Maximizing MIMO Capacity in Sparse Multipath With Reconfigurable Antenna Arrays
Maximizing MIMO Capacity in Sparse Multipath With Reconfigurable Antenna Arrays
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DOI：
10.1109/jstsp.2007.897057
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发表时间：
2007-05
影响因子：
7.5
通讯作者：
A. Sayeed;V. Raghavan
中科院分区：
文献类型：
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作者：
A. Sayeed;V. Raghavan
在可重构射频(RF)前端和天线阵列方面的新进展使得能够访问无线电频谱的新的物理模式成为可能，这些模式扩展和补充了无线通信系统中的波形分集的概念。然而，开发可重构射频前端潜力的理论和方法还没有完全开发出来。本文研究了稀疏多径环境下可重构天线阵列对最大化多输入多输出(MIMO)无线通信链路容量的影响。越来越多的实验证据表明，物理无线信道表现出稀疏的多径结构，即使在相对较低的天线维度上也是如此。我们提出了稀疏多径信道的模型，并证明了稀疏信道提供了一个新的维度来优化容量：稀疏统计独立自由度(DoF)在可用空间信号空间维度中的分布或配置。我们的结果表明，稀疏DOF的配置对容量有深刻的影响，并表征了在任何操作SNR下最大化容量的最优信道配置。然后，我们开发了一个框架，通过系统地调整发射端和接收端的天线间距来适应物理多径环境中的稀疏程度，从而实现在任何信噪比下的最优信道配置。令人惊讶的是，三种规范的阵列配置足以在整个SNR范围内实现近乎最佳的性能。在路径随机分布的稀疏散射环境中，最优配置所产生的容量增益与天线数目成正比。给出了基于真实物理模型的数值结果，以说明该框架的含义
Emerging advances in reconfigurable radio-frequency (RF) front-ends and antenna arrays are enabling new physical modes for accessing the radio spectrum that extend and complement the notion of waveform diversity in wireless communication systems. However, theory and methods for exploiting the potential of reconfigurable RF front-ends are not fully developed. In this paper, we study the impact of reconfigurable antenna arrays on maximizing the capacity of multiple input multiple output (MIMO) wireless communication links in sparse multipath environments. There is growing experimental evidence that physical wireless channels exhibit a sparse multipath structure, even at relatively low antenna dimensions. We propose a model for sparse multipath channels and show that sparse channels afford a new dimension over which capacity can be optimized: the distribution or configuration of the sparse statistically independent degrees of freedom (DoF) in the available spatial signal space dimensions. Our results show that the configuration of the sparse DoF has a profound impact on capacity and also characterize the optimal capacity-maximizing channel configuration at any operating SNR. We then develop a framework for realizing the optimal channel configuration at any SNR by systematically adapting the antenna spacings at the transmitter and the receiver to the level of sparsity in the physical multipath environment. Surprisingly, three canonical array configurations are sufficient for near-optimum performance over the entire SNR range. In a sparse scattering environment with randomly distributed paths, the capacity gain due to the optimal configuration is directly proportional to the number of antennas. Numerical results based on a realistic physical model are presented to illustrate the implications of our framework