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

Lokman Sboui, Hakim Ghazzai, Zouheir Rezki, Mohamed-Slim Alouini

Research output: Chapter in Book/Report/Conference proceedingConference contribution

2 Scopus citations


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.
Original languageEnglish (US)
Title of host publicationLecture Notes of the Institute for Computer Sciences, Social Informatics and Telecommunications Engineering
PublisherSpringer Nature
Number of pages13
ISBN (Print)9783319245393
StatePublished - Oct 24 2015

Bibliographical note

KAUST Repository Item: Exported on 2020-10-01


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