The Iu reference point of UMTS is defined to be at the boundary of the URAN and the IWU . In case the IWU is null, the Iu is between URAN and CN. The purpose of this document is to analyze the basic issues related to the Iu before starting the actual standardisation of the related interface(s).
This report identifies the requirements on the Iu and studies relevant principles to guide further standardisation of the related interface(s).
The different instances of the UMTS radio access currently identified are the following:
UMTS radio access network (URAN)
UMTS Terrestrial Radio Access Network (UTRAN)
Broadband Radio Access Network (BRAN)
UMTS satellite radio access network