@conference {ValcarceVazquez2009, title = {Wideband Spectrum Sensing in Cognitive Radio: Joint Estimation of Noise Variance and Multiple Signal Levels}, booktitle = {IEEE Workshop on Signal Processing Advances in Wireless Communications (SPAWC)}, year = {2009}, month = {June 21-24}, address = {Perugia, Italy}, author = {R. L{\'o}pez-Valcarce and Gonzalo V{\'a}zquez-Vilar} }