/* -*-  Mode: C++; c-file-style: "gnu"; indent-tabs-mode:nil; -*- */
/*
 * Copyright (c) 2011, 2012 Centre Tecnologic de Telecomunicacions de Catalunya (CTTC)
 *
 * 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: Nicola Baldo <nbaldo@cttc.es>
 */

#include <ns3/fatal-error.h>
#include <ns3/log.h>
#include <ns3/object-map.h>
#include <ns3/object-factory.h>
#include <ns3/node-list.h>
#include <ns3/node.h>

#include "lte-ue-rrc.h"
#include "lte-enb-rrc.h"
#include "lte-rlc.h"
#include "lte-rlc-tm.h"
#include "lte-rlc-um.h"
#include "lte-rlc-am.h"
#include "lte-pdcp.h"
#include "lte-pdcp-sap.h"
#include "lte-radio-bearer-info.h"
#include "lte-as-sap.h"
#include "lte-enb-net-device.h"

NS_LOG_COMPONENT_DEFINE ("LteUeRrc");

namespace ns3 {



/////////////////////////////
// CMAC SAP forwarder
/////////////////////////////

class UeMemberLteUeCmacSapUser : public LteUeCmacSapUser
{
public:
  UeMemberLteUeCmacSapUser (LteUeRrc* rrc);

  virtual void SetTemporaryCellRnti (uint16_t rnti);
  virtual void NotifyRandomAccessSuccessful ();
  virtual void NotifyRandomAccessFailed ();
  
private:
  LteUeRrc* m_rrc;
};

UeMemberLteUeCmacSapUser::UeMemberLteUeCmacSapUser (LteUeRrc* rrc)
  : m_rrc (rrc)
{
}

void
UeMemberLteUeCmacSapUser::SetTemporaryCellRnti (uint16_t rnti)
{
  m_rrc->DoSetTemporaryCellRnti (rnti);
}


void
UeMemberLteUeCmacSapUser::NotifyRandomAccessSuccessful ()
{
  m_rrc->DoNotifyRandomAccessSuccessful ();
}

void
UeMemberLteUeCmacSapUser::NotifyRandomAccessFailed ()
{
  m_rrc->DoNotifyRandomAccessFailed ();
}







const char* g_ueRrcStateName[LteUeRrc::NUM_STATES] = 
  {
    "IDLE_CELL_SELECTION",
    "IDLE_WAIT_SYSTEM_INFO",
    "IDLE_CAMPED_NORMALLY",
    "IDLE_RANDOM_ACCESS",
    "IDLE_CONNECTING",
    "CONNECTED_NORMALLY",
    "CONNECTED_REESTABLISHING",
    "CONNECTED_HANDOVER"
  };

std::string ToString (LteUeRrc::State s)
{
  return std::string (g_ueRrcStateName[s]);
}


/////////////////////////////
// ue RRC methods
/////////////////////////////

NS_OBJECT_ENSURE_REGISTERED (LteUeRrc);


LteUeRrc::LteUeRrc ()
  : m_cphySapProvider (0),
    m_cmacSapProvider (0),
    m_rrcSapUser (0),
    m_macSapProvider (0),
    m_asSapUser (0),
    m_state (IDLE_CELL_SELECTION),
    m_imsi (0),
    m_rnti (0),
    m_cellId (0),
    m_useRlcSm (true),
    m_connectionPending (0),
    m_receivedMib (0),
    m_receivedSib2 (0)

{
  NS_LOG_FUNCTION (this);
  m_cphySapUser = new MemberLteUeCphySapUser<LteUeRrc> (this);
  m_cmacSapUser = new UeMemberLteUeCmacSapUser (this);
  m_rrcSapProvider = new MemberLteUeRrcSapProvider<LteUeRrc> (this);
  m_drbPdcpSapUser = new LtePdcpSpecificLtePdcpSapUser<LteUeRrc> (this);
  m_asSapProvider = new MemberLteAsSapProvider<LteUeRrc> (this);
}


LteUeRrc::~LteUeRrc ()
{
  NS_LOG_FUNCTION (this);
}

void
LteUeRrc::DoDispose ()
{
  NS_LOG_FUNCTION (this);
  delete m_cphySapUser;
  delete m_cmacSapUser;
  delete m_drbPdcpSapUser;
  delete m_asSapProvider;
  m_drbMap.clear ();
}

TypeId
LteUeRrc::GetTypeId (void)
{
  static TypeId tid = TypeId ("ns3::LteUeRrc")
    .SetParent<Object> ()
    .AddConstructor<LteUeRrc> ()
    .AddAttribute ("DataRadioBearerMap", "List of UE RadioBearerInfo for Data Radio Bearers by LCID.",
                   ObjectMapValue (),
                   MakeObjectMapAccessor (&LteUeRrc::m_drbMap),
                   MakeObjectMapChecker<LteDataRadioBearerInfo> ())
    .AddAttribute ("CellId",
                   "Serving cell identifier",
                   UintegerValue (0), // unused, read-only attribute
                   MakeUintegerAccessor (&LteUeRrc::GetCellId),
                   MakeUintegerChecker<uint16_t> ())
    .AddAttribute ("C-RNTI",
                   "Cell Radio Network Temporary Identifier",
                   UintegerValue (0), // unused, read-only attribute
                   MakeUintegerAccessor (&LteUeRrc::GetRnti),
                   MakeUintegerChecker<uint16_t> ())
    .AddTraceSource ("StateTransition",
                     "fired upon every UE RRC state transition",
                     MakeTraceSourceAccessor (&LteUeRrc::m_stateTransitionCallback))
    ;
  return tid;
}


void
LteUeRrc::SetLteUeCphySapProvider (LteUeCphySapProvider * s)
{
  NS_LOG_FUNCTION (this << s);
  m_cphySapProvider = s;
}

LteUeCphySapUser*
LteUeRrc::GetLteUeCphySapUser ()
{
  NS_LOG_FUNCTION (this);
  return m_cphySapUser;
}

void
LteUeRrc::SetLteUeCmacSapProvider (LteUeCmacSapProvider * s)
{
  NS_LOG_FUNCTION (this << s);
  m_cmacSapProvider = s;
}

LteUeCmacSapUser*
LteUeRrc::GetLteUeCmacSapUser ()
{
  NS_LOG_FUNCTION (this);
  return m_cmacSapUser;
}

void
LteUeRrc::SetLteUeRrcSapUser (LteUeRrcSapUser * s)
{
  NS_LOG_FUNCTION (this << s);
  m_rrcSapUser = s;
}

LteUeRrcSapProvider*
LteUeRrc::GetLteUeRrcSapProvider ()
{
  NS_LOG_FUNCTION (this);
  return m_rrcSapProvider;
}

void
LteUeRrc::SetLteMacSapProvider (LteMacSapProvider * s)
{
  NS_LOG_FUNCTION (this << s);
  m_macSapProvider = s;
}

void
LteUeRrc::SetAsSapUser (LteAsSapUser* s)
{
  m_asSapUser = s;
}

LteAsSapProvider* 
LteUeRrc::GetAsSapProvider ()
{
  return m_asSapProvider;
}

void 
LteUeRrc::SetImsi (uint64_t imsi)
{
  NS_LOG_FUNCTION (this << imsi);
  m_imsi = imsi;
}

uint16_t
LteUeRrc::GetRnti () const
{
  NS_LOG_FUNCTION (this);
  return m_rnti;
}

uint16_t
LteUeRrc::GetCellId () const
{
  NS_LOG_FUNCTION (this);
  return m_cellId;
}


uint8_t 
LteUeRrc::GetUlBandwidth () const
{
  NS_LOG_FUNCTION (this);
  return m_ulBandwidth;
}

uint8_t 
LteUeRrc::GetDlBandwidth () const
{
  NS_LOG_FUNCTION (this);
  return m_dlBandwidth;
}

uint16_t 
LteUeRrc::GetDlEarfcn () const
{
  return m_dlEarfcn;
}

uint16_t 
LteUeRrc::GetUlEarfcn () const
{
  NS_LOG_FUNCTION (this);
  return m_ulEarfcn;
}


LteUeRrc::State
LteUeRrc::GetState (void)
{
  NS_LOG_FUNCTION (this);
  return m_state;
}

void
LteUeRrc::SetUseRlcSm (bool val) 
{
  NS_LOG_FUNCTION (this);
  m_useRlcSm = val;
}


void
LteUeRrc::DoStart (void)
{
  NS_LOG_FUNCTION (this);

  // setup the UE side of SRB0
  uint8_t lcid = 0;

  Ptr<LteRlc> rlc = CreateObject<LteRlcTm> ()->GetObject<LteRlc> ();
  rlc->SetLteMacSapProvider (m_macSapProvider);
  rlc->SetRnti (m_rnti);
  rlc->SetLcId (lcid);

  m_srb0 = CreateObject<LteSignalingRadioBearerInfo> ();  
  m_srb0->m_rlc = rlc;
  m_srb0->m_srbIdentity = 1;

  // CCCH (LCID 0) is pre-configured, here is the hardcoded configuration:
  LteUeCmacSapProvider::LogicalChannelConfig lcConfig;
  lcConfig.priority = 0; // highest priority
  lcConfig.prioritizedBitRateKbps = 65535; // maximum
  lcConfig.bucketSizeDurationMs = 65535; // maximum
  lcConfig.logicalChannelGroup = 0; // all SRBs mapped to LCG 0

  m_cmacSapProvider->AddLc (lcid, lcConfig, rlc->GetLteMacSapUser ());
    
}


void
LteUeRrc::DoSendData (Ptr<Packet> packet, uint8_t bid)
{
  NS_LOG_FUNCTION (this << packet);


  uint8_t drbid = Bid2Drbid (bid);

  std::map<uint8_t, Ptr<LteDataRadioBearerInfo> >::iterator it =   m_drbMap.find (drbid);
  NS_ASSERT_MSG (it != m_drbMap.end (), "could not find bearer with drbid == " << drbid);

  LtePdcpSapProvider::TransmitPdcpSduParameters params;
  params.pdcpSdu = packet;
  params.rnti = m_rnti;
  params.lcid = it->second->m_logicalChannelIdentity;
  
  NS_LOG_LOGIC (this << " RNTI=" << m_rnti << " sending " << packet << "on DRBID " << (uint32_t) drbid << " (LCID" << params.lcid << ")" << " (" << packet->GetSize () << " bytes)");
  it->second->m_pdcp->GetLtePdcpSapProvider ()->TransmitPdcpSdu (params);  
}

void
LteUeRrc::DoDisconnect ()
{
  NS_LOG_FUNCTION (this);

  switch (m_state)
    {      
    case IDLE_CELL_SELECTION:
    case IDLE_CAMPED_NORMALLY:
      NS_LOG_INFO ("already disconnected");
      break;

    case IDLE_CONNECTING:
      NS_LOG_INFO ("aborting connection setup procedure");
      SwitchToState (IDLE_CAMPED_NORMALLY);
      break;
      
    case CONNECTED_NORMALLY:
    case CONNECTED_REESTABLISHING:
    case CONNECTED_HANDOVER:
      LeaveConnectedMode ();
      break;
      
    default:
      NS_FATAL_ERROR ("method unexpected in state " << ToString (m_state));
      break;
    }
}

void
LteUeRrc::DoReceivePdcpSdu (LtePdcpSapUser::ReceivePdcpSduParameters params)
{
  NS_LOG_FUNCTION (this);
  m_asSapUser->RecvData (params.pdcpSdu);
}


void
LteUeRrc::DoSetTemporaryCellRnti (uint16_t rnti)
{
  NS_LOG_FUNCTION (this << rnti);
  m_rnti = rnti;
  m_rrcSapUser->Reestablish ();
  m_cphySapProvider->SetRnti (m_rnti);
}

void
LteUeRrc::DoNotifyRandomAccessSuccessful ()
{
  NS_LOG_FUNCTION (this << m_imsi << ToString (m_state));
  switch (m_state)
    {
    case IDLE_RANDOM_ACCESS:     
      {
        // we just received a RAR with a T-C-RNTI and an UL grant
        // send RRC connection request as message 3 of the random access procedure 
        SwitchToState (IDLE_CONNECTING);
        LteRrcSap::RrcConnectionRequest msg;
        msg.ueIdentity = m_imsi;
        m_rrcSapUser->SendRrcConnectionRequest (msg); 
      }
      break;
      
    case CONNECTED_HANDOVER:     
      {
        LteRrcSap::RrcConnectionReconfigurationCompleted msg;
        msg.rrcTransactionIdentifier = m_lastRrcTransactionIdentifier;
        m_rrcSapUser->SendRrcConnectionReconfigurationCompleted (msg);
        SwitchToState (CONNECTED_NORMALLY);
      }
      break;
          
    default:
      NS_FATAL_ERROR ("unexpected event in state " << ToString (m_state));
      break; 
    } 
}

void
LteUeRrc::DoNotifyRandomAccessFailed ()
{
  NS_LOG_FUNCTION (this);
}


void 
LteUeRrc::DoForceCampedOnEnb (uint16_t cellId, uint16_t earfcn)
{
  NS_LOG_FUNCTION (this << cellId << earfcn);
    
  m_cellId = cellId;
  m_dlEarfcn = earfcn;
  m_cphySapProvider->SyncronizeWithEnb (m_cellId, m_dlEarfcn); 
  SwitchToState (IDLE_WAIT_SYSTEM_INFO);
}

void 
LteUeRrc::DoConnect ()
{
  NS_LOG_FUNCTION (this);
  switch (m_state)
    {
    case IDLE_CELL_SELECTION:
    case IDLE_WAIT_SYSTEM_INFO:
      m_connectionPending = true;
      break;

    case IDLE_CAMPED_NORMALLY:     
      StartConnection ();
      break;

    case IDLE_RANDOM_ACCESS:
    case IDLE_CONNECTING:
      NS_LOG_WARN ("already connecting (state " << ToString (m_state) << ")");      
      break;

    case CONNECTED_NORMALLY:
    case CONNECTED_REESTABLISHING:
    case CONNECTED_HANDOVER:
      NS_LOG_WARN ("already connected (state " << ToString (m_state) << ")");      
      break;  
      
    default:
      NS_FATAL_ERROR ("cannot connect while in state " << ToString (m_state));
      break;
    }


}



// CPHY SAP methods

void 
LteUeRrc::DoRecvMasterInformationBlock (LteRrcSap::MasterInformationBlock msg)  
{ 
  NS_LOG_FUNCTION (this);
  m_dlBandwidth = msg.dlBandwidth;
  m_cphySapProvider->SetDlBandwidth (msg.dlBandwidth);
  m_receivedMib = true;
  if (m_state == IDLE_WAIT_SYSTEM_INFO && m_receivedMib && m_receivedSib2)
    {
       SwitchToState (IDLE_CAMPED_NORMALLY);
    }
}



// RRC SAP methods

void 
LteUeRrc::DoCompleteSetup (LteUeRrcSapProvider::CompleteSetupParameters params)
{
  NS_LOG_FUNCTION (this);
  m_srb0->m_rlc->SetLteRlcSapUser (params.srb0SapUser);
  m_srb1->m_pdcp->SetLtePdcpSapUser (params.srb1SapUser);
}


void 
LteUeRrc::DoRecvSystemInformationBlockType1 (LteRrcSap::SystemInformationBlockType1 msg)
{
  NS_LOG_FUNCTION (this);
  // to be implemented
}

 
void 
LteUeRrc::DoRecvSystemInformation (LteRrcSap::SystemInformation msg)
{
  NS_LOG_FUNCTION (this);
  if (msg.haveSib2)
    {
      m_receivedSib2 = true;
      m_ulBandwidth = msg.sib2.freqInfo.ulBandwidth;
      m_ulEarfcn = msg.sib2.freqInfo.ulCarrierFreq;
      LteUeCmacSapProvider::RachConfig rc;
      rc.numberOfRaPreambles = msg.sib2.radioResourceConfigCommon.rachConfigCommon.preambleInfo.numberOfRaPreambles;
      rc.preambleTransMax = msg.sib2.radioResourceConfigCommon.rachConfigCommon.raSupervisionInfo.preambleTransMax;
      rc.raResponseWindowSize = msg.sib2.radioResourceConfigCommon.rachConfigCommon.raSupervisionInfo.raResponseWindowSize;
      m_cmacSapProvider->ConfigureRach (rc);
      m_cphySapProvider->ConfigureUplink (m_ulEarfcn, m_ulBandwidth);
    }
  if (m_state == IDLE_WAIT_SYSTEM_INFO && m_receivedMib && m_receivedSib2)
    {
       SwitchToState (IDLE_CAMPED_NORMALLY);
    }
}


void 
LteUeRrc::DoRecvRrcConnectionSetup (LteRrcSap::RrcConnectionSetup msg)
{    
  NS_LOG_FUNCTION (this);
  switch (m_state)
    {
    case IDLE_CONNECTING:
      {
        ApplyRadioResourceConfigDedicated (msg.radioResourceConfigDedicated);
        SwitchToState (CONNECTED_NORMALLY);
        LteRrcSap::RrcConnectionSetupCompleted msg2;
        msg2.rrcTransactionIdentifier = msg.rrcTransactionIdentifier;
        m_rrcSapUser->SendRrcConnectionSetupCompleted (msg2);
        m_asSapUser->NotifyConnectionSuccessful ();
      }
      break;
      
    default:
      NS_FATAL_ERROR ("method unexpected in state " << ToString (m_state));
      break;
    }
}

void
LteUeRrc::DoRecvRrcConnectionReconfiguration (LteRrcSap::RrcConnectionReconfiguration msg)
{
  NS_LOG_FUNCTION (this << " RNTI " << m_rnti);
  switch (m_state)
    {
    case CONNECTED_NORMALLY:
      if (msg.haveRadioResourceConfigDedicated)
        {
          ApplyRadioResourceConfigDedicated (msg.radioResourceConfigDedicated);
        }      
      if (msg.haveMobilityControlInfo)
        {
          NS_LOG_INFO ("haveMobilityControlInfo == true");
          SwitchToState (CONNECTED_HANDOVER);
          const LteRrcSap::MobilityControlInfo& mci = msg.mobilityControlInfo;
          m_cellId = mci.targetPhysCellId;
          NS_ASSERT (mci.haveCarrierFreq);
          NS_ASSERT (mci.haveCarrierBandwidth);
          m_cphySapProvider->SyncronizeWithEnb (m_cellId, mci.carrierFreq.dlCarrierFreq); 
          m_cphySapProvider->SetDlBandwidth ( mci.carrierBandwidth.dlBandwidth); 
          m_cphySapProvider->ConfigureUplink (mci.carrierFreq.ulCarrierFreq, mci.carrierBandwidth.ulBandwidth); 
          m_rnti = msg.mobilityControlInfo.newUeIdentity;
          NS_ASSERT_MSG (mci.haveRachConfigDedicated, "handover is only supported with non-contention-based random access procedure");
          m_cmacSapProvider->StartNonContentionBasedRandomAccessProcedure (m_rnti, mci.rachConfigDedicated.raPreambleIndex, mci.rachConfigDedicated.raPrachMaskIndex);
          m_cphySapProvider->SetRnti (m_rnti);
          m_lastRrcTransactionIdentifier = msg.rrcTransactionIdentifier;
          // RRC connection reconfiguration completed will be sent
          // after handover is completed
        }
      else
        {
          NS_LOG_INFO ("haveMobilityControlInfo == false");
          LteRrcSap::RrcConnectionReconfigurationCompleted msg2;
          msg2.rrcTransactionIdentifier = msg.rrcTransactionIdentifier;
          m_rrcSapUser->SendRrcConnectionReconfigurationCompleted (msg2);
        }
      break;

    default:
      NS_FATAL_ERROR ("method unexpected in state " << ToString (m_state));
      break;
    }
}

void 
LteUeRrc::DoRecvRrcConnectionReestablishment (LteRrcSap::RrcConnectionReestablishment msg)
{
  switch (m_state)
    {
    case CONNECTED_REESTABLISHING:
      {
      }
      break;
      
    default:
      NS_FATAL_ERROR ("method unexpected in state " << ToString (m_state));
      break;
    }
}

void 
LteUeRrc::DoRecvRrcConnectionReestablishmentReject (LteRrcSap::RrcConnectionReestablishmentReject msg)
{
  NS_LOG_FUNCTION (this);
  switch (m_state)
    {
    case CONNECTED_REESTABLISHING:
      {
        LeaveConnectedMode ();
      }
      break;
      
    default:
      NS_FATAL_ERROR ("method unexpected in state " << ToString (m_state));
      break;
    }
}

void 
LteUeRrc::DoRecvRrcConnectionRelease (LteRrcSap::RrcConnectionRelease msg)
{
  NS_LOG_FUNCTION (this);
}




void 
LteUeRrc::ApplyRadioResourceConfigDedicated (LteRrcSap::RadioResourceConfigDedicated rrcd)
{
  NS_LOG_FUNCTION (this);
  const struct LteRrcSap::PhysicalConfigDedicated& pcd = rrcd.physicalConfigDedicated;
  
  if (pcd.haveAntennaInfoDedicated)
    {
      m_cphySapProvider->SetTransmissionMode (pcd.antennaInfo.transmissionMode);
    }
  if (pcd.haveSoundingRsUlConfigDedicated)
    {
      m_cphySapProvider->SetSrsConfigurationIndex (pcd.soundingRsUlConfigDedicated.srsConfigIndex);
    }

  std::list<LteRrcSap::SrbToAddMod>::const_iterator stamIt = rrcd.srbToAddModList.begin ();
  if (stamIt != rrcd.srbToAddModList.end ())
    {
      if (m_srb1 == 0)
        {
          // SRB1 not setup yet        
          NS_ASSERT_MSG (m_state == IDLE_CONNECTING, "expected state IDLE_CONNECTING, actual state " << ToString (m_state));
          NS_ASSERT_MSG (stamIt->srbIdentity == 1, "only SRB1 supported");

          const uint8_t lcid = 1; // fixed LCID for SRB1

          Ptr<LteRlc> rlc = CreateObject<LteRlcAm> ();
          rlc->SetLteMacSapProvider (m_macSapProvider);
          rlc->SetRnti (m_rnti);
          rlc->SetLcId (lcid);      

          Ptr<LtePdcp> pdcp = CreateObject<LtePdcp> ();
          pdcp->SetRnti (m_rnti);
          pdcp->SetLcId (lcid);
          pdcp->SetLtePdcpSapUser (m_drbPdcpSapUser);
          pdcp->SetLteRlcSapProvider (rlc->GetLteRlcSapProvider ());
          rlc->SetLteRlcSapUser (pdcp->GetLteRlcSapUser ());

          m_srb1 = CreateObject<LteSignalingRadioBearerInfo> ();
          m_srb1->m_rlc = rlc;
          m_srb1->m_pdcp = pdcp;
          m_srb1->m_srbIdentity = 1;
          
          m_srb1->m_logicalChannelConfig.priority = stamIt->logicalChannelConfig.priority;
          m_srb1->m_logicalChannelConfig.prioritizedBitRateKbps = stamIt->logicalChannelConfig.prioritizedBitRateKbps;
          m_srb1->m_logicalChannelConfig.bucketSizeDurationMs = stamIt->logicalChannelConfig.bucketSizeDurationMs;
          m_srb1->m_logicalChannelConfig.logicalChannelGroup = stamIt->logicalChannelConfig.logicalChannelGroup;

          struct LteUeCmacSapProvider::LogicalChannelConfig lcConfig;
          lcConfig.priority = stamIt->logicalChannelConfig.priority;
          lcConfig.prioritizedBitRateKbps = stamIt->logicalChannelConfig.prioritizedBitRateKbps;
          lcConfig.bucketSizeDurationMs = stamIt->logicalChannelConfig.bucketSizeDurationMs;
          lcConfig.logicalChannelGroup = stamIt->logicalChannelConfig.logicalChannelGroup;
      
          m_cmacSapProvider->AddLc (lcid, lcConfig, rlc->GetLteMacSapUser ());
      
          ++stamIt;
          NS_ASSERT_MSG (stamIt == rrcd.srbToAddModList.end (), "at most one SrbToAdd supported");     
        }
      else
        {
          NS_LOG_INFO ("request to modify SRB1 (skipping as currently not implemented)");
          // would need to modify m_srb1, and then propagate changes to the MAC
        }
    }


  std::list<LteRrcSap::DrbToAddMod>::const_iterator dtamIt;
  for (dtamIt = rrcd.drbToAddModList.begin ();
       dtamIt != rrcd.drbToAddModList.end ();
       ++dtamIt)
    {
      NS_LOG_INFO (this << " IMSI " << m_imsi << " adding/modifying DRBID " << (uint32_t) dtamIt->drbIdentity << " LC " << (uint32_t) dtamIt->logicalChannelIdentity);
      NS_ASSERT_MSG (dtamIt->logicalChannelIdentity > 2, "LCID value " << dtamIt->logicalChannelIdentity << " is reserved for SRBs");

      std::map<uint8_t, Ptr<LteDataRadioBearerInfo> >::iterator drbMapIt = m_drbMap.find (dtamIt->drbIdentity);
      if (drbMapIt == m_drbMap.end ())
        {
          NS_LOG_INFO ("New Data Radio Bearer");
        
          TypeId rlcTypeId;
          if (m_useRlcSm)
            {
              rlcTypeId = LteRlcSm::GetTypeId ();
            }
          else
            {
              switch (dtamIt->rlcConfig.choice)
                {
                case LteRrcSap::RlcConfig::AM: 
                  rlcTypeId = LteRlcAm::GetTypeId ();
                  break;
          
                case LteRrcSap::RlcConfig::UM_BI_DIRECTIONAL: 
                  rlcTypeId = LteRlcUm::GetTypeId ();
                  break;
          
                default:
                  NS_FATAL_ERROR ("unsupported RLC configuration");
                  break;                
                }
            }
  
          ObjectFactory rlcObjectFactory;
          rlcObjectFactory.SetTypeId (rlcTypeId);
          Ptr<LteRlc> rlc = rlcObjectFactory.Create ()->GetObject<LteRlc> ();
          rlc->SetLteMacSapProvider (m_macSapProvider);
          rlc->SetRnti (m_rnti);
          rlc->SetLcId (dtamIt->logicalChannelIdentity);

          Ptr<LteDataRadioBearerInfo> drbInfo = CreateObject<LteDataRadioBearerInfo> ();
          drbInfo->m_rlc = rlc;
          drbInfo->m_epsBearerIdentity = dtamIt->epsBearerIdentity;
          drbInfo->m_logicalChannelIdentity = dtamIt->logicalChannelIdentity;
          drbInfo->m_drbIdentity = dtamIt->drbIdentity;
 
          // we need PDCP only for real RLC, i.e., RLC/UM or RLC/AM
          // if we are using RLC/SM we don't care of anything above RLC
          if (rlcTypeId != LteRlcSm::GetTypeId ())
            {
              Ptr<LtePdcp> pdcp = CreateObject<LtePdcp> ();
              pdcp->SetRnti (m_rnti);
              pdcp->SetLcId (dtamIt->logicalChannelIdentity);
              pdcp->SetLtePdcpSapUser (m_drbPdcpSapUser);
              pdcp->SetLteRlcSapProvider (rlc->GetLteRlcSapProvider ());
              rlc->SetLteRlcSapUser (pdcp->GetLteRlcSapUser ());
              drbInfo->m_pdcp = pdcp;
            }

          m_bid2DrbidMap[dtamIt->epsBearerIdentity] = dtamIt->drbIdentity;
  
          m_drbMap.insert (std::pair<uint8_t, Ptr<LteDataRadioBearerInfo> > (dtamIt->drbIdentity, drbInfo));
  

          struct LteUeCmacSapProvider::LogicalChannelConfig lcConfig;
          lcConfig.priority = dtamIt->logicalChannelConfig.priority;
          lcConfig.prioritizedBitRateKbps = dtamIt->logicalChannelConfig.prioritizedBitRateKbps;
          lcConfig.bucketSizeDurationMs = dtamIt->logicalChannelConfig.bucketSizeDurationMs;
          lcConfig.logicalChannelGroup = dtamIt->logicalChannelConfig.logicalChannelGroup;      

          m_cmacSapProvider->AddLc (dtamIt->logicalChannelIdentity,
                                    lcConfig,
                                    rlc->GetLteMacSapUser ());
        }
      else
        {
          NS_LOG_INFO ("request to modify existing DRBID");
          Ptr<LteDataRadioBearerInfo> drbInfo = drbMapIt->second;
          // TODO: currently not implemented. Would need to modify drbInfo, and then propagate changes to the MAC
        }
    }
  
  std::list<uint8_t>::iterator dtdmIt;
  for (dtdmIt = rrcd.drbToReleaseList.begin ();
       dtdmIt != rrcd.drbToReleaseList.end ();
       ++dtdmIt)
    {
      uint8_t drbid = *dtdmIt;
      NS_LOG_INFO (this << " IMSI " << m_imsi << " releasing DRB " << (uint32_t) drbid << drbid);
      std::map<uint8_t, Ptr<LteDataRadioBearerInfo> >::iterator it =   m_drbMap.find (drbid);
      NS_ASSERT_MSG (it != m_drbMap.end (), "could not find bearer with given lcid");
      m_drbMap.erase (it);      
      m_bid2DrbidMap.erase (drbid);
    }
}


void 
LteUeRrc::StartConnection ()
{
  NS_LOG_FUNCTION (this);
  m_connectionPending = false;
  SwitchToState (IDLE_RANDOM_ACCESS);        
  m_cmacSapProvider->StartContentionBasedRandomAccessProcedure ();
}

void 
LteUeRrc::LeaveConnectedMode ()
{
  NS_LOG_FUNCTION (this << m_imsi);
  m_asSapUser->NotifyConnectionReleased ();
  m_cmacSapProvider->RemoveLc (1);
  std::map<uint8_t, Ptr<LteDataRadioBearerInfo> >::iterator it;
  for (it = m_drbMap.begin (); it != m_drbMap.end (); ++it)
    {
      m_cmacSapProvider->RemoveLc (it->second->m_logicalChannelIdentity);
    }
  m_drbMap.clear ();
  m_bid2DrbidMap.clear ();
  m_srb1 = 0;
  SwitchToState (IDLE_CAMPED_NORMALLY);
}


uint8_t 
LteUeRrc::Bid2Drbid (uint8_t bid)
{
  std::map<uint8_t, uint8_t>::iterator it = m_bid2DrbidMap.find (bid);
  NS_ASSERT_MSG (it != m_bid2DrbidMap.end (), "could not find BID " << bid);
  return it->second;
}


void 
LteUeRrc::SwitchToState (State newState)
{
  NS_LOG_FUNCTION (this << newState);
  State oldState = m_state;
  m_state = newState;
  NS_LOG_INFO ("IMSI " << m_imsi << " RNTI " << m_rnti << " UeRrc " << ToString (oldState) << " --> " << ToString (newState));
  m_stateTransitionCallback (oldState, newState);

  switch (newState)
    {
    case IDLE_CELL_SELECTION:
      break;

    case IDLE_WAIT_SYSTEM_INFO:
      break;

    case IDLE_CAMPED_NORMALLY:
      if (m_connectionPending)
        {
          StartConnection ();
        }
      break;

    case IDLE_RANDOM_ACCESS:
      break;

    case IDLE_CONNECTING:
      break;
 
    case CONNECTED_NORMALLY:
      break;

    case CONNECTED_REESTABLISHING:
      break;

    case CONNECTED_HANDOVER:
      break;
 
    default:
      break;
    }
}
  

    
  
} // namespace ns3