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fix: extend retransmission timeout for ROUTER_LATE broadcast window #9186

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fix: extend retransmission timeout for ROUTER_LATE broadcast window #9186

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5ebf52d
increase timeout. still ran into issue.
mdecourcy Jan 5, 2026
26a599e
Merge branch 'develop' into fix/router-late-implicit-ack-timeout
thebentern Jan 6, 2026
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9 changes: 5 additions & 4 deletions src/mesh/RadioInterface.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -251,10 +251,11 @@ uint32_t RadioInterface::getRetransmissionMsec(const meshtastic_MeshPacket *p)
uint32_t packetAirtime = getPacketTime(numbytes + sizeof(PacketHeader));
// Make sure enough time has elapsed for this packet to be sent and an ACK is received.
// LOG_DEBUG("Waiting for flooding message with airtime %d and slotTime is %d", packetAirtime, slotTimeMsec);
float channelUtil = airTime->channelUtilizationPercent();
uint8_t CWsize = map(channelUtil, 0, 100, CWmin, CWmax);
// Assuming we pick max. of CWsize and there will be a client with SNR at half the range
return 2 * packetAirtime + (pow_of_2(CWsize) + 2 * CWmax + pow_of_2(int((CWmax + CWmin) / 2))) * slotTimeMsec +
// Account for worst-case ROUTER_LATE delay: (2 * CWmax + pow_of_2(CWmax)) * slotTimeMsec
// ROUTER_LATE uses SNR-based CWsize independent of channel util, so we must assume CWmax for both terms
// to ensure timeout is always longer than the maximum possible ROUTER_LATE rebroadcast delay.
// This prevents MAX_RETRANSMIT errors when ROUTER_LATE nodes successfully rebroadcast but with delay.
return 2 * packetAirtime + (2 * pow_of_2(CWmax) + 2 * CWmax) * slotTimeMsec +
PROCESSING_TIME_MSEC;
}

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