61 research outputs found
Degrees of Freedom for the MIMO Interference Channel
We explore the available degrees of freedom (DoF) for the two user MIMO interference channel, and find a general inner bound and a genie aided outer bound that give us the exact # of DoF in many cases. We also study a share-and-transmit scheme and show how the gains of transmitter cooperation are entirely offset by the cost of enabling that cooperation so that the available DoF are not increased
On Achievable Rates of the Two-user Symmetric Gaussian Interference Channel
We study the Han-Kobayashi (HK) achievable sum rate for the two-user
symmetric Gaussian interference channel. We find the optimal power split ratio
between the common and private messages (assuming no time-sharing), and derive
a closed form expression for the corresponding sum rate. This provides a finer
understanding of the achievable HK sum rate, and allows for precise comparisons
between this sum rate and that of orthogonal signaling. One surprising finding
is that despite the fact that the channel is symmetric, allowing for asymmetric
power split ratio at both users (i.e., asymmetric rates) can improve the sum
rate significantly. Considering the high SNR regime, we specify the
interference channel value above which the sum rate achieved using asymmetric
power splitting outperforms the symmetric case.Comment: 7 pages, to appear in Allerton 201
A New Outer Bound and the Noisy-Interference Sum-Rate Capacity for Gaussian Interference Channels
A new outer bound on the capacity region of Gaussian interference channels is
developed. The bound combines and improves existing genie-aided methods and is
shown to give the sum-rate capacity for noisy interference as defined in this
paper. Specifically, it is shown that if the channel coefficients and power
constraints satisfy a simple condition then single-user detection at each
receiver is sum-rate optimal, i.e., treating the interference as noise incurs
no loss in performance. This is the first concrete (finite signal-to-noise
ratio) capacity result for the Gaussian interference channel with weak to
moderate interference. Furthermore, for certain mixed (weak and strong)
interference scenarios, the new outer bounds give a corner point of the
capacity region.Comment: 20 pages, 8 figures, submitted to IEEE Trans. Inform. Theory
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