Late Arriving Duplicate Uplink Packets

1

Hi, how does the network server manages duplicate uplink messages that are arriving late due to LORA GW disconnection from the NS.
I understand about the deduplication window as described below, and the option to define a cooldown window, but this whole process only works in a few seconds duration.

  1. Deduplication Window
    o When a LoRaWAN device transmits an uplink, multiple gateways may receive it.
    o Each gateway forwards the uplink to the Network Server (NS).
    o The NS waits for a short deduplication window (e.g., 200ms–2s) to gather all duplicate packets.
    o During this window, it aggregates the metadata (RSSI, SNR, gateway IDs) from all receptions and forwards one processed uplink to the application.
  2. Cooldown Window
    o Once the deduplication window closes, the NS enters a cooldown window (typically a few seconds).
    o During this period, any late-arriving duplicate uplinks (from gateways with network latency) are recognized as duplicates and discarded.
    o These late packets are not forwarded to the application.

My question is how the network server handles “Late Arriving Duplicates”, beyond the Deduplication and Cool Down Windows, such as packet being forwarded by the GW to the NS several minutes and even hours delayed due a to network connection issue.

Would these “late arriving duplicates”, still be forwarded by the NS to the Application Server? Or can the NS recognize the duplicate uplink by examining frame counter (FCnt) and discard it rather than forwarding to the application server?

Thank you for your clarification

2

LoRaWAN is time-sensitive. It’s not normal to have packets arrive so late. The reference implementation for LoRa gateways don’t store packets for uplink later.

But let’s say it does, since some gateway vendors have some feature like that. Yes, it’ll work as you say. It’ll likely get received by the LNS late and get ignored because the FCntUp was already seen. If it’s the only copy of the latest message (i.e. no other gateways received the message), then the uplink will be processed normally but it is likely that no downlink can be sent correctly in response to it.