Cognitive Radio Oriented Wireless Networks. 10th International Conference, CROWNCOM 2015, Doha, Qatar, April 21–23, 2015, Revised Selected Papers

Research Article

Achievable Rate of Multi-relay Cognitive Radio MIMO Channel with Space Alignment

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  • @INPROCEEDINGS{10.1007/978-3-319-24540-9_2,
        author={Lokman Sboui and Hakim Ghazzai and Zouheir Rezki and Mohamed-Slim Alouini},
        title={Achievable Rate of Multi-relay Cognitive Radio MIMO Channel with Space Alignment},
        proceedings={Cognitive Radio Oriented Wireless Networks. 10th International Conference, CROWNCOM 2015, Doha, Qatar, April 21--23, 2015, Revised Selected Papers},
        proceedings_a={CROWNCOM},
        year={2015},
        month={10},
        keywords={Underlay cognitive radio MIMO space alignment Amplify-and-forward multiple-relay},
        doi={10.1007/978-3-319-24540-9_2}
    }
    
  • Lokman Sboui
    Hakim Ghazzai
    Zouheir Rezki
    Mohamed-Slim Alouini
    Year: 2015
    Achievable Rate of Multi-relay Cognitive Radio MIMO Channel with Space Alignment
    CROWNCOM
    Springer
    DOI: 10.1007/978-3-319-24540-9_2
Lokman Sboui1,*, Hakim Ghazzai1,*, Zouheir Rezki1,*, Mohamed-Slim Alouini1,*
  • 1: King Abdullah University of Science and Technology (KAUST)
*Contact email: lokman.sboui@kaust.edu.sa, hakim.ghazzai@kaust.edu.sa, zouheir.rezki@kaust.edu.sa, slim.alouini@kaust.edu.sa

Abstract

We study the impact of multiple relays on the primary user (PU) and secondary user (SU) rates of underlay MIMO cognitive radio. Both users exploit amplify-and-forward relays to communicate with the destination. A space alignment technique and a special linear precoding and decoding scheme are applied to allow the SU to use the resulting free eigenmodes. In addition, the SU can communicate over the used eigenmodes under the condition of respecting an interference constraint tolerated by the PU. At the destination, a successive interference cancellation (SIC) is performed to estimate the secondary signal. We present the explicit expressions of the optimal PU and SU powers that maximize their achievable rates. In the numerical results, we show that our scheme provides cognitive rate gain even in absence of tolerated interference. In addition, we show that increasing the number of relays enhances the PU and SU rates at low power regime and/or when the relays power is sufficiently high.