NotifyRXDrop in TX and RX states

[amritha rajagopal]

Hi all ,

The following code snippet is a part of wifi-phy.cc .

Both in RX and TX states the simulator is triggering NotifyRxDrop. Kindly explain the logic, if this is not a bug.

case WifiPhyState::RX:

      NS_ASSERT (m_currentEvent != 0);

      if (m_frameCaptureModel != 0

          && m_frameCaptureModel->CaptureNewFrame (m_currentEvent, event))

        {

          AbortCurrentReception ();

          NS_LOG_DEBUG ("Switch to new packet");

          StartRx (packet, txVector, mpdutype, rxPowerW, rxDuration, event);

        }

      else

        {

          NS_LOG_DEBUG ("drop packet because already in Rx (power=" <<

                        rxPowerW << "W)");

          NotifyRxDrop (packet);

          if (endRx > Simulator::Now () + m_state->GetDelayUntilIdle ())

            {

              //that packet will be noise _after_ the reception of the

              //currently-received packet.

              MaybeCcaBusyDuration ();

              return;

            }

        }

      break;

    case WifiPhyState::TX:

      NS_LOG_DEBUG ("drop packet because already in Tx (power=" <<

                    rxPowerW << "W)");

      NotifyRxDrop (packet);

      if (endRx > Simulator::Now () + m_state->GetDelayUntilIdle ())

        {

          //that packet will be noise _after_ the transmission of the

          //currently-transmitted packet.

          MaybeCcaBusyDuration ();

          return;

        }

      break;

Thanks and regards,

Amritha

[Harshal Dev]

Hi, so basically the code is correct. What it is doing is checking the current state of the PHY layer when a packet reception is triggered for every device on the channel. If the PHY layer of your device is either already transmitting or receiving a transmission when the channel tells it that another packet has arrived, obviously the PHY layer will drop the packet.