Dropouts in TCP Bandwidth

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Novak Boskov

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May 12, 2022, 7:51:13 PM5/12/22
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I run run 4 SRNs under two scenarios:
- 1031 (Boston close static)
- 1033 (Boston close moderate)
My configuration file is always the same:
{
  "capture-pkts": "False",
  "colosseumcli": "True",
  "iperf": "False",  <--- NOTE THIS PART (I do iperf3 on my own)
  "users-bs": "3",
  "write-config-parameters": "True",
  "network-slicing": "True",  <--- AND THIS PART HERE
  "global-scheduling-policy": "0",
  "slice-scheduling-policy": "[1, 1, 1]",
  "tenant-number": "3",
  "slice-allocation": "{0: [0, 5], 1: [6, 11], 2: [12, 16]}",
  "slice-users": "{0: [3, 6, 9, 14, 17, 20, 25, 28, 31, 36, 39, 42], 1: [4, 7, 10, 15, 18, 21, 26, 29, 32, 37, 40, 43], 2: [2, 5, 8, 11, 13, 16, 19, 22, 24, 27, 30, 33, 35, 38, 41, 44]}",
  "custom-ue-slice": "True",
  "force-dl-modulation": "False",
  "heuristic-params": "{'buffer_thresh_bytes': [1000, 2000], 'thr_thresh_mbps': [0.25, 0.75]}",
  "bs-config": "{'dl_freq': 980000000, 'ul_freq': 1020000000, 'n_prb': 50}",
  "ue-config": "{'dl_freq': 980000000, 'ul_freq': 1020000000, 'force_ul_amplitude': 0.9}"
}

I pick two non-base station SRNs and use one as iperf3 server, the other as the client. Then I do the following:
- First, I run iperf3 for about 600 seconds in "client sends to server" mode.
- Second, I run iperf3 for about 600 seconds in "server sends to client" mode (these  two periods do not overlap).
Attached are the four resulting plots (upstream and downstream bandwidths for the two scenarios).

What I did not expect to find in these iperf3 measurements is this many dropouts in the case of moderate movements. The dropouts are depicted as data points at 0 bandwidth. 

Two main questions come to my mind:
1. How do I interpret these dropouts? Why is bandwidth 0 so many times ("see Boston close moderate Client->Server")?
2. How do we obtain the state of the physical channel as a scenario runs? Do these dropouts mean that the physical channel is cut off?

Best regards,
Novak Boškov
colosseum_moderate.png
colosseum_static.png

Novak Boskov

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May 18, 2022, 11:30:23 AM5/18/22
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Any updates on this one?
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