Graduate School and Research Center in Digital Sciences

Achieving full sum DoF in the SISO interference channel with feedback delay

Lejosne, Yohan; Slock, Dirk TM; Yuan-Wu, Yi

IEEE Communications Letters, Volume 18, N°7, July 2014, ISSN: 1089-7798

Channel state information at the transmitter (CSIT) is of utmost importance to manage interference in multi-user wireless networks, in which transmission rates at a high signal-to-noise ratio are characterized by (sum) degrees of freedom (DoF). Ingenious techniques have been proposed to deal with delayed CSIT, notably a scheme by Maddah-Ali and Tse, providing significant DoF with outdated CSIT. However, with most techniques, any delay in the CSIT feedback still results in a DoF loss. A notable exception is the work by Lee and Heath, allowing one to preserve the optimal DoF in the underdetermined MISO BC and IC, but for feedback delays $T_$ decreasing with the number of users $K$, up to a fraction $1/K$ of the channel coherence time $T_$. In this work, an ergodic interference alignment scheme that preserves the $K/2$ sum DoF of the $K$-user IC is proposed for$T_leq T_/2$. It is also proven that $T_=T_/2$ is the longest for which the optimal $K/2$DoF can still be obtained for all $K$.

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Title:Achieving full sum DoF in the SISO interference channel with feedback delay
Keywords:SISO IC, delayed CSIT, interference alignment
Department:Communication systems
Eurecom ref:4361
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Bibtex: @article{EURECOM+4361, doi = {}, year = {2014}, month = {07}, title = {{A}chieving full sum {D}o{F} in the {SISO} interference channel with feedback delay}, author = {{L}ejosne, {Y}ohan and {S}lock, {D}irk {TM} and {Y}uan-{W}u, {Y}i }, journal = {{IEEE} {C}ommunications {L}etters, {V}olume 18, {N}°7, {J}uly 2014, {ISSN}: 1089-7798}, url = {} }
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