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exploits not only the current CSI but also the outdated CSI.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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