Attachment #2377 for bug #2369

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(-)a/src/wifi/model/dca-txop.cc (-1 lines)

Lines 503-509	Link Here

503

DcaTxop::NotifyCollision (void)

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DcaTxop::NotifyCollision (void)

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  NS_LOG_FUNCTION (this);

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  NS_LOG_FUNCTION (this);

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  NS_LOG_DEBUG ("collision");

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  m_dcf->StartBackoffNow (m_rng->GetNext (0, m_dcf->GetCw ()));

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  m_dcf->StartBackoffNow (m_rng->GetNext (0, m_dcf->GetCw ()));

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  RestartAccessIfNeeded ();

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  RestartAccessIfNeeded ();

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  return false;
}

bool
DcfManager::IsWithinAifs (DcfState *state) const
{
  NS_LOG_FUNCTION (this << state);
  Time ifsEnd = GetAccessGrantStart () + MicroSeconds (state->GetAifsn () * m_slotTimeUs);
  if (ifsEnd > Simulator::Now ())
    {
      return true;
    }
  return false;
}

void
DcfManager::RequestAccess (DcfState *state)
{

   * If there is a collision, generate a backoff
   * by notifying the collision to the user.
   */
  if (state->GetBackoffSlots () == 0)
      && IsBusy ())
    {
      if (IsBusy ())
        {
          MY_DEBUG ("medium is busy: collision");
          // someone else has accessed the medium; generate a backoff.
          state->NotifyCollision ();
        }
      else if (IsWithinAifs (state))
        {
          MY_DEBUG ("busy within AIFS");
          // requested access while medium still conceptually busy; generate
          // a backoff.
          state->NotifyCollision ();
        }
    }
  DoGrantAccess ();
  DoRestartAccessTimeoutIfNeeded ();

(-)a/src/wifi/model/dcf-manager.h (+11 lines)

Lines 202-207	Link Here

202

   * that a normal collision occured, that is, that

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   * that a normal collision occured, that is, that

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   * the medium was busy when access was requested.

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   * the medium was busy when access was requested.

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   * This may also be called if the request for access occurred within

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   * the DIFS or AIFS between two frames.

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   * The subclass is expected to start a new backoff by

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   * The subclass is expected to start a new backoff by

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   * calling DcfState::StartBackoffNow and DcfManager::RequestAccess

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   * calling DcfState::StartBackoffNow and DcfManager::RequestAccess

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   * is access is still needed.

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   * is access is still needed.

Lines 521-526	Link Here

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   *         false otherwise

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   *         false otherwise

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*/

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*/

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  bool IsBusy (void) const;

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  bool IsBusy (void) const;

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/**

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   * Check if the device is between frames (in DIFS or AIFS interval)

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   * \param state the state to check

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   * \return true if the device is within AIFS,

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   *         false otherwise

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*/

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  bool IsWithinAifs (DcfState* state) const;

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/**

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/**

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   * typedef for a vector of DcfStates

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   * typedef for a vector of DcfStates




void
DcfManagerTest::DoRun (void)
{
  // SIFS + AIFSN = DIFS
  
  //  0      3       4         5         6          10      11   12
  //  | sifs | aifsn | backoff | backoff | tx | sifs | aifsn |   | tx |
  //
  StartTest (1, 3, 10);
  AddDcfState (1);
  AddAccessRequest (1, 1, 6, 0);
  ExpectCollision (1, 2, 0); //backoff: 2 slots
  AddAccessRequest (12, 2, 12, 0);
  EndTest ();
#if 0
  // Check that receiving inside SIFS shall be cancelled properly:
  //  0      3       4    5      8     9     12       13 14
  //  | sifs | aifsn | tx | sifs | ack | sifs | aifsn |  |tx |

  AddTxEvt (8, 1);
  AddAccessRequest (14, 2, 14, 0);
  EndTest ();
#endif
  // The test below mainly intends to test the case where the medium
  // becomes busy in the middle of a backoff slot: the backoff counter
  // must not be decremented for this backoff slot. This is the case

  ExpectCollision (30, 0, 0); //backoff: 0 slots
  EndTest ();

#if 0
  // The test below is subject to some discussion because I am
  // not sure I understand the intent of the spec here.
  // i.e., what happens if you make a request to get access

  AddRxOkEvt (20, 40);
  AddAccessRequest (62, 2, 70, 0);
  EndTest ();
#endif

  // Test an EIFS
  //

  ExpectInternalCollision (78, 1, 1); //backoff: 1 slot
  EndTest ();

#if 0
  // Test of AckTimeout handling: First queue requests access and ack procedure fails,
  // inside the ack timeout second queue with higher priority requests access.
  //

  AddAccessRequestWithAckTimeout (20, 20, 20, 0);
  AddAccessRequest (50, 10, 66, 1);
  EndTest ();
#endif
#if 0
  // Test of AckTimeout handling:
  //
  // First queue requests access and ack is 2 us delayed (got ack interval at the picture),

  ExpectCollision (39, 2, 0); //backoff: 2 slot
  EndTest ();

#endif
  // test simple NAV count. This scenario modelizes a simple DATA+ACK handshake
  // where the data rate used for the ACK is higher than expected by the DATA source
  // so, the data exchange completes before the end of nav.

  EndTest ();


#if 0
  // Channel switching tests

  //  0          20     23      24   25

  AddSwitchingEvt (0,20);
  AddAccessRequest (21, 1, 24, 0);
  EndTest ();
#endif

  //  20          40       50     53      54       55        56   57
  //   | switching |  busy  | sifs | aifsn | bslot0 | bslot 1 | tx | 

  AddAccessRequest (45, 1, 56, 0);
  EndTest ();

#if 0
  //  20     30          50     53      54   55
  //   |  rx  | switching | sifs | aifsn | tx |
  //                        |

  AddSwitchingEvt (30,20);
  AddAccessRequest (51, 1, 54, 0);
  EndTest ();
#endif

#if 0
  //  20     30          50     53      54   55
  //   | busy | switching | sifs | aifsn | tx |
  //                        |

  AddSwitchingEvt (30,20);
  AddAccessRequest (51, 1, 54, 0);
  EndTest ();
#endif

#if 0
  //  20      30          50     53      54   55
  //   |  nav  | switching | sifs | aifsn | tx |
  //                        |

  AddSwitchingEvt (30,20);
  AddAccessRequest (51, 1, 54, 0);
  EndTest ();
#endif

#if 0
  //  20      40             50          55     58      59   60
  //   |  tx   | ack timeout  | switching | sifs | aifsn | tx |
  //                  |                     |

  AddSwitchingEvt (50,5);
  AddAccessRequest (56, 1, 59, 0);
  EndTest ();
#endif

#if 0
  //  20         60     66      70       74       78  80         100    106     110  112
  //   |    rx    | sifs | aifsn | bslot0 | bslot1 |   | switching | sifs | aifsn | tx |
  //        |                                                        |

  AddSwitchingEvt (80,20);
  AddAccessRequest (101, 2, 110, 0);
  EndTest ();
#endif
}



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