Device for estimating a sequence of N bits corresponding to a received sequence of M digital data and associated methods

1. A method for estimating a sequence of N bits ({circumflex over (x)} 0 {circumflex over (x)} 1 . . . {circumflex over (x)} N−1 ) corresponding to a received sequence of M digital data (r 0 r 1 . . . r M−1 ), the method comprising:

a) determining candidate sequences of M RS digital data from a reduced reference sequence space comprising 2 N RS reduced reference sequences of M RS reference digital data (s 0 s 1 . . . s M RS −1 ), M RS being less than M, and 2 N RS being less than or equal to 2 N ;

b) making up each candidate sequence with the remaining reference digital data to obtain at least one complete candidate sequence of M digital data; and

c) determining the sequence of N bits ({circumflex over (x)} 0 {circumflex over (x)} 1 . . . {circumflex over (x)} N−1 ) from the complete candidate sequences.

2. The method according to claim 1 wherein the step a) comprises:

calculating for each reduced reference sequence a first correlation energy from the reduced reference sequence and the M RS first digital data of the received sequence (r 0 r 1 . . . r M RS −1 );

determining a threshold from a maximum of the calculated first correlation energies; and

taking into account the threshold for determining the candidate sequences.

3. The method according to claim 2 wherein the threshold is the maximum

(

E

max

,

beginning

M

RS

)

of the calculated first correlation energies.

4. The method according to claim 2 wherein the threshold determining step comprises:

determining the maximum

(

E

max

,

beginning

M

RS

)

 of the calculated first correlation energies;

making up the reduced reference sequence having the maximum

(

E

max

,

beginning

M

RS

)

 of the calculated first correlation energies, with a set of corresponding remaining reference sequence to obtain a complete reference sequence;

calculating a correlation energy

(

E

end

M

-

M

RS

)

 from the remaining M-M RS digital data of the received sequence (r 0 r 1 . . . r M−1 ) and the remaining M-M RS digital data of the made up reduced reference sequence; and

adding the maximum

(

E

max

,

beginning

M

RS

)

 of the calculated first correlation energies and the calculated correlation energy

(

E

end

M

-

M

RS

)

,

 to obtain the threshold.

5. The method according to claim 2 wherein the step a) comprises:

calculating the maximum possible correlation energy

(

E

max

,

end

M

-

M

RS

)

 from the remaining M-M RS digital data of the received sequence (r 0 r 1 . . . r M−1 );

for each reduced reference sequence, adding its first correlation energy to the calculated maximum possible correlation energy

(

E

max

,

end

M

-

M

RS

)

,

 to obtain a second correlation energy;

comparing each second correlation energy with the threshold

(

E

max

,

beginning

M

RS

)

;

 and

selecting as candidates the reduced sequences having their second correlation energy greater than the threshold

(

E

max

,

beginning

M

RS

)

.

6. The method according to claim 1 wherein the step b) comprises, for each candidate sequence, reading a predetermined set of stored possible M-M RS remaining reference digital data, to obtain a complete candidate sequence of M digital data.

7. The method according to claim 1 wherein the step b) comprises, for each candidate sequence, generating a set of possible M-M RS remaining reference digital data, to obtain a complete candidate sequence of M digital data.

8. The method according to claim 1 wherein the step c) comprises:

calculating for each complete candidate sequence a complete correlation energy from the complete candidate sequence and the received sequence (r 0 r 1 . . . r M−1 );

selecting a complete candidate sequence having the highest complete correlation energy; and

determining the sequence of N bits ({circumflex over (x)} 0 {circumflex over (x)} 1 . . . {circumflex over (x)} N−1 ) from the selected complete candidate.

9. A system for estimating a sequence of N bits ({circumflex over (x)} 0 {circumflex over (x)} 1 . . . {circumflex over (x)} N−1 ) corresponding to a received sequence of M digital data (r 0 r 1 . . . r M−1 ), the system comprising:

a first determiner for determining candidate sequences of M RS digital data from a reduced reference sequence space comprising 2 N RS reduced reference sequences of M RS reference digital data (s 0 s 1 . . . s M RS −1 ), M RS being less than M, and 2 N RS being less than or equal to 2 N ;

an assembler for making up each candidate sequence with remaining reference digital data to obtain at least one complete candidate sequence of M digital data; and

a second determiner for determining the sequence of N bits ({circumflex over (x)} 0 {circumflex over (x)} 1 . . . {circumflex over (x)} N−1 ) from the complete candidate sequences.

10. The system according to claim 9 , wherein said first determiner comprises

a first calculator for calculating for each reduced reference sequence a first correlation energy from the reduced reference sequence and the M RS first digital data of the received sequence (r 0 r 1 . . . r M RS −1 );

a second calculator for determining a threshold from the maximum

(

E

max

,

beginning

M

RS

)

 of the calculated first correlation energies; and

a processor for determining the candidate sequences, taking into account the threshold.

11. The system according to claim 10 , wherein said second calculator is for calculating the threshold as being the maximum

(

E

max

,

beginning

M

RS

)

of the calculated first correlation energies.

12. The system according to claim 11 , wherein said second calculator is for

determining the maximum

(

E

max

,

beginning

M

RS

)

 of the calculated first correlation energies;

making up the reduced reference sequence having the maximum

(

E

max

,

beginning

M

RS

)

 of the calculated first correlation energies, with a set of corresponding remaining reference sequence to obtain a complete reference sequence;

calculating a correlation energy

(

E

end

M

-

M

RS

)

 from the remaining M-M RS digital data of the received sequence (r 0 r 1 . . . r M−1 ) and the remaining M-M RS digital data of the made up reduced reference sequence; and

adding said maximum

(

E

max

,

beginning

M

RS

)

 of the calculated first correlation energies and the calculated correlation energy

(

E

end

M

-

M

RS

)

,

 in order to obtain the threshold.

13. The system according to claim 11 wherein said first determiner comprises:

a third calculator for calculating the maximum possible correlation energy

(

E

max

,

end

M

-

M

RS

)

 from the remaining M-M RS digital data of the received sequence (r 0 r 1 . . . r M−1 ); and

an adder for adding, for each reduced reference sequence, its first correlation energy to the calculated maximum possible correlation energy

(

E

max

,

end

M

-

M

RS

)

,

 to obtain a second correlation energy;

and wherein said processor comprises:

a comparator for comparing each second correlation energy with said threshold

(

E

max

,

beginning

M

RS

)

;

 and

a first selector for selecting as a candidate the reduced sequences having their second correlation energy greater than the threshold

(

E

max

,

beginning

M

RS

)

.

14. The system according to claim 10 wherein said assembler comprises

a memory for storing predetermined possible M-M RS remaining reference digital data, and

a reader for reading, for each candidate sequence, the stored predetermined possible M-M RS remaining reference digital data, to obtain a complete candidate sequence of M digital data.

15. The system according to claim 10 wherein said assembler comprises a generator for generating, for each candidate sequence, a set of possible M-M RS remaining reference digital data, to obtain a complete candidate sequence of M digital data.

16. The system according to claim 10 wherein said second determiner comprises:

a fourth calculator for calculating, for each complete candidate sequence, a complete correlation energy from the complete candidate sequence and the received sequence (r 0 r 1 . . . r M−1 );

a second selector for selecting a complete candidate sequence having the highest correlation energy; and

a demapper for determining the corresponding sequence of N bits ({circumflex over (x)} 0 {circumflex over (x)} 1 . . . {circumflex over (x)} N−1 ) from the selected complete candidate.

17. A receiving apparatus comprising:

a system for estimating a sequence of N bits ({circumflex over (x)} 0 {circumflex over (x)} 1 . . . {circumflex over (x)} N−1 ) corresponding to a received sequence of M digital data (r 0 r 1 . . . r M−1 ), the system comprising:

a first determiner for determining candidate sequences of M RS digital data from a reduced reference sequence space comprising 2 N RS reduced reference sequences of M RS reference digital data (s 0 s 1 . . . s M RS −1 ), M RS being less than M, and 2 N RS being less than or equal to 2 N ;

an assembler for making up each candidate sequence with remaining reference digital data to obtain at least one complete candidate sequence of M digital data; and

a second determiner for determining the sequence of N bits ({circumflex over (x)} 0 {circumflex over (x)} 1 . . . {circumflex over (x)} N−1 ) from the complete candidate sequences.

18. The receiving apparatus according to claim 17 wherein said receiving apparatus comprises a cellular mobile phone.