4G/LTE - LTE NB

RRC

As in physical layers, in RRC there has been drastical changes for LTE-NB introducing a lot of new RRC messages and IE (Information Elements) dedicated for LTE-NB. Understandably some of the functions of normal LTE function are not supported in LTE-NB.

< RRC Functions Not in LTE-NB >

Followings are the functionality that are supported in normal LTE but not supported in LTE-NB. These are based on 36.331 4.4 Functions.

• ETWS Notification, CMAS Notification
• InterRAT Mobility including e.g security activation transfer of RRC context information
• Measurement Configuration and Reporting
• Self-configuration and Self-optimization
• Measurement logging and reporting for network performance optimization

< LTE-NB RRC Messages at High Level >

Following is the high level RRC messages defined for NB-IoT. Just take a brief look at the overall message structure and refer to 36.331 6.7 NB-IoT RRC messages for the details.  

BCCH-BCH-Message-NB ::= SEQUENCE {

    message                 BCCH-BCH-MessageType-NB

}

BCCH-BCH-MessageType-NB::=  MasterInformationBlock-NB

BCCH-DL-SCH-Message-NB ::= SEQUENCE {

    message                 BCCH-DL-SCH-MessageType-NB

}

BCCH-DL-SCH-MessageType-NB ::= CHOICE {

    c1                      CHOICE {

        systemInformation-r13               SystemInformation-NB,

        systemInformationBlockType1-r13     SystemInformationBlockType1-NB

    },

    messageClassExtension   SEQUENCE {}

}

PCCH-Message-NB ::= SEQUENCE {

    message                 PCCH-MessageType-NB

}

PCCH-MessageType-NB ::= CHOICE {

    c1                      CHOICE {

        paging-r13                          Paging-NB

    },

    messageClassExtension   SEQUENCE {}

}

DL-CCCH-Message-NB ::= SEQUENCE {

    message                 DL-CCCH-MessageType-NB

}

DL-CCCH-MessageType-NB ::= CHOICE {

    c1                      CHOICE {

        rrcConnectionReestablishment-r13        RRCConnectionReestablishment-NB,

        rrcConnectionReestablishmentReject-r13  RRCConnectionReestablishmentReject,

        rrcConnectionReject-r13                 RRCConnectionReject-NB,

        rrcConnectionSetup-r13                  RRCConnectionSetup-NB,

        spare4 NULL, spare3 NULL, spare2 NULL, spare1 NULL

    },

    messageClassExtension   SEQUENCE {}

}

DL-DCCH-Message-NB ::= SEQUENCE {

    message                 DL-DCCH-MessageType-NB

}

DL-DCCH-MessageType-NB ::= CHOICE {

    c1                      CHOICE {

        dlInformationTransfer-r13               DLInformationTransfer-NB,

        rrcConnectionReconfiguration-r13        RRCConnectionReconfiguration-NB,

        rrcConnectionRelease-r13                RRCConnectionRelease-NB,

        securityModeCommand-r13                 SecurityModeCommand,

        ueCapabilityEnquiry-r13                 UECapabilityEnquiry-NB,

        rrcConnectionResume-r13                 RRCConnectionResume-NB,

        spare2 NULL, spare1 NULL

    },

    messageClassExtension   SEQUENCE {}

}

UL-CCCH-Message-NB ::= SEQUENCE {

    message                 UL-CCCH-MessageType-NB

}

UL-CCCH-MessageType-NB ::= CHOICE {

    c1                      CHOICE {

        rrcConnectionReestablishmentRequest-r13 RRCConnectionReestablishmentRequest-NB,

        rrcConnectionRequest-r13                RRCConnectionRequest-NB,

        rrcConnectionResumeRequest-r13          RRCConnectionResumeRequest-NB,

        spare1 NULL

    },

    messageClassExtension   SEQUENCE {}

}

UL-DCCH-Message-NB ::= SEQUENCE {

    message                 UL-DCCH-MessageType-NB

}

UL-DCCH-MessageType-NB ::= CHOICE {

    c1                      CHOICE {

        rrcConnectionReconfigurationComplete-r13    RRCConnectionReconfigurationComplete-NB,

        rrcConnectionReestablishmentComplete-r13    RRCConnectionReestablishmentComplete-NB,

        rrcConnectionSetupComplete-r13              RRCConnectionSetupComplete-NB,

        securityModeComplete-r13                    SecurityModeComplete,

        securityModeFailure-r13                     SecurityModeFailure,

        ueCapabilityInformation-r13                 UECapabilityInformation-NB,

        ulInformationTransfer-r13                   ULInformationTransfer-NB,

        rrcConnectionResumeComplete-r13             RRCConnectionResumeComplete-NB,

        spare8 NULL, spare7 NULL,

        spare6 NULL, spare5 NULL, spare4 NULL,

        spare3 NULL, spare2 NULL, spare1 NULL

    },

    messageClassExtension   SEQUENCE {}

}