/* -*- Mode: C++; c-file-style: "gnu"; indent-tabs-mode:nil; -*- */
/*
* Copyright (c) 2005,2006 INRIA
*
* 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: Mathieu Lacage <mathieu.lacage@sophia.inria.fr>
*/
#include "yans-error-rate-model.h"
#include "wifi-phy.h"
#include "ns3/log.h"
NS_LOG_COMPONENT_DEFINE ("YansErrorRateModel");
namespace ns3 {
NS_OBJECT_ENSURE_REGISTERED (YansErrorRateModel);
#ifndef ENABLE_GSL
const double YansErrorRateModel::WLAN_SIR_PERFECT = 10.0;
const double YansErrorRateModel::WLAN_SIR_IMPOSSIBLE = 0.1;
#endif
TypeId
YansErrorRateModel::GetTypeId (void)
{
static TypeId tid = TypeId ("ns3::YansErrorRateModel")
.SetParent<ErrorRateModel> ()
.AddConstructor<YansErrorRateModel> ()
;
return tid;
}
YansErrorRateModel::YansErrorRateModel ()
{}
double
YansErrorRateModel::Log2 (double val) const
{
return log(val) / log(2.0);
}
double
YansErrorRateModel::GetBpskBer (double snr, uint32_t signalSpread, uint32_t phyRate) const
{
double EbNo = snr * signalSpread / phyRate;
double z = sqrt(EbNo);
double ber = 0.5 * erfc(z);
NS_LOG_INFO ("bpsk snr="<<snr<<" ber="<<ber);
return ber;
}
double
YansErrorRateModel::GetQamBer (double snr, unsigned int m, uint32_t signalSpread, uint32_t phyRate) const
{
double EbNo = snr * signalSpread / phyRate;
double z = sqrt ((1.5 * Log2 (m) * EbNo) / (m - 1.0));
double z1 = ((1.0 - 1.0 / sqrt (m)) * erfc (z)) ;
double z2 = 1 - pow ((1-z1), 2.0);
double ber = z2 / Log2 (m);
NS_LOG_INFO ("Qam m="<<m<<" rate=" << phyRate << " snr="<<snr<<" ber="<<ber);
return ber;
}
uint32_t
YansErrorRateModel::Factorial (uint32_t k) const
{
uint32_t fact = 1;
while (k > 0)
{
fact *= k;
k--;
}
return fact;
}
double
YansErrorRateModel::Binomial (uint32_t k, double p, uint32_t n) const
{
double retval = Factorial (n) / (Factorial (k) * Factorial (n-k)) * pow (p, k) * pow (1-p, n-k);
return retval;
}
double
YansErrorRateModel::CalculatePdOdd (double ber, unsigned int d) const
{
NS_ASSERT ((d % 2) == 1);
unsigned int dstart = (d + 1) / 2;
unsigned int dend = d;
double pd = 0;
for (unsigned int i = dstart; i < dend; i++)
{
pd += Binomial (i, ber, d);
}
return pd;
}
double
YansErrorRateModel::CalculatePdEven (double ber, unsigned int d) const
{
NS_ASSERT ((d % 2) == 0);
unsigned int dstart = d / 2 + 1;
unsigned int dend = d;
double pd = 0;
for (unsigned int i = dstart; i < dend; i++)
{
pd += Binomial (i, ber, d);
}
pd += 0.5 * Binomial (d / 2, ber, d);
return pd;
}
double
YansErrorRateModel::CalculatePd (double ber, unsigned int d) const
{
double pd;
if ((d % 2) == 0)
{
pd = CalculatePdEven (ber, d);
}
else
{
pd = CalculatePdOdd (ber, d);
}
return pd;
}
double
YansErrorRateModel::GetFecBpskBer (double snr, double nbits,
uint32_t signalSpread, uint32_t phyRate,
uint32_t dFree, uint32_t adFree) const
{
double ber = GetBpskBer (snr, signalSpread, phyRate);
if (ber == 0.0)
{
return 1.0;
}
double pd = CalculatePd (ber, dFree);
double pmu = adFree * pd;
pmu = std::min (pmu, 1.0);
double pms = pow (1 - pmu, nbits);
return pms;
}
double
YansErrorRateModel::GetFecQamBer (double snr, uint32_t nbits,
uint32_t signalSpread,
uint32_t phyRate,
uint32_t m, uint32_t dFree,
uint32_t adFree, uint32_t adFreePlusOne) const
{
double ber = GetQamBer (snr, m, signalSpread, phyRate);
if (ber == 0.0)
{
return 1.0;
}
/* first term */
double pd = CalculatePd (ber, dFree);
double pmu = adFree * pd;
/* second term */
pd = CalculatePd (ber, dFree + 1);
pmu += adFreePlusOne * pd;
pmu = std::min (pmu, 1.0);
double pms = pow (1 - pmu, nbits);
return pms;
}
double
YansErrorRateModel::GetChunkSuccessRate (WifiMode mode, double snr, uint32_t nbits) const
{
if (mode == WifiPhy::Get6mba () || mode == WifiPhy::Get3mb10Mhz () || mode == WifiPhy::Get1_5mb5Mhz ())
{
return GetFecBpskBer (snr,
nbits,
mode.GetBandwidth (), // signal spread
mode.GetPhyRate (), // phy rate
10, // dFree
11 // adFree
);
}
else if (mode == WifiPhy::Get9mba () || mode == WifiPhy::Get4_5mb10Mhz () || mode == WifiPhy::Get2_25mb5Mhz ())
{
return GetFecBpskBer (snr,
nbits,
mode.GetBandwidth (), // signal spread
mode.GetPhyRate (), // phy rate
5, // dFree
8 // adFree
);
}
else if (mode == WifiPhy::Get12mba () || mode == WifiPhy::Get6mb10Mhz () || mode == WifiPhy::Get3mb5Mhz ())
{
return GetFecQamBer (snr,
nbits,
mode.GetBandwidth (), // signal spread
mode.GetPhyRate (), // phy rate
4, // m
10, // dFree
11, // adFree
0 // adFreePlusOne
);
}
else if (mode == WifiPhy::Get18mba () || mode == WifiPhy::Get9mb10Mhz () || mode == WifiPhy::Get4_5mb5Mhz ())
{
return GetFecQamBer (snr,
nbits,
mode.GetBandwidth (), // signal spread
mode.GetPhyRate (), // phy rate
4, // m
5, // dFree
8, // adFree
31 // adFreePlusOne
);
}
else if (mode == WifiPhy::Get24mba () || mode == WifiPhy::Get12mb10Mhz () || mode == WifiPhy::Get6mb5Mhz ())
{
return GetFecQamBer (snr,
nbits,
mode.GetBandwidth (), // signal spread
mode.GetPhyRate (), // phy rate
16, // m
10, // dFree
11, // adFree
0 // adFreePlusOne
);
}
else if (mode == WifiPhy::Get36mba () || mode == WifiPhy::Get18mb10Mhz () || mode == WifiPhy::Get9mb5Mhz ())
{
return GetFecQamBer (snr,
nbits,
mode.GetBandwidth (), // signal spread
mode.GetPhyRate (), // phy rate
16, // m
5, // dFree
8, // adFree
31 // adFreePlusOne
);
}
else if (mode == WifiPhy::Get48mba () || mode == WifiPhy::Get24mb10Mhz () || mode == WifiPhy::Get12mb5Mhz ())
{
return GetFecQamBer (snr,
nbits,
mode.GetBandwidth (), // signal spread
mode.GetPhyRate (), // phy rate
64, // m
6, // dFree
1, // adFree
16 // adFreePlusOne
);
}
else if (mode == WifiPhy::Get54mba () || mode == WifiPhy::Get27mb10Mhz () || mode == WifiPhy::Get13_5mb5Mhz ())
{
return GetFecQamBer (snr,
nbits,
mode.GetBandwidth (), // signal spread
mode.GetPhyRate (), // phy rate
64, // m
5, // dFree
8, // adFree
31 // adFreePlusOne
);
}
else if (mode == WifiPhy::Get1mbb ())
{
return Get80211bDsssDbpskSuccessRate (snr,nbits);
}
else if (mode == WifiPhy::Get2mbb ())
{
return Get80211bDsssDqpskSuccessRate (snr,nbits);
}
else if (mode == WifiPhy::Get5_5mbb ())
{
return Get80211bDsssDqpskCck5_5SuccessRate (snr,nbits);
}
else if (mode == WifiPhy::Get11mbb ())
{
return Get80211bDsssDqpskCck11SuccessRate (snr,nbits);
}
return 0;
}
// 802.11b ber based on "Wireless Network Coexistence: Wireless
// LAN in the 21st Century" by Robert Morrow page 187
double
YansErrorRateModel::DqpskFunction (double x) const
{
return ((sqrt (2.0) + 1.0) / sqrt (8.0*3.1415926*sqrt (2.0)))
*(1.0/sqrt (x))
*exp ( - (2.0 - sqrt (2.0)) * x) ;
}
double
YansErrorRateModel::Get80211bDsssDbpskSuccessRate (double sinr, uint32_t nbits) const
{
double EbN0 = sinr * 22000000.0 / 1000000.0; // 1 bit per symbol with 1 MSPS
double ber = 0.5 * exp (-EbN0);
return pow ((1.0 - ber), nbits);
}
double
YansErrorRateModel::Get80211bDsssDqpskSuccessRate (double sinr,uint32_t nbits) const
{
double EbN0 = sinr * 22000000.0 / 1000000.0 / 2.0; // 2 bits per symbol, 1 MSPS
double ber = DqpskFunction (EbN0);
return pow ((1.0 - ber), nbits);
}
double
YansErrorRateModel::Get80211bDsssDqpskCck5_5SuccessRate (double sinr,uint32_t nbits) const
{
#ifdef ENABLE_GSL
// symbol error probability
double EbN0 = sinr * 22000000.0 / 1375000.0 / 4.0;
double sep = SymbolErrorProb16Cck (4.0*EbN0/2.0);
return pow (1.0-sep,nbits/4.0);
#else
NS_LOG_WARN ("Running a 802.11b CCK Matlab model less accurate than GSL model");
// The matlab model
double ber;
if (sinr > WLAN_SIR_PERFECT)
{
ber = 0.0 ;
}
else if (sinr < WLAN_SIR_IMPOSSIBLE)
{
ber = 0.5;
}
else
{ // fitprops.coeff from matlab berfit
double a1 = 5.3681634344056195e-001;
double a2 = 3.3092430025608586e-003;
double a3 = 4.1654372361004000e-001;
double a4 = 1.0288981434358866e+000;
ber = a1 * exp (-(pow ((sinr-a2)/a3,a4)));
}
return pow ((1.0 - ber), nbits);
#endif
}
double
YansErrorRateModel::Get80211bDsssDqpskCck11SuccessRate (double sinr,uint32_t nbits) const
{
#ifdef ENABLE_GSL
// symbol error probability
double EbN0 = sinr * 22000000.0 / 1375000.0 / 8.0;
double sep = SymbolErrorProb256Cck (8.0*EbN0/2.0);
return pow (1.0-sep,nbits/8.0);
#else
NS_LOG_WARN ("Running a 802.11b CCK Matlab model less accurate than GSL model");
// The matlab model
double ber;
if (sinr > WLAN_SIR_PERFECT)
{
ber = 0.0 ;
}
else if (sinr < WLAN_SIR_IMPOSSIBLE)
{
ber = 0.5;
}
else
{ // fitprops.coeff from matlab berfit
double a1 = 7.9056742265333456e-003;
double a2 = -1.8397449399176360e-001;
double a3 = 1.0740689468707241e+000;
double a4 = 1.0523316904502553e+000;
double a5 = 3.0552298746496687e-001;
double a6 = 2.2032715128698435e+000;
ber = (a1*sinr*sinr+a2*sinr+a3)/(sinr*sinr*sinr+a4*sinr*sinr+a5*sinr+a6);
}
return pow ((1.0 - ber), nbits);
#endif
}
#ifdef ENABLE_GSL
double
IntegralFunction (double x, void *params)
{
double beta = ((FunctionParameters *) params)->beta;
double n = ((FunctionParameters *) params)->n;
double IntegralFunction = pow (2*gsl_cdf_ugaussian_P (x+ beta) - 1, n-1)
* exp (-x*x/2.0) / sqrt (2.0 * M_PI);
return IntegralFunction;
}
double
YansErrorRateModel::SymbolErrorProb16Cck (double e2) const
{
double sep;
double error;
FunctionParameters params;
params.beta = sqrt (2.0*e2);
params.n = 8.0;
gsl_integration_workspace * w = gsl_integration_workspace_alloc (1000);
gsl_function F;
F.function = &IntegralFunction;
F.params = ¶ms;
gsl_integration_qagiu (&F,-params.beta, 0, 1e-7, 1000, w, &sep, &error);
gsl_integration_workspace_free (w);
if (error == 0.0)
{
sep = 1.0;
}
return 1.0 - sep;
}
double YansErrorRateModel::SymbolErrorProb256Cck (double e1) const
{
return 1.0 - pow (1.0 - SymbolErrorProb16Cck (e1/2.0), 2.0);
}
#endif
} // namespace ns3