Distributed Space-Time Interference Alignment With Moderately Delayed CSIT

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 man...

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Bibliographic Details
Published in:IEEE transactions on wireless communications 2015-02, Vol.14 (2), p.1048-1059
Main Authors: Namyoon Lee, Tandon, Ravi, Heath, Robert W.
Format: Article
Language:English
Subjects:
Coherence
Delays
Interference channels
Receivers
Transmitters
Wireless communication
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Summary: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.
ISSN:1536-1276
1558-2248
DOI:10.1109/TWC.2014.2363475