RLC logical architecture

RLC logical Architecture

? Provides segmentation/reassembly (payload units, PU) and retransmission service for both user(Radio Bearer) and control data (Signalling Radio bearer).

? Transparent mode (Tr): no overhead is added to higher layer data.

? Unacknowledged mode (UM): no retransmission protocol is used and data delivery is not guaranteed.

? Acknowledged mode (AM): Automatic Repeat reQuest (ARQ) mechanism is used for error correction.

Really good doc