Optimal Combinationof Base Station Densitiesfor Cost- Efficient Two-tier Heterogeneous Cellular NetworksJan 1, 2013·DongxuCao,ShengZhou,ZhishengNiu· 0 min read CiteLast updated on Jan 1, 2013← Jointoptimizationoffrequencyallocationanduserassociationwith differentiatedserviceinhyper-cellularnetworks Jan 1, 2013Optimalwake-upmechanismforsinglebasestationwith sleepmode Jan 1, 2013 →