MIMO layers in 5G

As defined by 3GPP, LTE Layer 2 structure consists of PDCP/RLC/MAC layers . Transport channels are located between the physical layer and MAC layer. MAC multiplexes RLC links and manages scheduling and priority handling via logical channels. The diagrams below show the structure for the downlink and uplink of Layer 2.

(2) Layer Mapping : This is the process where each codeword is mapped to mapped to one or multiple layers . Refer to Layer Mapping page. (3) Precoding : This is process where the layer data are allocated to multiple antenna ports (logical antenna ports in this stage).

Single-user MIMO (SU-MIMO) is the ability to transmit one or multiple data streams , called layers, from one transmitting array to a single user. SU-MIMO can thereby increase the throughput for that user and increase the capacity of the network.

5G-NR Layer 3 (RRC) Functions: Establishment, maintenance, and release of an RRC connection between the UE and NG-RAN including Addition, modification, and release of carrier aggregation, Addition, modification, and release of Dual Connectivity in NR or between E-UTRA and NR.