共查询到20条相似文献,搜索用时 31 毫秒
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《IEEE transactions on information theory / Professional Technical Group on Information Theory》2009,55(4):1618-1626
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论文导出了分集增益与空间复用增益间的最佳折衷关系式。该关系式为阶梯递减右连续函数,阶梯数等于接收天线数目。分集增益的取值与分组长度有关,只有当分组长度不小于发射天线数目时才能获得满分集增益。折衷关系表明,采用合适的空时编码可以同时获得分集增益和空间复用增益,但是两种增益不能同时达到最大。由最佳折衷关系可以推测一定空间复用增益时可得到的最大分集增益,以及一定分集增益时能获得的最大空间复用增益。 相似文献
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Garcia-Ordonez L. Pages-Zamora A. Fonollosa J.R. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》2008,54(7):2959-2975
Following the seminal work of Zheng and Tse, this paper investigates the fundamental diversity and multiplexing tradeoff of multiple-input-multiple-output (MIMO) systems in which knowledge of the channel state at both sides of the link is employed to transmit independent data streams through the channel eigenmodes. First, the fundamental diversity and multiplexing tradeoff of each of the individual substreams is obtained and this result is then used to derive a tradeoff optimal scheme for rate allocation along channel eigenmodes. The tradeoff of spatial multiplexing is finally compared to the fundamental tradeoff of the MIMO channel and to the one of both space only codes and V-BLAST which do not require channel state information (CSI) at the transmit side. 相似文献
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《IEEE transactions on information theory / Professional Technical Group on Information Theory》2005,51(9):3086-3101
In this second part of our two-part paper, we consider the capacity analysis for wireless mobile systems with multiple-antenna architectures. We apply the results of the first part to a commonly known baseband, discrete-time multiple-antenna system where both the transmitter and receiver know the channel's statistical law. We analyze the capacity for additive white Gaussian noise (AWGN) channels, fading channels with full channel state information (CSI) at the receiver, fading channels with no CSI, and fading channels with partial CSI at the receiver. For each type of channels, we study the capacity value as well as issues such as the existence, uniqueness, and characterization of the capacity-achieving measures for different types of moment constraints. The results are applicable to both Rayleigh and Rician fading channels in the presence of arbitrary line-of-sight and correlation profiles. 相似文献
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《Antennas and Propagation, IEEE Transactions on》2009,57(8):2439-2451
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The Performance of Multiuser Diversity Scheduling for MIMO Channels With Spatially Correlated Fading
《Communications, IEEE Transactions on》2006,54(9):1533-1535
We study a cellular network with one multiantenna base station and a number of multiantenna users. Correlated fading may exist at the base station or at the users, or at both sides. With time-varying fading, multiuser diversity is exploited by always allowing the base station to transmit to the user with the best channel. For this network, we find that if the number of transmitter antennas and the number of receiver antennas grow with a fixed ratio, the multiuser diversity gain will approximately remain constant. 相似文献
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一种分布式多入多出(MIMO)信道的容量研究 总被引:10,自引:1,他引:10
分布式MIMO系统结合了点对点MIMO信道与分布式天线系统两者的特点,能改善链路的质量,提高覆盖面积。本文提出了一种包含路径损耗、阴影衰落与小尺度衰落的分布式MIMO信道模型,分析推导了采用该模型时的分布式MIMO信道容量。通过计算机仿真,研究分析了阴影衰落、Rice信道因子K等因素对分布式MIMO上行信道容量的影响,得出了分布式MIMO信道容量空间分布的特点。 相似文献
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《IEEE transactions on information theory / Professional Technical Group on Information Theory》2008,54(11):4887-4907
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MIMO Broadcast Channels With Finite-Rate Feedback 总被引:8,自引:0,他引:8
《IEEE transactions on information theory / Professional Technical Group on Information Theory》2006,52(11):5045-5060
Multiple transmit antennas in a downlink channel can provide tremendous capacity (i.e., multiplexing) gains, even when receivers have only single antennas. However, receiver and transmitter channel state information is generally required. In this correspondence, a system where each receiver has perfect channel knowledge, but the transmitter only receives quantized information regarding the channel instantiation is analyzed. The well-known zero-forcing transmission technique is considered, and simple expressions for the throughput degradation due to finite-rate feedback are derived. A key finding is that the feedback rate per mobile must be increased linearly with the signal-to-noise ratio (SNR) (in decibels) in order to achieve the full multiplexing gain. This is in sharp contrast to point-to-point multiple-input multiple-output (MIMO) systems, in which it is not necessary to increase the feedback rate as a function of the SNR 相似文献
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《Communications Letters, IEEE》2007,11(6):507-509
OFDMA systems inherently take advantages of both frequency diversity gain and frequency-selective scheduling gain. The former is achieved by allocating a user the subcarriers widely scattered over an entire frequency band, while the latter is achieved by allocating a user the subcarriers consecutively located within a subband of a limited bandwidth which is the most favorable to the user among many subbands in the entire frequency band. In this letter, the effect of user mobility is quantitatively investigated in relation to a trade-off between the frequency diversity gain and the frequency-selective scheduling gain in OFDMA systems. As a performance measure, outage capacity is considered. Also studied is how the spatial diversity resulting from multiple antenna techniques and the outage probability affect the dependence of the performance trade-off on the user mobility. 相似文献
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Time-Reversed Ultra-wideband (UWB) Multiple Input Multiple Output (MIMO) Based on Measured Spatial Channels 总被引:1,自引:0,他引:1
《Vehicular Technology, IEEE Transactions on》2009,58(6):2884-2898
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Moustakas A.L. Simon S.H. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》2007,53(11):3887-3903
The use of multiple-antenna arrays can dramatically increase the throughput of wireless communication systems. Thus, it is important to characterize the statistics of the mutual information for realistic correlated channels. Here, a mathematical approach is presented, using the method of replicas, that provides analytic expressions not only for the average, but also for the higher moments of the distribution of the mutual information for the most general zero-mean Gaussian multiple-input multiple-output (MIMO) channels when the channel is known at the receiver. These channels include multitap delay paths, and channels with covariance matrices that cannot be written as a Kronecker product, such as general dual-polarized correlated antenna arrays. This approach is formally valid for large antenna numbers, in which case all cumulant moments of the distribution, other than the first two, scale to zero. In addition, it is shown that the replica-symmetric result is valid if the variance of the mutual information is positive and finite. In this case, it is shown that the distribution of the mutual information tends to a Gaussian, which enables the calculation of the outage capacity. These results are quite accurate even for few antennas, which makes this approach applicable to realistic situations. 相似文献
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《IEEE transactions on information theory / Professional Technical Group on Information Theory》2005,51(9):3121-3145
This paper considers the capacity of spatially correlated Rician multiple-input multiple-output (MIMO) channels. We consider the general case with double-sided correlation and arbitrary rank channel means. We derive tight upper and lower bounds on the ergodic capacity. In the particular cases when the numbers of transmit and receive antennas are equal, or when the correlation is single sided, we derive more specific bounds which are computationally efficient. The bounds are shown to reduce to known results in cases of independent and identically distributed (i.i.d.) and correlated Rayleigh MIMO channels. We also analyze the outage characteristics of the correlated Rician MIMO channels at high signal-to-noise ratio (SNR). We derive the mean and variance of the mutual information and show that it is well approximated by a Gaussian distribution. Finally, we present numerical results which show the effect of the antenna configuration, correlation level (angle spreads), Rician$K$ -factor, and the geometry of the dominant Rician paths. 相似文献
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基于天线选择的低秩信道MIMO系统容量研究 总被引:1,自引:0,他引:1
最近的研究表明,在衰落信道多天线MIMO系统的容量随发射天线数线性增加.而对于低散射环境,即使信号经历独立的衰落,信道秩的降低也会严重影响系统容量的增加.对于这种低秩环境,选择天线发射或接收可以有效地降低系统的成本.本文研究了天线选择对低秩信道MIMO系统容量的影响.仿真结果表明,对不同的信道条件,适当选择天线发射不仅可以增加信道容量,而且可以降低系统的复杂度和射频成本.适当选择天线接收,在不严重降低系统容量的前提下,也达到了降低系统成本的目的. 相似文献
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This paper investigates the ergodic sum capacity for a MIMO group-broadcast channel with time-division scheduling (TDS). In this scheme, the overall user set is divided into subgroups, among which a single user subgroup which maximizes the instantaneous sum capacity will be scheduled at a time. In order to characterize the TDS performance, we first derived an asymptotic bound to the full capacity obtained by dirty paper coding (DPC). This bound is a closed-form expression and performs well for different system configurations. Further concerning practical precoding techniques, we studied its achievable sum capacity by using block-diagonalization (BD) and zero-forcing (ZF) precoding. Based on these results, the achieved scheduling gain by TDS over random scheduling is analyzed. We also compared the scheduling gains under different transmission strategies including DPC, BD, and ZF precoding. The results reveal that TDS provides the largest scheduling gain for the system with ZF precoding. Finally, we also discussed the effect of the group cardinality on the performance of TDS. Numerical results show the tightness of derived capacity bounds and verify the correctness of our analysis. 相似文献
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We analyze asymptotic ergodic capacity of multidimensional vector-sensor array MIMO (PMD-MIMO) channels established by the use of dual-polarized antennas in the form of 1D, 2D and/or 3D MIMO arrays. Based on the identification of the decomposition of PMD-MIMO channels into multiple independently-fading and scaled classical MIMO channels in parallel, we consequently derive corresponding asymptotic ergodic capacities analytically via tools out of free probability theory. The analysis of derived asymptotic ergodic capacity expressions in terms of antenna locus aspect ratio ?, average symbol SNR per antenna ˉ?s and cross-polar discrimination XPD as well as comparison with asymptotic ergodic capacity of classical MIMO channels present important gains in using compact multidimensional vector-sensor array MIMO systems in asymptotic regimes. 相似文献