Inquiry about "Time Stamp" and "HW Time Stamp" within QXDM_Pro_5.2.570 software

Tools
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I am using QXDM software to check the 5G packets of different layers (PDCP, RLC, MAC, PUCCH…) from my Samsung Galaxy Ultra 23 smartphone. I would like to understand the UL and DL latency for wireless transmission by comparing the timestamps.

  1. But for the “Time Stamp”, I found the RLC UL packet items always happen before PDCP UL Pdu, this does not make sense. Therefore, I would like to ask whether the “Time Stamp” is the time when each event happens or just logging time. If both are wrong, what is the meaning for “Time Stamp”.
  2. For the “HW Time Stamp”, I cannot capture any information. How to enable that? What is the meaning for that?
  3. When I try to capture the packet items, I can only get UL data packet for PDCP layer even if I enable to capture the DL PDCP packets. Do you know why does that happen?
  4. If I would like to understand the latency of UL and DL transmission, do you have any good ideas to achieve that?

Thanks!