5G SA注册过程---RRC建立

本文转载自查看原文 2019-10-13 21:22 2089 5G/ NR/ new radio/ standalone/ SA

　　1. UE选择一个ZC序列的随机接入码。UE随机选择前导码，此前导码与随机访问前导码ID（RAPID）一起关联引用。每个前导码都与一个RA-RNTI相关联。这个RA-RNTI的公式定义来自38.321的RA-RNTI= 1 + s_id + 14 × t_id + 14 × 80 × f_id + 14 × 80 × 8 × ul_carrier_id

　　2. gNB将给UE分配一个临时RNTI并在RAR中带给UE。

　　3. UE使用RA-RNTI检测并解扰DCI 1_0的PDCCH来获取RAR的传输块信息。

Field	Bits
Frequency domain resource assignment	⌈log₂(N_RB^DL,BWP(N_RB^DL,BWP + 1)/2)⌉ N_RB^DL,BWP is the size of CORESET 0
Time domain resource assignment	4
VRB-to-PRB mapping	1
Modulation and coding scheme	5
TB scaling	2
Reserved bits	16

　　4. UE解码RAR传输块获得msg3的UL Grant、MCS、TPC、CSI、Temp C-RNTI。

　　5. UE使用刚刚在RAR中获得的时频资源来发送msg3 RRC Setup Request，至少包含UE Identity和establishment cause。

EstablishmentCause ::= ENUMERATED {

emergency, highPriorityAccess, mt-Access, mo-Signalling,

mo-Data, mo-VoiceCall, mo-VideoCall, mo-SMS, mps-PriorityAccess, mcs-PriorityAccess,

spare6, spare5, spare4, spare3, spare2, spare1}

Log截取

　　6. gNB使用TC-RNTI加扰DCI 1_0的PDCCH并发送给UE，UE对应解扰获取msg4 RRC Setup。

　　7. 开始准备建立SRB1的参数。

　　8. UE解码RRC Setup消息获得无线承载相关配置和master cell group信息参数，如果解码OK则竞争冲突解决也同步完成。至此，SRB0建立完成，SRB1建立的参数也配置完成。

RRCSetup ::= SEQUENCE {

rrc-TransactionIdentifier RRC-TransactionIdentifier,

criticalExtensions CHOICE {

rrcSetup RRCSetup-IEs,

criticalExtensionsFuture SEQUENCE {}

}

RRCSetup-IEs ::= SEQUENCE {

radioBearerConfig RadioBearerConfig,

masterCellGroup OCTET STRING (CONTAINING CellGroupConfig),

lateNonCriticalExtension OCTET STRING OPTIONAL,

nonCriticalExtension SEQUENCE{} OPTIONAL

}

RadioBearerConfig ::= SEQUENCE {

srb-ToAddModList SRB-ToAddModList OPTIONAL, -- Cond HO-Conn

srb3-ToRelease ENUMERATED{true} OPTIONAL, -- Need N

drb-ToAddModList DRB-ToAddModList OPTIONAL, -- Cond HO-toNR

drb-ToReleaseList DRB-ToReleaseList OPTIONAL, -- Need N

securityConfig SecurityConfig OPTIONAL, -- Need M

...

}

SRB-ToAddModList ::= SEQUENCE (SIZE (1..2)) OF SRB-ToAddMod

SRB-ToAddMod ::= SEQUENCE {

srb-Identity SRB-Identity,

reestablishPDCP ENUMERATED{true} OPTIONAL, -- Need N

discardOnPDCP ENUMERATED{true} OPTIONAL, -- Need N

pdcp-Config PDCP-Config OPTIONAL, -- Cond PDCP

...

}

DRB-ToAddModList ::= SEQUENCE (SIZE (1..maxDRB)) OF DRB-ToAddMod

DRB-ToAddMod ::= SEQUENCE {

cnAssociation CHOICE {

eps-BearerIdentity INTEGER (0..15), -- EPS-DRB-Setup

sdap-Config SDAP-Config -- 5GC

} OPTIONAL, -- Cond DRBSetup

drb-Identity DRB-Identity,

reestablishPDCP ENUMERATED{true} OPTIONAL, -- Need N

recoverPDCP ENUMERATED{true} OPTIONAL, -- Need N

pdcp-Config PDCP-Config OPTIONAL, -- Cond PDCP

...

}

DRB-ToReleaseList ::= SEQUENCE (SIZE (1..maxDRB)) OF DRB-Identity

SecurityConfig ::= SEQUENCE {

securityAlgorithmConfig SecurityAlgorithmConfig OPTIONAL, -- Cond RBTermChange

keyToUse ENUMERATED{master, secondary} OPTIONAL, -- Cond RBTermChange

...

}

CellGroupConfig ::= SEQUENCE {

cellGroupId CellGroupId,

rlc-BearerToAddModList SEQUENCE (SIZE(1..maxLC-ID)) OF RLC-BearerConfig OPTIONAL, -- Need N

rlc-BearerToReleaseList SEQUENCE (SIZE(1..maxLC-ID)) OF LogicalChannelIdentity OPTIONAL, -- Need N

mac-CellGroupConfig MAC-CellGroupConfig OPTIONAL, -- Need M

physicalCellGroupConfig PhysicalCellGroupConfig OPTIONAL, -- Need M

spCellConfig SpCellConfig OPTIONAL, -- Need M

sCellToAddModList SEQUENCE (SIZE (1..maxNrofSCells)) OF SCellConfig OPTIONAL, -- Need N

sCellToReleaseList SEQUENCE (SIZE (1..maxNrofSCells)) OF SCellIndex OPTIONAL, -- Need N

...,

[[

reportUplinkTxDirectCurrent-v1530 ENUMERATED {true} OPTIONAL -- Cond BWP-Reconfig

]]

}

-- Serving cell specific MAC and PHY parameters for a SpCell:

SpCellConfig ::= SEQUENCE {

servCellIndex ServCellIndex OPTIONAL, -- Cond SCG

reconfigurationWithSync ReconfigurationWithSync OPTIONAL, -- Cond ReconfWithSync

rlf-TimersAndConstants SetupRelease { RLF-TimersAndConstants } OPTIONAL, -- Need M

rlmInSyncOutOfSyncThreshold ENUMERATED {n1} OPTIONAL, -- Need S

spCellConfigDedicated ServingCellConfig OPTIONAL, -- Need M

...

}

ReconfigurationWithSync ::= SEQUENCE {

spCellConfigCommon ServingCellConfigCommon OPTIONAL, -- Need M

newUE-Identity RNTI-Value,

t304 ENUMERATED {ms50, ms100, ms150, ms200, ms500, ms1000, ms2000, ms10000},

rach-ConfigDedicated CHOICE {

uplink RACH-ConfigDedicated,

supplementaryUplink RACH-ConfigDedicated

} OPTIONAL, -- Need N

...,

[[

smtc SSB-MTC OPTIONAL -- Need S

]]

}

SCellConfig ::= SEQUENCE {

sCellIndex SCellIndex,

sCellConfigCommon ServingCellConfigCommon OPTIONAL, -- Cond SCellAdd

sCellConfigDedicated ServingCellConfig OPTIONAL, -- Cond SCellAddMod

...,

[[

smtc SSB-MTC OPTIONAL -- Need S

]]

}

　　9. gNB使用C-RNTI加扰DCI 0_0的PDCCH并发送给UE，UE对应解扰获取发送msg5 RRC Setup Complete所需要的时频资源和MCS信息。

Field	Bits
Identifier of DCI formats	1
Frequency domain resource assignment	⌈log₂(N_RB^UL,BWP(N_RB^UL,BWP + 1)/2)⌉ N_RB^UL,BWP is the size of the active UL bandwidth part in case DCI format 0_0 is monitored in the UE specific search space if DCH sizes <= 4 and DCI size with C-RNTI <= 3. Otherwise N_RB^UL,BWP is the size of the initial UL bandwidth part.
Time domain resource assignment	4
Frequency hopping flag	1
Modulation and coding scheme	5
New data indicator	1
Redundancy version	2
HARQ process number	4
Downlink assignment index	2
TPC command for scheduled PUSCH	2
UL/SUL indicator	1

　　10. UE在对应时频资源位置使用gNB配置的MCS发送RRC Setup Complete消息，主要包含dedicatedNAS_Message (Registration type, 5G-GUTI, Last TAI, Requested NSSAI, UE Capability, List of PDU Sessions等)。