wave-frame-exchange-manager.cc

Go to the documentation of this file.

/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/*
 * Copyright (c) 2020 Universita' degli Studi di Napoli Federico II
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation;
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * Author: Stefano Avallone <stavallo@unina.it>
 */
 
#include "ns3/log.h"
#include "ns3/abort.h"
#include "ns3/wifi-protection.h"
#include "ns3/wifi-acknowledgment.h"
#include "wave-frame-exchange-manager.h"
#include "higher-tx-tag.h"
 
 
namespace ns3 {
 
NS_LOG_COMPONENT_DEFINE ("WaveFrameExchangeManager");
 
NS_OBJECT_ENSURE_REGISTERED (WaveFrameExchangeManager);
 
TypeId
WaveFrameExchangeManager::GetTypeId (void)
{
  static TypeId tid = TypeId ("ns3::WaveFrameExchangeManager")
    .SetParent<QosFrameExchangeManager> ()
    .AddConstructor<WaveFrameExchangeManager> ()
    .SetGroupName ("Wave")
  ;
  return tid;
}
 
WaveFrameExchangeManager::WaveFrameExchangeManager ()
{
  NS_LOG_FUNCTION (this);
}
 
WaveFrameExchangeManager::~WaveFrameExchangeManager ()
{
  NS_LOG_FUNCTION_NOARGS ();
}
 
void
WaveFrameExchangeManager::SetWaveNetDevice (Ptr<WaveNetDevice> device)
{
  m_scheduler = device->GetChannelScheduler ();
  m_coordinator = device->GetChannelCoordinator ();
  NS_ASSERT (m_scheduler != 0 && m_coordinator != 0);
}
 
WifiTxVector
WaveFrameExchangeManager::GetDataTxVector (Ptr<const WifiMacQueueItem> item) const
{
  NS_LOG_FUNCTION (this << *item);
  HigherLayerTxVectorTag datatag;
  bool found;
  found = ConstCast<Packet> (item->GetPacket ())->PeekPacketTag (datatag);
  // if high layer has not controlled transmit parameters, the real transmit parameters
  // will be determined by MAC layer itself.
  if (!found)
    {
      return m_mac->GetWifiRemoteStationManager ()->GetDataTxVector (item->GetHeader ());
    }
 
  // if high layer has set the transmit parameters with non-adaption mode,
  // the real transmit parameters are determined by high layer.
  if (!datatag.IsAdaptable ())
    {
      return datatag.GetTxVector ();
    }
 
  // if high layer has set the transmit parameters with non-adaption mode,
  // the real transmit parameters are determined by both high layer and MAC layer.
  WifiTxVector txHigher = datatag.GetTxVector ();
  WifiTxVector txMac = m_mac->GetWifiRemoteStationManager ()->GetDataTxVector (item->GetHeader ());
  WifiTxVector txAdapter;
  txAdapter.SetChannelWidth (10);
  // the DataRate set by higher layer is the minimum data rate
  // which is the lower bound for the actual data rate.
  if (txHigher.GetMode ().GetDataRate (txHigher.GetChannelWidth ()) > txMac.GetMode ().GetDataRate (txMac.GetChannelWidth ()))
    {
      txAdapter.SetMode (txHigher.GetMode ());
      txAdapter.SetPreambleType (txHigher.GetPreambleType ());
    }
  else
    {
      txAdapter.SetMode (txMac.GetMode ());
      txAdapter.SetPreambleType (txMac.GetPreambleType ());
    }
  // the TxPwr_Level set by higher layer is the maximum transmit
  // power which is the upper bound for the actual transmit power;
  txAdapter.SetTxPowerLevel (std::min (txHigher.GetTxPowerLevel (), txMac.GetTxPowerLevel ()));
 
  return txAdapter;
}
 
bool
WaveFrameExchangeManager::StartTransmission (Ptr<Txop> dcf)
{
  NS_LOG_FUNCTION (this << dcf);
 
  uint32_t curChannel = m_phy->GetChannelNumber ();
  // if current channel access is not AlternatingAccess, just do as FrameExchangeManager.
  if (m_scheduler == 0 || !m_scheduler->IsAlternatingAccessAssigned (curChannel))
    {
      return FrameExchangeManager::StartTransmission (dcf);
    }
 
  m_txTimer.Cancel ();
  m_dcf = dcf;
 
  Ptr<WifiMacQueue> queue = dcf->GetWifiMacQueue ();
 
  if (queue->IsEmpty ())
    {
      NS_LOG_DEBUG ("Queue empty");
      m_dcf->NotifyChannelReleased ();
      m_dcf = 0;
      return false;
    }
 
  m_dcf->NotifyChannelAccessed ();
  Ptr<WifiMacQueueItem> mpdu = queue->Peek ()->GetItem ();
  NS_ASSERT (mpdu != 0);
 
  // assign a sequence number if this is not a fragment nor a retransmission
  if (!mpdu->IsFragment () && !mpdu->GetHeader ().IsRetry ())
    {
      uint16_t sequence = m_txMiddle->GetNextSequenceNumberFor (&mpdu->GetHeader ());
      mpdu->GetHeader ().SetSequenceNumber (sequence);
    }
 
  WifiTxParameters txParams;
  txParams.m_txVector = GetDataTxVector (mpdu);
  Time remainingTime = m_coordinator->NeedTimeToGuardInterval ();
 
  if (!TryAddMpdu (mpdu, txParams, remainingTime))
    {
      // The attempt for this transmission will be canceled;
      // and this packet will be pending for next transmission by QosTxop class
      NS_LOG_DEBUG ("Because the required transmission time exceeds the remainingTime = "
                    << remainingTime.As (Time::MS)
                    << ", currently this packet will not be transmitted.");
    }
  else
    {
      SendMpduWithProtection (mpdu, txParams);
      return true;
    }
  return false;
}
 
void
WaveFrameExchangeManager::DoDispose (void)
{
  NS_LOG_FUNCTION (this);
  m_scheduler = 0;
  m_coordinator = 0;
  FrameExchangeManager::DoDispose ();
}
 
} //namespace ns3