A Discrete-Event Network Simulator
API
msdu-aggregator.cc
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1 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
2 /*
3  * Copyright (c) 2009 MIRKO BANCHI
4  *
5  * This program is free software; you can redistribute it and/or modify
6  * it under the terms of the GNU General Public License version 2 as
7  * published by the Free Software Foundation;
8  *
9  * This program is distributed in the hope that it will be useful,
10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12  * GNU General Public License for more details.
13  *
14  * You should have received a copy of the GNU General Public License
15  * along with this program; if not, write to the Free Software
16  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
17  *
18  * Author: Mirko Banchi <mk.banchi@gmail.com>
19  * Stefano Avallone <stavallo@unina.it>
20  */
21 
22 #include "ns3/log.h"
23 #include "ns3/packet.h"
24 #include "msdu-aggregator.h"
25 #include "qos-txop.h"
27 #include "ns3/ht-capabilities.h"
28 #include "regular-wifi-mac.h"
29 #include "wifi-mac-queue.h"
30 #include "wifi-mac-trailer.h"
31 #include "ns3/ht-frame-exchange-manager.h"
32 #include "wifi-tx-parameters.h"
33 #include <algorithm>
34 
35 namespace ns3 {
36 
37 NS_LOG_COMPONENT_DEFINE ("MsduAggregator");
38 
39 NS_OBJECT_ENSURE_REGISTERED (MsduAggregator);
40 
41 TypeId
43 {
44  static TypeId tid = TypeId ("ns3::MsduAggregator")
45  .SetParent<Object> ()
46  .SetGroupName ("Wifi")
47  .AddConstructor<MsduAggregator> ()
48  ;
49  return tid;
50 }
51 
53 {
54 }
55 
57 {
58 }
59 
60 void
62 {
63  m_mac = 0;
64  m_htFem = 0;
66 }
67 
68 void
70 {
71  NS_LOG_FUNCTION (this << mac);
72  m_mac = mac;
73  m_htFem = DynamicCast<HtFrameExchangeManager> (m_mac->GetFrameExchangeManager ());
74 }
75 
76 uint16_t
77 MsduAggregator::GetSizeIfAggregated (uint16_t msduSize, uint16_t amsduSize)
78 {
79  NS_LOG_FUNCTION (msduSize << amsduSize);
80 
81  // the size of the A-MSDU subframe header is 14 bytes: DA (6), SA (6) and Length (2)
82  return amsduSize + CalculatePadding (amsduSize) + 14 + msduSize;
83 }
84 
87  Time availableTime, WifiMacQueueItem::QueueIteratorPair& queueIt) const
88 {
89  NS_LOG_FUNCTION (this << *peekedItem << &txParams << availableTime);
90 
91  NS_ASSERT (peekedItem->IsQueued ());
92  NS_ASSERT (peekedItem->GetQueueIteratorPairs ().size () == 1);
93  WifiMacQueueItem::QueueIteratorPair peekedIt = peekedItem->GetQueueIteratorPairs ().front ();
94  NS_ASSERT ((*peekedIt.it)->GetPacket () == peekedItem->GetPacket ());
95 
96  uint8_t tid = peekedItem->GetHeader ().GetQosTid ();
97  Mac48Address recipient = peekedItem->GetHeader ().GetAddr1 ();
98 
99  /* "The Address 1 field of an MPDU carrying an A-MSDU shall be set to an
100  * individual address or to the GCR concealment address" (Section 10.12
101  * of 802.11-2016)
102  */
103  NS_ABORT_MSG_IF (recipient.IsBroadcast (), "Recipient address is broadcast");
104 
105  /* "A STA shall not transmit an A-MSDU within a QoS Data frame under a block
106  * ack agreement unless the recipient indicates support for A-MSDU by setting
107  * the A-MSDU Supported field to 1 in its BlockAck Parameter Set field of the
108  * ADDBA Response frame" (Section 10.12 of 802.11-2016)
109  */
110  // No check required for now, as we always set the A-MSDU Supported field to 1
111 
112  // TODO Add support for the Max Number Of MSDUs In A-MSDU field in the Extended
113  // Capabilities element sent by the recipient
114 
115  NS_ASSERT (m_htFem != 0);
116 
117  if (GetMaxAmsduSize (recipient, tid, txParams.m_txVector.GetModulationClass ()) == 0)
118  {
119  NS_LOG_DEBUG ("A-MSDU aggregation disabled");
120  return nullptr;
121  }
122 
123  Ptr<WifiMacQueueItem> amsdu = Copy (peekedItem);
124  uint8_t nMsdu = 1;
125 
126  peekedIt.it++;
127 
128  while ((peekedIt.it = peekedIt.queue->PeekByTidAndAddress (tid, recipient, peekedIt.it)) != peekedIt.queue->end ()
129  && m_htFem->TryAggregateMsdu (*peekedIt.it, txParams, availableTime))
130  {
131  amsdu->Aggregate (*peekedIt.it);
132  peekedIt.it++;
133  nMsdu++;
134  }
135 
136  if (nMsdu == 1)
137  {
138  NS_LOG_DEBUG ("Aggregation failed (could not aggregate at least two MSDUs)");
139  return nullptr;
140  }
141 
142  // Aggregation succeeded
143  queueIt = peekedIt;
144 
145  return amsdu;
146 }
147 
148 uint8_t
150 {
151  return (4 - (amsduSize % 4 )) % 4;
152 }
153 
154 uint16_t
156  WifiModulationClass modulation) const
157 {
158  NS_LOG_FUNCTION (this << recipient << +tid << modulation);
159 
160  AcIndex ac = QosUtilsMapTidToAc (tid);
161 
162  // Find the A-MSDU max size configured on this device
163  UintegerValue size;
164 
165  switch (ac)
166  {
167  case AC_BE:
168  m_mac->GetAttribute ("BE_MaxAmsduSize", size);
169  break;
170  case AC_BK:
171  m_mac->GetAttribute ("BK_MaxAmsduSize", size);
172  break;
173  case AC_VI:
174  m_mac->GetAttribute ("VI_MaxAmsduSize", size);
175  break;
176  case AC_VO:
177  m_mac->GetAttribute ("VO_MaxAmsduSize", size);
178  break;
179  default:
180  NS_ABORT_MSG ("Unknown AC " << ac);
181  return 0;
182  }
183 
184  uint16_t maxAmsduSize = size.Get ();
185 
186  if (maxAmsduSize == 0)
187  {
188  NS_LOG_DEBUG ("A-MSDU Aggregation is disabled on this station for AC " << ac);
189  return 0;
190  }
191 
192  Ptr<WifiRemoteStationManager> stationManager = m_mac->GetWifiRemoteStationManager ();
193  NS_ASSERT (stationManager);
194 
195  // Retrieve the Capabilities elements advertised by the recipient
196  Ptr<const VhtCapabilities> vhtCapabilities = stationManager->GetStationVhtCapabilities (recipient);
197  Ptr<const HtCapabilities> htCapabilities = stationManager->GetStationHtCapabilities (recipient);
198 
199  if (!htCapabilities)
200  {
201  /* "A non-DMG STA shall not transmit an A-MSDU to a STA from which it has
202  * not received a frame containing an HT Capabilities element" (Section
203  * 10.12 of 802.11-2016)
204  */
205  NS_LOG_DEBUG ("A-MSDU Aggregation disabled because the recipient did not"
206  " send an HT Capabilities element");
207  return 0;
208  }
209 
210  // Determine the constraint imposed by the recipient based on the PPDU
211  // format used to transmit the A-MSDU
212  if (modulation >= WIFI_MOD_CLASS_VHT)
213  {
214  // the maximum A-MSDU size is indirectly constrained by the maximum MPDU
215  // size supported by the recipient and advertised in the VHT Capabilities
216  // element (see Table 9-19 of 802.11-2016 as amended by 802.11ax)
217  NS_ABORT_MSG_IF (!vhtCapabilities, "VHT Capabilities element not received");
218 
219  maxAmsduSize = std::min (maxAmsduSize, static_cast<uint16_t>(vhtCapabilities->GetMaxMpduLength () - 56));
220  }
221  else if (modulation == WIFI_MOD_CLASS_HT)
222  {
223  // the maximum A-MSDU size is constrained by the maximum A-MSDU size
224  // supported by the recipient and advertised in the HT Capabilities
225  // element (see Table 9-19 of 802.11-2016)
226 
227  maxAmsduSize = std::min (maxAmsduSize, htCapabilities->GetMaxAmsduLength ());
228  }
229  else // non-HT PPDU
230  {
231  // the maximum A-MSDU size is indirectly constrained by the maximum PSDU size
232  // supported by the recipient (see Table 9-19 of 802.11-2016)
233 
234  maxAmsduSize = std::min (maxAmsduSize, static_cast<uint16_t>(3839));
235  }
236 
237  return maxAmsduSize;
238 }
239 
242 {
245 
247  Ptr<Packet> extractedMsdu = Create<Packet> ();
248  uint32_t maxSize = aggregatedPacket->GetSize ();
249  uint16_t extractedLength;
250  uint8_t padding;
251  uint32_t deserialized = 0;
252 
253  while (deserialized < maxSize)
254  {
255  deserialized += aggregatedPacket->RemoveHeader (hdr);
256  extractedLength = hdr.GetLength ();
257  extractedMsdu = aggregatedPacket->CreateFragment (0, static_cast<uint32_t> (extractedLength));
258  aggregatedPacket->RemoveAtStart (extractedLength);
259  deserialized += extractedLength;
260 
261  padding = (4 - ((extractedLength + 14) % 4 )) % 4;
262 
263  if (padding > 0 && deserialized < maxSize)
264  {
265  aggregatedPacket->RemoveAtStart (padding);
266  deserialized += padding;
267  }
268 
269  std::pair<Ptr<const Packet>, AmsduSubframeHeader> packetHdr (extractedMsdu, hdr);
270  set.push_back (packetHdr);
271  }
272  NS_LOG_INFO ("Deaggreated A-MSDU: extracted " << set.size () << " MSDUs");
273  return set;
274 }
275 
276 } //namespace ns3
WifiModulationClass
This enumeration defines the modulation classes per (Table 10-6 "Modulation classes"; IEEE 802...
uint32_t RemoveHeader(Header &header)
Deserialize and remove the header from the internal buffer.
Definition: packet.cc:280
bool IsBroadcast(void) const
Simulation virtual time values and global simulation resolution.
Definition: nstime.h:103
Smart pointer class similar to boost::intrusive_ptr.
Definition: ptr.h:73
#define NS_LOG_FUNCTION(parameters)
If log level LOG_FUNCTION is enabled, this macro will output all input parameters separated by "...
uint16_t GetMaxAmsduSize(Mac48Address recipient, uint8_t tid, WifiModulationClass modulation) const
Determine the maximum size for an A-MSDU of the given TID that can be sent to the given receiver when...
#define NS_ABORT_MSG(msg)
Unconditional abnormal program termination with a message.
Definition: abort.h:50
#define NS_OBJECT_ENSURE_REGISTERED(type)
Register an Object subclass with the TypeId system.
Definition: object-base.h:45
virtual void DoDispose()
Destructor implementation.
uint32_t GetSize(void) const
Returns the the size in bytes of the packet (including the zero-filled initial payload).
Definition: packet.h:852
AcIndex
This enumeration defines the Access Categories as an enumeration with values corresponding to the AC ...
Definition: qos-utils.h:57
#define min(a, b)
Definition: 80211b.c:42
Ptr< Packet > CreateFragment(uint32_t start, uint32_t length) const
Create a new packet which contains a fragment of the original packet.
Definition: packet.cc:227
WifiModulationClass GetModulationClass(void) const
Get the modulation class specified by this TXVECTOR.
#define NS_ASSERT(condition)
At runtime, in debugging builds, if this condition is not true, the program prints the source file...
Definition: assert.h:67
Information needed to remove an MSDU from the queue.
#define NS_LOG_COMPONENT_DEFINE(name)
Define a Log component with a specific name.
Definition: log.h:205
Ptr< RegularWifiMac > m_mac
the MAC of this station
#define NS_LOG_INFO(msg)
Use NS_LOG to output a message of level LOG_INFO.
Definition: log.h:281
virtual void DoDispose(void)
Destructor implementation.
Definition: object.cc:346
#define NS_LOG_FUNCTION_NOARGS()
Output the name of the function.
void RemoveAtStart(uint32_t size)
Remove size bytes from the start of the current packet.
Definition: packet.cc:362
Video.
Definition: qos-utils.h:64
static WifiMacQueueItem::DeaggregatedMsdus Deaggregate(Ptr< Packet > aggregatedPacket)
Hold an unsigned integer type.
Definition: uinteger.h:44
void SetWifiMac(const Ptr< RegularWifiMac > mac)
Set the MAC layer to use.
mac
Definition: third.py:99
AcIndex QosUtilsMapTidToAc(uint8_t tid)
Maps TID (Traffic ID) to Access classes.
Definition: qos-utils.cc:53
static TypeId GetTypeId(void)
Get the type ID.
Best Effort.
Definition: qos-utils.h:60
static uint16_t GetSizeIfAggregated(uint16_t msduSize, uint16_t amsduSize)
Compute the size of the A-MSDU resulting from the aggregation of an MSDU of size msduSize and an A-MS...
void Aggregate(Ptr< const WifiMacQueueItem > msdu)
Aggregate the MSDU contained in the given MPDU to this MPDU (thus constituting an A-MSDU)...
Ptr< const HtCapabilities > GetStationHtCapabilities(Mac48Address from)
Return the HT capabilities sent by the remote station.
uint64_t Get(void) const
Definition: uinteger.cc:35
WifiTxVector m_txVector
TXVECTOR of the frame being prepared.
Every class exported by the ns3 library is enclosed in the ns3 namespace.
Ptr< HtFrameExchangeManager > m_htFem
the HT Frame Exchange Manager of this station
Ptr< WifiMacQueueItem > GetNextAmsdu(Ptr< const WifiMacQueueItem > peekedItem, WifiTxParameters &txParams, Time availableTime, WifiMacQueueItem::QueueIteratorPair &queueIt) const
Attempt to aggregate other MSDUs to the given A-MSDU while meeting the following constraints: ...
Background.
Definition: qos-utils.h:62
an EUI-48 address
Definition: mac48-address.h:43
Headers for A-MSDU subframes.
Voice.
Definition: qos-utils.h:66
uint16_t GetLength(void) const
Get length function.
#define NS_ABORT_MSG_IF(cond, msg)
Abnormal program termination if a condition is true, with a message.
Definition: abort.h:108
#define NS_LOG_DEBUG(msg)
Use NS_LOG to output a message of level LOG_DEBUG.
Definition: log.h:273
Ptr< const VhtCapabilities > GetStationVhtCapabilities(Mac48Address from)
Return the VHT capabilities sent by the remote station.
This class stores the TX parameters (TX vector, protection mechanism, acknowledgment mechanism...
static uint8_t CalculatePadding(uint16_t amsduSize)
Calculate how much padding must be added to the end of an A-MSDU of the given size if a new MSDU is a...
Aggregator used to construct A-MSDUs.
A base class which provides memory management and object aggregation.
Definition: object.h:87
a unique identifier for an interface.
Definition: type-id.h:58
std::list< std::pair< Ptr< const Packet >, AmsduSubframeHeader > > DeaggregatedMsdus
DeaggregatedMsdus typedef.
TypeId SetParent(TypeId tid)
Set the parent TypeId.
Definition: type-id.cc:923
Ptr< T > Copy(Ptr< T > object)
Return a deep copy of a Ptr.
Definition: ptr.h:536