Generating downlink frame and searching for cell

Abstract

The present invention relates to a method for generating a downlink frame including generating a first short sequence and a second short sequence indicating cell group information, generating a first scrambling sequence determined by the first synchronization signal, generating a second scrambling sequence determined by the first short sequence, scrambling the first short sequence with the first scrambling sequence, scrambling the second short sequence with at least the second scrambling sequence, and mapping a second synchronization signal including the scrambled first short sequence and the scrambled second short sequence in the frequency domain.

What is claimed is: 
     
       1. A communication method of searching for a cell in a mobile station, comprising:
 receiving a downlink frame including a primary synchronization signal and; 
 receiving a first secondary synchronization signal, wherein the secondary synchronization signal contains cell identity group information and the primary synchronization signal contains cell identity information within a cell identity group; and 
 searching for a cell using the cell identity group information in the secondary synchronization signal and the cell identity information in the primary synchronization signaldetermining a cell identifier based on the primary synchronization signal and the first secondary synchronization signal, 
 wherein the first secondary synchronization signal comprises a first short sequence and a second short sequence, the first short first sequence comprises a third sequence is scrambled with a first scrambling sequence, and the second short sequence comprises a fourth sequence is scrambled with a second scrambling sequence, 
 wherein the first scrambling sequence is determined based on the cell identity information contained in the primary synchronization signal primary synchronization signal, and the second scrambling sequence is determined based on the first short third sequence. 
 
     
     
       2. The method of  claim 1 , wherein elements of the first short sequence scrambled with the first scrambling sequence and elements of the second short sequence scrambled with the second scrambling sequence are alternately disposed on a plurality of sub-carriers. 
     
     
       3. The method of  claim 1 , wherein the first scrambling sequence is different from the second scrambling sequence. 
     
     
       4. The method of  claim 1 , wherein the primary synchronization signal and the first secondary synchronization signal belong to a downlink frame, the downlink frame includes a plurality of slots, each slot having a plurality of symbols, wherein the primary synchronization signal is located on a last symbol of a slot, and the first secondary synchronization signal is located on a symbol right ahead of immediately preceding the last symbol of the slot. 
     
     
       5. The method of  claim 1 , wherein the primary synchronization signal and the first secondary synchronization signal belong to a downlink frame, the downlink frame comprises a second secondary synchronization signal containing the cell identity group information, wherein the second secondary synchronization signal comprises the first short sequence and the second short sequence a fifth sequence and a sixth sequence, the second short sequence is the fifth sequence comprises the fourth sequence scrambled with the first scrambling sequence, and the first short sixth sequence comprises the third sequence is scrambled with a third scrambling sequence, and
 wherein the third scrambling sequence is determined based on the second short fourth sequence. 
 
     
     
       6. The method of  claim 5 , wherein elements of the second short fifth sequence scrambled with the first scrambling sequence and elements of the first short sixth sequence scrambled with the third scrambling sequence are alternately disposed on a plurality of sub-carriers. 
     
     
       7. The method of  claim 5 , further comprising:
 identifying the cell identity group using at least one of the first secondary synchronization signal and the second secondary synchronization signal.   
     
     
       8. The method of  claim 5 , wherein the second secondary synchronization signal is different from the first secondary synchronization signal. 
     
     
       9. A method of searching for a cell by a mobile station in a wireless communication system, wherein the wireless communication system uses a plurality of short sequences grouped into a plurality of short sequence groups, the method comprising:
 receiving a downlink frame including a primary synchronization signal and a secondary synchronization signal, wherein the secondary synchronization signal contains cell identity group information and the primary synchronization signal contains cell identity information within a cell identity group; and   searching for a cell using the cell identity group information in the secondary synchronization signal and the cell identity information in the primary synchronization signal,   wherein the secondary synchronization signal comprises a first short sequence and a second short sequence, the first short sequence is scrambled with a first scrambling sequence, and the second short sequence is scrambled with a second scrambling sequence,   wherein the first scrambling sequence is determined based on the cell identity information contained in the primary synchronization signal, and the second scrambling sequence is determined based on a short sequence group to which the first short sequence is assigned and is determined based on a remainder of dividing an index of the first short sequence by 8.   
     
     
       10. The method of  claim 9 , wherein the wireless communication system has 31 short sequences, and the index of the first short sequence has one value among 0 to 30. 
     
     
       11. The method of  claim 10 , wherein short sequences within the short sequence group have the same remainder. 
     
     
       12. The method of  claim 9 , wherein the downlink frame comprises a second secondary synchronization signal containing the cell identity group information,
 wherein the second secondary synchronization signal comprises the first short sequence and the second short sequence, the second short sequence is scrambled with the first scrambling sequence, and the first short sequence is scrambled with a third scrambling sequence,   wherein the third scrambling sequence is determined based on a short sequence group to which the second short sequence is assigned and is determined based on a remainder of diving an index of the second short sequence by 8.   
     
     
       13. The method of  claim 12 , wherein the wireless communication system has 31 short sequences, and the index of the second short sequence has one value among 0 to 30. 
     
     
       14. The method of  claim 13 , wherein short sequences within the short sequence group have the same remainder. 
     
     
       15. A method of searching for a cell by a mobile station in a wireless communication system, the method comprising:
 receiving a downlink frame including a primary synchronization signal, a first secondary synchronization signal and a second secondary synchronization signal, wherein each of the first and second secondary synchronization signals contains cell identity group information and the primary synchronization signal contains cell identity information within a cell identity group; and   searching for a cell using the cell identity group information and the cell identity information, the cell identity group information being identified using at least one of the first secondary synchronization signal and the second secondary synchronization signal, and the cell identity information being identified using the primary synchronization signal,   wherein the first secondary synchronization signal comprises a first short sequence and a second short sequence, the first short sequence is scrambled with a first scrambling sequence, and the second short sequence is scrambled with a second scrambling sequence, and   the second secondary synchronization signal comprises the first short sequence and the second short sequence, the second short sequence is scrambled with the first scrambling sequence, and the first short sequence is scrambled with a third scrambling sequence, and   wherein the first scrambling sequence is determined based on the cell identity information contained in the primary synchronization signal, the second scrambling sequence is determined based on a remainder of dividing an index of the first short sequence by 8, and the third scrambling sequence is determined based on a remainder of dividing an index of the second short sequence by 8.   
     
     
       16. The method of  claim 15 , wherein the first short sequence scrambled with the first scrambling sequence and the second short sequence scrambled with the second scrambling sequence in the first secondary synchronization signal are alternately disposed on a plurality of sub-carriers, and the second short sequence scrambled with the first scrambling sequence and the first short sequence scrambled with the third scrambling sequence in the second secondary synchronization signal are alternately disposed on a plurality of sub-carriers. 
     
     
       17. The method of  claim 15 , wherein the first scrambling sequence is different from the second scrambling sequence. 
     
     
       18. The method of  claim 15 , wherein the downlink frame includes a plurality of slots, each slot having a plurality of symbols,
 wherein the primary synchronization signal is located on a last symbol of a first slot and the first secondary synchronization signal is located on a symbol right ahead of the last symbol of the first slot, and   the primary synchronization signal is located on a last symbol of a second slot and the second secondary synchronization signal is located on a symbol right ahead of the last symbol of the second slot.   
     
     
       19. The method of  claim 15 , wherein the second secondary synchronization signal is different from the first secondary synchronization signal. 
     
     
       20. The method of  claim 15 , wherein the wireless communication system has 31 short sequences, and
 the index of the first short sequence has one value among 0 to 30, and the index of the second short sequence has one value among 0 to 30.   
     
     
       21. A communication method of generating a down link frame in a base station, comprising:
 generating a primary synchronization signal based on a first part of a cell identifier;  
 including cell identity group information ingenerating a first secondary synchronization signal and including cell identity information within a cell identity group in a primary synchronization signal so that a terminal searches for a cell using the cell identity group information in the secondary synchronization signal and the cell identity information in the primary synchronization signalbased on a second part of the cell identifier; and 
 generating a downlink frame including comprising the primary synchronization signal and the first secondary synchronization signal; and 
 transmitting the downlink frame, 
 wherein the first secondary synchronization signal comprises a first short sequence and a second short sequence, the first short sequence comprises a third sequence is scrambled with a first scrambling sequence, and the second short sequence comprises a fourth sequence is scrambled with a second scrambling sequence, 
 wherein the first scrambling sequence is determined based on the cell identity information contained in the primary synchronization signal first part of the cell identifier, and the second scrambling sequence is determined based on the first short sequence second part of the cell identifier. 
 
     
     
       22. The method of  claim 21 , wherein elements of the first short sequence scrambled with the first scrambling sequence and elements of the second short sequence scrambled with the second scrambling sequence are alternately disposed on a plurality of sub-carriers. 
     
     
       23. The method of  claim 21 , wherein the first scrambling sequence is different from the second scrambling sequence. 
     
     
       24. The method of  claim 21 , wherein the downlink frame includes a plurality of slots, each slot having a plurality of symbols, wherein the primary synchronization signal is located on a last symbol of a slot, and the first secondary synchronization signal is located on a symbol right ahead of immediately preceding the last symbol of the slot. 
     
     
       25. The method of  claim 21 , wherein the downlink frame comprises a second secondary synchronization signal containing the cell identity group information, wherein the second secondary synchronization signal comprises the first short sequence and the second short sequence a fifth sequence and a sixth sequence, the second short sequence is the fifth sequence comprises the fourth sequence scrambled with the first scrambling sequence, and the first short sequence is the sixth sequence comprises the third sequence scrambled with a third scrambling sequence, and
 wherein the third scrambling sequence is determined based on the second short fourth sequence. 
 
     
     
       26. The method of  claim 25 , wherein the second short  elements of the fifth sequence scrambled with the first scrambling sequence and the first short sequence scrambled with the third scrambling sequence elements of the sixth sequence are alternately disposed on a plurality of sub-carriers. 
     
     
       27. The method of  claim 25 , wherein the cell identity group is identified using at least one of the first secondary synchronization signal and the second secondary synchronization signal. 
     
     
       28. The method of  claim 25 , wherein the second secondary synchronization signal is different from the first secondary synchronization signal. 
     
     
       29. A method of generating a downlink frame in a wireless communication system, wherein the wireless communication system uses a plurality of short sequences grouped into a plurality of short sequence groups, the method comprising:
 including cell identity group information in a secondary synchronization signal and including cell identity information within a cell identity group in a primary synchronization signal so that a terminal searches for a cell using the cell identity group information in the secondary synchronization signal and the cell identity information in the primary synchronization signal; and   generating a downlink frame including the primary synchronization signal and the secondary synchronization signal,   wherein the secondary synchronization signal comprises a first short sequence and a second short sequence, the first short sequence is scrambled with a first scrambling sequence, and the second short sequence is scrambled with a second scrambling sequence,   wherein the first scrambling sequence is determined based on the cell identity information contained in the primary synchronization signal, and the second scrambling sequence is determined based on a short sequence group to which the first short sequence is assigned and is determined based on a remainder of dividing an index of the first short sequence by 8.   
     
     
       30. The method of  claim 29 , wherein the wireless communication system has 31 short sequences, and the index of the first short sequence has one value among 0 to 30.  
     
     
       31. The method of  claim 30 , wherein short sequences within the short sequence group have the same remainder. 
     
     
       32. The method of  claim 29 , wherein the downlink frame comprises a second secondary synchronization signal containing the cell identity group information,
 wherein the second secondary synchronization signal comprises the first short sequence and the second short sequence, the second short sequence is scrambled with the first scrambling sequence, and the first short sequence is scrambled with a third scrambling sequence,   wherein the third scrambling sequence is determined based on a short sequence group to which the second short sequence is assigned and is determined base on a remainder of diving an index of the second short sequence by 8.   
     
     
       33. The method of  claim 32 , wherein the wireless communication system has 31 short sequences, and the index of the second short sequence has one value among 0 to 30. 
     
     
       34. The method of  claim 33 , wherein short sequences within the short sequence group have the same remainder. 
     
     
       35. A method of generating a downlink frame in a wireless communication system, the method comprising:
 including cell identity group information in each of first and second secondary synchronization signals and including cell identity information within a cell identity group in a primary synchronization signal so that a terminal searches for a cell using the cell identity group information and the cell identity information; and   generating a downlink frame including the primary synchronization signal, the first secondary synchronization signal and the second secondary synchronization signal; and   wherein the cell identity group information is identified using at least one of the first secondary synchronization signal and the second secondary synchronization signal, and the cell identity information is identified using the primary synchronization signal,   wherein the first secondary synchronization signal comprises a first short sequence and a second short sequence, the first short sequence is scrambled with a first scrambling sequence, and the second short sequence is scrambled with a second scrambling sequence,   wherein the second secondary synchronization signal comprises the first short sequence and the second short sequence, the second short sequence is scrambled with the first scrambling sequence, and the first short sequence is scrambled with a third scrambling sequence, and   wherein the first scrambling sequence is determined based on the cell identity information contained in the primary synchronization signal, the second scrambling sequence is determined based on a remainder of dividing an index of the first short sequence by 8, and the third scrambling sequence is determined based on a remainder of dividing an index of the second short sequence by 8.   
     
     
       36. The method of  claim 35 , wherein the first short sequence scrambled with the first scrambling sequence and the second short sequence scrambled with the second scrambling sequence in the first secondary synchronization signal are alternately disposed on a plurality of sub-carriers, and the second short sequence scrambled with the first scrambling sequence and the first short sequence scrambled with the third scrambling sequence in the second secondary synchronization signal are alternately disposed on a plurality of sub-carriers. 
     
     
       37. The method of  claim 35 , wherein the first scrambling sequence is different from the second scrambling sequence. 
     
     
       38. The method of  claim 35 , wherein the downlink frame includes a plurality of slots, each slot having a plurality of symbols,
 wherein the primary synchronization signal is located on a last symbol of a first slot and the first secondary synchronization signal is located on a symbol right ahead of the last symbol of the first slot, and   the primary synchronization signal is located on a last symbol of a second slot and the second secondary synchronization signal is located on a symbol right ahead of the last symbol of the second slot.   
     
     
       39. The method of  claim 35 , wherein the second secondary synchronization signal is different from the first secondary synchronization signal. 
     
     
       40. The method of  claim 35 , wherein the wireless communication system has 31 short sequences, and
 the index of the first short sequence has one value among 0 to 30, and the index of the second short sequence has one value among 0 to 30.    
     
     
       41. The communication method of claim 1, wherein the first secondary synchronization signal comprises information on a cell identity group and the primary synchronization signal comprises information on a cell identity within the cell identity group. 
     
     
       42. The communication method of claim 21, wherein the first secondary synchronization signal comprises information on the second part of the cell identifier and the primary synchronization signal comprises information on the first part of the cell identifier. 
     
     
       43. A communication device, comprising:
 a memory; and   a processor operably coupled to the memory,   wherein the processor, when executing program instructions stored in the memory, is configured to:   cause the communication device to receive a primary synchronization signal;   cause the communication device to receive a first secondary synchronization signal; and   determine a cell identifier based on the primary synchronization signal and the first secondary synchronization signal,   wherein the first secondary synchronization signal comprises a first sequence and a second sequence, the first sequence comprises a third sequence scrambled with a first scrambling sequence, and the second sequence comprises a fourth sequence scrambled with a second scrambling sequence,   wherein the first scrambling sequence is determined based on the primary synchronization signal, and the second scrambling sequence is determined based on the third sequence.   
     
     
       44. The communication device of claim 43, wherein elements of the first sequence and elements of the second sequence are alternately disposed on a plurality of sub-carriers. 
     
     
       45. The communication device of claim 43, wherein the first scrambling sequence is different from the second scrambling sequence. 
     
     
       46. The communication device of claim 43, wherein the primary synchronization signal and the first secondary synchronization signal belong to a downlink frame, the downlink frame includes a plurality of slots, each slot having a plurality of symbols, wherein the primary synchronization signal is located on a last symbol of a slot, and the first secondary synchronization signal is located on a symbol immediately preceding the last symbol of the slot. 
     
     
       47. The communication device of claim 43, wherein the primary synchronization signal and the first secondary synchronization signal belong to a downlink frame, the downlink frame comprises a second secondary synchronization signal, wherein the second secondary synchronization signal comprises a fifth sequence and a sixth sequence, the fifth sequence comprises the fourth sequence scrambled with the first scrambling sequence, and the sixth sequence comprises the third sequence scrambled with a third scrambling sequence, and
 wherein the third scrambling sequence is determined based on the fourth sequence.   
     
     
       48. The communication device of claim 47, wherein elements of the fifth sequence and elements of the sixth sequence are alternately disposed on a plurality of sub-carriers. 
     
     
       49. The communication device of claim 47, wherein the second secondary synchronization signal is different from the first secondary synchronization signal. 
     
     
       50. The communication device of claim 43, wherein the first secondary synchronization signal comprises information on a cell identity group and the primary synchronization signal comprises information on a cell identity within the cell identity group. 
     
     
       51. A communication apparatus, comprising:
 a memory; and   a processor operably coupled to the memory,   wherein the processor, when executing program instructions stored in the memory, is configured to:
 cause the communication apparatus to generate a primary synchronization signal based on a first part of a cell identifier; 
 cause the communication apparatus to generate a first secondary synchronization signal based on a second part of the cell identifier; 
 cause the communication apparatus to generate a downlink frame comprising the primary synchronization signal and the first secondary synchronization signal; and 
 cause the communication apparatus to transmit the downlink frame, 
   wherein the first secondary synchronization signal comprises a first sequence and a second sequence, the first sequence comprises a third sequence scrambled with a first scrambling sequence, and the second sequence comprises a fourth sequence scrambled with a second scrambling sequence,   wherein the first scrambling sequence is determined based on the first part of the cell identifier, and the second scrambling sequence is determined based on the second part of the cell identifier.   
     
     
       52. The communication apparatus of claim 51, wherein elements of the first sequence and elements of the second sequence are alternately disposed on a plurality of sub-carriers. 
     
     
       53. The communication apparatus of claim 51, wherein the first scrambling sequence is different from the second scrambling sequence. 
     
     
       54. The communication apparatus of claim 51, wherein the downlink frame includes a plurality of slots, each slot having a plurality of symbols, wherein the primary synchronization signal is located on a last symbol of a slot, and the first secondary synchronization signal is located on a symbol immediately preceding the last symbol of the slot. 
     
     
       55. The communication apparatus of claim 51, wherein the downlink frame comprises a second secondary synchronization signal, wherein the second secondary synchronization signal comprises a fifth sequence and a sixth sequence, the fifth sequence comprises the fourth sequence scrambled with the first scrambling sequence, and the sixth sequence comprises the third sequence scrambled with a third scrambling sequence, and
 wherein the third scrambling sequence is determined based on the fourth sequence.   
     
     
       56. The communication apparatus of claim 55, wherein elements of the fifth sequence and elements of the sixth sequence are alternately disposed on a plurality of sub-carriers. 
     
     
       57. The communication apparatus of claim 55, wherein the second secondary synchronization signal is different from the first secondary synchronization signal. 
     
     
       58. The communication apparatus of claim 51, wherein the first secondary synchronization signal comprises information on the second part of the cell identifier and the primary synchronization signal comprises information on the first part of the cell identifier.