The Downlink Shared Channel Procedures are executed at the function [pdsch_procedures()](https://github.com/joary/openairinterface5g/tree/study/openair1/SCHED/phy_procedures_lte_eNb.c#L938).
The following table shows the sequence of operations executed at the PDSCH encoding, and the respective function used to execute each step.
| # | Procedure | Executed at | Callee |
|---|---|---|---|
| 1 | Transport Block CRC | crc24a() | dlsch_encoding() |
| 2 | Code Block Segmentation & CRC | lte_segmentation() | dlsch_encoding() |
| 3 | Channel Coding | threegpplte_turbo_encoder() | dlsch_encoding() |
| 4.1 | Rate Matching: Sub Block Interleaver | sub_block_interleaving_turbo() | dlsch_encoding() |
| 4.2 | Rate Matching: Bit Collection/Selection | lte_rate_matching_turbo() | dlsch_encoding() |
| 5 | Code Word Scrambling | dlsch_scrambling() | pdsch_procedures() |
| 6 | Modulation Mapping | allocate_REs_in_RB() | dlsch_modulation() |
| 7 | Layer Mapping | allocate_REs_in_RB() | dlsch_modulation() |
| 8 | Precoding | allocate_REs_in_RB() | dlsch_modulation() |
| 9 | Resource Mapping | allocate_REs_in_RB() | dlsch_modulation() |
Also the following tree view shows the sub-functions called by [pdsch_procedures()](https://github.com/joary/openairinterface5g/tree/study/openair1/SCHED/phy_procedures_lte_eNb.c#L938)
- pdsch_procedures()
- Select wich information will be transmitted:
- If Randon Access Response:
- mac_xface->fill_rar()
- add_ue()
- If error on add_ue()
- mac_xface->cancel_ra_proc()
- generate_eNB_ulsch_params_from_rar()
- mac_xface->set_msg3_subframe()
- If Normal DLCSH data:
- mac_xface->get_dlsch_sdu()
- If Randon Access Response:
- eNB->te() - Pointer to the Downlink Shared Channel Encoding Function
- dlsch_scrambling()
- dlsch_modulation()
- Parse the modulation, layer-mapping and precoding parameters
- allocate_REs_in_RB()
- Select wich information will be transmitted: