Design and implementation of spatial interweave LTE-TDD cognitive radio communication on an experimental platform

Cognitive radio, which enables smart use of wireless resources, is a key ingredient to achieve high spectral efficiency. LTE, the latest evolution of cellular standards, is widely adopted and also targets high spectral efficiency. Hence, to enable wide adoption of cognitive radio, using LTE as the physical layer is a natural choice. Targeting a real-time implementation of LTEbased cognitive radio, we focus on spatial interweave cognitive radio, in which a secondary user uses an antenna array to perform null-beamforming in the primary user's direction, hence reusing the spectrum spatially. To allow this, without any help from the primary system, we use the time-division duplex mode and take advantage of the channel reciprocity. However, this reciprocity is jeopardized by the mismatch between the RF front-ends. Hence, we design a calibration protocol to restore it. A key contribution is that this cognitive system calibration does not require cooperation from the primary user. The whole system is implemented and evaluated on EURECOM's experimental OpenAirInterface platform. Performance results are presented, showing the feasibility of spatial interweave cognitive radio on a real-time platform.

[1]  Raymond Knopp,et al.  A practical method for wireless channel reciprocity exploitation through relative calibration , 2005, Proceedings of the Eighth International Symposium on Signal Processing and Its Applications, 2005..

[2]  Danijela Cabric,et al.  Cognitive radio: Ten years of experimentation and development , 2011, IEEE Communications Magazine.

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

[4]  Stefania Sesia,et al.  LTE - The UMTS Long Term Evolution, Second Edition , 2011 .

[5]  Giuseppe Caire,et al.  Hardware-impairment compensation for enabling distributed large-scale MIMO , 2013, 2013 Information Theory and Applications Workshop (ITA).

[6]  Sabine Van Huffel,et al.  Overview of total least-squares methods , 2007, Signal Process..

[7]  Irfan Ghauri,et al.  Transmission techniques and channel estimation for Spatial Interweave TDD Cognitive Radio systems , 2009, 2009 Conference Record of the Forty-Third Asilomar Conference on Signals, Systems and Computers.

[8]  Luc Deneire,et al.  Reciprocity calibration techniques, implementation on the OpenAirInterface platform , 2011, CogART '11.

[9]  Luc Deneire,et al.  On the performance of calibration techniques for cognitive radio systems , 2011, 2011 The 14th International Symposium on Wireless Personal Multimedia Communications (WPMC).

[10]  Raymond Knopp,et al.  Relative channel reciprocity calibration in MIMO/TDD systems , 2010, 2010 Future Network & Mobile Summit.

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

[12]  Raymond Knopp,et al.  Software implementation of spatial interweave cognitive radio communication using OpenAirInterface platform , 2012, 2012 International Symposium on Wireless Communication Systems (ISWCS).

[13]  Florian Kaltenberger,et al.  Towards practical channel reciprocity exploitation: Relative calibration in the presence of frequency offset , 2013, 2013 IEEE Wireless Communications and Networking Conference (WCNC).

[14]  Hiroshi Harada,et al.  International standardization of cognitive radio systems , 2011, IEEE Communications Magazine.

[15]  B.D. Van Veen,et al.  Beamforming: a versatile approach to spatial filtering , 1988, IEEE ASSP Magazine.