CSI Feedback Delay and Degrees of Freedom Gain Trade-Off for the MISO Interference Channel


Namyoon Lee and Robert W. Heath, Jr.


Asilomar Conference on Signals, Systems & Computers, Nov. 2012.


Channel state information at transmitter (CSIT) plays a significant role in managing interference in many wireless communications. Due to time-varying wireless channel characteristic and feedback delay, the transmitter may not employ CSI and it results in degrading system performance. Thus, it is an important problem for characterizing the behavior of how the CSI feedback delay affects to system performance. As an initial step to address this problem, in this paper, a simple ¡°CSI feedback delay-degrees of freedom (DoF) gain trade-off¡± is characterized for the 3-user multiple-input-single-output interference channel. To characterize this trade-off, a new transmission method called space-time interference alignment is proposed, which actively exploits not only the current CSI but also the outdated CSI. From this trade-off characterization, an insight is provided about the interplay between CSI feedback delay and DoF gain perspective.

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