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sta-wifi-mac.cc
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1 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
2 /*
3  * Copyright (c) 2006, 2009 INRIA
4  * Copyright (c) 2009 MIRKO BANCHI
5  *
6  * This program is free software; you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License version 2 as
8  * published by the Free Software Foundation;
9  *
10  * This program is distributed in the hope that it will be useful,
11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13  * GNU General Public License for more details.
14  *
15  * You should have received a copy of the GNU General Public License
16  * along with this program; if not, write to the Free Software
17  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
18  *
19  * Author: Mathieu Lacage <mathieu.lacage@sophia.inria.fr>
20  * Author: Mirko Banchi <mk.banchi@gmail.com>
21  */
22 #include "sta-wifi-mac.h"
23 
24 #include "ns3/log.h"
25 #include "ns3/simulator.h"
26 #include "ns3/string.h"
27 #include "ns3/pointer.h"
28 #include "ns3/boolean.h"
29 #include "ns3/trace-source-accessor.h"
30 
31 #include "qos-tag.h"
32 #include "mac-low.h"
33 #include "dcf-manager.h"
34 #include "mac-rx-middle.h"
35 #include "mac-tx-middle.h"
36 #include "wifi-mac-header.h"
37 #include "msdu-aggregator.h"
38 #include "amsdu-subframe-header.h"
39 #include "mgt-headers.h"
40 #include "ht-capabilities.h"
41 
42 NS_LOG_COMPONENT_DEFINE ("StaWifiMac");
43 
44 
45 /*
46  * The state machine for this STA is:
47  -------------- -----------
48  | Associated | <-------------------- -------> | Refused |
49  -------------- \ / -----------
50  \ \ /
51  \ ----------------- -----------------------------
52  \-> | Beacon Missed | --> | Wait Association Response |
53  ----------------- -----------------------------
54  \ ^
55  \ |
56  \ -----------------------
57  \-> | Wait Probe Response |
58  -----------------------
59  */
60 
61 namespace ns3 {
62 
63 NS_OBJECT_ENSURE_REGISTERED (StaWifiMac);
64 
65 TypeId
66 StaWifiMac::GetTypeId (void)
67 {
68  static TypeId tid = TypeId ("ns3::StaWifiMac")
69  .SetParent<RegularWifiMac> ()
70  .AddConstructor<StaWifiMac> ()
71  .AddAttribute ("ProbeRequestTimeout", "The interval between two consecutive probe request attempts.",
72  TimeValue (Seconds (0.05)),
73  MakeTimeAccessor (&StaWifiMac::m_probeRequestTimeout),
74  MakeTimeChecker ())
75  .AddAttribute ("AssocRequestTimeout", "The interval between two consecutive assoc request attempts.",
76  TimeValue (Seconds (0.5)),
77  MakeTimeAccessor (&StaWifiMac::m_assocRequestTimeout),
78  MakeTimeChecker ())
79  .AddAttribute ("MaxMissedBeacons",
80  "Number of beacons which much be consecutively missed before "
81  "we attempt to restart association.",
82  UintegerValue (10),
83  MakeUintegerAccessor (&StaWifiMac::m_maxMissedBeacons),
84  MakeUintegerChecker<uint32_t> ())
85  .AddAttribute ("ActiveProbing", "If true, we send probe requests. If false, we don't. NOTE: if more than one STA in your simulation is using active probing, you should enable it at a different simulation time for each STA, otherwise all the STAs will start sending probes at the same time resulting in collisions. See bug 1060 for more info.",
86  BooleanValue (false),
87  MakeBooleanAccessor (&StaWifiMac::SetActiveProbing),
88  MakeBooleanChecker ())
89  .AddTraceSource ("Assoc", "Associated with an access point.",
90  MakeTraceSourceAccessor (&StaWifiMac::m_assocLogger))
91  .AddTraceSource ("DeAssoc", "Association with an access point lost.",
92  MakeTraceSourceAccessor (&StaWifiMac::m_deAssocLogger))
93  ;
94  return tid;
95 }
96 
97 StaWifiMac::StaWifiMac ()
98  : m_state (BEACON_MISSED),
99  m_probeRequestEvent (),
100  m_assocRequestEvent (),
101  m_beaconWatchdogEnd (Seconds (0.0))
102 {
103  NS_LOG_FUNCTION (this);
104 
105  // Let the lower layers know that we are acting as a non-AP STA in
106  // an infrastructure BSS.
107  SetTypeOfStation (STA);
108 }
109 
110 StaWifiMac::~StaWifiMac ()
111 {
112  NS_LOG_FUNCTION (this);
113 }
114 
115 void
116 StaWifiMac::SetMaxMissedBeacons (uint32_t missed)
117 {
118  NS_LOG_FUNCTION (this << missed);
119  m_maxMissedBeacons = missed;
120 }
121 
122 void
123 StaWifiMac::SetProbeRequestTimeout (Time timeout)
124 {
125  NS_LOG_FUNCTION (this << timeout);
126  m_probeRequestTimeout = timeout;
127 }
128 
129 void
130 StaWifiMac::SetAssocRequestTimeout (Time timeout)
131 {
132  NS_LOG_FUNCTION (this << timeout);
133  m_assocRequestTimeout = timeout;
134 }
135 
136 void
137 StaWifiMac::StartActiveAssociation (void)
138 {
139  NS_LOG_FUNCTION (this);
140  TryToEnsureAssociated ();
141 }
142 
143 void
144 StaWifiMac::SetActiveProbing (bool enable)
145 {
146  NS_LOG_FUNCTION (this << enable);
147  if (enable)
148  {
149  Simulator::ScheduleNow (&StaWifiMac::TryToEnsureAssociated, this);
150  }
151  else
152  {
153  m_probeRequestEvent.Cancel ();
154  }
155 }
156 
157 void
158 StaWifiMac::SendProbeRequest (void)
159 {
160  NS_LOG_FUNCTION (this);
161  WifiMacHeader hdr;
162  hdr.SetProbeReq ();
163  hdr.SetAddr1 (Mac48Address::GetBroadcast ());
164  hdr.SetAddr2 (GetAddress ());
165  hdr.SetAddr3 (Mac48Address::GetBroadcast ());
166  hdr.SetDsNotFrom ();
167  hdr.SetDsNotTo ();
168  Ptr<Packet> packet = Create<Packet> ();
169  MgtProbeRequestHeader probe;
170  probe.SetSsid (GetSsid ());
171  probe.SetSupportedRates (GetSupportedRates ());
172  if (m_htSupported)
173  {
174  probe.SetHtCapabilities (GetHtCapabilities());
175  hdr.SetNoOrder();
176  }
177 
178  packet->AddHeader (probe);
179 
180  // The standard is not clear on the correct queue for management
181  // frames if we are a QoS AP. The approach taken here is to always
182  // use the DCF for these regardless of whether we have a QoS
183  // association or not.
184  m_dca->Queue (packet, hdr);
185 
186  if (m_probeRequestEvent.IsRunning ())
187  {
188  m_probeRequestEvent.Cancel ();
189  }
190  m_probeRequestEvent = Simulator::Schedule (m_probeRequestTimeout,
191  &StaWifiMac::ProbeRequestTimeout, this);
192 }
193 
194 void
195 StaWifiMac::SendAssociationRequest (void)
196 {
197  NS_LOG_FUNCTION (this << GetBssid ());
198  WifiMacHeader hdr;
199  hdr.SetAssocReq ();
200  hdr.SetAddr1 (GetBssid ());
201  hdr.SetAddr2 (GetAddress ());
202  hdr.SetAddr3 (GetBssid ());
203  hdr.SetDsNotFrom ();
204  hdr.SetDsNotTo ();
205  Ptr<Packet> packet = Create<Packet> ();
206  MgtAssocRequestHeader assoc;
207  assoc.SetSsid (GetSsid ());
208  assoc.SetSupportedRates (GetSupportedRates ());
209  if (m_htSupported)
210  {
211  assoc.SetHtCapabilities (GetHtCapabilities());
212  hdr.SetNoOrder();
213  }
214 
215  packet->AddHeader (assoc);
216 
217  // The standard is not clear on the correct queue for management
218  // frames if we are a QoS AP. The approach taken here is to always
219  // use the DCF for these regardless of whether we have a QoS
220  // association or not.
221  m_dca->Queue (packet, hdr);
222 
223  if (m_assocRequestEvent.IsRunning ())
224  {
225  m_assocRequestEvent.Cancel ();
226  }
227  m_assocRequestEvent = Simulator::Schedule (m_assocRequestTimeout,
228  &StaWifiMac::AssocRequestTimeout, this);
229 }
230 
231 void
232 StaWifiMac::TryToEnsureAssociated (void)
233 {
234  NS_LOG_FUNCTION (this);
235  switch (m_state)
236  {
237  case ASSOCIATED:
238  return;
239  break;
240  case WAIT_PROBE_RESP:
241  /* we have sent a probe request earlier so we
242  do not need to re-send a probe request immediately.
243  We just need to wait until probe-request-timeout
244  or until we get a probe response
245  */
246  break;
247  case BEACON_MISSED:
248  /* we were associated but we missed a bunch of beacons
249  * so we should assume we are not associated anymore.
250  * We try to initiate a probe request now.
251  */
252  m_linkDown ();
253  SetState (WAIT_PROBE_RESP);
254  SendProbeRequest ();
255  break;
256  case WAIT_ASSOC_RESP:
257  /* we have sent an assoc request so we do not need to
258  re-send an assoc request right now. We just need to
259  wait until either assoc-request-timeout or until
260  we get an assoc response.
261  */
262  break;
263  case REFUSED:
264  /* we have sent an assoc request and received a negative
265  assoc resp. We wait until someone restarts an
266  association with a given ssid.
267  */
268  break;
269  }
270 }
271 
272 void
273 StaWifiMac::AssocRequestTimeout (void)
274 {
275  NS_LOG_FUNCTION (this);
276  SetState (WAIT_ASSOC_RESP);
277  SendAssociationRequest ();
278 }
279 
280 void
281 StaWifiMac::ProbeRequestTimeout (void)
282 {
283  NS_LOG_FUNCTION (this);
284  SetState (WAIT_PROBE_RESP);
285  SendProbeRequest ();
286 }
287 
288 void
289 StaWifiMac::MissedBeacons (void)
290 {
291  NS_LOG_FUNCTION (this);
292  if (m_beaconWatchdogEnd > Simulator::Now ())
293  {
294  if (m_beaconWatchdog.IsRunning ())
295  {
296  m_beaconWatchdog.Cancel ();
297  }
298  m_beaconWatchdog = Simulator::Schedule (m_beaconWatchdogEnd - Simulator::Now (),
299  &StaWifiMac::MissedBeacons, this);
300  return;
301  }
302  NS_LOG_DEBUG ("beacon missed");
303  SetState (BEACON_MISSED);
304  TryToEnsureAssociated ();
305 }
306 
307 void
308 StaWifiMac::RestartBeaconWatchdog (Time delay)
309 {
310  NS_LOG_FUNCTION (this << delay);
311  m_beaconWatchdogEnd = std::max (Simulator::Now () + delay, m_beaconWatchdogEnd);
312  if (Simulator::GetDelayLeft (m_beaconWatchdog) < delay
313  && m_beaconWatchdog.IsExpired ())
314  {
315  NS_LOG_DEBUG ("really restart watchdog.");
316  m_beaconWatchdog = Simulator::Schedule (delay, &StaWifiMac::MissedBeacons, this);
317  }
318 }
319 
320 bool
321 StaWifiMac::IsAssociated (void) const
322 {
323  return m_state == ASSOCIATED;
324 }
325 
326 bool
327 StaWifiMac::IsWaitAssocResp (void) const
328 {
329  return m_state == WAIT_ASSOC_RESP;
330 }
331 
332 void
333 StaWifiMac::Enqueue (Ptr<const Packet> packet, Mac48Address to)
334 {
335  NS_LOG_FUNCTION (this << packet << to);
336  if (!IsAssociated ())
337  {
338  NotifyTxDrop (packet);
339  TryToEnsureAssociated ();
340  return;
341  }
342  WifiMacHeader hdr;
343 
344  // If we are not a QoS AP then we definitely want to use AC_BE to
345  // transmit the packet. A TID of zero will map to AC_BE (through \c
346  // QosUtilsMapTidToAc()), so we use that as our default here.
347  uint8_t tid = 0;
348 
349  // For now, an AP that supports QoS does not support non-QoS
350  // associations, and vice versa. In future the AP model should
351  // support simultaneously associated QoS and non-QoS STAs, at which
352  // point there will need to be per-association QoS state maintained
353  // by the association state machine, and consulted here.
354  if (m_qosSupported)
355  {
356  hdr.SetType (WIFI_MAC_QOSDATA);
357  hdr.SetQosAckPolicy (WifiMacHeader::NORMAL_ACK);
358  hdr.SetQosNoEosp ();
359  hdr.SetQosNoAmsdu ();
360  // Transmission of multiple frames in the same TXOP is not
361  // supported for now
362  hdr.SetQosTxopLimit (0);
363 
364  // Fill in the QoS control field in the MAC header
365  tid = QosUtilsGetTidForPacket (packet);
366  // Any value greater than 7 is invalid and likely indicates that
367  // the packet had no QoS tag, so we revert to zero, which'll
368  // mean that AC_BE is used.
369  if (tid >= 7)
370  {
371  tid = 0;
372  }
373  hdr.SetQosTid (tid);
374  }
375  else
376  {
377  hdr.SetTypeData ();
378  }
379 if (m_htSupported)
380  {
381  hdr.SetNoOrder();
382  }
383 
384  hdr.SetAddr1 (GetBssid ());
385  hdr.SetAddr2 (m_low->GetAddress ());
386  hdr.SetAddr3 (to);
387  hdr.SetDsNotFrom ();
388  hdr.SetDsTo ();
389 
390  if (m_qosSupported)
391  {
392  // Sanity check that the TID is valid
393  NS_ASSERT (tid < 8);
394  m_edca[QosUtilsMapTidToAc (tid)]->Queue (packet, hdr);
395  }
396  else
397  {
398  m_dca->Queue (packet, hdr);
399  }
400 }
401 
402 void
403 StaWifiMac::Receive (Ptr<Packet> packet, const WifiMacHeader *hdr)
404 {
405  NS_LOG_FUNCTION (this << packet << hdr);
406  NS_ASSERT (!hdr->IsCtl ());
407  if (hdr->GetAddr3 () == GetAddress ())
408  {
409  NS_LOG_LOGIC ("packet sent by us.");
410  return;
411  }
412  else if (hdr->GetAddr1 () != GetAddress ()
413  && !hdr->GetAddr1 ().IsGroup ())
414  {
415  NS_LOG_LOGIC ("packet is not for us");
416  NotifyRxDrop (packet);
417  return;
418  }
419  else if (hdr->IsData ())
420  {
421  if (!IsAssociated ())
422  {
423  NS_LOG_LOGIC ("Received data frame while not associated: ignore");
424  NotifyRxDrop (packet);
425  return;
426  }
427  if (!(hdr->IsFromDs () && !hdr->IsToDs ()))
428  {
429  NS_LOG_LOGIC ("Received data frame not from the DS: ignore");
430  NotifyRxDrop (packet);
431  return;
432  }
433  if (hdr->GetAddr2 () != GetBssid ())
434  {
435  NS_LOG_LOGIC ("Received data frame not from the BSS we are associated with: ignore");
436  NotifyRxDrop (packet);
437  return;
438  }
439 
440  if (hdr->IsQosData ())
441  {
442  if (hdr->IsQosAmsdu ())
443  {
444  NS_ASSERT (hdr->GetAddr3 () == GetBssid ());
445  DeaggregateAmsduAndForward (packet, hdr);
446  packet = 0;
447  }
448  else
449  {
450  ForwardUp (packet, hdr->GetAddr3 (), hdr->GetAddr1 ());
451  }
452  }
453  else
454  {
455  ForwardUp (packet, hdr->GetAddr3 (), hdr->GetAddr1 ());
456  }
457  return;
458  }
459  else if (hdr->IsProbeReq ()
460  || hdr->IsAssocReq ())
461  {
462  // This is a frame aimed at an AP, so we can safely ignore it.
463  NotifyRxDrop (packet);
464  return;
465  }
466  else if (hdr->IsBeacon ())
467  {
468  MgtBeaconHeader beacon;
469  packet->RemoveHeader (beacon);
470  bool goodBeacon = false;
471  if (GetSsid ().IsBroadcast ()
472  || beacon.GetSsid ().IsEqual (GetSsid ()))
473  {
474  goodBeacon = true;
475  }
476  SupportedRates rates = beacon.GetSupportedRates ();
477  for (uint32_t i = 0; i < m_phy->GetNBssMembershipSelectors (); i++)
478  {
479  uint32_t selector = m_phy->GetBssMembershipSelector (i);
480  if (!rates.IsSupportedRate (selector))
481  {
482  goodBeacon = false;
483  }
484  }
485  if ((IsWaitAssocResp () || IsAssociated ()) && hdr->GetAddr3 () != GetBssid ())
486  {
487  goodBeacon = false;
488  }
489  if (goodBeacon)
490  {
491  Time delay = MicroSeconds (beacon.GetBeaconIntervalUs () * m_maxMissedBeacons);
492  RestartBeaconWatchdog (delay);
493  SetBssid (hdr->GetAddr3 ());
494  }
495  if (goodBeacon && m_state == BEACON_MISSED)
496  {
497  SetState (WAIT_ASSOC_RESP);
498  SendAssociationRequest ();
499  }
500  return;
501  }
502  else if (hdr->IsProbeResp ())
503  {
504  if (m_state == WAIT_PROBE_RESP)
505  {
506  MgtProbeResponseHeader probeResp;
507  packet->RemoveHeader (probeResp);
508  if (!probeResp.GetSsid ().IsEqual (GetSsid ()))
509  {
510  //not a probe resp for our ssid.
511  return;
512  }
513  SupportedRates rates = probeResp.GetSupportedRates ();
514  for (uint32_t i = 0; i < m_phy->GetNBssMembershipSelectors (); i++)
515  {
516  uint32_t selector = m_phy->GetBssMembershipSelector (i);
517  if (!rates.IsSupportedRate (selector))
518  {
519  return;
520  }
521  }
522  SetBssid (hdr->GetAddr3 ());
523  Time delay = MicroSeconds (probeResp.GetBeaconIntervalUs () * m_maxMissedBeacons);
524  RestartBeaconWatchdog (delay);
525  if (m_probeRequestEvent.IsRunning ())
526  {
527  m_probeRequestEvent.Cancel ();
528  }
529  SetState (WAIT_ASSOC_RESP);
530  SendAssociationRequest ();
531  }
532  return;
533  }
534  else if (hdr->IsAssocResp ())
535  {
536  if (m_state == WAIT_ASSOC_RESP)
537  {
538  MgtAssocResponseHeader assocResp;
539  packet->RemoveHeader (assocResp);
540  if (m_assocRequestEvent.IsRunning ())
541  {
542  m_assocRequestEvent.Cancel ();
543  }
544  if (assocResp.GetStatusCode ().IsSuccess ())
545  {
546  SetState (ASSOCIATED);
547  NS_LOG_DEBUG ("assoc completed");
548  SupportedRates rates = assocResp.GetSupportedRates ();
549  if (m_htSupported)
550  {
551  HtCapabilities htcapabilities = assocResp.GetHtCapabilities ();
552  m_stationManager->AddStationHtCapabilities (hdr->GetAddr2 (),htcapabilities);
553  }
554 
555  for (uint32_t i = 0; i < m_phy->GetNModes (); i++)
556  {
557  WifiMode mode = m_phy->GetMode (i);
558  if (rates.IsSupportedRate (mode.GetDataRate ()))
559  {
560  m_stationManager->AddSupportedMode (hdr->GetAddr2 (), mode);
561  if (rates.IsBasicRate (mode.GetDataRate ()))
562  {
563  m_stationManager->AddBasicMode (mode);
564  }
565  }
566  }
567  if(m_htSupported)
568  {
569  HtCapabilities htcapabilities = assocResp.GetHtCapabilities ();
570  for (uint32_t i = 0; i < m_phy->GetNMcs(); i++)
571  {
572  uint8_t mcs=m_phy->GetMcs(i);
573  if (htcapabilities.IsSupportedMcs (mcs))
574  {
575  m_stationManager->AddSupportedMcs (hdr->GetAddr2 (), mcs);
576  //here should add a control to add basic MCS when it is implemented
577  }
578  }
579  }
580  if (!m_linkUp.IsNull ())
581  {
582  m_linkUp ();
583  }
584  }
585  else
586  {
587  NS_LOG_DEBUG ("assoc refused");
588  SetState (REFUSED);
589  }
590  }
591  return;
592  }
593 
594  // Invoke the receive handler of our parent class to deal with any
595  // other frames. Specifically, this will handle Block Ack-related
596  // Management Action frames.
597  RegularWifiMac::Receive (packet, hdr);
598 }
599 
600 SupportedRates
601 StaWifiMac::GetSupportedRates (void) const
602 {
603  SupportedRates rates;
604  if(m_htSupported)
605  {
606  for (uint32_t i = 0; i < m_phy->GetNBssMembershipSelectors(); i++)
607  {
608  rates.SetBasicRate(m_phy->GetBssMembershipSelector(i));
609  }
610  }
611  for (uint32_t i = 0; i < m_phy->GetNModes (); i++)
612  {
613  WifiMode mode = m_phy->GetMode (i);
614  rates.AddSupportedRate (mode.GetDataRate ());
615  }
616  return rates;
617 }
618 HtCapabilities
619 StaWifiMac::GetHtCapabilities (void) const
620 {
621  HtCapabilities capabilities;
622  capabilities.SetHtSupported(1);
623  capabilities.SetLdpc (m_phy->GetLdpc());
624  capabilities.SetShortGuardInterval20 (m_phy->GetGuardInterval());
625  capabilities.SetGreenfield (m_phy->GetGreenfield());
626 for (uint8_t i =0 ; i < m_phy->GetNMcs();i++)
627  {
628  capabilities.SetRxMcsBitmask(m_phy->GetMcs(i));
629  }
630  return capabilities;
631 }
632 void
633 StaWifiMac::SetState (MacState value)
634 {
635  if (value == ASSOCIATED
636  && m_state != ASSOCIATED)
637  {
638  m_assocLogger (GetBssid ());
639  }
640  else if (value != ASSOCIATED
641  && m_state == ASSOCIATED)
642  {
643  m_deAssocLogger (GetBssid ());
644  }
645  m_state = value;
646 }
647 
648 } // namespace ns3