Methods for accurate use of finite dynamic range measurement data in radio path loss propagation model calibration

Abstract

Methods for accurately predicting radio propagation from signal strength measurements. Dynamic range limitations in the measurement data are explicitly taken into account. The resulting propagation models accurately predict signal strength for calculation of coverage and interference.

1 . A method of accurately calculating an optimal parameter set for application to a signal propagation model describing data of limited dynamic range, comprising the steps of: 
 a) representing a set of N data points collected by a receiver as a truncated data set, wherein said truncated data set is truncated using a set of N lower truncation limits, wherein a lower truncation limit is calculated for each data point according to a sensitivity threshold of said receiver, and wherein said truncated data set is further truncated using an upper truncation limit calculated according to an upper limit of the linear range of said receiver;    b) excluding from said truncated data set all data outside a range defined by said lower and upper truncation limits; and    c) based on said truncated data set, based on said lower and upper truncation limits, and based on a given signal propagation model, calculating an optimal parameter set maximizing the accuracy with which said signal propagation model describes said data set.    
     
     
         2 . The method of  claim 1 , wherein said step of calculating comprises maximizing the likelihood of said signal propagation model given said data, said lower truncation limit, and said upper truncation limit.  
     
     
         3 . The method of  claim 1 , wherein said data is radio signal data.  
     
     
         4 . The method of  claim 1 , wherein said data is microwave signal data.  
     
     
         5 . The method of  claim 1 , wherein said data is signal strength data.  
     
     
         6 . The method of  claim 1 , wherein said data pertains to a cellular phone network.  
     
     
         7 . The method of  claim 1 , wherein said data is cellular phone signal strength data.  
     
     
         8 . The method of  claim 1 , wherein said step of calculating is performed using a maximum likelihood (ML) fit.  
     
     
         9 . The method of  claim 1 , wherein said receiver is one of a CDMA radio scanner and a UMTS radio scanner, and wherein the lower truncation limit is calculated at each data point by adding the minimum detectable Ec/I 0  at said data point to the measured I 0  at said data point.  
     
     
         10 . The method of  claim 1 , wherein said receiver is a GSM radio scanner, and wherein the lower truncation limit is calculated at each data point by adding the minimum detectable C/I at said data point to the measured I at said data point.  
     
     
         11 . A method of accurately calculating an optimal parameter set for application to a signal propagation model describing data of limited dynamic range, comprising the steps of: 
 a) representing a set of data points collected by a receiver as a censored data set, wherein said censored data set comprises a set of uncensored observations, a set of left-censored observations, and a set of right-censored observations;    b) defining the set of uncensored observations as all measured data points with signal level within the linear range of said receiver;    c) defining the set of right-censored observations as the set of all measured points with a measured signal level above the receiver's linear range;    d) defining the set of left-censored observations as the set of all signals not detected due to being below the minimum detection level of the receiver;    e) defining an upper censoring limit as equal to the upper limit on the linear range of said receiver;    f) defining a lower censoring limit as equal to the minimum detection level of said receiver; and    g) based on said censored data set, based on said lower and upper censoring limits, and based on a given signal propagation model, calculating an optimal parameter set maximizing the accuracy with which said signal propagation model describes said data set.    
     
     
         12 . The method of  claim 11 , wherein said step of calculating comprises maximizing the likelihood of said signal propagation model given said data, said lower censoring limit, and said upper censoring limit.  
     
     
         13 . The method of  claim 11 , wherein said data is radio signal data.  
     
     
         14 . The method of  claim 11 , wherein said data is microwave signal data.  
     
     
         15 . The method of  claim 11 , wherein said data is signal strength data.  
     
     
         16 . The method of  claim 11 , wherein said data pertains to a cellular phone network.  
     
     
         17 . The method of  claim 11 , wherein said data is cellular phone signal strength data.  
     
     
         18 . The method of  claim 11 , wherein said step of calculating is performed using a maximum likelihood (ML) fit.  
     
     
         19 . The method of  claim 11 , wherein said receiver is one of a CDMA radio scanner and a UMTS radio scanner, and wherein a set of left-censored observations is defined at each geographic point where signals were detected, by examining the set of all detected signals and adding left-censored observations for all signals that were not detected, using a lower censoring limit obtained by adding the minimum detectable Ec/I 0  for said data point to the measured I 0  for said data point.  
     
     
         20 . The method of  claim 11 , wherein said receiver is a GSM radio scanner, and wherein a set of left-censored observations is defined at each geographic point where signals were detected, by examining the set of all detected signals and adding left-censored observations for all signals that were not detected, using a lower censoring limit obtained by adding the minimum detectable C/I for said data point to the measured I for said data point.