Error estimation method and apparatus

Abstract

Bit error rate or bit error probability of a received signal of a wireless telecommunication system is estimated, wherein a channel impulse response is estimated from the received signal, and the received signal is subjected to a channel equalizing operation performed on the basis of time statistics derived from the channel impulse response. Additionally, adaptive reference time domain characteristics are calculated from a weighting information obtained from the channel impulse response estimation that may be used to perform a reference channel equalizing operation for obtaining an additional output signal to be compared with the output signal of the channel equalizing operation so as to determine an estimation of the bit error rate based on the detected difference.

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         8 . A method for estimating a bit error probability of a received signal of a wireless telecommunication system, said method comprising the steps of: 
 a) estimating a channel impulse response from said received signal;    b) subjecting said received signal to a channel equalizing operation performed on the basis of time statistics derived from said channel impulse response; and    c) calculating said bit error probability by using an actual weighting information obtained from said channel estimation step and an output signal of said channel equalizing operation.    
     
     
         9 . A method according to  claim 8 , wherein said bit error probability is calculated burstwise on the basis of the following equation;  
       
         
           
             
               BEP 
               = 
               
                 
                   1 
                   N 
                 
                  
                 
                   
                     ∑ 
                     
                       k 
                       = 
                       1 
                     
                     N 
                   
                    
                   
                     1 
                     
                       1 
                       + 
                       
                          
                          
                         
                            
                           
                             a 
                             · 
                             
                               L 
                               k 
                             
                           
                            
                         
                       
                     
                   
                 
               
             
           
           
           
               
           
         
       
       wherein N denotes the number of bits in a burst, L k  denotes a k-th soft bit, and a denotes a channel-specific parameter.  
     
     
         10 . A method according to  claim 9 , wherein said channel-specific parameter is a constant.  
     
     
         11 . A method according to  claim 9 , wherein said channel-specific parameter is calculated on the basis of the following equation:  
       
         
           
             
               a 
               = 
               
                 b 
                 + 
                 
                   E 
                   
                     E 
                     + 
                     var 
                   
                 
               
             
           
           
           
               
           
         
       
       wherein a denotes said channel-specific parameter, b denotes a predetermined scaling constant, E denotes energy of the burst, and var denotes variance of the burst.  
     
     
         12 . A method according to  claim 9 , wherein said channel-specific parameter is determined in dependence on an amount of phase error determined in said channel equalizing operation.  
     
     
         13 . A method according to  claim 9 , wherein said channel-specific parameter is determined in dependence on an amount of energy included in a predetermined number of taps of said estimated channel impulse response.  
     
     
         14 . A method according to  claim 8 , wherein said calculating said bit error probability is performed in dependence on a relation between a standard deviation or variance and the mean of the means of a predetermined number of soft bits obtained from said channel equalizing operation.  
     
     
         15 . A method according to  claim 14 , wherein said bit error probability is calculated using only said predetermined number of soft bits of a block with a smallest mean, if said relation exceeds a predetermined threshold.  
     
     
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         22 . An apparatus for estimating a bit error probability of a received signal of a wireless telecommunication system, said apparatus comprising: 
 a) estimating means ( 1 ) for estimating a channel impulse response based on said received signal;    b) channel equalizing means ( 4 ) for subjecting said received signal to a channel equalizing operation performed on the basis of time statistics derived from said channel impulse response; and    c) calculating means ( 10 ) for calculating said error probability by using an actual weighting information obtained from said estimating means ( 1 ) and an output signal of said channel equalizing means ( 4 ).    
     
     
         23 . An apparatus according to  claim 22 , wherein said calculating means ( 10 ) is arranged to determine a channel-specific parameter in dependence on an amount of phase error determined in said channel equalizing means ( 4 ).  
     
     
         24 . An apparatus according to  claim 23 , wherein said calculating means ( 10 ) is arranged to determine said channel-specific parameter in dependence on an amount of energy included in a predetermined number of taps of said estimated channel impulse response and obtained from said estimating means ( 1 ).  
     
     
         25 . An apparatus according to  claim 22 , wherein said calculating means ( 10 ) is arranged to calculate said bit error probability in dependence on a relation between a standard deviation or variance and the means of a predetermined number of soft bits.