Seong-Jun Oh Kimberly M. Wasserman Optimality of Greedy Power Control and Variable Spreading Gain in Multi-Class CDMA Mobile Networks. 102-112 1999 conf/mobicom/1999 MOBICOM http://doi.acm.org/10.1145/313451.313498 db/conf/mobicom/mobicom1999.html#OhW99