mirror of
https://gitlab.eurecom.fr/oai/openairinterface5g.git
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8107939f08
- all RAN code, CI code, configuration files, dockerfiles, in CSSL v1.0
- all deployment code (openshift, charts, ancillary files like shell
scripts), in MIT
- documentation in CC-BY-4.0
- exceptions might apply and are listed in NOTICE
- there is a new LICENSES folder with all licenses
- CONTRIBUTIONS.md has been updated accordingly
For automated changes based on OAI PL v1.1:
perl -i~ -0pe 's/\/\*.*Licensed to the OpenAirInterface.*openairinterface.org\n#?/\/*\n * SPDX-License-Identifier: LicenseRef-CSSL-1.0\n/s' **/*.{c,h,cpp}
perl -i~ -0pe 's/\/\*.*Licensed to the OpenAirInterface.*openairinterface.org\n#?/\/*\n * SPDX-License-Identifier: LicenseRef-CSSL-1.0\n/s' **/*.ts
perl -i~ -0pe 's/<!--.*Licensed to the OpenAirInterface.*openairinterface.org\n.*-->/<!-- SPDX-License-Identifier: LicenseRef-CSSL-1.0 -->/s' **/*.xml
The rest (cmake, files with missing license, cmake) manually.
106 lines
4.4 KiB
Markdown
106 lines
4.4 KiB
Markdown
<!-- SPDX-License-Identifier: CC-BY-4.0 -->
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# Overview
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This implements a shared memory realtime and near-realtime radio interface.
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This is performed using `shm_td_iq_channel` which handles the shared memory
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interface.
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# Architecture
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The `vrtsim` architecture follows a server-client model:
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- **Server (gNB)**: On startup, the server writes connection information to a
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file as provided in `--vrtsim.descriptor`, default location is
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`/tmp/vrtsim_connection`. This file contains information required by the client
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to establish communication.
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- **Client (UE)**: The client reads this file from, verifies its contents, and uses
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the provided information to open and connect to the shared memory channel.
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- **Shared Memory Channel**: Both server and client use the `shm_td_iq_channel` to
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exchange IQ samples and control data in real time or near-real time.
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## Channel modelling:
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# Limitations
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- Only 1gNB to 1nrUE: gNB as a server, UE as a client.
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# Usage
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On the UE and gNB: use `device.name vrtsim` command line argument.
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Additionally on gNB use `vrtsim.role server` and optionally
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`vrtsim.timescale <timescale>` to set the timescale. Timescale 1.0
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is the default and means realtime.
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To use `vrtsim` in containers, you have to enable inter-process communication,
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and mount the directory of the connection information in a shared volume
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between server and clients. For instance, in docker and default
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`vrtsim.connection_descriptor`, set `ipc: host` and share the server's and
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client's `/tmp` directory through a volume. For an example, refer to
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[this docker-compose file](../../ci-scripts/yaml_files/5g_vrtsim_cirdb/docker-compose.yaml).
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Channel modelling can be enabled by adding `vrtsim.chanmod 1` to the
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command line and should work the same as channel modelling in rfsimulator,
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see rfsimulator [documentation](../rfsimulator/README.md) with a slight difference:
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channel modelling is done on transmission instead of reception. To refect this,
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the model names are slightly different: the server expects a model named
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`server_tx_channel_model` while the client expects a model named `client_tx_channel_model`
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Additionally, `taps_client` is available in vrtsim. This allows to connect to
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channel emulation server and receive external taps (or channel impulse responses).
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To use external taps, use `--taps-socket` and provide a nanomsg PUB socket address
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that will publish the taps.
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# Debugging
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## Realtime issues
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Realtime issues can prevent the UE from connecting to the gNB, especially with
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channel modelling enabled. Consider adjusting `timescale` parameter until
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the UE can connect reliably.
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On exit, vrtsim will output a histogram of the measured transmission budget, which
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is defined as the number of microseconds before the transmitted samples could be
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read by peer.
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Example:
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```
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[HW] VRTSIM: Average TX budget 939.210 uS (more is better)
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[HW] VRTSIM: TX budget histogram: 216 samples
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[HW] Bin 0 [0.0 - 100.0uS]: 0
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[HW] Bin 1 [100.0 - 200.0uS]: 0
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[HW] Bin 2 [200.0 - 300.0uS]: 0
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[HW] Bin 3 [300.0 - 400.0uS]: 0
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[HW] Bin 4 [400.0 - 500.0uS]: 0
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[HW] Bin 5 [500.0 - 600.0uS]: 0
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[HW] Bin 6 [600.0 - 700.0uS]: 0
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[HW] Bin 7 [700.0 - 800.0uS]: 0
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[HW] Bin 8 [800.0 - 900.0uS]: 0
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[HW] Bin 9 [900.0 - 1000.0uS]: 117
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[HW] Bin 10 [1000.0 - 1100.0uS]: 0
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[HW] Bin 11 [1100.0 - 1200.0uS]: 0
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[HW] Bin 12 [1200.0 - 1300.0uS]: 0
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[HW] Bin 13 [1300.0 - 1400.0uS]: 0
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[HW] Bin 14 [1400.0 - 1500.0uS]: 0
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[HW] Bin 15 [1500.0 - 1600.0uS]: 0
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[HW] Bin 16 [1600.0 - 1700.0uS]: 0
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[HW] Bin 17 [1700.0 - 1800.0uS]: 0
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[HW] Bin 18 [1800.0 - 1900.0uS]: 0
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[HW] Bin 19 [1900.0 - 2000.0uS]: 0
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[HW] Bin 20 [2000.0 - 2100.0uS]: 0
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[HW] Bin 21 [2100.0 - 2200.0uS]: 0
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[HW] Bin 22 [2200.0 - 2300.0uS]: 0
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[HW] Bin 23 [2300.0 - 2400.0uS]: 0
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[HW] Bin 24 [2400.0 - 2500.0uS]: 0
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[HW] Bin 25 [2500.0 - 2600.0uS]: 0
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[HW] Bin 26 [2600.0 - 2700.0uS]: 0
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[HW] Bin 27 [2700.0 - 2800.0uS]: 0
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[HW] Bin 28 [2800.0 - 2900.0uS]: 0
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[HW] Bin 29 [2900.0 - 3000.0uS]: 0
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```
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Samples in bin 0 indicate realtime issues.
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