Distributed Space-Time Interference Alignment With Moderately Delayed CSIT
Distributed Space-Time Interference Alignment With Moderately Delayed CSIT
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DOI：
10.1109/twc.2014.2363475
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发表时间：
2015-02-01
影响因子：
10.4
通讯作者：
Heath, Robert W., Jr.
中科院分区：
文献类型：
--
作者：
Lee, Namyoon;Tandon, Ravi;Heath, Robert W., Jr.
针对一类干扰网络，提出了一种基于发送端分布式延迟信道状态信息（CSIT）的干扰对准方法。该方法的核心思想是以分布式的方式将干扰信号随时间在非预期接收机处对齐。利用所提出的方法，在x通道和三用户干扰通道中分别表征了CSI的和自由度（sum- dof）和反馈延迟之间的可实现权衡，揭示了CSI反馈延迟如何影响干扰网络的和自由度。导出的结果的一个主要含义是，在某类干扰网络中，分布式和适度延迟的CSIT对于严格提高发射机无CSI情况下的和自由度是有用的。对于一类x通道，结果显示了如何最佳地使用分布式和适度延迟的CSIT来产生与瞬时和全局CSIT相同的和自由度。此外，利用所提出的传输方法和已知的外界结果，具有一组特定信道系数的双用户x信道的和容量在常数位数内表征。
This paper proposes an interference alignment method with distributed and delayed channel state information at the transmitter (CSIT) for a class of interference networks. The core idea of the proposed method is to align interference signals over time at the unintended receivers in a distributed manner. With the proposed method, achievable tradeoffs between the sum of degrees of freedom (sum-DoF) and feedback delay of CSI are characterized in both the X-channel and three-user interference channel to reveal the impact on how the CSI feedback delay affects the sum-DoF of the interference networks. A major implication of derived results is that distributed and moderately delayed CSIT is useful to strictly improve the sum-DoF over the case of no CSI at the transmitter in a certain class of interference networks. For a class of X-channels, the results show how to optimally use distributed and moderately delayed CSIT to yield the same sum-DoF as instantaneous and global CSIT. Furthermore, leveraging the proposed transmission method and the known outer bound results, the sum-capacity of the two-user X-channel with a particular set of channel coefficients is characterized within a constant number of bits.