Ernesto Zimmermann David L. Milliner John R. Barry Gerhard Fettweis Optimal LLR Clipping Levels for Mixed Hard/Soft Output Detection. 1122-1126 2008 GLOBECOM http://dx.doi.org/10.1109/GLOCOM.2008.ECP.222 conf/globecom/2008 db/conf/globecom/globecom2008.html#ZimmermannMBF08