[ns] wifi association and scanning in infrastructure mode

[ichrak amdouni]

Hi all,

I am working with ns3.3.

I want to simulate scanning, association in an infrastructure wifi network.

1) I used the patch provided by *Gustavo J. A. M. Carneiro (wifi scanning)
to make the station switch from a channel to another looking for existent
infrastructures to probe.*

*The issue is that association always fails. Even if I use the same channel
but I still setting the wifi channel to the same address, it always fails.
>From my logs, I noticed that the AP is always 'in Sync' state even at the
absence of any other traffic. Should it be an error while adapting the patch
to version 3.3?*


 *I have already posted this problem, but I am restating it in order to make
link with the second problem I have:*

   1.

   *now apart from switching from channel to another and in order to
   simulate scanning and association, I used the same method from the
   aforementioned patch (StartActiveScanning) (adapted to ns3.3). I still face
   the bug 396 (ap has records failure status of association while the sta
   believes it is associated) and here is my log:*



   *3.10116s [mac=00:00:00:00:00:01] NqstaWifiMac:Receive(assoc complete
   with, 00:00:00:00:00:03)*

   *3.10116s [mac=00:00:00:00:00:01] NqstaWifiMac:Receive(): assoc completed
   *

   *3.11038s [mac=00:00:00:00:00:03] MacLow:NormalAckTimeout(0x9e928e0)*

   *3.11038s [mac=00:00:00:00:00:03] MacLow:NormalAckTimeout(): normal ack
   timeout*

   *3.11038s DcaTxop:MissedAck(0x9e92c60)*

   *3.11038s DcaTxop:MissedAck(): 00:00:00:00:00:03 missed ack*

   *3.11038s DcaTxop:MissedAck(): 00:00:00:00:00:03 Ack Fail*

   *3.11038s [mac=00:00:00:00:00:03] NqapWifiMac:TxFailed(0x9e927e8)*

   *3.11038s [mac=00:00:00:00:00:03] NqapWifiMac:TxFailed(): assoc failed
   with sta=00:00:00:00:00:01*

 *So, the same problem, missing acknowledgment leads to two different status
in the AP and the sta. *

   1.

   *the normal behavior of such an access point (with that bug) would be to
   refuse disseminating data generated in this sta since it consider that it is
   not associated to it. Even if I comment the test performed by the ap as
   follows. *

   *NqapWifiMac while receiving data from the sta, that is :*

   *void *

   *NqapWifiMac::Receive (Ptr<Packet> packet, WifiMacHeader const *hdr)*

   *{*

   *NS_LOG_FUNCTION (this << packet << hdr);*

    *Mac48Address from = hdr->GetAddr2 ();*

   *WifiRemoteStation *fromStation = m_stationManager->Lookup (from);*

   *if (hdr->IsData ()) *

   *{*

   *Mac48Address bssid = hdr->GetAddr1 ();*

   *if (!hdr->IsFromDs () && *

   *hdr->IsToDs () &&*

   *bssid == GetAddress () /*&&*

   *fromStation->IsAssociated ()*/) *

    *Of course, omitting the test his does not radically solve the problem,
   but it was in purpose to debug an other problem:*

   2.

   *I try to send data from an UdpEchoClientApplication installed on the sta
   to an UdpEchoClientServer, to which the AP is connected via P2P link. From
   my logs, I noticed that the sta can't resolve an arp request looking for the
   ap address, in fact the ap to which it is associated does not receive the
   ARP request (there was no loss at physical layer) and then the traffic sent
   by the sta never reaches its destination.*

   *Does the fact that the AP consider the sta not associated let him ignore
   ARP request?*


 *Thank you in advance for any feedback.*