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rfsimulator: add support to simulate a long propagation delay

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Add the option `--rfsimulator.prop_delay` to specify the simulated receive-path (gNB: UL, UE: DL) propagation delay in ms.
This option can be used e.g. to simulate a simple GEO satellite channel by specifying `--rfsimulator.prop_delay 238.74` to both, the gNB and the UE.

This is part of the work developed by Fraunhofer IIS within the ESA-funded project 5G-GOA (https://connectivity.esa.int/projects/5ggoa).
This commit is contained in:
Thomas Schlichter
2024-05-07 20:46:37 +02:00
parent 82bd07ebd5
commit 5ac881b7c1
5 changed files with 75 additions and 89 deletions
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radio/rfsimulator/README.md
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@@ -73,10 +73,11 @@ The RF simulator is using the configuration module, and its parameters are defin
|:--------------------- |:-------------------------------------------------------------------------------|----: |
|`--rfsimulator.serveraddr <addr>`| ip address to connect to, or `server` to behave as a tcp server | 127.0.0.1 |
|`--rfsimulator.serverport <port>`| port number to connect to or to listen on (eNB, which behaves as a tcp server) | 4043 |
| `--rfsimulator.options` | list of comma separated run-time options, two are supported: `chanmod`, `saviq`| all options disabled |
| `--rfsimulator.options saviq` | store IQs to a file for future replay | disabled |
|`--rfsimulator.options` | list of comma separated run-time options, two are supported: `chanmod`, `saviq`| all options disabled |
|`--rfsimulator.options saviq` | store IQs to a file for future replay | disabled |
|`--rfsimulator.options chanmod` | enable the channel model | disabled |
|`--rfsimulator.IQfile <file>` | path to a file to store the IQ samples to (only with `saviq`) | `/tmp/rfsimulator.iqs` |
|`--rfsimulator.prop_delay` | simulated receive-path (gNB: UL, UE: DL) propagation delay in ms | 0 |
|`--rfsimulator.wait_timeout` | wait timeout when no UE is connected | 1 |
Please refer to this document [`SIMULATION/TOOLS/DOC/channel_simulation.md`](../../openair1/SIMULATION/TOOLS/DOC/channel_simulation.md) for information about using the RFSimulator options to run the simulator with a channel model.
@@ -152,6 +153,24 @@ The format intends to be compatible with the OAI store/replay feature on USRP.
Please refer to this document [`channel_simulation.md`](../../openair1/SIMULATION/TOOLS/DOC/channel_simulation.md) to get familiar with channel simulation in RFSIM and to see the list of commands for real-time usage with telnet.
## How to simulate a simple GEO satellite channel model
A simple channel model for satellites on a geostationary orbit (GEO) simulates simply one line-of-sight propagation channel.
The most basic version is to simply simulate a constant propagation delay, without any other effects.
In case of a transparent GEO satellite, the minumum one-way propagation delay (DL: gNB -> satellite -> UE, or UL: UE -> satellite -> gNB) is 238.74 ms.
So, additionally to other parameters, this parameter should be given when executing the gNB and the UE executables:
```
--rfsimulator.prop_delay 238.74
```
Note:
To successfully establish a connection with such a GEO satellite channel, both gNB and UE need to have the NTN support configured.
# Caveats
There are issues in power control: txgain/rxgain setting is not supported.