The coexistence of Multiple RATs introduces many operational coordination problems for network operators. The co-existence of various RATs (i.e. LTE/UMTS/GSM/CDMA/WLAN) is an obvious reality and it will remain relevant in the future. This raises important issues for operators in terms of coordination across the RATs to achieve better user experience (QoE), efficient resource usage, higher network capacity and easier maintenance, especially in a multi-vendor environment. For an operator with multi-RAT networks, frequent updated information from all RATs (radio resource management, mobility and traffic load) is required in order to enable efficient coordination by the network. It will be beneficial to consider a general Multi-RATs coordination from RAN perspective.

The present document provides descriptions and possible solutions of use cases for the multi-RAT joint operation, and also provides analysis of these solutions. Considerations with regards to requested functionality in scope of other 3GPP groups, if any, may be captured in this document as well.