Using statistical information to improve communication in MIMO networks
Using statistical information to improve communication in MIMO networks
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使用统计信息改善 MIMO 网络中的通信
DOI：
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发表时间：
2012
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通讯作者：
Sagnik Ghosh
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作者：
Sagnik Ghosh
本文讨论了多用户MIMO网络中信道统计信息的应用。这里涉及三个主要主题。第一个是关于如何在多用户环境中有效地将CDI用于反馈。其次是为多用户MIMO网络开发新的中断框架，并为网络中的波束成形和功率控制提供近乎最佳的解决方案。第三是将有限CSI反馈添加到CDI方案以减少中断，执行更好的功率控制，并且提供更可靠的网络。在这项工作的第一部分，我们开发的技术，有效地在MIMO瑞利衰落环境中的信道协方差矩阵。虽然这些协方差矩阵的变化频率低于信道矩阵本身，但当它发生变化时，需要更新此信息。此外，这些协方差矩阵比其信道矩阵对应物具有显著更多的参数来进行优化。由于许多应用集中于利用信道协方差矩阵的最强本征模，并且由于这些矩阵往往是低秩的，因此我们集中于有效地量化这些矩阵的主导本征向量。我们根据环境中的训练数据开发了一种类似的算法来开发我们的码本。我们还开发了一个算法的基础上减少参数Kronecker和Weichselberger模型生成码本减少实时码字搜索。在这项工作的第二部分，我们研究了单用户和多用户MIMO波束成形网络与CDI。由于CDI与CSI相比很少改变，因此与基于CSI的算法相比，基于CDI的算法可以实现反馈的显著节省。使用CDI，我们只能保证网络中指定中断概率的服务质量。假设相关的瑞利衰落的所有链接，我们推导出一个封闭形式的中断概率的表达式。然后，使用这个表达式，我们推导出联合发射/接收波束成形和功率控制算法，以最小化网络中的加权和功率，同时保证这些中断概率。对于单用户和多用户MIMO的情况下，我们提出了最佳的算法下的克罗内克模型假设，我们提出了近似最佳的算法，假设一般的相关性结构的链接。然后，我们表明，使用这些算法的基础上CDI，如果我们愿意接受给定的中断的链接，我们可以实现可比的功率使用在网络中相对于基于CSI的算法。然后，我们将此框架扩展到具有多个接收器和发射器的广播信道。在第三部分中，我们扩展了以前的中断框架的基础上CDI利用CSI的直接链路的信道。这里考虑的CDI框架着眼于满足指定中断概率的每个用户的最小信号与干扰加噪声（SINR）要求。链接上的这种中断是不受欢迎的。然而，在许多标准中，在接收器处经由来自其对应发射器的训练数据来测量CSI。干扰链路上的CSI通常不可用。如果可以测量该CSI，则可以将该信息反馈给发射机，使得它们在给定链路中断时将不进行发送。此外，CSI反馈可以用于功率降低，从而潜在地使先前处于中断的链路能够进行传输。算法讨论这些想法的开发和讨论。此外，一个信干噪比量化器的发展，以最大限度地减少功耗，并结合CDI和CSI的结果也讨论了广播信道的情况下，与多个发射机和接收机
This dissertation discusses the use of statistical information about channels, or Channel Distribution Information (CDI), in multiuser MIMO networks. There are three main topics covered here. The first is on how to efficiently quantize CDI for feedback in a multiuser environment. The second is to develop a new outage framework for multiuser MIMO networks, and to provide a near-optimal solution for beamforming and power control in the network. The third is to add limited CSI feedback to the CDI scheme to reduce outage, perform better power control, and provide a more reliable network. In the first part of this work, we develop techniques to efficiently quantize channel covariance matrices in MIMO Rayleigh fading environments. While these covariance matrices change less frequently than the channel matrices themselves, this information needs to be updated when it does change. Furthermore, these covariance matrices have significantly more parameters to quantize than their channel matrix counterparts. Since many applications focus on utilizing the strongest eigenmodes of the channel covariance matrix and since these matrices tend to be low- rank, we focus on efficiently quantizing the dominant eigenvectors of these matrices. We develop Lloyd-type algorithms based on training data from the environment to develop our codebooks. We also develop an algorithm based on the reduced-parameter Kronecker and Weichselberger models to generate codebooks with reduced real-time codeword search. In the second part of this work, we examine single user and multiuser MIMO beamforming networks with CDI. Since CDI changes infrequently compared to CSI, algorithms based on CDI can achieve significant savings in feedback compared to algorithms based on CSI. With CDI, we can only guarantee quality of service for a specified outage probability in the network. Assuming correlated Rayleigh fading on all the links, we derive a closed-form expression for the outage probability. Then, using this expression, we derive algorithms for joint transmit/receive beamforming and power control to minimize the weighted sum power in the network while guaranteeing these outage probabilities. For both single-user and multiuser MIMO scenarios, we present optimal algorithms under the Kronecker model assumption, and we present near- optimal algorithms assuming general correlation structures on the links. We then show that using these algorithms based on CDI, if we are willing to accept given outages on the links, we can achieve comparable power usage in the network relative to algorithms based on CSI. We then extend this framework to the broadcast channel with multiple receivers and transmitters. In the third part of this work, we extend the previous outage framework based on CDI to utilize CSI of the direct links of the channels. The CDI framework considered here looks at minimum Signal- to-Interference-plus-Noise (SINR) requirements from each user that is met with a specified outage probability. This outage on the links is undesirable. However, in many standards, CSI is measured at the receiver via training data from its corresponding transmitter. The CSI on the interfering links is typically unavailable. If this CSI can be measured, this information can be fed back to the transmitters so they will not transmit when a given link is in outage. In addition, CSI feedback can be used for power reduction and thus potentially enable links that were previously in outage to transmit. Algorithms discussing these ideas are developed and discussed. Furthermore, an SINR quantizer is developed to minimize power usage, and combined CDI and CSI results are also discussed for the case of the broadcast channel with multiple transmitters and receivers