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arXiv · 1508.04359

Informational Bottlenecks in Two-Unicast Wireless Networks with Delayed CSIT

Alireza Vahid·Ilan Shomorony·Robert Calderbank
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Abstract

We study the impact of delayed channel state information at the transmitters (CSIT) in two-unicast wireless networks with a layered topology and arbitrary connectivity. We introduce a technique to obtain outer bounds to the degrees-of-freedom (DoF) region through the new graph-theoretic notion of bottleneck nodes. Such nodes act as informational bottlenecks only under the assumption of delayed CSIT, and imply asymmetric DoF bounds of the form $mD_1 + D_2 \leq m$. Combining this outer-bound technique with new achievability schemes, we characterize the sum DoF of a class of two-unicast wireless networks, which shows that, unlike in the case of instantaneous CSIT, the DoF of two-unicast networks with delayed CSIT can take an infinite set of values.

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Alireza Vahid, Ilan Shomorony, Robert Calderbank. 2015-08-18. Informational Bottlenecks in Two-Unicast Wireless Networks with Delayed CSIT. https://arxiv.org/abs/1508.04359

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