Tulino, Antonia M.Lozano Solsona, AngelVerdú, SergioUniversitat Pompeu Fabra2012-01-192012-01-192006Tulino A M, Lozano A, Verdú S. Capacity-achieving input covariance for single-user multi-antenna channels. IEEE Transactions on Wireless Communications. 2006; 5(3): 662-671. DOI 10.1109/TWC.2006.16110961536-1276http://hdl.handle.net/10230/16125We characterize the capacity-achieving input covariance for multi-antenna channels known instantaneously at the receiver and in distribution at the transmitter. Our characterization, valid for arbitrary numbers of antennas, encompasses both the eigenvectors and the eigenvalues. The eigenvectors are found for zero-mean channels with arbitrary fading profiles and a wide range of correlation and keyhole structures. For the eigenvalues, in turn, we present necessary and sufficient conditions as well as an iterative algorithm that exhibits remarkable properties: universal applicability, robustness and rapid convergence. In addition, we identify channel structures for which an isotropic input achieves capacity.application/pdfeng© 2006 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works./nThe final published article can be found at http://dx.doi.org/10.1109/TWC.2006.1611096Ràdio -- AntenesTractament del senyalinfo:eu-repo/semantics/articlehttp://dx.doi.org/10.1109/TWC.2006.1611096Channel capacityMulti-antenna arraysInput optimizationFading channelsAntenna correlationRicean channelsKeyhole channelsChannel-state Informationinfo:eu-repo/semantics/openAccess