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wifi: Do not request channel access on links always in the same order

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This commit is contained in:
Stefano Avallone
2023-11-14 18:17:35 +01:00
committed by Stefano Avallone
parent 15632d0db1
commit 65271d8eaf
3 changed files with 46 additions and 18 deletions
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2
examples/wireless/examples-to-run.py
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@@ -180,7 +180,7 @@ cpp_examples = [
"True",
),
(
"wifi-eht-network --simulationTime=0.2 --udp=0 --downlink=0 --useRts=0 --nStations=4 --dlAckType=AGGR-MU-BAR --enableUlOfdma=1 --enableBsrp=1 --mpduBufferSize=1024 --mcs=4 --muSchedAccessReqInterval=45ms --frequency2=6 --minExpectedThroughput=50 --maxExpectedThroughput=415",
"wifi-eht-network --simulationTime=0.2 --udp=0 --downlink=0 --useRts=0 --nStations=4 --dlAckType=AGGR-MU-BAR --enableUlOfdma=1 --enableBsrp=1 --mpduBufferSize=1024 --mcs=7 --muSchedAccessReqInterval=45ms --frequency2=6 --minExpectedThroughput=70 --maxExpectedThroughput=550",
"True",
"True",
),

50
src/wifi/model/txop.cc
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@@ -29,10 +29,12 @@
#include "ns3/attribute-container.h"
#include "ns3/log.h"
#include "ns3/pointer.h"
#include "ns3/random-variable-stream.h"
#include "ns3/simulator.h"
#include "ns3/socket.h"
#include <iterator>
#include <sstream>
#undef NS_LOG_APPEND_CONTEXT
#define NS_LOG_APPEND_CONTEXT WIFI_TXOP_NS_LOG_APPEND_CONTEXT
@@ -137,7 +139,7 @@ Txop::Txop(Ptr<WifiMacQueue> queue)
: m_queue(queue)
{
NS_LOG_FUNCTION(this);
m_rng = CreateObject<UniformRandomVariable>();
m_rng = m_shuffleLinkIdsGen.GetRv();
}
Txop::~Txop()
@@ -529,9 +531,22 @@ void
Txop::Queue(Ptr<WifiMpdu> mpdu)
{
NS_LOG_FUNCTION(this << *mpdu);
const auto linkIds = m_mac->GetMacQueueScheduler()->GetLinkIds(m_queue->GetAc(), mpdu);
auto linkIds = m_mac->GetMacQueueScheduler()->GetLinkIds(m_queue->GetAc(), mpdu);
std::map<uint8_t, bool> hasFramesToTransmit;
// ignore the links for which a channel access request event is already running
for (auto it = linkIds.begin(); it != linkIds.end();)
{
if (const auto& event = GetLink(*it).accessRequest.event; event.IsRunning())
{
it = linkIds.erase(it);
}
else
{
++it;
}
}
// save the status of the AC queues before enqueuing the MPDU (required to determine if
// backoff is needed)
for (const auto linkId : linkIds)
@@ -539,20 +554,31 @@ Txop::Queue(Ptr<WifiMpdu> mpdu)
hasFramesToTransmit[linkId] = HasFramesToTransmit(linkId);
}
m_queue->Enqueue(mpdu);
for (const auto linkId : linkIds)
// shuffle link IDs not to request channel access on links always in the same order
std::vector<uint8_t> shuffledLinkIds(linkIds.cbegin(), linkIds.cend());
std::shuffle(shuffledLinkIds.begin(), shuffledLinkIds.end(), m_shuffleLinkIdsGen);
if (!linkIds.empty() && g_log.IsEnabled(ns3::LOG_DEBUG))
{
std::stringstream ss;
std::copy(shuffledLinkIds.cbegin(),
shuffledLinkIds.cend(),
std::ostream_iterator<uint16_t>(ss, " "));
NS_LOG_DEBUG("Request channel access on link IDs: " << ss.str());
}
for (const auto linkId : shuffledLinkIds)
{
// schedule a call to StartAccessIfNeeded() to request channel access after that all the
// packets of a burst have been enqueued, instead of requesting channel access right after
// the first packet. The call to StartAccessIfNeeded() is scheduled only after the first
// packet
if (auto& event = GetLink(linkId).accessRequest.event; !event.IsRunning())
{
event = Simulator::ScheduleNow(&Txop::StartAccessAfterEvent,
this,
linkId,
hasFramesToTransmit.at(linkId),
CHECK_MEDIUM_BUSY);
}
GetLink(linkId).accessRequest.event = Simulator::ScheduleNow(&Txop::StartAccessAfterEvent,
this,
linkId,
hasFramesToTransmit.at(linkId),
CHECK_MEDIUM_BUSY);
}
}

12
src/wifi/model/txop.h
View File

@@ -25,6 +25,7 @@
#include "ns3/nstime.h"
#include "ns3/object.h"
#include "ns3/traced-value.h"
#include "ns3/uniform-random-bit-generator.h"
#include <map>
#include <memory>
@@ -555,11 +556,12 @@ class Txop : public Object
*/
const std::map<uint8_t, std::unique_ptr<LinkEntity>>& GetLinks() const;
DroppedMpdu m_droppedMpduCallback; //!< the dropped MPDU callback
Ptr<WifiMacQueue> m_queue; //!< the wifi MAC queue
Ptr<MacTxMiddle> m_txMiddle; //!< the MacTxMiddle
Ptr<WifiMac> m_mac; //!< the wifi MAC
Ptr<UniformRandomVariable> m_rng; //!< the random stream
DroppedMpdu m_droppedMpduCallback; //!< the dropped MPDU callback
Ptr<WifiMacQueue> m_queue; //!< the wifi MAC queue
Ptr<MacTxMiddle> m_txMiddle; //!< the MacTxMiddle
Ptr<WifiMac> m_mac; //!< the wifi MAC
Ptr<UniformRandomVariable> m_rng; //!< the random stream
UniformRandomBitGenerator m_shuffleLinkIdsGen; //!< random number generator to shuffle link IDs
/// TracedCallback for backoff trace value typedef
typedef TracedCallback<uint32_t /* value */, uint8_t /* linkId */> BackoffValueTracedCallback;