Apparatus and method for generating synchronization channel for relay station in wireless communication system

• US 20080039013A1
• Filed: 08/10/2007
• Published: 02/14/2008
• Est. Priority Date: 08/11/2006
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Lim, Eun-Taek, Park, Dong-Seek, Cho, Jae-Weon, Lee, Mi-Hyun, Chang, Young-Bin, Park, Sung-Eun, Lim, Chi-Woo, Lee, Sung-Jin, Oh, Chang-Yoon, Kang, Hyun-Jeong, Son, Jung-Je, Lim, Hyoung-Kyu, Cho, Soon-Mi, Joo, Pah-Yuh
• Granted Patent: US 7,920,508 B2
• Time in Patent Office: Days
• US Class Current: 455/11.1
• CPC Class Codes: H04B 7/155 Ground-based stations H04B7/204 takes precedence

Abstract

An apparatus and method for generating an RS SCH in a wireless communication system are provided, in which a base station checks a BS SCH sequence and a mask sequence, and generates an RS SCH sequence by XOR-operating the BS SCH sequence and the mask sequence.

Claims

1. A method for generating a Synchronization CHannel (SCH) in an upper node in a wireless communication system, comprising:

checking a sequence of a first SCH being an SCH for a mobile station (MS) and a mask sequence; and

generating a sequence of a second SCH being an SCH for a relay station (RS) by XOR-operating the first SCH sequence and the mask sequence.

2. The method of claim 1, wherein the mask sequence has one of a length equal to a length of the first SCH sequence and a length different from the length of the first SCH sequence.

3. The method of claim 1, wherein the mask sequence is a sequence that minimizes the Peak-to-Average Power Ratio (PAPR) of the second SCH.

4. The method of claim 1, wherein if the first SCH sequence is of length 568, the mask sequence is given in the following table,

5. The method of claim 1, wherein the mask sequence is one of a common Pseudo Noise (PN) sequence, a common sync symbol sequence, and a sequence of all 0s.

6. The method of claim 5, wherein the common PN sequence is a sequence having a length equal to a length of the first SCH sequence, generated in a Pseudo Random Binary Sequence (PRBS) generator.

7. The method of claim 5, wherein the common PN sequence is cyclically shifted according to a start symbol position of the second SCH.

8. The method of claim 7, wherein the start symbol position of the second SCH is determined according to one of the start of an entire frame, the start of a frame for the relay station, and the start of a subchannel zone.

9. The method of claim 5, wherein the common sync symbol sequence has a length equal to a length of the first SCH sequence.

10. The method of claim 1, further comprising transmitting information about the mask sequence to a lower relay station by a broadcast message.

11. The method of claim 1, further comprising:

determining whether to improve the PAPR performance of the second SCH;

selecting replacement positions in the second SCH sequence if it is determined to improve the PAPR performance of the second SCH;

calculating replacement elements to substitute at the replacement positions;

substituting the replacement elements at the replacement positions of the second SCH sequence; and

transmitting the second SCH with the replacement elements to the relay station.

12. The method of claim 11, further comprising transmitting the second SCH to the relay station, if it is determined not to improve the PAPR performance of the second SCH.

13. The method of claim 11, wherein the replacement positions are one of distributed and successive in the second SCH sequence.

14. The method of claim 11, wherein the number of the replacement elements is determined according to the PAPR performance and correlation characteristics of the second SCH.

15. The method of claim 11, wherein a sequence of the replacement elements is one of a random sequence and a complementary sequence.

16. The method of claim 11, wherein the substitution comprises:

substituting the calculated replacement elements for elements of the second SCH sequence at the replacement positions;

comparing the PAPR of the second SCH with the replacement elements with a threshold; and

re-generating replacement elements, if the PAPR is higher than the threshold.

17. The method of claim 16, wherein if the PAPR is lower than the threshold, the second SCH with the replacement elements is transmitted to the relay station.

18. The method of claim 11, wherein the substitution comprises:

changing the value of an i^th element at one of the replacement positions in the second SCH sequence and measuring the PAPR of the second SCH with the i^th element having the changed value; and

changing the value of an (i+1)^th element at one of the replacement positions in the second SCH sequence and measuring the PAPR of the second SCH with the (i+1)^th element having the changed value, if the PAPR is lower than before the value change of the i^th element.

19. The method of claim 18, wherein the substitution further comprises:

recovering an original value of the i^th element, if the PAPR is higher than before the value change of the i^th element; and

changing the value of the (i+1)^th element at one of the replacement positions in the second SCH sequence.

20. The method of claim 11, further comprising transmitting information about the replacement positions to the relay station.

21. The method of claim 20, wherein the replacement position information transmission comprises transmitting the information about the replacement positions to the relay station by a broadcast message.

22. The method of claim 21, wherein if the replacement positions are distributed, the broadcast message includes information about the number of the replacement elements and information about an interval between the replacement elements.

23. The method of claim 21, wherein if the replacement positions are successive, the broadcast message includes information about the number of the replacement elements and information about a start position of the replacement elements.

24. The method of claim 1, wherein the upper node is one of a base station and an upper relay station.

25. The method of claim 1, wherein if a subframe for a BS-MS link and a subframe for a BS-RS link are fixed in length, the second SCH is positioned at one of the start and end of the subframe for the BS-RS link.

26. The method of claim 1, wherein if a subframe for an RS-MS link and a subframe for an RS-RS link are fixed in length, the second SCH is positioned at one of the start and end of the subframe for the RS-RS link.

27. The method of claim 1, wherein if a subframe for a BS-MS link and a subframe for a BS-RS link are variable in length, the second SCH is positioned at the end of the subframe for the BS-RS link.

28. The method of claim 1, wherein if a subframe for an RS-MS link and a subframe for an RS-RS link are variable in length, the second SCH is positioned at the end of the subframe for the RS-RS link.

29. The method of claim 1, wherein if the upper node transmits information about the position of the second SCH, the second SCH is dynamically positioned.

30. The method of claim 1, wherein if subframes for BS-RS link are spatially multiplexed, the second SCH generation comprises generating different second SCHs for different relay stations in the subframes using mask sequences associated with the subframes.

31. The method of claim 1, wherein if subframes for RS-RS link are spatially multiplexed, the second SCH generation comprises generating different second SCHs in the subframes for different relay stations using mask sequences associated with the subframes.

32. An apparatus for generating a Synchronization CHannel (SCH) for a relay station (RS) in a wireless communication system, comprising:

a storage for storing a sequence of a first SCH being an SCH for a mobile station (MS) and a mask sequence; and

an SCH generator for generating a sequence of a second SCH being an SCH for a relay station by XOR-operating the first SCH sequence and the mask sequence.

33. The apparatus of claim 32, wherein the storage further stores the generated second SCH sequence.

34. The apparatus of claim 32, wherein the mask sequence has one of a length equal to a length of the first SCH sequence and a length different from the length of the first SCH sequence.

35. The apparatus of claim 32, wherein the mask sequence is a sequence that minimizes the Peak-to-Average Power Ratio (PAPR) of the second SCH.

36. The apparatus of claim 32, wherein if the first SCH sequence is of length 568, the mask sequence is given in the following table,

37. The apparatus of claim 32, wherein the mask sequence is one of a common Pseudo Noise (PN) sequence, a common sync symbol sequence, and a sequence of all 0s.

38. The apparatus of claim 32, further comprising a PAPR controller for substituting replacement elements for elements of the second SCH sequence to improve the PAPR performance of the second SCH.

39. The apparatus of claim 38, wherein the PAPR controller comprises:

a replacement sequence calculator for determining replacement positions in the second SCH sequence and calculating a sequence of the replacement elements; and

an element exchanger for substituting the replacements elements at the replacement positions of the second SCH sequence.

40. The apparatus of claim 39, wherein the replacement positions are one of distributed and successive in the second SCH sequence.

41. The apparatus of claim 39, wherein the replacement sequence calculator determined the number of the replacement elements according to the PAPR performance and correlation characteristics of the second SCH.

42. A method for acquiring a Synchronization CHannel (SCH) in a relay station (RS) in a wireless communication system, comprising:

checking a sequence of a first SCH being an SCH for a mobile station (MS) received from an upper node and a mask sequence;

generating a sequence of a second SCH being an SCH for a relay station by XOR-operating the first SCH sequence and the mask sequence; and

acquiring, upon receipt of a second SCH from the upper node, synchronization to the upper node by correlating the generated second SCH with the received second SCH.

43. The method of claim 42, wherein the upper node is one of a base station (BS) and an upper relay station.

44. The method of claim 42, wherein the first SCH sequence is received from the upper node during initial access.

45. The method of claim 42, wherein the mask sequence is identical to a sequence used in generating the second SCH in the upper node.

46. The method of claim 42, wherein the mask sequence is one of a common Pseudo Noise (PN) sequence, a common sync symbol sequence, and a sequence of all 0s.

47. The method of claim 46, wherein the common PN sequence is a sequence having a length equal to a length of the first SCH sequence, generated in a Pseudo Random Binary Sequence (PRBS) generator.

48. The method of claim 46, wherein the common PN sequence is cyclically shifted according to a start symbol position of the second SCH.

49. The method of claim 48, wherein the a start symbol position of the second SCH is determined according to one of the start of an entire frame, the start of a frame for the relay station, and the start of a subchannel zone.

50. The method of claim 46, wherein the common sync symbol sequence has a length equal to a length of the first SCH sequence.

51. The method of claim 42, further comprising:

determining whether the Peak-to-Average Power Ratio (PAPR) performance of the received second SCH was improved;

determining positions of replacement elements used to improve the PAPR performance by the upper node, if the PAPR performance of the received second SCH was improved; and

removing the replacement elements from the received second SCH sequence and the generated second SCH sequence,

whereby acquiring synchronization to the upper node by correlating the received second SCH sequence without the replacement elements and the generated second SCH sequence without the replacement elements.

52. The method of claim 51, wherein the determination as to the PAPR performance improvement comprises determining whether the PAPR performance of the received second SCH was improved by control information received from the upper node.

53. The method of claim 51, wherein if the PAPR performance of the received second SCH was not improved, the received second SCH sequence is correlated with the generated second SCH sequence.

54. The method of claim 51, wherein the replacement element positions determination comprises determining the positions of the replacement elements by a broadcast message received from the upper node.

55. The method of claim 54, wherein if the positions of the replacement elements are distributed, the broadcast message includes information about the number of the replacement elements and information about an interval between the replacement elements.

56. The method of claim 54, wherein if the positions of the replacement elements are successive, the broadcast message includes information about the number of the replacement elements and information about a start position of the replacement elements.

57. An apparatus for acquiring a Synchronization CHannel (SCH) in a relay station (RS) in a wireless communication system, comprising:

a storage for storing a sequence of a first SCH being an SCH for a mobile station (MS) received from an upper node and a mask sequence;

an SCH generator for generating a sequence of a second SCH being an SCH for a relay station by XOR-operating the stored first SCH sequence and the stored mask sequence;

a receiver for receiving a second SCH from the upper node; and

a correlator for correlating the generated second SCH with the received second SCH.

58. The apparatus of claim 57, wherein the upper node is one of a base station (BS) and an upper relay station.

59. The apparatus of claim 57, wherein the storage further stores the generated second SCH and the received second SCH.

60. The apparatus of claim 57, wherein the mask sequence is one of a common Pseudo Noise (PN) sequence, a common sync symbol sequence, and a sequence of all 0s.

61. The apparatus of claim 57, wherein the mask sequence is identical to a mask sequence used in generating the second SCH channel by the upper node.

62. The apparatus of claim 57, further comprising a sequence remover for removing elements from both the received second SCH sequence and the generated second SCH sequence, if the Peak-to-Average Power Ratio (PAPR) performance of the received second SCH was improved,

wherein the correlator correlates the element-removed received second SCH sequence and the element-removed generated second SCH sequence.

63. The apparatus of claim 62, wherein the positions of the eliminated elements have the same values and the same positions as elements that the upper node substituted in the second SCH sequence to improve the PAPR performance.

64. A wireless network comprising at least one base station and at least one relay station for communicating with mobile stations in a coverage area of the wireless network, wherein a first one of the at least one base station generates a synchronization channel (SCH) signal for a first one of the at least one relay station, the first base station comprising:

a storage for storing a first SCH sequence suitable for transmission to a mobile station; and

an SCH generator for receiving the first SCH sequence and generating therefrom a second SCH sequence suitable for transmission to the first relay station.

65. The wireless network of claim 64, wherein the SCH generator further receives a mask sequence and generates the second SCH sequence from the first SCH sequence and the mask sequence.

66. The wireless network of claim 65, wherein the SCH generator comprises an exclusive-OR circuit that performs an XOR operation on the first SCH sequence and the mask sequence.

67. The wireless network of claim 65, wherein the mask sequence has one of a length equal to a length of the first SCH sequence and a length different from the length of the first SCH sequence.

68. The wireless network of claim 65, wherein the mask sequence is selected by the first base station to minimize the Peak-to-Average Power Ratio (PAPR) of the second SCH sequence.

69. The wireless network of claim 68, wherein the mask sequence is one of a common Pseudo Noise (PN) sequence, a common sync symbol sequence, and a sequence of all 0s.

70. The wireless network of claim 68, wherein the base station further comprises a PAPR controller for substituting replacement elements for elements of the second SCH sequence to improve the PAPR performance of the second SCH.

71. For use in a wireless network comprising at least one base station and at least one relay station for communicating with mobile stations in a coverage area of the wireless network, a method of generating in a first one of the at least one base station a synchronization channel (SCH) signal for a first one of the at least one relay station, the method comprising the steps of:

receiving a first SCH sequence suitable for transmission to a mobile station; and

generating from the first SCH sequence a second SCH sequence suitable for transmission to the first relay station.

72. The method of claim 71, further comprising the step of receiving a mask sequence, wherein the step of generating the second SCH sequence comprises the substep of generating the second SCH sequence from the first SCH sequence and the mask sequence.

73. The method of claim 72, wherein the substep of generating the second SCH sequence from the first SCH sequence and the mask sequence comprises the substep of performing an exclusive-OR operation on the first SCH sequence and the mask sequence.

74. The method of claim 73, wherein the mask sequence has one of a length equal to a length of the first SCH sequence and a length different from the length of the first SCH sequence.

75. The method of claim 72, wherein the mask sequence is selected to minimize the Peak-to-Average Power Ratio (PAPR) of the second SCH sequence.

76. The method of claim 72, wherein the mask sequence is one of a common Pseudo Noise (PN) sequence, a common sync symbol sequence, and a sequence of all 0s.