dsss-ppdu.cc

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/*
 * Copyright (c) 2020 Orange Labs
 *
 * 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: Rediet <getachew.redieteab@orange.com>
 *         Muhammad Iqbal Rochman <muhiqbalcr@uchicago.edu>
 *         Sébastien Deronne <sebastien.deronne@gmail.com> (DsssSigHeader)
 */
 
#include "dsss-ppdu.h"
 
#include "dsss-phy.h"
 
#include "ns3/log.h"
#include "ns3/wifi-phy.h"
#include "ns3/wifi-psdu.h"
 
namespace ns3
{
 
NS_LOG_COMPONENT_DEFINE("DsssPpdu");
 
DsssPpdu::DsssPpdu(Ptr<const WifiPsdu> psdu,
                   const WifiTxVector& txVector,
                   uint16_t txCenterFreq,
                   Time ppduDuration,
                   uint64_t uid)
    : WifiPpdu(psdu, txVector, txCenterFreq, uid)
{
    NS_LOG_FUNCTION(this << psdu << txVector << txCenterFreq << ppduDuration << uid);
    SetPhyHeaders(txVector, ppduDuration);
}
 
void
DsssPpdu::SetPhyHeaders(const WifiTxVector& txVector, Time ppduDuration)
{
    NS_LOG_FUNCTION(this << txVector);
 
#ifdef NS3_BUILD_PROFILE_DEBUG
    DsssSigHeader dsssSig;
    SetDsssHeader(dsssSig, txVector, ppduDuration);
    m_phyHeaders->AddHeader(dsssSig);
#else
    SetDsssHeader(m_dsssSig, txVector, ppduDuration);
#endif
}
 
void
DsssPpdu::SetDsssHeader(DsssSigHeader& dsssSig,
                        const WifiTxVector& txVector,
                        Time ppduDuration) const
{
    dsssSig.SetRate(txVector.GetMode().GetDataRate(22));
    Time psduDuration = ppduDuration - WifiPhy::CalculatePhyPreambleAndHeaderDuration(txVector);
    dsssSig.SetLength(psduDuration.GetMicroSeconds());
}
 
WifiTxVector
DsssPpdu::DoGetTxVector() const
{
    WifiTxVector txVector;
    txVector.SetPreambleType(m_preamble);
    txVector.SetChannelWidth(22);
 
#ifdef NS3_BUILD_PROFILE_DEBUG
    DsssSigHeader dsssSig;
    if (m_phyHeaders->PeekHeader(dsssSig) == 0)
    {
        NS_FATAL_ERROR("Missing DSSS SIG PHY header in DSSS PPDU");
    }
 
    SetTxVectorFromDsssHeader(txVector, dsssSig);
#else
    SetTxVectorFromDsssHeader(txVector, m_dsssSig);
#endif
 
    return txVector;
}
 
void
DsssPpdu::SetTxVectorFromDsssHeader(WifiTxVector& txVector, const DsssSigHeader& dsssSig) const
{
    txVector.SetMode(DsssPhy::GetDsssRate(dsssSig.GetRate()));
}
 
Time
DsssPpdu::GetTxDuration() const
{
    Time ppduDuration = Seconds(0);
    const WifiTxVector& txVector = GetTxVector();
    uint16_t length = 0;
#ifdef NS3_BUILD_PROFILE_DEBUG
    DsssSigHeader dsssSig;
    m_phyHeaders->PeekHeader(dsssSig);
    length = dsssSig.GetLength();
#else
    length = m_dsssSig.GetLength();
#endif
    ppduDuration = MicroSeconds(length) + WifiPhy::CalculatePhyPreambleAndHeaderDuration(txVector);
    return ppduDuration;
}
 
Ptr<WifiPpdu>
DsssPpdu::Copy() const
{
    return Ptr<WifiPpdu>(new DsssPpdu(*this), false);
}
 
DsssPpdu::DsssSigHeader::DsssSigHeader()
    : m_rate(0b00001010),
      m_length(0)
{
}
 
TypeId
DsssPpdu::DsssSigHeader::GetTypeId()
{
    static TypeId tid = TypeId("ns3::DsssSigHeader")
                            .SetParent<Header>()
                            .SetGroupName("Wifi")
                            .AddConstructor<DsssSigHeader>();
    return tid;
}
 
TypeId
DsssPpdu::DsssSigHeader::GetInstanceTypeId() const
{
    return GetTypeId();
}
 
void
DsssPpdu::DsssSigHeader::Print(std::ostream& os) const
{
    os << "SIGNAL=" << GetRate() << " LENGTH=" << m_length;
}
 
uint32_t
DsssPpdu::DsssSigHeader::GetSerializedSize() const
{
    return 6;
}
 
void
DsssPpdu::DsssSigHeader::SetRate(uint64_t rate)
{
    /* Here is the binary representation for a given rate:
     * 1 Mbit/s: 00001010
     * 2 Mbit/s: 00010100
     * 5.5 Mbit/s: 00110111
     * 11 Mbit/s: 01101110
     */
    switch (rate)
    {
    case 1000000:
        m_rate = 0b00001010;
        break;
    case 2000000:
        m_rate = 0b00010100;
        break;
    case 5500000:
        m_rate = 0b00110111;
        break;
    case 11000000:
        m_rate = 0b01101110;
        break;
    default:
        NS_ASSERT_MSG(false, "Invalid rate");
        break;
    }
}
 
uint64_t
DsssPpdu::DsssSigHeader::GetRate() const
{
    uint64_t rate = 0;
    switch (m_rate)
    {
    case 0b00001010:
        rate = 1000000;
        break;
    case 0b00010100:
        rate = 2000000;
        break;
    case 0b00110111:
        rate = 5500000;
        break;
    case 0b01101110:
        rate = 11000000;
        break;
    default:
        NS_ASSERT_MSG(false, "Invalid rate");
        break;
    }
    return rate;
}
 
void
DsssPpdu::DsssSigHeader::SetLength(uint16_t length)
{
    m_length = length;
}
 
uint16_t
DsssPpdu::DsssSigHeader::GetLength() const
{
    return m_length;
}
 
void
DsssPpdu::DsssSigHeader::Serialize(Buffer::Iterator start) const
{
    start.WriteU8(m_rate);
    start.WriteU8(0); /* SERVICE */
    start.WriteU16(m_length);
    start.WriteU16(0); /* CRC */
}
 
uint32_t
DsssPpdu::DsssSigHeader::Deserialize(Buffer::Iterator start)
{
    Buffer::Iterator i = start;
    m_rate = i.ReadU8();
    i.ReadU8(); /* SERVICE */
    m_length = i.ReadU16();
    i.ReadU16(); /* CRC */
    return i.GetDistanceFrom(start);
}
 
} // namespace ns3