2026-04-25 20:54 UTC
I start by showing how to process the NPSS and NSSS synchronization signals and the NRS reference signals. I detect 6 cells with different SNRs. Interestingly, one of them is not synchronized to the rest. I show how the NPSS and NSSS are beamed in patterns of 4 transmissions. Then I show how to decode the NPBCH, the SIB1-NB, and the SI messages containing the rest of the system information. I explain what all the values in the SIB-NBs mean, parsing them in Wireshark.
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@destevez@mastodon.social 2026-04-25 20:55
Next I show how to spot paging messages by their power, and how to decode their corresponding NPDCCH and NPDSCH transmissions. I explain how paging scheduling works in terms of the UE IMSI. Finally I decode the downlink messages sent to the V16 beacon that I was testing. The eNB to which the beacon had attached is the one that is not synchronized with the rest, and unfortunately it is weaker than other eNBs, so some messages cannot be decoded due to interference.