41 lines
1.7 KiB
Markdown
41 lines
1.7 KiB
Markdown
# ADR-269: Qualcomm CSI Wire Protocol
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- **Status**: accepted
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- **Date**: 2026-07-18
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- **Tags**: qualcomm, csi, protocol, rust, udp, replay
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## Decision
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Define `QCS1` version 1 as a vendor-boundary envelope, not a Qualcomm firmware ABI.
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It uses a 72-byte little-endian header plus payload and CRC-32/IEEE. The header
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records report kind, total length, sequence, monotonic timestamp, device ID,
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chipset profile, center frequency, bandwidth, flags, Tx/Rx counts, numeric format,
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PPDU type, subcarrier count, noise floor, scale, subcarrier spacing, calibration
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ID and payload length.
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CSI payloads contain one signed RSSI byte per receive chain followed by
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`tx * rx * subcarriers` complex i16 or finite f32 values in Tx-major, Rx-major,
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subcarrier-major order. Capability reports carry bounded opaque bytes. One QCS1
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frame maps to one UDP datagram; replay files prefix each frame with a little-endian
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u32 length.
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Parsers fail closed on unknown enums, bad CRC, truncation, trailing datagram data,
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non-finite values, inconsistent dimensions, chipset chain/bandwidth violations,
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payload mismatches, arithmetic overflow and the IPv4 UDP payload ceiling. A
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synthetic flag provides end-to-end simulator provenance.
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Version 1 profiles are QCA9300, QCN9074 and QCN9274. QCA9300 is capped at three
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chains and 40 MHz; modern profiles are capped at four chains and 160 MHz.
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## Consequences
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- Simulator, replay and future hardware adapters share one validated Rust API.
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- No private firmware layout is represented or redistributed.
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- 320 MHz/EHT matrices require segmentation or a later protocol revision.
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## Links
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- [ADR-268: Qualcomm platform strategy](ADR-268-qualcomm-atheros-csi-platform.md)
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- [ADR-267: MediaTek MTC1 protocol](ADR-267-mediatek-mimo-csi-wire-protocol.md)
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