请问UE是如何知道使用哪种mode的？比如CDD还是闭环预编码

according to the transmissionMode contained in RRCConnnectionReconfiguration

那UE怎么知道如何去配置RRCConnnectionReconfiguration这个参数呢？eNB是如何告诉UE该怎么配置的？

RRCOnnectinReconfiguration is a RRC singalling which is sent from eNB to UE, in other words, the switching of transmission mode is decided at eNB side and is informed to UE via RRC signalling.

非常感谢，再问一下，RRC信令是在PDSCH中传输的吗？

信道映射关系:
RRC信令 -> DCCH -> DL-SCH -> PDSCH

pls refer to section 6.2.1 of 36.331

[font=Courier New][size=2]rrcConnectionReconfiguration
RRCConnectionReconfiguration,[/size][/font]
找到了，谢谢

是RRCConnectionReconfiguration中的哪个参数决定了发送模式的呢？

-- ASN1START

RRCConnectionReconfiguration ::= SEQUENCE {
rrc-TransactionIdentifier RRC-TransactionIdentifier,
criticalExtensions CHOICE {
c1 CHOICE{
rrcConnectionReconfiguration-r8 RRCConnectionReconfiguration-r8-IEs,
spare7 NULL,
spare6 NULL, spare5 NULL, spare4 NULL,
spare3 NULL, spare2 NULL, spare1 NULL
},
criticalExtensionsFuture SEQUENCE {}
}
}

RRCConnectionReconfiguration-r8-IEs ::= SEQUENCE {
measConfig MeasConfig OPTIONAL, -- Need ON
mobilityControlInfo MobilityControlInfo OPTIONAL, -- Cond HO
dedicatedInfoNASList SEQUENCE (SIZE(1..maxDRB)) OF
DedicatedInfoNAS OPTIONAL, -- Cond nonHO
radioResourceConfigDedicated RadioResourceConfigDedicated OPTIONAL, -- Cond HO-toEUTRA
securityConfigHO SecurityConfigHO OPTIONAL, -- Cond HO
nonCriticalExtension RRCConnectionReconfiguration-v890-IEs OPTIONAL
}

RRCConnectionReconfiguration-v890-IEs ::= SEQUENCE {
lateNonCriticalExtension OCTET STRING OPTIONAL, -- Need OP
nonCriticalExtension RRCConnectionReconfiguration-v920-IEs OPTIONAL
}

RRCConnectionReconfiguration-v920-IEs ::= SEQUENCE {
otherConfig-r9 OtherConfig-r9 OPTIONAL, -- Need ON
fullConfig-r9 ENUMERATED {true} OPTIONAL, -- Cond HO-Reestab
nonCriticalExtension RRCConnectionReconfiguration-v1020-IEs OPTIONAL
}

RRCConnectionReconfiguration-v1020-IEs ::= SEQUENCE {
sCellToReleaseList-r10 SCellToReleaseList-r10 OPTIONAL, -- Need ON
sCellToAddModList-r10 SCellToAddModList-r10 OPTIONAL, -- Need ON
nonCriticalExtension SEQUENCE {} OPTIONAL -- Need OP
}

SCellToAddModList-r10 ::= SEQUENCE (SIZE (1..maxSCell-r10)) OF SCellToAddMod-r10

SCellToAddMod-r10 ::= SEQUENCE {
sCellIndex-r10 SCellIndex-r10,
cellIdentification-r10 SEQUENCE {
physCellId-r10 PhysCellId,
dl-CarrierFreq-r10 ARFCN-ValueEUTRA
} OPTIONAL, -- Cond SCellAdd
radioResourceConfigCommonSCell-r10 RadioResourceConfigCommonSCell-r10 OPTIONAL, -- Cond SCellAdd
radioResourceConfigDedicatedSCell-r10 RadioResourceConfigDedicatedSCell-r10 OPTIONAL, -- Cond SCellAdd2
...
}

SCellToReleaseList-r10 ::= SEQUENCE (SIZE (1..maxSCell-r10)) OF SCellIndex-r10

SecurityConfigHO ::= SEQUENCE {
handoverType CHOICE {
intraLTE SEQUENCE {
securityAlgorithmConfig SecurityAlgorithmConfig OPTIONAL, -- Cond fullConfig
keyChangeIndicator BOOLEAN,
nextHopChainingCount NextHopChainingCount
},
interRAT SEQUENCE {
securityAlgorithmConfig SecurityAlgorithmConfig,
nas-SecurityParamToEUTRA OCTET STRING (SIZE(6))
}
},
...
}

-- ASN1STOP

hi,
radioResourceConfigDedicated - physicalConfigDedicated - antennaInfo - transmissionMode

the simplest method is to search 36.331 by keyword "transmissionMode ".

thank you!