Every single unused Wh may save precious resources and prevent exceeding thresholds for irreversible climate change. It also will help to lower the cost of mobile telecommunication. Therefore any efficient effort to reduce the energy consumption of mobile networks is worthwhile. OAM can contribute to these efforts through solutions that can manage underused network resources by activating or deactivating them as necessary to fulfil the service levels required by mobile network users. This activation / reactivation is not restricted to single RATs, but different RATS can work together to find the optimal balance between energy consumption and service readiness. Only LTE offers a possibility to directly exchange information between radio network elements (X2 interface). The other RATs in the scope of this study may not support this. Therefore OAM based methods are one possible solution for Inter-RAT Energy Saving.

General material - [2], [3] - and detailed material - [4], [5], [6] - on Energy Saving and/or its Management aspects have been created by 3GPP. The present document focuses on Inter-RAT aspects of Energy Saving, i.e. reducing the capabilities of one RAT to reduce its energy consumption while providing a back-up by another RAT. Concepts and scenarios described in [2], [3] and methods defined in [4], [5], [6] as well as additions to them are analysed to identify the most favourable management solutions in this context and their possible limitations. The following RATs are considered in this study: GSM, UMTS; LTE, CDMA.