C.2 Disambiguation at the RNC

25.4673GPPRelease 17Stage 2TSUTRAN architecture for 3G Home Node B (HNB)

This implementation option can be split in two different steps:

Step 1: At first, during previous HNB to RNC mobility, the RNC builds a local database of necessary information concerning neighbouring cells with PSC confusion (e.g., neighbouring cells PSCs, Cell IDs, Observed Time Difference (OTD)). This local database is built/maintained via handover preparation signalling. The HNB shall include the full Measurement Report and the source cell ID in the handover preparation signalling, and the target RNC collects incoming data and adds/updates OTD information to its database.

Step 2: In a second phase, during RNC to HNB mobility (hand-in), the RNC uses the information previously gathered in order to disambiguate the target HNB in case of a certain PSC is reused in a given (target) area.

C.2.1 Step 1: Construction of HNB database in the RNC

Figure C.2.1-1 depicts the first step of this implementation option. It consists in the RNC building the database of HNBs during HNB to RNC mobility. Such database includes PSCs, Cell IDs and Assistance data (e.g., OTD).

Figure C.2.1-1: Step 1 – Example of RNC constructing database of HNBs during HNB to RNC mobility.

This first step can be split in the following sub-steps:

A. The UE under control of the HNB is configured to provide measurement reports, including OTD data.

Such measurement report, e.g., can be carried within an RRC:Measurement Report to the HNB and, subsequently, to the target RNC via handover preparation procedures.

B. The HNB initiates relocation towards macro cells, by including the source cell identity and full Measurement Report in the Source RNC to Target RNC Transparent Container;

C. The Macro RNC collects incoming data and adds/updates OTD information to its database.

At this stage, the Macro RNC has built a database with all necessary information for future RNC to HNB relocation (hand-in).

C.2.2 Step 2: PSC disambiguation executed by the RNC during RNC to HNB hand-in

Figure C.2.2-1 depicts the second step of implementation option. The RNC, during RNC to HNB mobility (hand-in), can disambiguate the target HNB on the basis of the information collected in the target cells database.

Figure C.2.2-1: Step 2 – Example of PSC disambiguation at RNC during RNC to HNB relocation.

As shown in the figure above, the second step of this implementation option consists of the following sub-steps:

A. The RNC enables the normal measurement reporting to a “shared” PSC in the area;

B. In case of shared target PSC and if the UE is not SI reading capable, the RNC checks the cells reported in the measurement report, calculates the OTD information based on the measurement report and finds the best match in the database created in Step 1;

C. The RNC initiates relocation towards the selected target HNB as per normal mobility procedures.