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Bugzilla – Full Text Bug Listing |
| Summary: | WifiPhy::NotifyMonitorSniffRx() is insensitive to RxNoiseFigure | ||
|---|---|---|---|
| Product: | ns-3 | Reporter: | Tom Henderson <tomh> |
| Component: | wifi | Assignee: | sebastien.deronne |
| Status: | RESOLVED FIXED | ||
| Severity: | normal | CC: | Izydor.sokoler, ns-bugs |
| Priority: | P3 | ||
| Version: | unspecified | ||
| Hardware: | All | ||
| OS: | All | ||
I agree with the proposed change. Before the patch:
----------------
$ ./waf --run 'wifi-spectrum-per-example --ns3::WifiPhy::RxNoiseFigure=7'
wifiType: ns3::SpectrumWifiPhy distance: 50m; sent: 1000 TxPower: 1 dBm (1.3 mW)
index MCS Rate (Mb/s) Tput (Mb/s) Received Signal (dBm) Noise (dBm) SNR (dB)
0 0 6.5 5.76513 7414 -79.6633 -100.966 21.3027
1 1 13 11.58 14892 -79.6633 -100.966 21.3027
2 2 19.5 17.3856 22358 -79.6633 -100.966 21.3027
3 3 26 22.9991 29577 -79.6633 -100.966 21.3027
4 4 39 0 0 N/A N/A N/A
$ ./waf --run 'wifi-spectrum-per-example --ns3::WifiPhy::RxNoiseFigure=10'
wifiType: ns3::SpectrumWifiPhy distance: 50m; sent: 1000 TxPower: 1 dBm (1.3 mW)
index MCS Rate (Mb/s) Tput (Mb/s) Received Signal (dBm) Noise (dBm) SNR (dB)
0 0 6.5 5.76513 7414 -79.6633 -100.966 21.3027
1 1 13 11.58 14892 -79.6633 -100.966 21.3027
2 2 19.5 17.3825 22354 -79.6633 -100.966 21.3027
3 3 26 0 0 N/A N/A N/A
After the patch:
----------------
$ ./waf --run 'wifi-spectrum-per-example --ns3::WifiPhy::RxNoiseFigure=7'
wifiType: ns3::SpectrumWifiPhy distance: 50m; sent: 1000 TxPower: 1 dBm (1.3 mW)
index MCS Rate (Mb/s) Tput (Mb/s) Received Signal (dBm) Noise (dBm) SNR (dB)
0 0 6.5 5.76513 7414 -79.6633 -93.966 14.3027
1 1 13 11.58 14892 -79.6633 -93.966 14.3027
2 2 19.5 17.3856 22358 -79.6633 -93.966 14.3027
3 3 26 22.9991 29577 -79.6633 -93.966 14.3027
4 4 39 0 0 N/A N/A N/A
$ ./waf --run 'wifi-spectrum-per-example --ns3::WifiPhy::RxNoiseFigure=10'
wifiType: ns3::SpectrumWifiPhy distance: 50m; sent: 1000 TxPower: 1 dBm (1.3 mW)
index MCS Rate (Mb/s) Tput (Mb/s) Received Signal (dBm) Noise (dBm) SNR (dB)
0 0 6.5 5.76513 7414 -79.6633 -90.966 11.3027
1 1 13 11.58 14892 -79.6633 -90.966 11.3027
2 2 19.5 17.3825 22354 -79.6633 -90.966 11.3027
3 3 26 0 0 N/A N/A N/A
i.e. performance is not affected by the patch, but reporting of SNR is. Conceptually, this patch shifts the point of SNR measurement from input to output of amplifier, but this is probably what is expected by users. I will update and also update documentation (doxygen and manual) about this.
fixed in changeset 13076:a04e85356951 |
NotifyMonitorSniffRx() reports signal and noise as follows (line 2550 in wifi-phy.cc): signalNoise.signal = RatioToDb (event->GetRxPowerW ()) + 30; signalNoise.noise = RatioToDb (event->GetRxPowerW () / snrPer.snr) - GetRxNoiseFigure () + 30; However, RxNoiseFigure is already accounted for in the snrPer calculation of InterferenceHelper. A user (Izydor Sokoler) suggests this statement instead: signalNoise.noise = RatioToDb (event->GetRxPowerW () / snrPer.snr) + 30; and complained that, e.g. the wifi-spectrum-per-example.cc, which reports this trace as the SNR, is insensitive to changing RxNoiseFigure values.