共查询到18条相似文献,搜索用时 140 毫秒
1.
多用户MIMO(Multi-input multi-output)系统中,研究空间相关对联合空间分集和多用户分集的性能影响.推导了接收天线之间存在相关的多用户MIMO STBC(Space-time block coding)和MIMO MRT/MRC(Maximum-ratio-transmis-sion/maximal-ratio-combining)系统的中断容量、平均容量表达式,并由此进行性能分析.计算机仿真验证了理论分析的有效性.结果表明,相对于闭环的多用户MI-MO MRT/MRC系统,空间相关下开环的多用户MIMO STBC系统具有较低的平均容量和较高的调度增益. 相似文献
2.
分布式天线系统(DAS)由于其具有更大的覆盖范围,较好的功率效率,以及更高的系统容量在近年来备受关注,但很多文献都只是基于以上几个方面进行分析,而没有考虑多用户分集。该文提出了一种考虑用户公平性的最小容量损失轮询调度算法,并以该算法为基础,从多用户分集的角度研究了基于迫零波束成形算法的下行分布式天线系统的信道容量。结果表明,在天线数目和总功率相同的情况下,采用分布式天线系统可以得到比集中放置天线系统(CAS)更大的多用户分集增益。最小容量损失轮询调度算法明显优于普通轮询调度算法,该算法对DAS和CAS都适用。 相似文献
3.
4.
多天线的发送分集系统中多用户分集的研究 总被引:2,自引:0,他引:2
研究了如何通过选择发送天线和天线组合来提高整个多用户多天线系统的性能。本文分别讨论了STOBC、选择式发送分集、相位加权等各种发送信号结构下系统的调度性能。和其它发送信号结构相比,STOBC对于调度性能有着很大危害。信道反馈信息越多,调度性能就越好。不同的发送天线选择和组合策略得到不同的性能。本文讨论了三种选择策略:max-max, max-sum和max-min。max-max的调度性能优于其它两种策略。因此,发送信号的结构和选择策略都严重影响着多用户分集。 相似文献
5.
协作分集技术是一种新型的空间分集技术,它通过使多个具有单天线的终端共享彼此的天线,达到获得多天线分集增益的目的.协作分集技术能够提高系统的容量,降低系统的误码率.本文主要介绍了协作分集的概念分类,以及在多用户协作条件下的系统模型. 相似文献
6.
多天线无线数据通信系统中多用户分集的研究 总被引:1,自引:0,他引:1
研究当接收天线不少于发送天线时多输入多输出(MIMO)系统的多用户分集能力。首先从理论上分析了发送天线个数等于1和2时最大似然接收和迫零接收系统的平均吞吐量和调度增益,以及仿真分析了发送天线个数大于2时系统性能。理论分析和仿真表明:在多用户的MIMO系统中,接收的平均信噪比、用户个数、收发天线个数、接收机的结构等对于多用户分集有很大的影响。当发送天线个数为1时,接收天线较少(1,2,3)和平均信噪比为.10dB时调度增益很大,但调度增益随着天线个数和发送功率增大急剧下降。和最大似然接收相比,迫零接收具有更大的多用户分集增益,因此迫零接收机的吞吐量可以很容易超过最大似然接收机。 相似文献
7.
协作分集技术是一种新型的空间分集技术,它通过使多个具有单天线的终端共享彼此的天线,达到获得多天线分集增益的目的。协作分集技术能够提高系统的容量,降低系统的误码率。本文主要介绍了协作分集的概念分类,以及在多用户协作条件下的系统模型。 相似文献
8.
9.
该文研究了下行多用户MIMO通信系统中多用户分集问题,并且提出了两种基于最大系统容量准则的多用户分组调度算法。提出了一种基于相关用户的信道向量间内积的价值因子。通过使用该价值因子作为信道容量的评价标准,有效地降低了分组调度过程的复杂度。仿真结果显示该文提出的多用户调度算法可以明显提高系统容量;且随着系统中激活用户数量的增加,系统的调度增益不断增大。 相似文献
10.
11.
12.
Performance Analysis of Multiuser Selection Diversity 总被引:2,自引:0,他引:2
《Vehicular Technology, IEEE Transactions on》2006,55(6):1848-1861
13.
Mario Michael Josef A. 《AEUE-International Journal of Electronics and Communications》2008,62(4):288-298
Multiuser diversity is an inherent form of diversity present in any time-varying system with several users. An opportunistic scheduler has to be used in order to exploit this type of diversity. A scheme that increases the effective dynamic range of the channel by deploying multiple antennas at the transmitter is called opportunistic beamforming. Opportunistic beamforming increases the degree of multiuser diversity in several scenarios, including correlated channels. Nevertheless, multiuser diversity can also be combined with other transmit schemes that have proven to be effective in correlated channels, such as eigenbeamforming. Eigenbeamforming is a point-to-point link transmit technique that could easily be combined with an opportunistic scheduler to extract multiuser diversity. We refer to the joint use of eigenbeamforming with an opportunistic scheduler as opportunistic eigenbeamforming. In this work, we show that the available multiuser diversity with opportunistic eigenbeamforming is larger than the one achieved when opportunistic beamforming is employed using the proportional fair scheduler under different degrees of correlation in the channel. In the present work we have considered a single-cell scenario. 相似文献
14.
《Communications, IEEE Transactions on》2006,54(1):179-179
A Unified Capacity Analysis for Wireless Systems With Joint Multiuser Scheduling and Antenna Diversity in Nakagami Fading Channels In this paper, we present a cross-layer analytical framework to jointly investigate antenna diversity and multiuser scheduling under the generalized Nakagami fading channels. We derive a unified capacity formula for the multiuser scheduling system with different multiple-input multiple-output antenna schemes, including: 1) selective transmission/selective combining (ST/SC); (2) maximum ratio transmission/maximum ratio combining (MRT/MRC); 3) ST/MRC; and 4) space–time block codes (STBC). Our analytical results lead to the following four observations regarding the interplay of multiuser scheduling and antenna diversity. First, the higher the Nakagami fading parameter, the lower the multiuser diversity gain for all the considered antenna schemes. Second, from the standpoint of multiuser scheduling, the multiple antennas with the ST/SC method can be viewed as virtual users to amplify multiuser diversity order. Third, the boosted array gain of the MRT/MRC scheme can compensate the detrimental impact of the reduced amount of fading gain on multiuser scheduling, thereby resulting in greater capacity than the ST/SC method. Last, employing the STBC scheme together with multiuser diversity may cause capacity loss due to the reduced amount of fading gain, but without the supplement of array gain. 相似文献
15.
Hee-jin Joung Cheol Mun 《Communications Letters, IEEE》2008,12(10):752-754
This letter provides an analysis of the interaction between cooperative diversity and multiuser diversity in downlink channels. Through an approximation of the signal-to-noise ratio (SNR) distribution of each cooperative link using gamma distribution, we can derive an analytic expression for the average throughput of a single-cell wireless system with multiple cooperative diversity links combined with a fair-access scheduler. The proposed analytic approach is verified through comparisons with simulated results and shows that cooperative diversity has a detrimental impact on multiuser diversity. 相似文献
16.
17.
Liang Yang 《Wireless Personal Communications》2007,43(4):1717-1725
In this paper, we consider the multiple-input multiple-output (MIMO) wireless systems employing maximal ratio combining (MRC)
in the absence and presence of multiuser diversity. First, using the well-known moment generating function-based analysis
approach, we derive the error performance of the MIMO MRC systems without multiuser diversity over spatially correlated fading
channels. Second, we present the average capacity of MIMO MRC systems with multiuser diversity. Numerical results demonstrate
the accuracy of our analytical expressions. 相似文献
18.
Daeyoung Park Seung Young Park 《Communications, IEEE Transactions on》2008,56(4):666-674
In this paper, we investigate the effect of spatial correlation on throughput performance of downlink multi-antenna transmission schemes exploiting multiuser diversity, in which partial channel information such as signal-to-interference plus noise power ratio (SINR) is available at the transmitter. The asymptotic analysis is performed based on the extreme value theory. From this analysis, we demonstrate that the throughput optimal transmission scheme depends on the degree of the antenna correlation and the operating SNR. Especially, the multiuser spatial multiplexing known as the asymptotically optimal transmission scheme is no longer optimal in highly correlated multiple antenna channels. 相似文献