IP Multimedia Relay Architectures with Multi-RAT Support in LTE-Advanced Wireless Network

LTE/LTE-Advanced is the competing leader of access network technology in 4G wireless networks. LTE is one of 3GPP standards, and furthermore LTE and LTE-Advanced are developed by 3GPP which are organized by telecommunication manufacturers and operators. Moreover, LTE and LTE-Advanced are backward compatible with 3G/UMTS cellular systems. To improve radio resource utilization, simultaneously deploying Multiple Radio Access Technologies (Multi-RATs) in a given coverage area, to carry the complete offered user traffic, provides a superior user experience. The LTE-Advanced has added a new entity called relay node (RN) to enlarge service coverage and provides flexibility of deployment. If RN can support Multi-RATs including UMTS, IEEE 802.11 and 802.16, the LTE-advanced system can provide more flexible IP multimedia services. However, the virtualization system architecture for Multi-RAT support is still under development. This paper focuses on integrated architecture design by which RN can provide services for both UMTS UEs and LTE UEs. Two novel architectures (Arch-A and Arch-B) with three useful alternatives respectively, namely Alt_1, Alt_2 and Alt_3 are presented in this paper. As shown in the protocol stacks, our proposed approaches can integrate the services of 3G UMTS and 4G LTE-Advanced wireless network. Thus, the transition between 3G and 4G is more easily achieved between our proposed novel Alt_1, Alt_2 and Alt_3 alternatives based on two architectures via IP Multimedia Core Network Subsystem (IMS).