SRB( Signaling Radio Bearer)就是无线信令承载;SRBs(Signalling Radio Bearers)是传输RRC和NAS消息的无线承载;根据3GPP TS38.331,5G (NR)的SRB有四种:
1.SRB的类型
SRB#0 RRC消息承载于CCCH信道
SRB#1 RRC和NAS消息,用在SRB2(含NAS消息)建立之前,承载于DCCH信道;
SRB#2 NAS消息,承载于DCCH信道;空口加密完成后由网络侧配置,SRB2较SRB1优先级低,;
SRB#3 UE双连接(EN-DC)中RRC消息,承载于DCCH信道;
SRB的功能在5G(NR)和LTE网络中相同。5G(NR)网络中只是增加了SRB3,它用在双连接(EN-DC)中,通过5G(NR)无线网络传递UE与SgNB之间SRB3消息;
2.SRB配置表
Information Element
SRB#1
SRB#2
SRB#3
PDCP-Config
t-Reordering
Infinite
RLC-Config CHOICE
AM
ul-RLC-Config
sn-FieldLength
size12
t-PollRetransmit
ms45
pollPDU
Infinity
pollByte
maxRetxThreshold
t8
dl-RLC-Config
t-Reassembly
ms35
t-StatusProhibit
ms0
logicalChannelIdentity
1
2
3
LogicalChannelConfig
priority
prioritisedBitRate
logicalChannelGroup
0
3.SRBs中NAS和 RRC消息映射
Message(消息)
Direction(方向)
Logical Channel (逻辑信道)
RLC Mode(模式)
SRB Mapping(映射)
MasterInformationBlock
UE <– NW
BCCH
TM
N/A
SIB1
SystemInformation
RRCSetupRequest
UE –> NW
CCCH
SRB0
RRCSetup
RRCResumeRequest1
CCCH1
RRCSystemInfoRequest
RRCReject
RRCResumeRequest
RRCReestablishmentRequest
RRCSetupComplete
DCCH
SRB1
RRCRelease
RRCReconfiguration
SRB1,SRB3
RRCReconfigurationComplete
MeasurementReport
MobilityFromNRCommand
Paging
PCCH
RRCReestablishment
RRCReestablishmentComplete
RRCResume
RRCResumeComplete
SecurityModeCommand
SecurityModeComplete
SecurityModeFailure
UEAssistanceInformation
UECapabilityEnquiry
UECapabilityInformation
ULInformationTransfer
SRB1,SRB2
非常有用的总结
您即将访问的地址是其它网站的内容,MSCBSC将不再对其安全性和可靠性负责,请自行判断是否继续前往
继续访问 取消访问,关闭