Computer Science – Information Theory
Scientific paper
2011-12-20
Computer Science
Information Theory
57 pages
Scientific paper
Interference alignment is a key technique for communication scenarios with multiple interfering links. In several such scenarios, interference alignment was used to characterize the degrees-of-freedom of the channel. However, these degrees-of-freedom capacity approximations are often too weak to make accurate predictions about the behavior of channel capacity at finite signal-to-noise ratios (SNRs). The aim of this paper is to significantly strengthen these results by showing that interference alignment can be used to characterize capacity to within a constant gap. We focus on real time-invariant frequency-flat X-channels. The only known solutions achieving the degrees-of-freedom of this channel are either based on real interference alignment or on layer-selection schemes. Neither of these solutions seems sufficient for a constant-gap capacity approximation. In this paper, we propose a new communication scheme and show that it achieves the capacity of the Gaussian X-channel to within a constant gap. To aid in this process, we develop a novel deterministic channel model. This deterministic model depends on the 0.5log(SNR) most-significant bits of the channel coefficients rather than only the single most-significant bit used in conventional deterministic models. The proposed deterministic model admits a wider range of achievable schemes that translate to a solution for the Gaussian channel. For this deterministic model, we find an approximately optimal communication scheme. We then translate the solution for the deterministic channel to the original Gaussian X-channel and show that it achieves capacity to within a constant gap.
Maddah-Ali Mohammad A.
Niesen Urs
No associations
LandOfFree
Interference Alignment: From Degrees-of-Freedom to Constant-Gap Capacity Approximations does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Interference Alignment: From Degrees-of-Freedom to Constant-Gap Capacity Approximations, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Interference Alignment: From Degrees-of-Freedom to Constant-Gap Capacity Approximations will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-189138