METHOD OF SEARCHING CODE SEQUENCE IN MOBILE COMMUNICATION SYSTEM

• US 20090170508A1
• Filed: 02/26/2007
• Published: 07/02/2009
• Est. Priority Date: 02/24/2006
• Status: Active Grant

• Current Assignee: LG Electronics, Inc. (LG Corporation)
• Original Assignee: LG Electronics, Inc. (LG Corporation)
• Inventors: Noh, Min Seok, Han, Seung Hee, Kwon, Yeong Hyeon
• Granted Patent: US 8,483,036 B2
• Time in Patent Office: Days
• US Class Current: 455/434
• CPC Class Codes: H04J 11/0069 Cell search, i.e. determining cell identity [cell-ID] design of multiplexing codes H04J13/00; processing access restriction or access information H04W48/16; discovery of network devices for network data management H04W8/005; sounding signals for channel estimation H04L25/0226; structure of reference signals in multicarrier modulation systems H04L27/2613; frame, time or carrier synchronisation in multicarrier modulation systems H04L27/2655
• CPC Class Codes: H04J 13/0055 ZCZ [zero correlation zone]
• CPC Class Codes: H04J 13/16 Code allocation
• CPC Class Codes: H04J 3/06 Synchronising arrangements for television systems H04N5/04; bit-synchronisation H04L7/00
• CPC Class Codes: H04J 3/0605 Special codes used as synchronising signal
• CPC Class Codes: H04J 3/0611 PN codes H04J3/0608 takes precedence
• CPC Class Codes: H04L 5/0003 Two-dimensional division time-code division H04J11/00, H04J13/00; for time-space division H04B7/0413, H04B7/0697
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04L 5/005 of common pilots, i.e. pilots destined for multiple users or terminals
• CPC Class Codes: H04W 48/16 Discovering, processing access restriction or access information
• CPC Class Codes: H04W 56/001 Synchronization between nodes
• CPC Class Codes: H04W 88/08 Access point devices

Abstract

The present invention relates to a method of searching a code sequence in a cell based mobile communication system, by which a receiving side is able to code sequence detection efficiently. In a code sequence transmitting method for an efficient code sequence search in a mobile communication system, the code sequence transmitting method includes a step of boosting at least one tone for a code sequence and a step of transmitting the code sequence having the boosted at least one tone to a receiving side.

Claims

1. A method of transmitting a code sequence for an efficient code sequence search in a mobile communication system, the method comprising:

boosting at least one tone for a code sequence; and

transmitting the code sequence having the boosted at least one tone to a receiving side.

2. The method of claim 1, the at least one tone boosting step comprising:

increasing an amplitude of a code element corresponding to the at least one tone in the code sequence; and

modulating the code sequence through a plurality of sub-carriers.

3. The method of claim 2, wherein the amplitude of the code element is increased in a manner of boosting the at least one tone while an overall power allocated to the code sequence is uniformly maintained.

4. The method of claim 1, wherein a specific one of the at least one tone has a prescribed relation with code identification information for identifying the code sequence in a code sequence set including the code sequence.

5. The method of claim 4, wherein if an index of the code sequence is L, the specific tone is an L^th tone.

6. The method of claim 1, wherein the code sequence is a CAZAC sequence.

7. A method of transmitting a code sequence for an efficient code sequence search in a mobile communication system, the method comprising:

shifting a phase of a code element corresponding to at least one tone for a code sequence;

modulating the code sequence through a plurality of sub-carriers; and

transmitting the code sequence to a receiving side.

8. A method of receiving a code sequence for an efficient code sequence search in a mobile communication system, the method comprising:

receiving signals for a code sequence having a tone boosted by a transmitting side; and

obtaining prescribed information previously agreed between the transmitting side and a receiving side from at least one of identification information for the code sequence and identification information for the boosted tone of the code sequence.

9. A method of receiving a code sequence for an efficient code sequence search in a mobile communication system, the method comprising:

receiving signals for a code sequence having at least two tones boosted by a transmitting side; and

obtaining prescribed information previously agreed between the transmitting side and a receiving side from at least one of identification information for the code sequence and a combination of identification information for the boosted at least two tones of the code sequence.

10. A method of signal processing for an efficient code sequence search in a mobile communication system, the method comprising:

increasing an amplitude of a code element of a code sequence for cell search; and

modulating the code sequence through a plurality of sub-carriers.

11. The method of claim 10, wherein amplitudes of other code elements except the code element are adjusted to uniformly maintain a total power allocated to the code sequence.

12. A method of transmitting a code sequence for cell search in a cell based mobile communication system, the method comprising:

transmitting a first code sequence for identifying a cell group including at least one cell to a receiving side; and

transmitting a second code sequence for identifying a specific cell included in the cell group identified by the first code sequence to the receiving side,

wherein a specific tone of at least one of the first and second code sequences is boosted to be transmitted.

13. A method of cell search in a cell based mobile communication system, comprising:

receiving signals for a code sequence of which a tone is boosted, the signals transmitted from a transmitting side;

obtaining code identification information for identifying the code sequence from element identification information for identifying a code element corresponding to the boosted tone; and

identifying a cell using the code identification information.

14. The method of claim 13, wherein the element identification information has a prescribed relation with the code identification information.

15. A method of cell search in a cell based mobile communication system, comprising:

receiving signals for a code sequence having a tone boosted by a transmitting side;

obtaining a cell group identifier for identifying a cell group including at least one cell from element identification information for identifying a code element corresponding to the boosted tone; and

identifying a cell included within the cell group using the code sequence.

16. A method of cell search in a cell based mobile communication system, comprising:

obtaining a cell group identifier for identifying a cell group including at least one cell using a first code sequence transmitted from a transmitting side; and

obtaining a cell identifier for identifying a cell included in the cell group identified by the cell group identifier using a second code sequence transmitted from the transmitting side,

wherein the transmitting side boosts a specific tone of at least one of the first and second sequences.

17. A transmitter for a mobile communication system, comprising:

means for adjusting an amplitude of a code element for boosting a specific tone in a specific code sequence; and

means for converting the code sequence into time domain signals.

18. A method of transmitting signals for cell search in a cell based mobile communication system, the method comprising:

configuring a preamble by combining at least one code sequence selected from a first code set and at least one code sequence selected from a second code set together, the preamble transmitted ahead of transmission of control signals and data signals; and

transmitting the configured preamble.

19. The method of claim 18, wherein a weight is given to each of the selected code sequences to transmit.

20. The method of claim 18, wherein the first code set is a CAZAC (constant modulus and zero autocorrelation) sequence.

21. The method of claim 18, wherein the second code set is a single tone sequence.

22. The method of claim 18, wherein the combination of the selected sequences is performed using

$s_k$

( n ) = ∑

j = 1 P 

w j 

c j k 

( n )

(s_k is a preamble code corresponding to a k^th cell, w_j is a weight for each code set, c_j^k is a k^th code in a j^th code set, and each element of the c_j^k is represented as c_j^k(n)).

23. A method of cell search in a cell based mobile communication system, the method comprising:

receiving a preamble including a combination of code sequences selected from at least two code sets, respectively; and

performing cell search by using characteristics of the code sequences configuring the combination.

24. The method of claim 23, wherein the selected code sequences comprise the code sequences transmitted by having a prescribed weight applied thereto.

25. The method of claim 23, wherein the preamble includes a first code sequence and a second code sequence selected from two code sets.

26. The cell detecting method of claim 25, wherein the two code sets include a CAZAC (constant modulus and zero autocorrelation) sequence and a single tone sequence.

27. The method of claim 26, the cell search performing step comprising:

detecting a code index corresponding to a peak of a correlation value for the first code sequence;

detecting indexes of code sequences corresponding to a periphery of the peak on a frequency axis;

calculating a correlation value for the second code sequence corresponding to the code index corresponding to the peak and the code index corresponding to the peak periphery; and

performing the cell search by using the correlation value for the first code sequence and the correlation value for the second code sequence.

28. The method of claim 27, the cell search performing step comprising:

calculating a maximum value by multiplying the correlation value for the first code sequence by the correlation value for the second code sequence corresponding to the first code sequence according to the code indexes;

selecting the code index corresponding to the maximum value; and

detecting a cell corresponding to the selected code index.