LTE-A Mobile Relay Handling: Architecture Aspects

Relaying is one of the new key features that has been defined for LTE-Advanced (3GPP Rel' 10) in order to improve to and extend the coverage area among other advantages. In the 3GPP Technical Report [1] some architecture alternatives were considered for a case when relay becomes a part of the fixed access network. It is concluded in the report that the architecture based on proxy S1/X2 has more benefits in compare with other alternatives and has to be selected as the baseline architecture to support a fixed relay node. This paper reviews, outlines and sums up the main network architecture aspects for mobile relay handling. Taking into account that mobile relay support has additional requirements such as the group mobility, persistent IP connectivity during handover, etc. the other alternatives considered in [1] could bring more advantages. For this reason, we re-analyze relay architectures presented in [1] aiming to clarify the basic differences and distinguish between the architecture alternatives in the context of relay mobility support. Further to this comparative analysis we review latency budget of handover procedures for different architectures. As a result of the study we conclude that the architecture with a full L3 relay (transparent for Donor eNB) is more appropriate than other architecture alternatives for enabling mobile relay.