6 MS supporting access technologies defined both by 3GPP and 3GPP2

23.1223GPPNon-Access-Stratum (NAS) functions related to Mobile Station (MS) in idle modeRelease 18TS

Tools: ARFCN - Frequency Conversion for 5G NR/LTE/UMTS/GSM

6.1 General

An MS that supports access technologies defined both by 3GPP and 3GPP2 (see 3GPP TS 31.102 [40]) shall consider all supported access technologies in all supported bands when performing PLMN selection.

The goal of the PLMN selection process for such a multi mode MS is to find the highest priority PLMN and to attempt to register to it.

A multi mode MS shall follow the requirements in the present document for the PLMN selection procedures across both 3GPP and 3GPP2 access technologies. Additionally, the MS shall follow the requirements of the present document in its signalling procedures towards any 3GPP network. If the common PLMN selection procedure leads to selection of a 3GPP2 network, then the MS shall follow 3GPP2 specifications in meeting any 3GPP2 specific system selection constraints and in all signalling procedures towards the 3GPP2 network.

While registered to VPLMN via 3GPP2 access, the MS shall follow the 3GPP2 specifications for scan of higher priority PLMNs. Additionally to the requirements specified for 3GPP2 system, a multi mode MS while registered to a 3GPP2 VPLMN shall follow the requirements specified in clause 4.4.3.3.

NOTE: It is assumed that the MS can determine the PLMN identity of networks supporting 3GPP2 technologies from the information broadcast over the air.

Annex A (normative):
HPLMN Matching Criteria

With the introduction of PCS1900 with the regulatory mandate to allocate 3-digit MNC codes, additional functionality is required to identify the HPLMN.

Assumptions

An MNC code shall consist of 2 or 3 decimal digits. In NA PCS1900, all SIMs shall store 3 digit MNCs.

Any network using a 2 digit MNC code shall broadcast the hexadecimal code "F" in place of the 3^rd digit.

For PCS1900 for North America, regulations mandate that a 3-digit MNC shall be used; however during a transition period, a 2 digit MNC may be broadcast by the Network and, in this case, the 3^rd digit of the SIM is stored as 0 (this is the 0 suffix rule).

With the exception of North America during the transition period:

a) Within a single country (or area identified by a MCC) all networks shall broadcast a 2 digit MNC code, or all networks shall broadcast a 3 digit MNC code. A mixture of broadcast 2 and 3 digit MNC codes is not permitted within a single country (or area identified by a MCC).

b) A network which broadcasts a 2 digit MNC code, will issue SIMs with a 2 digit MNC code in the IMSI on the SIM. A network which broadcasts a 3 digit MNC code, will issue SIMs with a 3 digit MNC code in the IMSI on the SIM.

Definitions and abbreviations

BCCH-MCC For GERAN, the MCC part of the LAI read from System Information type 3 messages broadcast on the BCCH by the network (see 3GPP TS 44.018 [34]), for UTRA, the MCC part of the PLMN broadcasted as specified in 3GPP TS 25.331 [33], for E-UTRA, the MCC part of the PLMN broadcasted as specified in 3GPP TS 36.331 [42], or for NR, the MCC part of the PLMN broadcasted as specified in 3GPP TS 38.331 [65].

BCCH-MNC For GERAN the MNC part of the LAI read from System Information type 3 messages broadcast on the BCCH by the network (see 3GPP TS 44.018 [34]), for UTRA, the MNC part of the PLMN broadcasted as specified in 3GPP TS 25.331 [33], for E-UTRA, the MNC part of the PLMN broadcasted as specified in 3GPP TS 36.331 [42], or for NR, the MNC part of the PLMN broadcasted as specified in 3GPP TS 38.331 [65].

SIM-MCC The MCC part of the IMSI or of additional entries in the EHPLMN list read from the SIM.

SIM-MNC The MNC part of the IMSI or of additional entries in the EHPLMN list read from the SIM.

HPLMN Matching Criteria in mobiles which don’t support PCS1900 for NA:

Figure A.1 illustrates the logic flow described below. The text below is normative. Figure A.1 is informative.

(1) The MS shall compare using all 3 digits of the SIM-MCC with the BCCH-MCC. If the values do not match, then the HPLMN match fails.

NOTE: If the MCC codes match, then the number of digits used for the SIM-MNC must be the same as the number of digits used for the BCCH-MNC.

(2) The MS shall read the 3^rd digit of the BCCH-MNC. If the 3^rd digit is Hex F, then proceed to step (4).

(3) The MS shall compare using all 3 digits of the SIM-MNC with the BCCH-MNC. If the values match, then the HPLMN match succeeds, otherwise the HPLMN match fails.

(4) The MS shall compare using just the 1^st 2 digits the SIM-MNC with the BCCH-MNC. If the values match, then the HPLMN match succeeds, otherwise the HPLMN match fails.

If the EHPLMN list is present and is empty or if the EHPLMN list is not present, the matching procedure shall be done for the MCC/MNC of the IMSI.

If the EHPLMN list is present and is not empty, the matching procedure shall be done for all entries in the EHPLMN list until a match is found or all matches fail.

Figure A.1: HPLMN Matching Criteria Logic Flow for mobiles which support GSM and DCS1800 (informative)

HPLMN Matching Criteria for mobiles which support PCS1900 for NA:

Figure A.2 illustrates the logic flow described below. The text below is normative. Figure A.2 is informative.

(1) The MS shall compare using all 3 digits the SIM-MCC with the BCCH-MCC. If the values do not match, then the HPLMN match fails.

(2) The MS shall read the 3^rd digit of the BCCH-MNC. If the 3^rd digit is Hex F, then proceed to step (4).

(3) The MS shall compare using all 3 digits the SIM-MNC with the BCCH-MNC. If the values match, then the HPLMN match succeeds, otherwise the HPLMN match fails.

NOTE: These rules (1) – (3) are the same as for mobiles which don’t support PCS1900 for NA, except step (4) is different.

(4) The MS shall determine if the BCCH-MCC lies in the range 310-316 (i.e., whether this network is a PCS1900 for NA network). If the BCCH-MCC lies outside the range 310-316, then proceed to step (6).

(5) The MS shall compare the 3^rd digit of the SIM-MNC with ‘0’. If the 3^rd digit is not ‘0’ then the HPLMN match fails.

NOTE: This is the ‘0’ suffix rule.

(6) The MS shall compare using just the 1^st 2 digits of the SIM-MNC with the BCCH-MNC. If the values match, then the HPLMN match succeeds, otherwise the HPLMN match fails.

NOTE: When PCS1900 for NA switches over to broadcasting 3 digit MNCs in all networks, then the additional requirements for PCS1900 for NA can be deleted.

If the EHPLMN list is present and is empty or if the EHPLMN list is not present, the matching procedure shall be done for the MCC/MNC of the IMSI.

If the EHPLMN list is present and is not empty, the matching procedure shall be done for all entries in the EHPLMN list until a match is found or all matches fail.

Guidance for Networks in PCS1900 for NA

There may be some problems in the transition period from broadcasting 2 MNC digits to broadcasting 3 MNC digits. Here are some guidelines to avoid these problems.

(1) Existing network codes. Operators who currently use a 2 digit BCCH-MNC xy should use the new code xy0.

(2) New operators allocated 3 digit MNC codes with the same 1^st 2 digits as an existing operator shall not use a 3^rd digit of 0.

Figure A.2: HPLMN Matching Criteria Logic Flow for mobiles which support PCS1900 for NA (informative)

Annex B (normative):
PLMN matching criteria to be of same country as VPLMN

While an MS is roaming on a VPLMN, the VPLMN and a PLMN are of the same country only if their MCC values identify the same country. See clause 1.2 for the definition of country.

Annex C (normative):
Control plane solution for steering of roaming in 5GS