比时可以有效地提升系统性能。
