Sinan Gezici Mung Chiang H. Vincent Poor Hisashi Kobayashi Optimal and Suboptimal Finger Selection Algorithms for MMSE Rake Receivers in Impulse Radio UWB Systems http://arxiv.org/abs/cs/0604092 2006 CoRR abs/cs/0604092 db/journals/corr/corr0604.html#abs-cs-0604092 informal publication