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 method of searching for a cell in a mobile station, 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 the first short sequence.   
     
     
       2. The method of  claim 1 , wherein the first short sequence scrambled with the first scrambling sequence and 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 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 secondary synchronization signal is located on a symbol right ahead of the last symbol of the slot.   
     
     
       5. The method of  claim 1 , 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, and   wherein the third scrambling sequence is determined based on the second short sequence.   
     
     
       6. The method of  claim 5 , wherein the second short sequence scrambled with the first scrambling sequence and the first short 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 method of generating a down link frame in a base station, 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 the first short sequence.   
     
     
       22. The method of  claim 21 , wherein the first short sequence scrambled with the first scrambling sequence and 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 secondary synchronization signal is located on a symbol right ahead of 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, 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 third scrambling sequence is determined based on the second short sequence.   
     
     
       26. The method of  claim 25 , wherein the second short sequence scrambled with the first scrambling sequence and the first short sequence scrambled with the third scrambling 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. A communication method, comprising:
 receiving a first primary synchronization signal;   receiving a first secondary synchronization signal;   receiving a second primary synchronization signal;   receiving a second secondary synchronization signal;   determining a first identity based on the first secondary synchronization signal;   determining a second identity based on the first primary synchronization signal; and   determining a cell identifier based on the first identity and the second identity,   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 second identity, and the second scrambling sequence is determined based on the first identity, and   wherein the first primary synchronization signal, the first secondary synchronization signal, the second primary synchronization signal, and the second secondary synchronization signal are received in a frame,   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.   
     
     
       42. The method of claim 41, wherein the frame comprises a plurality of subframes, the first primary synchronization signal is received in a first subframe, the first subframe includes a first plurality of slots, each slot having a first plurality of symbols, and
 wherein the first primary synchronization signal is received on a last symbol of a first slot among the first plurality of slots.   
     
     
       43. The method of claim 42, wherein the second secondary synchronization signal is received in a second subframe, the second subframe includes a second plurality of slots, each slot having a second plurality of symbols, and
 wherein the second secondary synchronization signal is received on a symbol immediately preceding a last symbol of a second slot among the second plurality of slots.   
     
     
       44. The method of claim 43, wherein the second secondary synchronization signal is received through a first number of sub-carriers of the symbol immediately preceding the last symbol of the second slot, and elements of the fifth sequence and elements of the sixth sequence are alternately disposed on the first number of sub-carriers. 
     
     
       45. The method of claim 43, wherein the first subframe is same as the second subframe. 
     
     
       46. The method of claim 41, wherein the first primary synchronization signal is identical to the second primary synchronization signal, the first scrambling sequence is different from the second scrambling sequence, and the first scrambling sequence is different from the third scrambling sequence. 
     
     
       47. The method of claim 46, wherein the first secondary synchronization signal is received on a first slot, and the second secondary synchronization signal is received on a second slot different from the first slot. 
     
     
       48. A communication method, comprising:
 generating a first secondary synchronization signal based on a first identity;   generating a first primary synchronization signal based on a second identity;   transmitting the first primary synchronization signal;   transmitting the first secondary synchronization signal;   generating a second secondary synchronization signal based on the first identity;   generating a second primary synchronization signal based on the second identity;   transmitting the second primary synchronization signal; and   transmitting the second 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 second identity, and the second scrambling sequence is determined based on the first identity,   wherein the first primary synchronization signal, the first secondary synchronization signal, the second primary synchronization signal, and the second secondary synchronization signal are transmitted in a frame, and   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.   
     
     
       49. The method of claim 48, wherein the frame comprises a plurality of subframes, the first primary synchronization signal is transmitted in a first subframe, the first subframe includes a first plurality of slots, each slot having a first plurality of symbols, and
 wherein the first primary synchronization signal is transmitted on a last symbol of a first slot among the first plurality of slots.   
     
     
       50. The method of claim 49, wherein the second secondary synchronization signal is transmitted in a second subframe, the second subframe includes a second plurality of slots, each slot having a second plurality of symbols, and
 wherein the second secondary synchronization signal is transmitted on a symbol immediately preceding a last symbol of a second slot among the second plurality of slots.   
     
     
       51. The method of claim 50, wherein the second secondary synchronization signal is received through a first number of sub-carriers of the symbol immediately preceding the last symbol of the second slot, and elements of the fifth sequence and elements of the sixth sequence are alternately disposed on the first number of sub-carriers. 
     
     
       52. The method of claim 50, wherein the first subframe is same as the second subframe. 
     
     
       53. The method of claim 48, wherein the first primary synchronization signal is identical to the second primary synchronization signal, the first scrambling sequence is different from the second scrambling sequence, and the first scrambling sequence is different from the third scrambling sequence. 
     
     
       54. The method of claim 53, wherein the first secondary synchronization signal is transmitted on a first slot, and the second secondary synchronization signal is transmitted on a second slot different from the first slot. 
     
     
       55. A terminal, comprising:
 a circuitry which is configured to:
 cause the terminal to receive a first primary synchronization signal; 
 cause the terminal to receive a first secondary synchronization signal; 
 cause the terminal to receive a second primary synchronization signal; 
 cause the terminal to receive a second secondary synchronization signal; 
 cause the terminal to determine a first identity based on the first secondary synchronization signal; 
 cause the terminal to determine a second identity based on the first primary synchronization signal; and 
 cause the terminal to determine a cell identifier based on the first identity and the second identity, 
   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 second identity, and the second scrambling sequence is determined based on the first identity,   wherein the first primary synchronization signal, the first secondary synchronization signal, the second primary synchronization signal, and the second synchronization signal are received in a frame, and   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.   
     
     
       56. The terminal of claim 55, wherein the frame comprises a plurality of subframes, the first primary synchronization signal is received in a first subframe, the first subframe includes a first plurality of slots, each slot having a first plurality of symbols, and
 wherein the first primary synchronization signal is received on a last symbol of a first slot among the first plurality of slots.   
     
     
       57. The terminal of claim 56, wherein the second secondary synchronization signal is received in a second subframe, the second subframe includes a second plurality of slots, each slot having a second plurality of symbols, and
 wherein the second secondary synchronization signal is received on a symbol immediately preceding a last symbol of a second slot among the second plurality of slots.   
     
     
       58. The terminal of claim 57, wherein the second secondary synchronization signal is received through a first number of sub-carriers of the symbol immediately preceding the last symbol of the second slot, and elements of the fifth sequence and elements of the sixth sequence are alternately disposed on the first number of sub-carriers. 
     
     
       59. The terminal of claim 57, wherein the first subframe is same as the second subframe. 
     
     
       60. The terminal of claim 55, wherein the first primary synchronization signal is identical to the second primary synchronization signal, the first scrambling sequence is different from the second scrambling sequence, and the first scrambling sequence is different from the third scrambling sequence. 
     
     
       61. The terminal of claim 60, wherein the first secondary synchronization signal is received on a first slot, and the second secondary synchronization signal is received on a second slot different from the first slot. 
     
     
       62. A communication device for a terminal, the communication device comprising:
 a circuitry which is configured to:
 cause the terminal to receive a first primary synchronization signal; 
 cause the terminal to receive a first secondary synchronization signal; 
 cause the terminal to receive a second primary synchronization signal; 
 cause the terminal to receive a second secondary synchronization signal; 
 cause the terminal to determine a first identity based on the first secondary synchronization signal; 
 cause the terminal to determine a second identity based on the first primary synchronization signal; and 
 cause the terminal to determine a cell identifier based on the first identity and the second identity, 
   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 second identity, and the second scrambling sequence is determined based on the first identity,   wherein the first primary synchronization signal, the first secondary synchronization signal, the second primary synchronization signal, and the second synchronization signal are received in a frame, and   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.   
     
     
       63. The communication device of claim 62, wherein the frame comprises a plurality of subframes, the first primary synchronization signal is received in a first subframe, the first subframe includes a first plurality of slots, each slot having a first plurality of symbols, and
 wherein the first primary synchronization signal is received on a last symbol of a first slot among the first plurality of slots.   
     
     
       64. The communication device of claim 63, wherein the second secondary synchronization signal is received in a second subframe, the second subframe includes a second plurality of slots, each slot having a second plurality of symbols, and
 wherein the second secondary synchronization signal is received on a symbol immediately preceding a last symbol of a second slot among the second plurality of slots.   
     
     
       65. The communication device of claim 64, wherein the second secondary synchronization signal is received through a first number of sub-carriers of the symbol immediately preceding the last symbol of the second slot, and elements of the fifth sequence and elements of the sixth sequence are alternately disposed on the first number of sub-carriers. 
     
     
       66. The communication device of claim 64, wherein the first subframe is same as the second subframe. 
     
     
       67. The communication device of claim 62, wherein the first primary synchronization signal is identical to the second primary synchronization signal, the first scrambling sequence is different from the second scrambling sequence, and the first scrambling sequence is different from the third scrambling sequence. 
     
     
       68. The terminal of claim 67, wherein the first secondary synchronization signal is received on a first slot, and the second secondary synchronization signal is received on a second slot different from the first slot. 
     
     
       69. A communication apparatus, comprising:
 a circuitry configured to:
 cause the communication apparatus to generate a first secondary synchronization signal based on a first identity; 
 cause the communication apparatus to generate a first primary synchronization signal based on a second identity; 
 cause the communication apparatus to transmit the first primary synchronization signal; 
 cause the communication apparatus to transmit the first secondary synchronization signal; 
 cause the communication apparatus to generate a second secondary synchronization signal based on the first identity; 
 cause the communication apparatus to generate a second primary synchronization signal based on the second identity; 
 cause the communication apparatus to transmit the second primary synchronization signal; and 
 cause the communication apparatus to transmit the second 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 second identity, and the second scrambling sequence is determined based on the first identity,   wherein the first primary synchronization signal, the first secondary synchronization signal, the second primary synchronization signal, and the second secondary synchronization signal are transmitted in a frame, and   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.   
     
     
       70. The communication apparatus of claim 69, wherein the frame comprises a plurality of subframes, the first primary synchronization signal is transmitted in a first subframe, the first subframe includes a first plurality of slots, each slot having a first plurality of symbols, and
 wherein the first primary synchronization signal is transmitted on a last symbol of a first slot among the first plurality of slots.   
     
     
       71. The communication apparatus of claim 70, wherein the second secondary synchronization signal is transmitted in a second subframe, the second subframe includes a second plurality of slots, each slot having a second plurality of symbols, and
 wherein the second secondary synchronization signal is transmitted on a symbol immediately preceding a last symbol of a second slot among the second plurality of slots.   
     
     
       72. The communication apparatus of claim 71, wherein the second secondary synchronization signal is received through a first number of sub-carriers of the symbol immediately preceding the last symbol of the second slot, and elements of the fifth sequence and elements of the sixth sequence are alternately disposed on the first number of sub-carriers. 
     
     
       73. The communication apparatus of claim 71, wherein the first frame is same as the second frame. 
     
     
       74. The communication apparatus of claim 69, wherein the first primary synchronization signal is identical to the second primary synchronization signal, the first scrambling sequence is different from the second scrambling sequence, and the first scrambling sequence is different from the third scrambling sequence. 
     
     
       75. The communication apparatus of claim 74, wherein the first secondary synchronization signal is transmitted on a first slot, and the second secondary synchronization signal is transmitted on a second slot different from the first slot.