PREAMBLE FOR SYNCHRONIZATION

Abstract

It is proposed a receiver comprising receiving means for receiving a preamble signal (26) that comprises a long PN sequence (33) being a combination of a plurality of short PN sequences (29, 30, 31,32), wherein said short PN sequences (29, 30, 31,32) are selected on the basis of their auto-correlation and/or cross-correlation properties. At least one of said short PN sequences (29, 30, 31,32) referred to as a coarse timing short PN sequence (PN1) is adapted to perform a coarse timing synchronization, extracting means (41) for extracting said coarse timing short PN sequence (PN1) from said long PN sequence (33), first auto-correlating means (42, 43, 44, 45) for performing a coarse timing synchronization using said coarse timing short PN sequence (PN1), and second auto-correlating means (52, 53, 54, 55) for performing a fine timing synchronization using said long PN sequence (33).

Description

The features, objects, and advantages of the present invention will become more apparent from the detailed description set forth below when taken in conjunction with the drawings in which like reference characters identify correspondingly throughout and wherein:

FIG. 1 is a block diagram of a receiver of a wireless communication system, in accordance with the present invention,

FIG. 2 shows the structure of a frame for wireless communication according to the invention,

FIG. 3 shows the construction of a pseudo-noise sequence according to the invention,

FIG. 4 is a block diagram of a circuit for generating pseudo-noise sequences according to the invention,

FIG. 5 shows a method for generating a pseudo-noise sequence and a preamble according to the invention,

FIG. 6 shows an alternative method for generating a pseudo-noise sequence and a preamble according to the invention,

FIG. 7 is a block diagram of a frame timing detector circuit supporting parallel processing for coarse timing synchronization according to the invention,

FIG. 8 is a block diagram of a frame timing detector circuit supporting serial processing for coarse timing synchronization according to the invention,

FIG. 9 is a block diagram of a frame timing detector circuit supporting parallel processing for fine timing synchronization according to the invention,

FIG. 10 shows the segmentation of a pseudo-noise sequence according to the present invention.

Claims

1. A method for generating a preamble signal for a wireless communication system, wherein said preamble signal comprises a long PN sequence (33) that is obtained by combining a plurality of short PN sequences (29, 30, 31,32), at least one of said plurality of short PN sequences (29, 30, 31,32) being adapted for coarse timing synchronization and said long PN sequence (33) being adapted for fine timing synchronization.

2. A method according to claim 1, comprising the steps of selecting M different short PN sequences (29, 30, 31,32) having a length N,combining said M different short PN sequences (29, 30, 31,32) or the opposite thereof for obtaining said long PN sequence (33) having the length M*N.

3. A method according to claim 1, wherein M different short PN sequences (29, 30, 31,32) having a respective binary sequence S′short,i={bi,1 bi,2 . . . bi,N}, i being comprised between 1 and M, are selected, andthe binary sequence Slong of the long PN sequence (33) is constructed as follows: S′long={b1,1b2,1 . . . bM,1 b1,2b2,2 . . . bM,2 . . .b1,Nb2,N . . . bM,N}

4. A method according to claim 3, comprising the additional steps of constructing at least one additional long PN sequence S′long,add by changing the sign of at least one short PN sequence,among the constructed long PN sequences S′long and S′long,add, selecting the one having the best auto-correlation property and including it in said preamble signal.

5. A method according to claim 3, wherein the binary sequence S′short,1={b1,1, b1,2 . . . b1,N} is allocated to the short PN sequence adapted for coarse timing synchronization.

6. A method according to claim 1, wherein said short PN sequences (29, 30, 31,32) are selected from the set of m-sequences, Gold sequences, or Kasami sequences of length N.

7. A method according to claim 1, wherein said short PN sequences (29, 30, 31,32) are selected on the basis of their auto-correlation and/or cross-correlation properties.

8. A method according to claim 1, wherein the short PN sequence adapted for coarse timing synchronization is the sequence that has the best auto-correlation and cross-correlation properties among the plurality of short PN sequences (29, 30, 31,32) used to build said long PN sequence (33).

9. A transmitter of a wireless communication system comprising means designed for implementing a method for generating a preamble signal according to claim 1.

10. A preamble signal for timing synchronization in a wireless communication system comprising a long PN sequence (33) being a combination of a plurality of short PN sequences (29, 30, 31,32), wherein at least one of said plurality of short PN sequences (29, 30, 31,32) is used for coarse timing synchronization, and said long PN sequence (33) is used for fine timing synchronization.

11. A receiver comprising receiving means for receiving a preamble signal (26) that comprises a long PN sequence (33) being a combination of a plurality of short PN sequences (29, 30, 31,32), wherein at least one of said short PN sequences (29, 30, 31,32) referred to as a coarse timing short PN sequence (PN1) is adapted to perform a coarse timing synchronization,extracting means (41) for extracting said coarse timing short PN sequence (PN1) from said long PN sequence (33),first auto-correlating means (42, 43, 44, 45) for performing a coarse timing synchronization using said coarse timing short PN sequence (PN1), andsecond auto-correlating means (52, 53, 54, 55) for performing a fine timing synchronization using said long PN sequence (33).

12. A receiver according to claim 111 wherein said extracting means (41) is adapted to extract said short PN sequences (29, 30, 31,32) from said long PN sequence (33),said second auto-correlation means is adapted to perform a fine timing synchronization using said short PN sequences (29, 30, 31,32).

13. A receiver according to claim 11 wherein said extracting means (41) is a serial to parallel unit.

14. A receiver according to claim 11 wherein said long PN sequence (33) is a combination of M different short PN sequences (29, 30, 31,32) of length N, wherein M and N are integers greater than 1.

15. A receiver according to claim 11 wherein said long PN sequence (33) has a binary sequence Slong={c1 c2 . . . cM*N−1 cM*N}, M and N being integers greater than 1, andsaid extracting means (41) is adapted to extract from said long PN sequence (33) M short PN sequences (29, 30, 31,32) of length N having following binary sequences: Sshort,1={c1cM+1 . . . cM*(N−1)+1},Sshort,2={c2cM+2 . . . cM*(N−1)+2},. . . ,Sshort,M={cMcM*2 . . . cM*N},

16. A receiver according to claim 15 wherein the binary sequence Sshort,1 is used as coarse timing short PN sequence (PN1).

17. A receiver according to claim 11 wherein said extracting means (41) comprises a plurality of parallel outputs (42′, 43′, 44′, 45′),each of said outputs (42′, 43′, 44′, 45′) is connected to one of a plurality of said first auto-correlating means (42, 43, 44, 45) for auto-correlating said coarse timing short PN sequence (PN1),each of said first auto-correlating means (42, 43, 44, 45) is connected to one of a plurality of peak detectors (46, 47, 48, 49) for peak detection and coarse frame timing.

18. A receiver according to claim 11 wherein said extracting means (41) comprises a plurality of parallel outputs (42′, 43′, 44′, 45′),said outputs (42′, 43′, 44′, 45′) are connected to a multiplexer (51) for generating a multiplexed signal,said first auto-correlating means (53) uses said multiplexed signal for auto-correlating said coarse timing short PN sequence (PN1),a peak detector (54) is adapted to perform peak detection and coarse frame timing.

19. A receiver according to claim 11 wherein said second auto-correlating means (52, 53, 54, 55) is adapted to auto-correlate in parallel each short PN sequence (29, 30, 31, 32),an adder (58) is adapted to add the auto-correlation results of said second auto-correlation means (52, 53, 54, 55) to determine a fine frame timing.

20. A receiver according to claim 11wherein at least one analog-to-digital converter (15, 16) is placed before said first (42, 43, 44, 45) and second auto-correlating means (52, 53, 54, 55).

21. A mobile terminal of a wireless communication system comprising a receiver according to claim 11.

22. A synchronization method for a receiver in a wireless communication system, comprising the steps of receiving a preamble signal (26) that comprises a long PN sequence (33) being a combination a plurality of short PN sequences (29, 30, 31,32),extracting at least one of said short PN sequence (29, 30, 31,32) from said long PN sequence (33) for coarse timing synchronization,performing a coarse timing synchronization using said extracted short PN sequence (PN1), andperforming a fine timing synchronization using said long PN sequence (33).

23. A method according to claim 22, comprising receiving a long PN sequence (33) having the following binary sequence: Slong={c1 c2 . . . cM*N}, with M and N being integers greater than 1,extracting the following M short PN sequences (29, 30, 31,32) of length N from said long PN sequence (33): Sshort,1={c1cM+1 . . . cM*(N−1)+1},Sshort,2={c2cM+2 . . . cM*(N−1)+2},. . . ,Sshort,M={cMcM*2 . . . cM*N},

24. A method according to claim 23, wherein the short PN sequence Sshort,1 is used for coarse timing synchronization.

25. A method according to claim 22, comprising receiving a binary data stream,demultiplexing (41) said binary data stream into M parallel binary data streams,correlating (42, 43, 44, 45) in parallel said short PN sequence for coarse timing synchronization with each parallel binary data stream,comparing the correlation results with a predefined threshold to determine a coarse frame timing.

26. A method according to claim 22, comprising receiving a binary data stream,demultiplexing (41) said binary data stream into M parallel binary data streams,multiplexing (51) said parallel binary data streams according to the length N of a short PN sequence,correlating (53) said short PN sequence for coarse timing synchronization with the multiplexed binary data stream,comparing the correlation result with a predefined threshold to determine a coarse frame timing.

27. A method according to claim 22, receiving a binary data stream,demultiplexing (41) said binary data stream into M parallel binary data streams,correlating (52, 53, 54, 55) in parallel each short PN sequence with a different parallel binary data stream,adding (58) the M correlation values to determine a fine frame timing.