Performance Evaluation of Closed-Loop Spatial Multiplexing Codebook Based on Indoor MIMO Channel Measurement
Performance Evaluation of Closed-Loop Spatial Multiplexing Codebook Based on Indoor MIMO Channel Measurement
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DOI：
10.1155/2012/701985
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发表时间：
2012-11
影响因子：
1.5
通讯作者：
Junjun Gao;Jian-hua Zhang;Yanwei Xiong;Yanliang Sun;Xiaofeng Tao
中科院分区：
文献类型：
--
作者：
Junjun Gao;Jian-hua Zhang;Yanwei Xiong;Yanliang Sun;Xiaofeng Tao
LTE中标准化的闭环MIMO技术可以通过预编码操作来支持不同层的传输，以匹配信道复用能力。然而，有限大小码本的性能仍然需要在真实的信道环境中进行评估以进一步了解。基于典型室内场景下的宽带MIMO信道测量，首先研究了两种极端信道条件下有限码本相对于理想预编码的容量损失。结果表明，目前的单层传输码本设计几乎是容量无损的，并且CL会随着传输层数的增加而增加。此外，与CL相比，更好的码本选择准则的容量改进非常有限。然后定义了频域层自适应（FDLA）实现的最大容量提升，并研究了其对信噪比和信道条件的敏感性。为了研究频域信道变化对MIMO-OFDM系统的影响，定义了一个函数来度量子带内关键信道指标的波动水平，揭示了它们之间的内在关系。最后，在频域中，随着反馈间隔的增加，导致容量地板。
Closed-loop MIMO technique standardized in LTE can support different layer transmissions through precoding operation to match the channel multiplexing capability. However, the performance of the limited size codebook still needs to be evaluated in real channel environment for further insights. Based on the wideband MIMO channel measurement in a typical indoor scenario, capacity loss (CL) of the limited size codebook relative to perfect precoding is studied first in two extreme channel conditions. The results show that current codebook design for single layer transmission is nearly capacity lossless, and the CL will increase with the number of transmitted layers. Furthermore, the capacity improvement of better codebook selection criterions is very limited compared to CL. Then we define the maximum capacity boost achieved by frequency domain layer adaption (FDLA) and investigate its sensitivity to SNR and channel condition. To survey the effect of frequency domain channel variation on MIMO-OFDM system, we define a function to measure the fluctuation levels of the key channel metrics within a subband and reveal the inherent relationship between them. Finally, a capacity floor resulted as the feedback interval increases in frequency domain.