What is the difference between a TM, UM, and am three ways RLC can be used

Transfer from MSCBSC Heclong
Voice services in the RLC layer is not through the transmission, see the protocol stack on the understanding! As shown, the business surface in the RLC layer only Am,um mode, no TM,TM only bearer signaling, used to transmit SRB0, paging, and broadcast messages.

Claw3in1
Take the information from the top of the process, for example, in short:
TM: Do not add additional information to the upper PDU for direct transmission;
UM: Add additional information, the transmitted information does not need peer entity confirmation;
AM: Add additional information and the transmitted information needs to be confirmed by the peer entity.

PS: Refer to the specific
3GPP 25.332
"Radio Link Control (RLC) protocol Specification"

Marinelick
The choice of TM mode transmission of data for real-time requirements, and integrity or accuracy requirements are not high, such as voice services;
For the AM mode data, the requirements for accuracy are very high, in order to ensure the correct reception of data will be sacrificed some real-time, such as PS business, or very critical signaling (such as switching commands);
While the data in UM mode is in between, it is often seen that non-critical signaling such as periodic reporting of measurement reports

Dashing
TM: Do not add additional information to the upper PDU for direct transmission;
UM: Add additional information, the transmitted information does not require peer entity confirmation
AM: Add additional information, the transmitted information must be confirmed by the peer entity

Xxcbzq
TM mode is transparent mode, CS voice service mainly to ensure the real-time voice services, the transmission of relevant data RLC layer does not do processing.

Am um mode RLC layer in the establishment of the entity is configured, there are UM mode and am mode two classes, am mode in the issuance of the message needs to be confirmed by the AM mode, srb2,3; The UM mode is configured to SRB1 when releasing messages: For example, Rrc_conn_rel can be used without waiting for confirmation. Also I need to see the poll parameter's placement information if the AM mode returns an ACK message in L2

Cagio
Am and UM is only the difference between the processing mechanism of RLC, AM, BS will require the UE feedback status report, there is ARQ mechanism to re-transmit the lost Pdu,um word is sent regardless of, no retransmission. AM Lower packet loss rate, but am dependent on the upstream feedback, the upstream is required.

Z92nick
You confuse LTE and W/td,lte without CS domain. The CS RB of W or TD is built on the TM.

What is the difference between a TM, UM, and am three ways RLC can be used