Vahid, A; Shomorony, I; Calderbank, R, *Informational bottlenecks in two-unicast wireless networks with delayed CSIT*,
2015 53rd Annual Allerton Conference on Communication, Control, and Computing, Allerton 2015
(April, 2016),
pp. 1256-1263, IEEE [doi] .
**Abstract:**

*© 2015 IEEE. 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 mD1 + D2 ≤ 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.*