T1a parameter

Accelerated Computing Aerial Forum
1

Hi Team,

I want to know what is exact time the aerial SW will sent the traffic, e.g. as the below parameters, the configuration is cat-A rru, 4t4r.

  T1a_max_cp_ul_ns: 345000
  T1a_min_cp_ul_ns: 300000
  T1a_max_cp_dl_ns: 345000
  T1a_min_cp_dl_ns: 300000
  T1a_max_up_ns: 220000 # T1a_max_cp_dl - Tcp_adv_dl

because when I tcpdump the pcap in DU, I found that some packet is not in the Tx window as {T1min, T1max} defined. In FlexRAN, usually only the parameter of max is used in cat-a.

2

The basic workflow is that Aerial enqueues Tx packets with a timestamp to transmit to the NIC, and then NIC transmits the packets at the requested time based on its PHC.
Aerial usually finishes the packet/IQ generation well before the given time unless you have many cells, e.g., more than 20 cells on GH200, or more than 4 cells on DGX Spark.
The NIC should start transmitting the given packets at the right time unless the data path from the GPU memory (or unified system memory on DGX Spark) to the NIC is congested.
The timestamp captured in tcpdump is sometimes inaccurate.