Improper Gaussian Signaling for Multiple-Access Channels in Underlay Cognitive Radio
| Title | Improper Gaussian Signaling for Multiple-Access Channels in Underlay Cognitive Radio |
| Publication Type | Journal Article |
| Year of Publication | 2019 |
| Authors | Lameiro, C., I. Santamaría, and P. J. Schreier |
| Journal | IEEE Transactions on Communications |
| Volume | 67 |
| Issue | 3 |
| Pagination | 1817-1830 |
| Month Published | March |
| ISSN | 1558-0857 |
| Abstract | This paper considers an unlicensed multiple-accesschannel (MAC) that coexists witha licensed point-to-point user,following the underlay cognitive radio paradigm. We assumethat every transceiver except the secondary base station hasone antenna and that the primary user (PU) is protected bya minimum rate constraint. In contrast to the conventionalassumption of proper Gaussian signaling, we allow the secondaryusers to transmit improper Gaussian signals, which are corre-lated with their complex conjugate. When the secondary basestation performs zero-forcing, we show that improper signalingis optimal if the sum of the interference channel gains (inan equivalent canonical model) is above a certain threshold.Additionally, we derive an efficient algorithm to compute thetransmission parameters that attain the rate region boundaryfor this scenario. The proposed algorithm exploits a single-userrepresentation of the secondary MAC along with new results onthe optimality of improper signaling in the single-user case whenthe PU is corrupted by an improper noise. |
| DOI | 10.1109/TCOMM.2018.2880765 |
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