8.2.16 System Information Update

25.4333GPPRelease 17TSUTRAN Iub interface Node B Application Part (NBAP) signalling

8.2.16.1 General

The System Information Update procedure performs the necessary operations in order for the Node B to apply the correct scheduling of and/or to include the appropriate contents to the system information segments broadcast on the BCCH.

8.2.16.2 Successful Operation

Figure 22: System Information Update procedure, Successful Operation

The procedure is initiated with a SYSTEM INFORMATION UPDATE REQUEST message sent from the CRNC to the Node B using the Node B Control Port.

The Node B shall consider the requested updates to the BCCH schedule in the same order as the MIB/SB/SIB information is included in the SYSTEM INFORMATION UPDATE REQUEST message.

If the SYSTEM INFORMATION UPDATE REQUEST message includes the BCCH Modification Time IE, the updates to the BCCH schedule (possibly consisting of IB occurrence additions, IB occurrence deletions and IB occurrence contents updates) indicated in the SYSTEM INFORMATION UPDATE REQUEST message shall be applied by the Node B at the first time instance starting from the SFN value set by the BCCH Modification Time IE. If no BCCH Modification Time IE is included, the updates to the BCCH schedule shall be applied as soon as possible.

The Node B shall consider the requested updates to be the BCH mapped on SCCPCH if the BCH mapped on SCCPCH Indication IE is included in the SYSTEM INFORMATION UPDATE REQUEST message.

Information Block addition:
If the SYSTEM INFORMATION UPDATE REQUEST message includes segments of a certain MIB/SB/SIB, the Node B shall assume that all segments for that Information Block are included in the message and ordered with increasing Segment Index (starting from 0). For each included segment, segment type information and IB SG POS IE are also given in the SYSTEM INFORMATION UPDATE REQUEST message.

The Node B shall determine the correct cell system frame number(s) (SFN) for transmission of the segments of system information, from the scheduling parameters provided in the SYSTEM INFORMATION UPDATE REQUEST message. The SFN for transmitting the segments shall be determined by the IB SG REP IE and IB SG POS IE such that:

– SFN mod IB_SG_REP = IB_SG_POS

If the SYSTEM INFORMATION UPDATE REQUEST message contains Master Information Block (MIB) segments in addition to SIB or SB segments, the MIB segments shall first be sent in the physical channel by the Node B. Once these MIB segments have been sent in the physical channel, the updated SB/SIB segments shall then be sent in the physical channel.

Only if the inclusion of each new IB segment in the BCCH schedule leads to a valid segment combination according to TS 25.331 [18], the Node B shall accept the system information update.

If the SIB Originator IE value is set to "Node B", the Node B shall create the SIB segment of the SIB type given by the IB Type IE and autonomously update the SIB segment and apply the scheduling and repetition as given by the IB SG REP IE and IB SG POS IE.

SIBs originating from the Node B can only be SIBs containing information that the Node B can obtain on its own.

If the SYSTEM INFORMATION UPDATE REQUEST message contains SB3 segment in addition to SIB, the BCH mapped on SCCPCH is used. The SB3 segments shall first be sent in the physical channel SCCPCH by the Node B. Once the SB3 segment has been sent in the physical channel SCCPCH, the updated SIB segments shall then be sent in the physical channel SCCPCH.

Information Block deletion:
If an IB Deletion is indicated in an instance of MIB/SB/SIB information IE in the SYSTEM INFORMATION UPDATE REQUEST message, the Node B shall delete the IB indicated by the IB Type IE and IB OC ID IE from the transmission schedule on BCCH.

If the BCH mapped on SCCPCH Indication IE is included, and an IB Deletion is indicated in an instance of MIB/SB/SIB information IE in the SYSTEM INFORMATION UPDATE REQUEST message, the Node B shall delete the IB indicated by the IB Type IE and IB OC ID IE from the transmission schedule on BCH which is mapped on SCCPCH.

Information Block update:
If the SYSTEM INFORMATION UPDATE REQUEST message contains segments for an IB without IB SG REP IE and IB SG POS IE and there is already an IB in the BCCH schedule with the same IB Type and IB OC ID which is not requested to be deleted from the BCCH schedule by an IB deletion indicated in a MIB/SB/SIB information IE repetition present in the SYSTEM INFORMATION UPDATE REQUEST message before the IB segments are included, then the Node B shall only update the contents of the IB segments without any modification in segment scheduling.

If the SYSTEM INFORMATION UPDATE REQUEST message contains the BCH mapped on SCCPCH Indication IE and the segments for an IB without IB SG REP IE and IB SG POS IE and there is already an IB in the BCH mapped on SCCPCH schedule with the same IB Type and IB OC ID which is not requested to be deleted from the BCH mapped on SCCPCH schedule by an IB deletion indicated in a MIB/SB/SIB information IE repetition present in the SYSTEM INFORMATION UPDATE REQUEST message before the IB segments are included, then the Node B shall only update the contents of the IB segments without any modification in segment scheduling.

If the Node B successfully completes the updating of the physical channel scheduling cycle according to the parameters given in the SYSTEM INFORMATION UPDATE REQUEST message, it shall respond to the CRNC with a SYSTEM INFORMATION UPDATE RESPONSE message.

8.2.16.3 Unsuccessful Operation

Figure 23: System Information Update procedure, Unsuccessful Operation

If the Node B is unable to update the physical channel scheduling cycle according to all the parameters given in the SYSTEM INFORMATION UPDATE REQUEST message, it shall respond with a SYSTEM INFORMATION UPDATE FAILURE message with an appropriate cause value.

The Node B shall not incorporate any of the requested changes into the physical channel scheduling cycle, and the previous system information configuration shall remain intact.

Typical cause values are:

Radio Network Layer Cause:

– SIB Origination in Node B not Supported

– BCH mapped on SCCPCH scheduling error

Miscellaneous Cause:

– Hardware failure

– Control Processing overload

– O&M Intervention

8.2.16.4 Abnormal Conditions

The Node B shall reject, with the cause value "SIB origination in Node B not supported", requests for Node B originated system information blocks that make use of a value tag.

The Node B shall reject the requested update with cause value "BCCH scheduling error" if:

– After having handled a certain MIB/SB/SIB information IE repetition, an illegal BCCH schedule results;

– If a MIB/SB/SIB Information IE repetition includes an IB SG REP IE or an IB SG POS IE and there is already an IB in the BCCH schedule with the same IB Type and IB OC ID which is not requested to be deleted from the BCCH schedule by an IB deletion indicated in a MIB/SB/SIB information IE repetition present in the SYSTEM INFORMATION UPDATE REQUEST message before the IB addition is indicated. This rule shall apply even if the scheduling instructions in IB SG REP IE and IB SG POS IE were the same as the current scheduling instructions for the concerned IB;

– If a MIB/SB/SIB Information IE repetition includes no IB SG REP IE and IB SG POS IE and there is no IB in the BCCH schedule with the same IB Type and IB OC ID;

– If a MIB/SB/SIB Information IE repetition includes no IB SG REP IE and IB SG POS IE and there is already an IB in the BCCH schedule with the same IB Type and IB OC ID but it is requested to be deleted from the BCCH schedule by an IB deletion indicated in a MIB/SB/SIB information IE repetition present in the SYSTEM INFORMATION UPDATE REQUEST message before the IB addition is indicated.

The Node B shall reject the requested update with cause value "BCH mapped on SCCPCH scheduling error":

– If a MIB/SB/SIB Information IE repetition includes the MIB segement and the SB3 segment in the SYSTEM INFORMATION UPDATE REQUEST message.

– If a MIB/SB/SIB Information IE repetition includes the SB3 segment in the SYSTEM INFORMATION UPDATE REQUEST message, but the BCH mapped to SCCPCH Indication IE is not set to “InUse”.