Efficient Beamforming Technique for Cognitive Radio Networks

In cognitive radio, the received signal to interference noise ratio (SINR) of the secondary users (SUs) should be at certain level to protect primary users (PUs) from harmful interference for reliable communication. Therefore, firstly, a new beamforming problem has been formulated in this paper considering few new constraints in addition to the only constraint of the conventional minimum variance beamformer and secondly, a solution has been provided using Lagrange multiplier method and complex- matrix calculus to reduce the interference due to the presence of SUs. The simulation results show that our proposed solution has placed a deeper null towards the direction of the PUs than the conventional beamformer. Furthermore, the response of the presented beamformer has been examined with different number of array elements and inter-element spacing.

[1]  Joseph Mitola,et al.  Cognitive radio: making software radios more personal , 1999, IEEE Wirel. Commun..

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

[3]  Z. Hossain,et al.  A new Minimum Variance beamforming technique for cognitive radio network , 2010, 5th International Conference on Computer Sciences and Convergence Information Technology.

[4]  Zhongding Lei,et al.  IEEE 802.22: The first cognitive radio wireless regional area network standard , 2009, IEEE Communications Magazine.

[5]  Ying-Chang Liang,et al.  Joint power control and beamforming for cognitive radio networks , 2008, IEEE Transactions on Wireless Communications.

[6]  Md. Abdul Matin,et al.  Robust Power Control using Efficient Minimum Variance Beamforming for Cognitive Radio Networks , 2012 .

[7]  Stephen P. Boyd,et al.  Robust minimum variance beamforming , 2005, IEEE Transactions on Signal Processing.

[8]  Tapan K. Sarkar,et al.  Smart Antennas , 2003 .

[9]  B. A. D. H. Brandwood.  A complex gradient operator and its applica-tion in adaptive array theory , 1983 .

[10]  Josef A. Nossek,et al.  Smart antennas , 2001, Eur. Trans. Telecommun..