As wireless communications experience exponential growth, energy consumption has became a crucial problem in the wireless industry. Energy efficiency of wireless systems has to be significantly improved in order to guarantee the sustainable growth of the wireless industry. Plenty of efforts have been carried on to achieve so called green wireless world. In this paper, focusing on energy saving in wireless access networks, we provide an overview on energy saving studies currently conducted in 3GPP LTE standard body. The aim of the paper is to gain a better understanding on energy consumption problems in wireless access networks and identify key research problems in this field. Currently most of research focus on base station energy saving with efforts to reduce energy consumed by power amplifiers. Less attention are spent on the network level. We believe a holistic network level solution based on novel architecture and methods, such as relay, user cooperation, as well as cognitive approaches, will be prosing enablers towards green wireless access networks.