On Degrees of Freedom of Cognitive Networks with User Cooperation

In this letter, the degrees of freedom (DoF) outer bound is characterized for cognitive networks. We have devised an interference alignment scheme with appropriate cooperation between primary users and secondary users to achieve the DoF outer bound. Moreover, to encourage the primary users to participate in the proposed cooperation, we also design two aided interference alignment schemes, where both the primary users and the secondary users can tap more DoF out of the cognitive channels than the existing systems and thereby benefit from the cooperation.

[1]  Bruce A. Fette,et al.  Cognitive Radio Technology , 2006 .

[2]  Andrea J. Goldsmith,et al.  Breaking Spectrum Gridlock With Cognitive Radios: An Information Theoretic Perspective , 2009, Proceedings of the IEEE.

[3]  Syed A. Jafar,et al.  Interference Alignment: A New Look at Signal Dimensions in a Communication Network , 2011, Found. Trends Commun. Inf. Theory.

[4]  V. Tarokh,et al.  Cognitive Decomposition of Wireless Networks ( Invited Paper ) , 2006 .

[5]  Syed Ali Jafar,et al.  Interference Alignment and Degrees of Freedom of the $K$-User Interference Channel , 2008, IEEE Transactions on Information Theory.

[6]  Amr El-Keyi,et al.  Constrained Interference Alignment and the Spatial Degrees of Freedom of MIMO Cognitive Networks , 2011, IEEE Transactions on Information Theory.

[7]  Simon Haykin,et al.  Cognitive radio: brain-empowered wireless communications , 2005, IEEE Journal on Selected Areas in Communications.

[8]  Syed Ali Jafar,et al.  Degrees of Freedom of the MIMO Interference Channel With Cooperation and Cognition , 2009, IEEE Transactions on Information Theory.

[9]  Patrick Mitran,et al.  Cognitive Decompiosition of Wirless Networks , 2006, 2006 1st International Conference on Cognitive Radio Oriented Wireless Networks and Communications.