3.8 Network sharing

3GPP44.018GSM/EDGE Radio Resource Control (RRC) protocolMobile radio interface Layer 3 specificationRelease 17TS

3.8.1 General

A network supporting network sharing shall broadcast network sharing information indicating the core network operators sharing the Radio Access Network (see sub-clause 3.8.2;

Additionally, in a cell where network sharing information is broadcast in SYSTEM INFORMATION TYPE 22 message, the network:

– shall broadcast network sharing information indicating the core network operators sharing the Radio Access Network;

– shall configure the contents of the SYSTEM INFORMATION TYPE 5/5bis/5ter and SYSTEM INFORMATION TYPE 6 messages to indicate the selected PLMN when the mobile station supports network sharing;

– may broadcast domain-specific access control information. Only networks and mobile stations supporting network sharing may support domain-specific access control.

– may broadcast when applicable PLMN-specific UTRAN and/or E-UTRAN information for inter-RAT cell re-selection.

A mobile station supporting network sharing shall use this information for PLMN (re)selection, cell reselection, E-UTRAN measurement reporting and to determine whether or not access to the network is allowed, possibly on a domain (CS or PS) basis.

A mobile station that has enabled EC operation shall use the network sharing information (if broadcast in the cell) for PLMN (re-)selection, cell reselection and to determine whether or not access to the network is allowed, see sub-clause 3.8.3.2.

NOTE: In a network supporting network sharing, a mobile station not supporting network sharing may reselect cells of other RATs not belonging to an equivalent PLMN of the registered PLMN. Setting different priorities for frequencies belonging to different PLMNs but in the same RAT may favour one PLMN over the other in areas shared by these PLMNs.

3.8.2 Network side

3.8.2.1 Provision of network sharing information

A cell where network sharing is supported shall broadcast the SYSTEM INFORMATION TYPE 22 message in which it shall indicate:

– whether or not mobile stations supporting network sharing are allowed to select the Common PLMN; and

– the PLMN ID (MCC and MNC) of up to four Additional PLMNs; and

– the permitted NCCs for cell (re)selection and measurement reporting corresponding to each of the up to four Additional PLMNs.

Additionally and individually for each of the up to four Additional PLMNs SYSTEM INFORMATION TYPE 22 may indicate the applicable access control information to be used for accessing the network (see sub-clauses 3.3.1.1.1, 3.5.2.1.1).

The network may also indicate in the SYSTEM INFORMATION TYPE 21 message access control information for EAB used for the preliminary access barring check (see sub-clause 3.3.1.4) individually for each of the up to four Additional PLMNs.

If domain-specific access control is used for a PLMN (Common PLMN and/or any of the up to four Additional PLMNs), the network shall include the corresponding information in the SYSTEM INFORMATION TYPE 22 message and SYSTEM INFORMATION TYPE 21 message as applicable.

The network may include PLMN-specific UTRAN and/or E-UTRAN information for inter-RAT cell re-selection purpose in the SYSTEM INFORMATION TYPE 23 message. When the SYSTEM INFORMATION TYPE 23 message is broadcast, the network shall broadcast the UTRAN and/or E-UTRAN information for inter-RAT cell re-selection related to a given PLMN in consecutive instances of the SYSTEM INFORMATION TYPE 23 message.

NOTE: So as to take into account the monitoring capabilities (see 3GPP TS 45.008) of mobile stations not supporting network sharing, the network may provide updates of the UTRAN/E-UTRAN frequencies lists broadcast within the SI2ter/SI2quater messages that are not applicable to mobile stations supporting network sharing (see sub-clause 3.8.3).

The network shall use the PLMN index provided by a mobile station supporting network sharing (see sub-clause 3.8.3) to map it upon the list of PLMN IDs it broadcasts in order to derive the PLMN selected by the mobile station and to route the initial access to the appropriate CN node (see subclause 10.3.1 and 3GPP TS 48.008 for the CS domain, see 3GPP TS 48.018 for the PS domain).

The network shall indicate the selected PLMN when configuring the neighbour cell information included in the SYSTEM INFORMATION TYPE 5/5bis/5ter messages for a mobile station supporting network sharing.

The network shall indicate the selected PLMN ID when configuring the Location Area Identification IE included in the SYSTEM INFORMATION TYPE 6 message for a mobile station supporting network sharing. Otherwise, it shall configure the Location Area Identification IE to indicate the common PLMN.

3.8.2.2 EC System information broadcasting

A cell supporting EC-GSM-IoT may broadcast the EC SYSTEM INFORMATION TYPE 4 message in which it shall indicate:

– whether or not the mobile station in EC operation is allowed to select the Common PLMN; and

– the PLMN ID (MCC and MNC) of up to four Additional PLMNs; and

– the permitted NCCs for cell (re)selection corresponding to each of the up to four Additional PLMNs; and

– whether or not sending of exception reports (see sub-clause 9.1.65) is allowed in each of the four Additional PLMNs.

Additionally and individually for each of the up to four Additional PLMNs the EC SYSTEM INFORMATION TYPE 4 message may indicate the applicable access control information to be used for accessing the network (see sub-clause 3.5.2a.1).

The network shall use the PLMN index provided by the mobile station to map it upon the list of PLMN IDs it broadcasts in order to derive the PLMN selected by the mobile station and to route the initial access to the appropriate CN node (see 3GPP TS 48.018).

3.8.3 Mobile station side

A mobile station supporting network sharing that has not enabled EC operation shall read the SYSTEM INFORMATION TYPE 22 message if broadcast in the cell and acquire the Network Sharing Information.

The mobile station shall use this information to determine the PLMNs available in this cell for (re)selection, the applicable access control information for the selected PLMN and the allowed NCC for measurement reporting and cell reselection (see 3GPP TS 45.008, 3GPP TS 23.003) for the selected PLMN.

A mobile station that has enabled EC operation shall read the EC SYSTEM INFORMATION TYPE 4 message if broadcast in the cell and acquire the Network Sharing Information therein. The mobile station shall use this information to determine the PLMNs available in the cell for (re)selection, the applicable access control information for the selected PLMN and the allowed NCC for cell reselection (see 3GPP TS 45.008 [34], 3GPP TS 23.003) for the selected PLMN.

The mobile station shall consider the Common PLMN (only if the Common PLMN is indicated as allowed in the SYSTEM INFORMATION TYPE 22 message or in the EC SYSTEM INFORMATION TYPE 4 message) and each indicated Additional PLMN in its PLMN selection process as specified in 3GPP TS 23.122.

Once a PLMN is selected, the mobile station shall only use the information applicable to this PLMN (i.e. PLMN ID, access control information, NCC Permitted) within the serving cell, until it is either modified, becomes invalid or a different PLMN or a new cell is reselected, whichever occurs first. If the applicable information is made invalid in the cell (see sub-clause 3.2.1), the mobile station shall assume network sharing is not used in the cell until it can again determine that network sharing is used.

For the mobile station, "applicable to this PLMN" shall be understood as meaning either "explicitly broadcast within (EC) SYSTEM INFORMATION messages for this PLMN" or "derived by the mobile station using a field explicitly provided by (EC) SYSTEM INFORMATION messages for a PLMN listed previous to its selected PLMN"; using a "previously listed field" means the mobile station attempts to find a PLMN previous to its selected PLMN for which a field of interest is explicitly provided by (EC) SYSTEM INFORMATION messages. The Annex M provides examples of using a "previously listed field".

A UTRAN and/or E-UTRAN capable mobile station supporting network sharing shall also read the SYSTEM INFORMATION TYPE 23 message if broadcast in the cell, to acquire PLMN-specific UTRAN and/or E-UTRAN information used for inter-RAT cell re-selection.

If so indicated by the SI_CHANGE_ALT field provided in the SYSTEM INFORMATION TYPE 13 message (see sub-clause 10.5.2.37b), a UTRAN and/or E-UTRAN capable mobile station supporting network sharing shall ignore any change in system information signalled by a SI_CHANGE_FIELD value ‘2’ provided in the same message.

When accessing the network, the mobile station shall indicate the selected PLMN index as follows:

– For access to CS domain via Initial Layer 3 message (see 3GPP TS 24.008 and sub-clause 10.3.1).

– For access to PS domain via AS signalling (see 3GPP TS 44.060).

3.8.4 Abnormal cases

The mobile station shall ignore any information provided for an Additional PLMN in the SYSTEM INFORMATION TYPE 22 message or in the EC SYSTEM INFORMATION TYPE 4 message if this Additional PLMN is the same as the Common PLMN.

If the same Additional PLMN ID is provided more than once in the SYSTEM INFORMATION TYPE 22 message or in the EC SYSTEM INFORMATION TYPE 4 message, the mobile station shall use the information corresponding to the first instance of that Additional PLMN.

If the number of Additional PLMNs broadcast in the SYSTEM INFORMATION TYPE 21 message as part of the EAB Network Sharing Information (see sub-clause 10.5.2.37m) differs from the number of Additional PLMNs broadcast in the SYSTEM INFORMATION TYPE 22 message as part of the Network Sharing Information (see sub-clause 10.5.2.37n) a mobile station supporting network sharing and configured for EAB shall ignore the EAB Network Sharing Information in the SYSTEM INFORMATION TYPE 21 message and assume the EAB Authorization Mask and EAB Subcategory information otherwise included in this message applies to all PLMNs in this cell (i.e. Common PLMN and all Additional PLMNs).

If the SYSTEM INFORMATION TYPE 21 message indicates that EAB is used for an Additional PLMN for which the previously listed EAB Authorization Mask/Subcategory apply, but no corresponding Additional EAB Authorization Mask / Additional EAB Subcategory fields and EAB Authorization Mask / EAB Subcategory fields are provided by the network (see Table 10.5.2.37m.2), the mobile station shall assume that EAB is not used for this Additional PLMN in this cell.

If the SYSTEM INFORMATION TYPE 21 message indicates that domain-specific access control is used for EAB for an Additional PLMN for which the previously listed EAB Authorization Mask/Subcategory apply, but no corresponding PS EAB Authorization Mask / PS EAB Subcategory fields and Common PS EAB Authorization Mask / Common PS EAB Subcategory fields are provided by the network (see Table 10.5.2.37m.2), the mobile station shall assume that domain-specific access control for EAB is not used for this Additional PLMN in this cell.

If the SYSTEM INFORMATION TYPE 22 message indicates that domain-specific access control is used for an Additional PLMN for which the previously listed Access Control Class bitmap applies, but no corresponding PS_ACC field and Common_PLMN_PS_ACC field are provided by the network (see Table 10.5.2.37n.2), the mobile station shall assume that domain-specific access control is not used for this Additional PLMN in this cell. If this occurs, this will not preclude a mobile station from using domain-specific access control information for EAB.

If the number of Additional PLMNs broadcast in the SYSTEM INFORMATION TYPE 23 message as part of the IRAT Cell Reselection Information (see sub-clause 10.5.2.37o) differs from the number of Additional PLMNs broadcast in the SYSTEM INFORMATION TYPE 22 message as part of the Network Sharing Information (see sub-clause 10.5.2.37n) a mobile station supporting network sharing shall ignore the IRAT Cell reselection Information in the SYSTEM INFORMATION TYPE 23 message and assume the SYSTEM INFORMATION TYPE 2ter/2quater messages fully apply to all PLMNs in this cell (i.e. Common PLMN and all Additional PLMNs).