Frequency hopping for random access

Abstract

A wireless communication device ( 14 ) (e.g., a user equipment) in a wireless communication system ( 10 ) is configured for transmitting a random access preamble signal ( 16 ). The wireless communication device ( 14 ) in particular is configured to generate a random access preamble signal ( 16 ) that comprises multiple symbol groups ( 18 ), with each symbol group ( 18 ) on a single tone during a different time resource, according to a frequency hopping pattern that hops the random access preamble signal ( 16 ) a fixed frequency distance at one or more symbol groups ( 18 ) and hops the random access preamble signal ( 16 ) a pseudo random frequency distance at one or more other symbol groups ( 18 ). Each symbol group ( 18 ) comprises one or more symbols. The wireless communication device ( 14 ) is also configured to transmit the random access preamble signal ( 16 ).

What is claimed is: 
     
         1 . A method implemented by a user equipment ( 14 ) configured for use in a wireless communication system ( 10 ), the method comprising:
 transmitting a random access preamble signal ( 16 ) that comprises multiple symbol groups ( 18 ), with each symbol group ( 18 ) on a single tone during a different time resource, according to a frequency hopping pattern that hops the random access preamble signal ( 16 ) a fixed frequency distance at one or more symbol groups ( 18 ) and hops the random access preamble signal ( 16 ) a pseudo random frequency distance at one or more other symbol groups ( 18 ), wherein each symbol group ( 18 ) comprises one or more symbols.   
     
     
         2 . The method of  claim 1 , further comprising randomly selecting a single tone on which to transmit a first one of the multiple symbol groups ( 18 ), and selecting the single tones on which to respectively transmit subsequent ones of the multiple symbol groups ( 18 ) according to the frequency hopping pattern. 
     
     
         3 . A method implemented by a radio network node ( 12 ) configured for use in a wireless communication system ( 10 ), the method comprising:
 processing ( 220 ) a signal received from a user equipment, in an attempt to detect a random access preamble signal ( 16 ) that comprises multiple symbol groups ( 18 ), with each of the symbol groups ( 18 ) on a single tone during a different time resource, according to a frequency hopping pattern that hops the random access preamble signal ( 16 ) a fixed frequency distance at one or more symbol groups ( 18 ) and hops the random access preamble signal ( 16 ) a pseudo random frequency distance at one or more other symbol groups ( 18 ), wherein each symbol group ( 18 ) comprises one or more symbols.   
     
     
         4 . The method of  claim 3 , further comprising receiving one or more other signals from one or more other user equipments, and processing the one or more other signals in an attempt to detect one or more other random access preamble signals multiplexed in frequency with the random access preamble signal ( 16 ), according to different frequency hopping patterns. 
     
     
         5 . The method of any of  claim 1 , wherein the pseudo random frequency distance is a function of:
 f hop (i)=(f hop (i−1)+(Σ k=i*10   i*10+9 c(k)*2 k-(i*10+1) )mod(N b   sc −1)+1)modN b   sc , wherein   
       
         
           
             
               
                 i 
                 = 
                 
                   t 
                   T 
                 
               
               , 
             
           
         
       
       wherein t is a symbol group index, wherein the random access preamble signal ( 16 ) hops a pseudo random frequency distance every T symbol groups ( 18 ), wherein N b   sc  is a number of tones within which hopping is defined for the random access preamble signal ( 16 ), and c(k) is a pseudo random sequence. 
     
     
         6 . The method of any of  claim 1 , wherein the pseudo random frequency distance is a function of:
 f hop (i)=(f hop (i−1)+(Σ k=i*10   i*10+9 c(k)*2 k-(i*10+1) )mod(N b   sc −1)+1)modN b   sc , wherein N b   sc  is a number of tones within which hopping is defined for the random access preamble signal ( 16 ), wherein c(k) is a pseudo random sequence, and wherein i=0, 1, 2, . . . is an index of consecutive pseudo random frequency hops in the frequency hopping pattern.   
     
     
         7 . The method of any of  claim 5 , wherein the pseudo random sequence c(k) comprises a sequence of length M PN , where k=0, 1, . . . , M PN −1, and is defined by
     c ( k )=( x   1 ( k+N   C )+ x   2 ( k+N   C )) mod 2 
     x   1 ( k+ 31)=( x   1 ( k+ 3)+ x   1 ( k )) mod 2 
     x   2 ( k+ 31)=( x   2 ( k+ 3)+ x   2 ( k+ 2)+ x   2 ( k+ 1)+ x   2 ( k )) mod 2 
 
       where N C =1600, x 1 (0)=1, x 1 (k)=0, k=1, 2, . . . , 30, c init =Σ i=0   30  x 2 (i)·2 i , c init =N ID   Ncell , and N ID   Ncell  is a physical-layer cell identity. 
     
     
         8 . The method of any of  claim 1 , wherein the pseudo random frequency distance is a function of a cell identity. 
     
     
         9 . The method of any of  claim 1 , wherein the fixed frequency distance comprises a frequency distance of a single tone. 
     
     
         10 . The method of any of  claim 1 , wherein each symbol group ( 18 ) in the random access preamble signal ( 16 ) comprises a cyclic prefix and two or more symbols. 
     
     
         11 . The method of any of  claim 1 , wherein the frequency hopping pattern hops the random access preamble signal ( 16 ) a fixed frequency distance at each symbol group ( 18 ) in a first set of one or more symbol groups ( 18 ), and hops the random access preamble signal ( 16 ) a pseudo random frequency distance at each symbol group ( 18 ) in a second set of one or more symbol groups ( 18 ) different than the first set. 
     
     
         12 . A user equipment ( 14 ) for use in a wireless communication system ( 10 ) for transmitting a random access preamble signal ( 16 ), the user equipment ( 14 ) comprising:
 processing circuitry ( 920 ) and radio circuitry ( 910 ), whereby the processing circuitry is configured to:
 transmit a random access preamble signal ( 16 ) that comprises multiple symbol groups ( 18 ), with each symbol group ( 18 ) on a single tone during a different time resource, according to a frequency hopping pattern that hops the random access preamble signal ( 16 ) a fixed frequency distance at one or more symbol groups ( 18 ) and hops the random access preamble signal ( 16 ) a pseudo random frequency distance at one or more other symbol groups ( 18 ), wherein each symbol group ( 18 ) comprises one or more symbols. 
   
     
     
         14 . A radio network node ( 12 ) for use in a wireless communication system ( 10 ) for receiving a random access preamble signal ( 16 ), the radio network node ( 12 ) comprising:
 processing circuitry ( 1020 ) and radio circuitry ( 1010 ), whereby the processing circuitry is configured to:
 process a signal, received from a user equipment, in an attempt to detect a random access preamble signal ( 16 ) that comprises multiple symbol groups ( 18 ), with each of the symbol groups ( 18 ) on a single tone during a different time resource, according to a frequency hopping pattern that hops the random access preamble signal ( 16 ) a fixed frequency distance at one or more symbol groups ( 18 ) and hops the random access preamble signal ( 16 ) a pseudo random frequency distance at one or more other symbol groups ( 18 ), wherein each symbol group ( 18 ) comprises one or more symbols.