Graduate School and Research Center in Digital Sciences

Degrees of freedom of certain interference alignment schemes with distributed CSI

de Kerret, Paul; Guillaud, Maxime; Gesbert, David

SPAWC 2013, 14th IEEE International Workshop on Signal Processing Advances in Wireless Communications, June 16-19, 2013, Darmstadt, Germany

In this work, we consider the use of interference alignment (IA) in a MIMO interference channel (IC) under the assumption that each transmitter (TX) has access to channel state information (CSI) that generally differs from that available to other TXs. This setting is referred to as distributed CSIT. In a setting where CSI accuracy is controlled by a set of power exponents, we show that in the static 3-user MIMO square IC, the number of degrees-of-freedom (DoF) that can be achieved with distributed CSIT is at least equal to the DoF achieved with the worst accuracy taken across the TXs and across the interfering links. We conjecture further that this represents exactly the DoF achieved. This result is in strong contrast with the centralized CSIT configuration usually studied (where all the TXs share the same, possibly imperfect, channel estimate) for which it was shown that the DoF achieved at receiver (RX) i is solely limited by the quality of its own feedback. This shows the critical impact of CSI discrepancies between the TXs, and highlights the price paid by distributed precoding.

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Title:Degrees of freedom of certain interference alignment schemes with distributed CSI
Department:Communication systems
Eurecom ref:3998
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Bibtex: @inproceedings{EURECOM+3998, doi = {}, year = {2013}, title = {{D}egrees of freedom of certain interference alignment schemes with distributed {CSI}}, author = {de {K}erret, {P}aul and {G}uillaud, {M}axime and {G}esbert, {D}avid}, booktitle = {{SPAWC} 2013, 14th {IEEE} {I}nternational {W}orkshop on {S}ignal {P}rocessing {A}dvances in {W}ireless {C}ommunications, {J}une 16-19, 2013, {D}armstadt, {G}ermany}, address = {{D}armstadt, {GERMANY}}, month = {06}, url = {} }
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