SpectrumWifiPhy with multiple interfering APs.

[Michael Rademacher]

Hi everybody, 

I have started to use the new ns-3 SpectrumWifiPhy module which is, as far as I understand, in the final review phase.
See:
https://codereview.appspot.com/293380043/ 

https://www.nsnam.org/bugzilla/show_bug.cgi?id=2400

First (but simple) experiments with this new module look promising. Thanks to the developers.

I am currently working with the following code base:

https://github.com/tomhenderson/ns-3-dev-git/tree/spectrum-wifi

However, multiple WiFi APs and stations on the same MultiModelSpectrumChammel seems not to be working. 

I slightly modified the code in examples/wireless/wifi-spectrum-per-example.cc  by adding one additional AP and station on the same spectrumchannel:

***** Snippet from the lines 440-458

else if (wifiType == "ns3::SpectrumWifiPhy")

    {

    mac.SetType ("ns3::StaWifiMac",

                "Ssid", SsidValue (ssid),

                "ActiveProbing", BooleanValue (false));

    staDevice = wifi.Install (spectrumPhy, mac, wifiStaNode);

    mac.SetType ("ns3::ApWifiMac",

                "Ssid", SsidValue (ssid));

    apDevice = wifi.Install (spectrumPhy, mac, wifiApNode);

    // Added

    spectrumPhy.Set ("ChannelNumber", UintegerValue (36)); // 5.180 GHz

    mac.SetType ("ns3::StaWifiMac",

                "Ssid", SsidValue (ssid2),

                "ActiveProbing", BooleanValue (false));

    staDevice2 = wifi.Install (spectrumPhy, mac, wifiStaNode2);

    mac.SetType ("ns3::ApWifiMac",

                "Ssid", SsidValue (ssid2));

    apDevice2 = wifi.Install (spectrumPhy, mac, wifiApNode2);

    }

****

I have attached the modified example to this post. When I run the simulation, it terminates immediately with: 

msg="Received Wi-Fi Spectrum Signal with no WifiPhyTag", file=../src/wifi/model/spectrum-wifi-phy.cc, line=707

terminate called without an active exception

At the moment, I am stuck. Any suggestions how I should proceed?

Thanks, 

Michael

[Michael Rademacher]

A small update on this issue, perhaps useful for others and for future references. 

Mr. Henderson updated the code in his github repo

https://github.com/tomhenderson/ns-3-dev-git/tree/spectrum-wifi

and provided a new patch set here:
https://codereview.appspot.com/293380043/

The msg="Received Wi-Fi Spectrum Signal with no WifiPhyTag" is resolved!

However, a new bug was introduced and the provided example still fails with the following message:

assert failed. cond="m_current >= m_dataStart && m_current < m_dataEnd", msg="You have attempted to read beyond the bounds of the available buffer space. This usually indicates that a Header::Deserialize or Trailer::Deserialize method is trying to read data which was not written by a Header::Serialize or Trailer::Serialize method. In short: check the code of your Serialize and Deserialize methods.", file=./ns3/buffer.h, line=996

[Tom Henderson]

On 07/20/2016 03:03 AM, Michael Rademacher wrote:

A small update on this issue, perhaps useful for others and for future references. 

Mr. Henderson updated the code in his github repo

https://github.com/tomhenderson/ns-3-dev-git/tree/spectrum-wifi

and provided a new patch set here: https://codereview.appspot.com/293380043/ The msg="Received Wi-Fi Spectrum Signal with no WifiPhyTag" is resolved!

However, a new bug was introduced and the provided example still fails with the following message:

Sorry that I missed the earlier post on this.  I just pushed a small fix to the above issue to my github branch. - Tom

[Michael Rademacher]

Thank you very much Tom. It works now. 

I will conduct some further testing and report back if I encounter anything else related to SpetrumWifiPhy.