Section: 4.3.20.2 RN startup and attach procedure 4.3.20.2.1 General
Content: The startup procedure for the Relay Node is based on the normal UE attach procedure and consists of the following two phases: - Phase I: Attach for RN preconfiguration. - Phase II: Attach for RN operation (MME of the RN). NOTE: When the certificate-based solution is used, the RN uses USIM-INI in Phase I and USIM-RN in Phase II with necessarily different IMSIs. When pre-shared key is used, there is only need for one USIM and the RN uses the same IMSI during Phase I and Phase II. The MME does not treat certificate-based and pre-shared key-based solution differently. The use of the certificate-based and pre-shared key solutions is specified in Annex D of TS 33.401[ 3GPP System Architecture Evolution (SAE); Security architecture ]  [41].