35 lines
2.1 KiB
Markdown
35 lines
2.1 KiB
Markdown
# PHY and MAC Interface
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The PHY sends scheduling requests and data indication to MAC via `nr_ue_dl_indication` for DL path and `nr_ue_ul_indication()` for UL path and the MAC sends scheduling configuration to PHY via `nr_ue_scheduled_response()`. The following diagram shows the interaction for PDCCH and PDSCH reception.
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```mermaid
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sequenceDiagram
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PHY->>+MAC: Requests for PDCCH config (via nr_ue_dl_indication)
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MAC->>+PHY: Schedules PDCCH reception (via nr_ue_scheduled_response)
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PHY->>+MAC: Indicates decoded DCI(s) (via nr_ue_dl_indication)
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MAC->>+PHY: Schedules PDSCH reception (via nr_ue_scheduled_response)
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```
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# Multi-threading Design
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The `UE_thread` function in `nr-ue.c` is the main top level thread that interacts with the radio unit. Once the thread spawns, it starts the 'Initial Synchronization'. Once its complete, the regular processing of slots commences.
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The UE exits when at any point in operation it gets out of synchronization. When the command line option `--non-stop` is used, the UE goes to 'Initial Synchronization' mode when it loses synchronization with gNB. However, this feature is not fully implemented and it is a work in progress at the time of writing this documentation. This will be the default behavior (not a command line option) when the feature is fully implemented.
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## Initial Synchronization Block
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```mermaid
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graph TD
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A(Start) -->|UE_thread| B["readFrame<br/>--Reads samples worth 2 frames"]
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B --> |Tpool thread| C["UE_synch<br/>--PSS & SSS detection<br/>--PBCH decode"]
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B --> |UE_thread| D["readFrame<br/>--trash samples to unblock radio"]
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C --> |Tpool thread| E[syncInFrame<br/>--shift first sample to start of frame]
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D --> |UE_thread| E
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```
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## Regular Slot Processing
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```mermaid
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graph TD
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E[syncInFrame<br/>--shift first sample to start of frame] -->|UE_thread| F["trx_read_func (slot n)"]
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F --> |Tpool thread| G["processSlotTX (slot n+4)<br/>--PUSCH encode<br/>--PUCCH encode<br/>--trx_write_func"]
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F --> |UE_thread| H["UE_processing (slot n)<br/>--PDCCH decode<br/>--PDSCH decode"]
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G --> |Tpool thread| I(Merge)
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H --> |UE_thread| I(Merge)
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I --> |Go to next slot<br/>UE_thread| F
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```
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