[Tinyos-2-commits] CVS: tinyos-2.x/tos/lib/tossim CpmModelC.nc, 1.11, 1.12

[SunHee Yoon]

Update of /cvsroot/tinyos/tinyos-2.x/tos/lib/tossim
In directory ddv4jf1.ch3.sourceforge.com:/tmp/cvs-serv22141

Modified Files:
	CpmModelC.nc 
Log Message:
fixed prr_estimate_from_snr function

Index: CpmModelC.nc
===================================================================
RCS file: /cvsroot/tinyos/tinyos-2.x/tos/lib/tossim/CpmModelC.nc,v
retrieving revision 1.11
retrieving revision 1.12
diff -C2 -d -r1.11 -r1.12
*** CpmModelC.nc	5 Feb 2009 22:45:41 -0000	1.11
--- CpmModelC.nc	26 May 2009 06:11:51 -0000	1.12
***************
*** 220,234 ****
  
    double prr_estimate_from_snr(double SNR) {
!     double beta1 = 1.3687;
!     double beta2 = 0.9187;
!     double SNR_lin = pow(10.0, SNR/10.0);
!     double X = fabs(SNR_lin-beta2);
!     double PSE = 0.5*erfc(beta1*sqrt(X/2));
      double prr_hat = pow(1-PSE, 23*2);
      dbg("CpmModelC,SNR", "SNR is %lf, PRR is %lf\n", SNR, prr_hat);
      if (prr_hat > 1)
!       prr_hat = 1;
      else if (prr_hat < 0)
!       prr_hat = 0;
  	
      return prr_hat;
--- 220,236 ----
  
    double prr_estimate_from_snr(double SNR) {
!     // Based on CC2420 measurement by Kannan.
!     // The updated function below fixes the problem of non-zero PRR
!     // at very low SNR. With this function PRR is 0 for SNR <= 3.
!     double beta1 = 0.9794;
!     double beta2 = 2.3851;
!     double X = SNR-beta2;
!     double PSE = 0.5*erfc(beta1*X/sqrt(2));
      double prr_hat = pow(1-PSE, 23*2);
      dbg("CpmModelC,SNR", "SNR is %lf, PRR is %lf\n", SNR, prr_hat);
      if (prr_hat > 1)
!       prr_hat = 1.1;
      else if (prr_hat < 0)
!       prr_hat = -0.1;
  	
      return prr_hat;
***************
*** 238,242 ****
      double prr = prr_estimate_from_snr(SNR);
      double coin = RandomUniform();
!     if ( (prr != 0) && (prr != 1) ) {
        if (coin < prr)
  	prr = 1.0;
--- 240,244 ----
      double prr = prr_estimate_from_snr(SNR);
      double coin = RandomUniform();
!     if ( (prr >= 0) && (prr <= 1) ) {
        if (coin < prr)
  	prr = 1.0;