implement WifiPhy::GetChunkSuccessRate
This commit is contained in:
Mathieu Lacage
@@ -764,6 +764,248 @@ WifiPhy::AppendEvent (Ptr<RxEvent> event)
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/**
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* Stuff specific to the BER model here.
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*/
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double
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WifiPhy::Log2 (double val) const
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{
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return log(val) / log(2.0);
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}
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double
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WifiPhy::GetBpskBer (double snr, uint32_t signalSpread, uint32_t phyRate) const
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{
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double EbNo = snr * signalSpread / phyRate;
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double z = sqrt(EbNo);
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double ber = 0.5 * erfc(z);
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return ber;
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}
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double
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WifiPhy::GetQamBer (double snr, unsigned int m, uint32_t signalSpread, uint32_t phyRate) const
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{
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double EbNo = snr * signalSpread / phyRate;
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double z = sqrt ((1.5 * Log2 (m) * EbNo) / (m - 1.0));
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double z1 = ((1.0 - 1.0 / sqrt (m)) * erfc (z)) ;
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double z2 = 1 - pow ((1-z1), 2.0);
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double ber = z2 / Log2 (m);
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return ber;
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}
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uint32_t
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WifiPhy::Factorial (uint32_t k) const
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{
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uint32_t fact = 1;
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while (k > 0)
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{
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fact *= k;
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k--;
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}
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return fact;
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}
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double
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WifiPhy::Binomial (uint32_t k, double p, uint32_t n) const
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{
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double retval = Factorial (n) / (Factorial (k) * Factorial (n-k)) * pow (p, k) * pow (1-p, n-k);
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return retval;
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}
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double
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WifiPhy::CalculatePdOdd (double ber, unsigned int d) const
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{
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NS_ASSERT ((d % 2) == 1);
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unsigned int dstart = (d + 1) / 2;
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unsigned int dend = d;
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double pd = 0;
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for (unsigned int i = dstart; i < dend; i++)
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{
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pd += Binomial (i, ber, d);
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}
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return pd;
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}
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double
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WifiPhy::CalculatePdEven (double ber, unsigned int d) const
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{
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NS_ASSERT ((d % 2) == 0);
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unsigned int dstart = d / 2 + 1;
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unsigned int dend = d;
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double pd = 0;
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for (unsigned int i = dstart; i < dend; i++)
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{
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pd += Binomial (i, ber, d);
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}
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pd += 0.5 * Binomial (d / 2, ber, d);
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return pd;
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}
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double
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WifiPhy::CalculatePd (double ber, unsigned int d) const
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{
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double pd;
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if ((d % 2) == 0)
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{
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pd = CalculatePdEven (ber, d);
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}
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else
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{
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pd = CalculatePdOdd (ber, d);
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}
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return pd;
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}
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double
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WifiPhy::GetFecBpskBer (double snr, double nbits,
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uint32_t signalSpread, uint32_t phyRate,
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uint32_t dFree, uint32_t adFree) const
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{
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double ber = GetBpskBer (snr, signalSpread, phyRate);
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if (ber == 0.0)
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{
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return 1.0;
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}
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double pd = CalculatePd (ber, dFree);
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double pmu = adFree * pd;
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if (pmu > 1.0)
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{
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/**
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* If pmu is bigger than 1, then, this calculation is
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* giving us a useless bound. A better bound in this case
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* is 1 - ber which is necessarily bigger than the real
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* success rate.
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*/
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return ber;
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}
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double pms = pow (1 - pmu, nbits);
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return pms;
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}
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double
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WifiPhy::GetFecQamBer (double snr, uint32_t nbits,
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uint32_t signalSpread,
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uint32_t phyRate,
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uint32_t m, uint32_t dFree,
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uint32_t adFree, uint32_t adFreePlusOne) const
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{
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double ber = GetQamBer (snr, m, signalSpread, phyRate);
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if (ber == 0.0)
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{
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return 1.0;
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}
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/* first term */
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double pd = CalculatePd (ber, dFree);
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double pmu = adFree * pd;
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/* second term */
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pd = CalculatePd (ber, dFree + 1);
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pmu += adFreePlusOne * pd;
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if (pmu > 1.0)
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{
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/**
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* If pmu is bigger than 1, then, this calculation is
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* giving us a useless bound. A better bound in this case
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* is 1 - ber which is necessarily bigger than the real
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* success rate.
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*/
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return ber;
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}
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double pms = pow (1 - pmu, nbits);
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return pms;
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}
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double
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WifiPhy::GetChunkSuccessRate (WifiMode mode, double snr, uint32_t nbits) const
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{
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if (mode.GetUid () == g_6mba.GetUid ())
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{
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return GetFecBpskBer (snr,
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nbits,
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20000000, // signal spread
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6000000, // phy rate
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10, // dFree
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11 // adFree
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);
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}
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else if (mode.GetUid () == g_9mba.GetUid ())
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{
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return GetFecBpskBer (snr,
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nbits,
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20000000, // signal spread
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9000000, // phy rate
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5, // dFree
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8 // adFree
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);
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}
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else if (mode.GetUid () == g_12mba.GetUid ())
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{
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return GetFecQamBer (snr,
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nbits,
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20000000, // signal spread
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12000000, // phy rate
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4, // m
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10, // dFree
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11, // adFree
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0 // adFreePlusOne
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);
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}
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else if (mode.GetUid () == g_18mba.GetUid ())
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{
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return GetFecQamBer (snr,
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nbits,
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20000000, // signal spread
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18000000, // phy rate
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4, // m
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5, // dFree
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8, // adFree
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31 // adFreePlusOne
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);
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}
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else if (mode.GetUid () == g_24mba.GetUid ())
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{
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return GetFecQamBer (snr,
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nbits,
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20000000, // signal spread
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24000000, // phy rate
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16, // m
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10, // dFree
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11, // adFree
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0 // adFreePlusOne
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);
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}
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else if (mode.GetUid () == g_36mba.GetUid ())
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{
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return GetFecQamBer (snr,
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nbits,
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20000000, // signal spread
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36000000, // phy rate
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16, // m
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5, // dFree
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8, // adFree
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31 // adFreePlusOne
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);
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}
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else if (mode.GetUid () == g_48mba.GetUid ())
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{
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return GetFecQamBer (snr,
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nbits,
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20000000, // signal spread
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48000000, // phy rate
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64, // m
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6, // dFree
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1, // adFree
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16 // adFreePlusOne
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);
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}
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else if (mode.GetUid () == g_54mba.GetUid ())
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{
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return GetFecQamBer (snr,
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nbits,
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20000000, // signal spread
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54000000, // phy rate
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64, // m
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5, // dFree
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8, // adFree
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31 // adFreePlusOne
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);
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}
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return 0;
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}
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double
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WifiPhy::CalculateSnr (double signal, double noiseInterference, WifiMode mode) const
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@@ -158,6 +158,22 @@ private:
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double CalculateChunkSuccessRate (double snir, Time delay, WifiMode mode) const;
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double CalculatePer (Ptr<const RxEvent> event, NiChanges *ni) const;
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void EndSync (Packet const packet, Ptr<RxEvent> event, uint32_t stuff);
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double Log2 (double val) const;
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double GetBpskBer (double snr, uint32_t signalSpread, uint32_t phyRate) const;
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double GetQamBer (double snr, unsigned int m, uint32_t signalSpread, uint32_t phyRate) const;
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uint32_t Factorial (uint32_t k) const;
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double Binomial (uint32_t k, double p, uint32_t n) const;
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double CalculatePdOdd (double ber, unsigned int d) const;
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double CalculatePdEven (double ber, unsigned int d) const;
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double CalculatePd (double ber, unsigned int d) const;
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double GetFecBpskBer (double snr, double nbits,
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uint32_t signalSpread, uint32_t phyRate,
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uint32_t dFree, uint32_t adFree) const;
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double GetFecQamBer (double snr, uint32_t nbits,
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uint32_t signalSpread,
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uint32_t phyRate,
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uint32_t m, uint32_t dfree,
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uint32_t adFree, uint32_t adFreePlusOne) const;
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double GetChunkSuccessRate (WifiMode mode, double snr, uint32_t nbits) const;
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/* rxPower unit is Watt */
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void ReceivePacket (Packet packet,
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