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.
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0. 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.
0. 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.
0. 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.
0. 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.
0. 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.
0. 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.
0. 2. The method of
0. 3. The method of
0. 4. The method of
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.
0. 5. The method of
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.
0. 6. The method of
0. 7. The method of
identifying the cell identity group using at least one of the first secondary synchronization signal and the second secondary synchronization signal.
0. 8. The method of
0. 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.
0. 10. The method of
0. 11. The method of
0. 12. The method of
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.
0. 13. The method of
0. 14. The method of
0. 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.
0. 16. The method of
0. 17. The method of
0. 18. The method of
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.
0. 19. The method of
0. 20. The method of
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.
0. 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.
0. 22. The method of
0. 23. The method of
0. 24. The method of
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.
0. 25. The method of
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.
0. 26. The method of
0. 27. The method of
0. 28. The method of
0. 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.
0. 30. The method of
0. 31. The method of
0. 32. The method of
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.
0. 33. The method of
0. 34. The method of
0. 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.
0. 36. The method of
0. 37. The method of
0. 38. The method of
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.
0. 39. The method of
0. 40. The method of
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.
0. 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.
0. 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.
0. 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.
0. 45. The method of claim 43, wherein the first subframe is same as the second subframe.
0. 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.
0. 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.
0. 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.
0. 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.
0. 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.
0. 52. The method of claim 50, wherein the first subframe is same as the second subframe.
0. 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.
0. 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.
0. 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.
0. 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.
0. 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.
0. 59. The terminal of claim 57, wherein the first subframe is same as the second subframe.
0. 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.
0. 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.
0. 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.
0. 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.
0. 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.
0. 66. The communication device of claim 64, wherein the first subframe is same as the second subframe.
0. 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.
0. 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.
0. 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.
0. 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.
0. 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.
0. 73. The communication apparatus of claim 71, wherein the first frame is same as the second frame.
0. 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.
0. 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.
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Here, k represents an index of the even subcarrier used for the synchronization channel.
The second short sequence (w1) is a sequence allocated to the odd subcarrier of the first (slot 0) secondary synchronization channel and is expressed in Equation 2.
w1=[w1(0),w1(1), . . . ,w1(m), . . . ,w1(30)] [Equation 2]
Here, m represents an index of the odd subcarrier used for the synchronization channel.
The third short sequence (w2) is a sequence allocated to the even subcarrier of the second (slot 10) secondary synchronization channel and is expressed in Equation 3.
w2=[w2(0),w2(1), . . . ,w2(k), . . . ,w2(30)] [Equation 3]
The fourth short sequence (w3) is a sequence allocated to the odd subcarrier of the second (slot 10) secondary synchronization channel and is expressed in Equation 4.
w3=[w3(0),w3(1), . . . ,w3(m), . . . ,w3(30)] [Equation 4]
w0, w1, w2, and w3 may be different sequences from each other, and it may be that w0=w3 and w1=w2, or it may be that w0=w2 and w1=w3. When it is given that w0=w3 and w1=w2, the short sequences of the second secondary synchronization channel can be allocated by using the short sequences allocated to the first synchronization channel, and a terminal only needs to memorize the 170 short sequences allocated to the first secondary synchronization channel and thereby reduce the complexity.
The first method for generating the secondary synchronization signal is to allocate the first short sequence to every even subcarrier of the first secondary synchronization channel and the second short sequence to every odd subcarrier of the first secondary synchronization channel as shown in
According to the first method for generating the secondary synchronization signal, since the secondary synchronization signal is generated by the combination of two short sequences with the length of 31, the number of the secondary synchronization signals becomes 961 which is sufficiently greater than the required number of 170 or 340.
The second method for generating the secondary synchronization signal is to allocate the first sequence determined by Equation 5 to every even subcarrier of the first (slot 0) secondary synchronization channel, and the second sequence determined by Equation 6 to every odd subcarrier of the first (slot 0) secondary synchronization channel, as shown in
A scrambling sequence Pj,1 for scrambling the first short sequence w0 is given as Pj,1=[Pj,1(0), Pj,1(1), . . . Pj,1(k) . . . Pj,1(30)], and j (j=0, 1, 2) is a number of a cell identifying sequence allocated to the primary synchronization channel. Therefore, Pj,1 is determined by the primary synchronization signal. Pj,1 is a known value when the mobile station demaps the sequence in order to know the cell ID group and the frame boundary.
As expressed in Equation 5, respective elements of the first sequence c0 according to the second method for generating the secondary synchronization signal are products of respective elements of the first short sequence w0 and respective corresponding elements of Pj,1.
c0=[w0(0)Pj,1(0),w0(1)Pj,1(1), . . . ,w0(k)Pj,1(k), . . . ,w0(30)Pj,1(30)] [Equation 5]
Here, k is an index of the even subcarrier used for the synchronization channel.
A scrambling sequence Sw0 for scrambling the second short sequence w1 is given as Sw0=[Sw0(0), Sw0(1), . . . , Sw0(m), . . . , Sw0(30)], and Sw0 is determined by the first short sequence (w0).
In this instance, it is possible to determine Sw0 according to the short sequence group to which the first short sequence belongs by combining the short sequences into a group.
For example, since the length of the short sequence is 31 in the exemplary embodiment of the present invention, there are 31 short sequences. Therefore, the 0 to 7 short sequences are set to belong to the group 0, the 8 to 15 short sequences are set to belong to the group 1, the 16 to 23 short sequences are set to belong to the group 2, and the 24 to 30 short sequences are set to belong to the group 3, a scrambling code is mapped on each group, and the scrambling code mapped on the group to which the first short sequence belongs is determined to be Sw0.
It is possible to divide the number of the short sequence by 8, combine the short sequences having the same residuals, and thereby classify the 31 short sequences as 8 groups. That is, the number of the short sequence is divided by 8, the short sequence having the residual 0 is set to belong to the group 0, the short sequence having the residual 1 is set to belong to the group 1, the short sequence having the residual 2 is set to belong to the group 2, the short sequence having the residual 3 is set to belong to the group 3, the short sequence having the residual 4 is set to belong to the group 4, the short sequence having the residual 5 is set to belong to the group 5, the short sequence having the residual 6 is set to belong to the group 6, the short sequence having the residual 7 is set to belong to the group 7, a scrambling code is mapped on each group, and the scrambling code mapped on the group to which the first short sequence belongs is determined to be Sw0.
As expressed in Equation 6, the respective elements of the second sequence c1 according to the second method for generating the secondary synchronization signal are products of the respective elements of the second short sequence w1 and the corresponding respective elements of Sw0.
c1[w1(0)Sw0(0),w1(1)Sw0(1), . . . ,w1(m)Sw0(m), . . . ,w1(30)Sw0(30)] [Equation 6]
Here, m is an index of the odd subcarrier used for the synchronization channel.
The scrambling sequence Pj,2 for scrambling the third short sequence w2 is given as Pj,2=[Pj,2(0), Pj,2(1), . . . Pj,2(k) . . . Pj,2(30)], and j (j=0, 1, 2) is a number of a cell identifying sequence allocated to the primary synchronization channel. Therefore, Pj,2 is determined by the primary synchronization signal. Pj,2 is a known value when the terminal demaps the code in order to know the cell ID group and the frame boundary.
As expressed in Equation 7, the respective elements of the third sequence c2 according to the second method for generating the secondary synchronization signal are products of the respective elements of the third short sequence w2 and the corresponding respective elements of Pj,2.
c2=[w2(0)Pj,2(0),w2(1)Pj,2(1), . . . ,w2(k)Pj,2(k), . . . ,w2(30)Pj,2(30)] [Equation 7]
Here, k is an index of the even subcarrier used for the synchronization channel.
The scrambling sequence Sw2 for scrambling the fourth short sequence is given as Sw2=[Sw2(0), Sw2(1), Sw2(m), . . . Sw2(30)], and Sw2 is determined by the third short sequence w2.
In this instance, it is possible to combine the short sequences into a group and determine Sw2 according to the short sequence group to which the third short sequence belongs.
For example, since the length of the short sequence according to the exemplary embodiment of the present invention is 31, there are 31 short sequences. Therefore, the 0 to 7 short sequences are set to belong to the group 0, the 8 to 15 short sequences are set to belong to the group 1, the 16 to 23 short sequences are set to belong to the group 2, the 24 to 30 short sequences are set to belong to the group 3, a scrambling code is mapped on each group, and the scrambling code mapped on the group to which the third short sequence belongs is determine to be Sw2.
It is also possible to divide the number of the short sequence by 8, combine the short sequences with the same residual, and classify the 31 short sequences as 8 groups. That is, the number of the short sequence is divided by 8, the short sequence with the residual 0 is set to belong to the group 0, the short sequence with the residual 1 is set to belong to the group 1, the short sequence with the residual 2 is set to belong to the group 2, the short sequence with the residual 3 is set to belong to the group 3, the short sequence with the residual 4 is set to belong to the group 4, the short sequence with the residual 5 is set to belong to the group 5, the short sequence with the residual 6 is set to belong to the group 6, the short sequence with the residual 7 is set to belong to the group 7, a scrambling code is mapped on each group, and the scrambling code mapped on the group to which the third short sequence belongs is determined to be Sw2.
As expressed in Equation 8, the respective elements of the fourth sequence c3 according to the second method for generating the secondary synchronization signal are the products of the respective elements of the fourth short sequence and the corresponding respective elements of Sw2.
c3=[w3(0)Sw20,w3(1)Sw2(1), . . . ,w3(m)Sw2(m), . . . ,w3(30)Sw2(30)] [Equation 8]
Here, m is an index of the odd subcarrier used for the synchronization channel.
Here, it is given that Pj,1=Pj,2, and w0≠w1≠w2≠w3 or w0=w3, w1=w2. In this case, the cell group and frame identifying information are mapped on the combination of the first to fourth short sequences, and the number of descrambling hypotheses of the terminal for the scramble of the secondary synchronization channel defined by the cell identifying sequence number of the primary synchronization channel is reduced.
It is set that Pj,1≠Pj,2 and w0=w2, w1=w3. In this case, cell group information is mapped on the combination of the first short sequence and the second short sequence, and frame synchronization information is mapped on the scrambling sequences Pj,1 and Pj,2 of the secondary synchronization channel defined by the cell identifying sequence number of the primary synchronization channel. The number of descrambling hypotheses of the terminal for the scramble of the secondary synchronization channel defined by the cell identifying sequence number of the primary synchronization channel is increased, but the complexity is reduced since the combination of cell group identifying sequences is reduced to half.
The frequency mapper 430 maps the secondary synchronization signal and the transmission traffic data generated by the synchronization signal generator 420 in the time and frequency domains to generate a frame of the downlink signal (S530).
The OFDM transmitter 440 receives the frame of the downlink signal and transmits it through the transmitting antenna (S540).
A method for a terminal to search for the cell by using a downlink signal according to an exemplary embodiment of the present invention will now be described with reference to
As shown in
A cell searching method according to a first exemplary embodiment of the present invention will now be described with reference to
As shown in
The Fourier transformer 830 performs a Fourier transform process on the received signal with reference to the symbol synchronization estimated by the symbol synchronization estimation and frequency offset compensator 820 (S920).
The cell ID estimator 840 correlates the Fourier transformed received signal and a plurality of predetermined secondary synchronization signals to estimate a cell ID group and frame synchronization (S930). The cell ID estimator 840 correlates the Fourier transformed received signal and a plurality of secondary synchronization signals that are generated by applying Pj,1 and Pj,2 that are determined by the primary synchronization signal corresponding to the number of the primary synchronization signal transmitted by the symbol synchronization estimation and frequency offset compensator 820 to Equation 5 to Equation 8, and estimates the frame synchronization and the cell ID group by using the secondary synchronization signal having the greatest correlation value. In this instance, when the synchronization channel symbol in one frame is provided within one slot or one OFDM symbol, there is no need of additionally acquiring frame synchronization since the symbol synchronization becomes the frame synchronization.
The cell ID estimator 840 estimates the cell ID by using the number of the primary synchronization signal transmitted by the symbol synchronization estimation and frequency offset compensator 820 and the estimated cell ID group (S940). In this instance, the cell ID estimator 840 estimates the cell ID by referring to the mapping relation of the predetermined primary synchronization signal number, cell ID group, and cell ID.
The estimated cell ID information can be checked by using scrambling sequence information included in the pilot symbol interval.
A cell searching method according to a second exemplary embodiment of the present invention will now be described with reference to
The receiver 810 receives the frame from the base station, and the symbol synchronization estimation and frequency offset compensator 820 filters the received signal by the bandwidth allocated to the synchronization channel, correlates the filtered received signal and a plurality of predetermined primary synchronization signals to acquire symbol synchronization, and estimates frequency synchronization to compensate the frequency offset (S710). The symbol synchronization estimation and frequency offset compensator 820 correlates the filtered received signal and a plurality of predetermined primary synchronization signals to estimate the time having the greatest correlation value to be symbol synchronization, and transmits a plurality of correlation values that are generated by correlating the primary synchronization signals and the filtered received signal to the cell ID estimator 840. In this instance, the frequency offset can be compensated in the frequency domain after Fourier transform.
The Fourier transformer 830 performs a Fourier transform process on the received signal with reference to the symbol synchronization estimated by the symbol synchronization estimation and frequency offset compensator 820 (S720).
The cell ID estimator 840 estimates the cell ID by using a plurality of correlation values transmitted by the symbol synchronization estimation and frequency offset compensator 820, the Fourier transformed received signal, and correlation values of a plurality of predetermined secondary synchronization signals (S730). The cell ID estimator 840 correlates the Fourier transformed received signal and a plurality of secondary synchronization signals that are generated by applying Pj,1 and Pj,2 that are determined according to the corresponding primary synchronization signals to Equation 5 to Equation 8, and finds the secondary synchronization signal having the greatest correlation value, regarding a plurality of respective primary synchronization signals.
The cell ID estimator 840 combines the correlation value of the corresponding primary synchronization signal transmitted by the symbol synchronization estimation and frequency offset compensator 820 and the correlation value of the secondary synchronization signal having the greatest correlation value with the Fourier transformed received signal from among a plurality of secondary synchronization signals that are generated by applying Pj,1 and Pj,2 that are determined by the corresponding primary synchronization signal to Equation 5 to Equation 8, regarding a plurality of respective primary synchronization signals.
The cell ID estimator 840 estimates the frame synchronization and the cell ID group by using the secondary synchronization signal having the greatest value generated by combining the correlation value of the primary synchronization signal and the correlation value of the secondary synchronization signal. The cell ID estimator 840 estimates the cell ID by using the estimated cell ID group and the primary synchronization signal having the greatest value generated by combining the correlation value of the primary synchronization signal and the correlation value of the secondary synchronization signal. In this instance, the cell ID estimator 840 estimates the cell ID by referring to the mapping relation of the predetermined primary synchronization signal number, cell ID group, and cell ID.
The above-described embodiments can be realized through a program for realizing functions corresponding to the configuration of the embodiments or a recording medium for recording the program in addition to through the above-described device and/or method, which is easily realized by a person skilled in the art. Examples of the recording medium may include, but not limited to, a read only memory (ROM), a random access memory (RAM), an electrically programmable read-only memory (EEPROM), a flash memory, etc. The program may be executed by one or more hardware processors to achieve the function corresponding to the configuration of the exemplary embodiment. Examples of the hardware processor may include, but not limited to, a DSP (digital signal processor), a CPU (central processing unit), an ASIC (application specific integrated circuit), a programmable logic element, such as an FPGA (field programmable gate array), etc.
While this invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.
Kim, Young Hoon, Kim, Il Gyu, Bang, Seung Chan, Ko, Young Jo, Chang, Kap Seok, Lee, Moon Sik, Park, Hyeong Geun, Yi, Hyo Seok
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