排序方式: 共有62条查询结果,搜索用时 265 毫秒
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下行多用户MIMO-OFDMA/SDMA系统动态资源分配 总被引:2,自引:0,他引:2
该文对下行多用户MIMO-OFDMA/SDMA系统动态资源分配算法进行了研究,在满足各种约束条件的前提下,以最大化系统吞吐量为目标建立了相应的优化模型。由于最优解难以获得,将整个优化过程分两步完成,第1步定义了一个用于度量配置多根天线的用户空间兼容性的指标,并根据该指标提出了相应的调度算法;第2步提出了两种次优的资源分配算法。仿真结果表明,所提算法优于传统的随机调度算法,与功率复用策略结合时,所提算法的性能接近于基于用户选择的最优分配算法的性能。 相似文献
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Resource allocation problem in multiuser multiple input single output-orthogonal frequency division multiple access (MISO-OFDMA) systems with downlink beamforming for frequency selective fading channels is studied. The article aims at maximizing system throughput with the constraints of total power and bit error rate (BER) while supporting fairness among users. The downlink proportional fairness (PF) scheduling problem is reformulated as a maximization of the sum of logarithmic user data rate. From necessary conditions on optimality obtained analytically by Karush-Kuhn-Tucker (KKT) condition, an efficient user selection and resource allocation algorithm is proposed. The computer simulations reveal that the proposed algorithm achieves tradeoff between system throughput and fairness among users. 相似文献
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Dynamic Spatial Channel Assignment for Smart Antenna 总被引:1,自引:0,他引:1
The paper describes an optimal dynamic channel assignment algorithm for smart antennas. This algorithm can deal with the Spatial Division Multiple Access (SDMA) and traditional channel multiple accesses (FDMA, TDMA, or CDMA) simultaneously to enlarge the capacity of communication systems. This algorithm has several merits, including less computer time, the largest capacity, and avoidance of co-channel interference. The paper also describes the idea of a spatial channel pattern, in which several users can share a channel. Several simulation results are presented in the paper. 相似文献
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In this paper, we propose two low-complexity adaptive step size mechanisms to enhance the performance of stochastic gradient (SG) algorithms for adaptive beamforming. The beamformer is designed according to the constrained constant modulus (CCM) criterion and the proposed mechanisms are employed in the SG algorithm for implementation. A complexity comparison is provided to show their advantages over existing methods, and a sufficient condition for the convergence of the mean weight vector is established. Theoretical expressions of the excess mean-squared error (EMSE), in both the steady-state and tracking cases, are derived based on the energy conservation approach. The effects of multiple access interference (MAI) and additive noise are considered. Simulation experiments are presented for both the stationary and non-stationary scenarios, illustrating that the proposed algorithms achieve superior performance compared with existing methods, and verifying the accuracy of the analyses. 相似文献
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智能天线及其在移动通信中的应用 总被引:11,自引:0,他引:11
智能天线被公认为是未来移动通信的一种发展趋势。文章对天线的基本概念、关键技术、系统性能的改善及国外研究状况等进行了阐述 ,指出了研究过程中存在的问题及发展方向。 相似文献
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We propose and demonstrate a visible light communication (VLC) scheme based on space-division multiple access (SDMA) optical beamforming to accommodate multiple user devices in the VLC based on optical beamforming. SDMA optical bealnforming is a technique which separates light-emitting diode light spa- tially and focuses each part on different target devices simultaneously. We show the experimental results of the VLC signal amplitudes, the optical power densities, and the bit-error rate performance as a function of transmission distance before and after the SDMA optical beamforming. The results show that the VLC signal amplitudes and optical power densities are improved by 8-2 and 3.8- 5 dB, respectively, with the help of SDMA optical beamforming. 相似文献
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Toward the Energy Efficiency of Resource Allocation Algorithms for OFDMA Downlink MIMO Systems
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Wei-Chiang Wu 《电子科技学刊:英文版》2019,17(4):358-371
The problem of the simultaneous multi-user resource allocation algorithm in orthogonal frequency division multiple access (OFDMA) based systems has recently attracted significant interest. However, most studies focus on maximizing the system throughput and spectral efficiency. As the green radio is essential in 5G and future networks, the energy efficiency becomes the major concern. In this paper, we develop four resource allocation schemes in the downlink OFDMA network and the main focus is on analyzing the energy efficiency of these schemes. Specifically, we employ the advanced multi-antenna technology in a multiple input-multiple output (MIMO) system. The first scheme is based on transmit spatial diversity (TSD), in which the vector channel with the highest gain between the base station (BTS) and specific antenna at the remote terminal (RT) is chosen for transmission. The second scheme further employs spatial multiplexing on the MIMO system to enhance the throughput. The space-division multiple-access (SDMA) scheme assigns single subcarrier simultaneously to RTs with pairwise “nearly orthogonal” spatial signatures. In the fourth scheme, we propose to design the transmit beamformers based on the zero-forcing (ZF) criterion such that the multi-user interference (MUI) is completely removed. We analyze the tradeoff between the throughput and power consumption and compare the performance of these schemes in terms of the energy efficiency. 相似文献
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蜂窝通信的空分多址:概念、算法和性能 总被引:6,自引:0,他引:6
蜂窝通信采用空分多址正在移动通信领域引起广泛关注。本文对空分多址的基本概念、空间信道模型及其知识利用、上下行链路的实现方法和算法、以及对系统性能的改善等诸方面,进行了比较全面的论述。对目前空分多址研究中值得关注的问题,表达了作者的观点。 相似文献