Two-Step Contention-Based Random Access Over Radio Resources in LAA

• US 20180146498A1
• Filed: 10/28/2016
• Published: 05/24/2018
• Est. Priority Date: 10/30/2015
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Sahlin, Henrik, Mukherjee, Amitav
• Granted Patent: US 10,772,135 B2
• Time in Patent Office: Days
• CPC Class Codes: H04W 16/14 Spectrum sharing arrangements between different networks
• CPC Class Codes: H04W 56/0005 synchronizing of arrival of multiple uplinks
• CPC Class Codes: H04W 56/0045 compensating for timing error by altering transmission time
• CPC Class Codes: H04W 74/002 Transmission of channel access control information
• CPC Class Codes: H04W 74/0841 with collision treatment

Abstract

A contending radio node (200) is configured for attempting contention-based random access. The contending radio node (200) obtains a timing advance sequence that is susceptible to contention. The contending radio node (200) transmits, using the same transmission advancement timing, the timing advance sequence and a contention-resolving identity to a recipient radio node (250). Responsive to that transmission, the contending radio node (200) receives a response signal that indicates a contention-resolving identity and a timing advance. The contending radio node (200) resolves any contention in its favor when the contention-resolving identity indicated by the response signal corresponds to the contention-resolving identity that the contending radio node (200) transmitted. The contending radio node (200), responsive to resolving the contention in its favor, adjusts its transmission advancement timing according to the timing advance indicated by the response signal.

Claims

1-51. -51. (canceled)

52. A contending radio node configured for attempting contention-based random access over one or more radio resources, the contending radio node comprising:

processing circuitry and a memory, the memory containing instructions executable by the processing circuitry whereby the contending radio node is configured to;

obtain a timing advance sequence based on which a timing advance for transmission from the contending radio node to a recipient radio node is derivable, wherein the timing advance sequence is susceptible to contention;

obtain a contention-resolving identity of the contending radio node;

transmit, via radio circuitry, using the same transmission advancement timing, the timing advance sequence and the contention-resolving identity to the recipient radio node on the one or more radio resources;

responsive to said transmitting, receive from the recipient radio node a response signal that indicates a contention-resolving identity as well as a timing advance derived from a timing advance sequence received by the recipient radio node;

resolve the contention in favor of the contending radio node when the contention-resolving identity indicated by the response signal corresponds to the contention-resolving identity that the contending radio node transmitted; and

responsive to resolving the contention in favor of the contending radio node, adjust the transmission advancement timing that governs the timing advancement of transmissions from the contending radio node to the recipient radio node, according to the timing advance indicated by the response signal.

53. The contending radio node of claim 52, the memory containing instructions executable by the processing circuitry whereby the contending radio node is further configured to determine that the one or more radio resources are deemed clear of transmission activity, and to transmit the timing advance sequence and the contention-resolving identity responsive to determining that the one or more radio resources are deemed clear of transmission activity.

54. The contending radio node of claim 52, the memory containing instructions executable by the processing circuitry whereby the contending radio node is further configured to perform a clear channel assessment on the one or more radio resources for a defined duration, and to transmit the timing advance sequence and the contention-resolving identity responsive to the clear channel assessment indicating that the one or more radio resources are clear of transmission activity, wherein any amount of time between transmitting the timing advance sequence and transmitting the contention-resolving identity is less than the defined duration.

55. The contending radio node of claim 52, the memory containing instructions executable by the processing circuitry whereby the contending radio node is configured to maintain control of the one or more radio resources throughout transmission of the timing advance sequence and the contention-resolving identity.

56. The contending radio node of claim 52, wherein one or more of the time resources over which the timing advance sequence is transmitted are the same as or are contiguous to one or more of the time resources over which the contention-resolving identity is transmitted by the contending radio node to the recipient radio.

57. The contending radio node of claim 52, wherein the one or more radio resources extend in time across a single subframe, and wherein the timing advance sequence and the contention-resolving identity are transmitted by the contending radio node to the recipient node in the single subframe.

58. The contending radio node of claim 52, wherein the one or more radio resources extend in time across multiple subframes, and wherein the timing advance sequence and the contention-resolving identity are transmitted by the contending radio node to the recipient node in consecutive subframes.

59. The contending radio node of claim 52, the memory containing instructions executable by the processing circuitry whereby the contending radio node is further configured to determine a frequency offset between one or more radio resources on which the timing advance sequence is transmitted and one or more radio resources on which the contention-resolving identity is transmitted by the contending radio node to the recipient node, based on one or more predefined rules, wherein the one or more predefined rules specify the frequency offset as a function of at least one of:

the timing advance sequence;

one or more frequency resources on which the timing advance sequence is to be transmitted;

one or more time resources on which the timing advance sequence is to be transmitted;

an estimated path loss between the contending radio node and the recipient radio node; and

system information broadcast by the recipient radio node.

60. The contending radio node of claim 52, wherein the timing advance sequence and/or the contention-resolving identity are transmitted by the contending radio node to the recipient node on non-contiguous frequency resources that are evenly distributed in frequency.

61. The contending radio node of claim 52, wherein the timing advance sequence is transmitted within one or more symbols preceding the contention-resolving identity within the same subframe and is transmitted across a frequency interval that is larger than a frequency interval over which the contention-resolving identity is transmitted.

62. The contending radio node of claim 52, wherein the timing advance sequence is a function of a slot or frame number in which it is transmitted, and/or an estimated path loss between the contending radio node and the recipient radio node.

63. The contending radio node of claim 52, wherein the contention-resolving identity transmitted by the contending radio node is transmitted in time as a sequence of symbol groups, with each symbol group comprising consecutive symbols that convey the same data.

64. The contending radio node of claim 52, wherein the contention-resolving identity transmitted by the contending radio node is transmitted in time as a sequence of symbol pairs, with each symbol pair comprising a head symbol that has a cyclic prefix portion and a tail symbol that has a cyclic postfix portion, wherein the tail symbol is contiguous in time after the head symbol and has the same data portion as the head symbol.

65. The contending radio node of claim 52, wherein the contention-resolving identity transmitted by the contending radio node is transmitted in time as a sequence of symbol pairs, with each symbol pair comprising a head symbol that has a cyclic prefix portion and a tail symbol that is contiguous in time after the head symbol and has the same data portion as the head symbol.

66. The contending radio node of claim 52, wherein the contending radio node and the recipient radio node communicate using Orthogonal Frequency Division Multiplexing (OFDM).

67. The contending radio node of claim 52, wherein the timing advance sequence comprises a random access preamble transmitted over a physical random access channel (PRACH) and the contention-resolving identity is transmitted from the contending radio node to the recipient radio node over a physical uplink shared channel (PUSCH) in a system that is or evolves from Long Term Evolution (LTE).

68. The contending radio node of claim 52, wherein the contention-resolving identity transmitted from the contending radio node to the recipient radio node comprises either a cell radio network temporary identifier (C-RNTI) of the contending radio node or a core-network terminal identifier of the contending radio node that is mapped to the C-RNTI of the contending radio node, and the contention-resolving identity indicated by the response signal is the C-RNTI of the contending radio node.

69. The contending radio node of claim 52, wherein the one or more radio resources comprise unlicensed radio resources.

70. The contending radio node of claim 52, wherein the contending radio node is a user equipment and the recipient radio node is a base station.

71. A recipient radio node for facilitating contention-based random access over one or more radio resources, the recipient radio node comprising:

processing circuitry and a memory, the memory containing instructions executable by the processing circuitry whereby the recipient radio node is configured to;

receive, from a contending radio node and on the one or more radio resources, a timing advance sequence and a contention-resolving identity of the contending radio node that have been transmitted using the same transmission advancement timing, wherein the timing advance sequence is susceptible to contention;

responsive to said receiving and based on the received timing advance sequence, derive a timing advance for transmission from the contending radio node to the recipient radio node; and

responsive to said deriving, transmit, via radio circuitry, from the recipient radio node to the contending radio node a response signal that indicates the derived timing advance as well as a contention-resolving identity that corresponds to the contention-resolving identity received from the contending radio node.

72. The recipient radio node of claim 71, the memory containing instructions executable by the processing circuitry whereby the recipient radio node is further configured to determine that one or more radio resources are deemed clear of transmission activity, and to transmit the response signal responsive to determining that those one or more radio resources are deemed clear of transmission activity.

73. The recipient radio node of claim 71, the memory containing instructions executable by the processing circuitry whereby the recipient radio node is further configured to perform a clear channel assessment on one or more radio resources for a defined duration, and to transmit the response signal responsive to to the clear channel assessment indicating that the one or more radio resources are clear of transmission activity, \wherein any amount of time between transmitting the timing advance and transmitting the contention-resolving identity is less than the defined duration.

74. The recipient radio node of claim 71, the memory containing instructions executable by the processing circuitry whereby the recipient radio node is configured to transmit the response signal on one or more radio resources, and maintain control of those one or more radio resources throughout transmission of the response signal.

75. The recipient radio node of claim 71, wherein one or more of the time resources over which the timing advance sequence is received are the same as or are contiguous to one or more of the time resources over which the contention-resolving identity is received by the recipient radio.

76. The recipient radio node of claim 71, wherein the timing advance sequence and/or the contention-resolving identity are received by the recipient node on non-contiguous frequency resources that are evenly distributed in frequency.

77. The recipient radio node of claim 71, wherein the timing advance sequence is received within one or more symbols preceding the contention-resolving identity within the same subframe and is received across a frequency interval that is larger than a frequency interval over which the contention-resolving identity is received.

78. The recipient radio node of claim 71, wherein the response signal is transmitted on one or more unlicensed radio resources.

79. The recipient radio node of claim 71, wherein the response signal further indicates a random access sequence to which the response signal is responsive.

80. The recipient radio node of claim 71, wherein any amount of time between the contention-resolving identity and the timing advance in the response signal is less than a defined duration for performing a clear channel assessment on one or more radio resources.

81. The recipient radio node of claim 71, wherein one or more of the time resources over which the timing advance is transmitted are the same as or are contiguous to one or more of the time resources over which the contention-resolving identity is transmitted by the recipient radio to the contending radio node.

82. The recipient radio node of claim 71, wherein the contention-resolving identity is received in time as a sequence of symbol groups, with each symbol group comprising consecutive symbols that convey the same data.

83. The recipient radio node of claim 71, wherein the contention-resolving identity is received in time as a sequence of symbol pairs, with each symbol pair comprising a head symbol that has a cyclic prefix portion and a tail symbol that has a cyclic postfix portion, wherein the tail symbol is contiguous in time after the head symbol and has the same data portion as the head symbol.

84. The recipient radio node of claim 71, wherein the contention-resolving identity is received by the recipient radio node in time as a sequence of symbol pairs, with each symbol pair comprising a head symbol that has a cyclic prefix portion and a tail symbol that is contiguous in time after the head symbol and has the same data portion as the head symbol.

85. The recipient radio node of claim 71, wherein the contending radio node and the recipient radio node communicate using Orthogonal Frequency Division Multiplexing (OFDM).

86. The recipient radio node of claim 71, wherein the timing advance sequence comprises a random access preamble received over a physical random access channel (PRACH) and the contention-resolving identity is received over a physical uplink shared channel (PUSCH) in a system that is or evolves from Long Term Evolution (LTE).

87. The recipient radio node of claim 71, wherein the contention-resolving identity received the recipient radio node comprises either a cell radio network temporary identifier (C-RNTI) of the contending radio node or a core-network terminal identifier of the contending radio node that is mapped to the C-RNTI of the contending radio node, and the contention-resolving identity indicated by the response signal is the C-RNTI of the contending radio node.

88. The recipient radio node of claim 71, wherein the one or more radio resources comprise unlicensed radio resources.

89. The recipient radio node of claim 71, wherein the contending radio node (200) is a user equipment and the recipient radio node is a base station.

90. A method implemented by a contending radio node for attempting contention-based random access over one or more radio resources, the method comprising:

obtaining a timing advance sequence based on which a timing advance for transmission from the contending radio node to a recipient radio node is derivable, wherein the timing advance sequence is susceptible to contention;

obtaining a contention-resolving identity of the contending radio node;

transmitting, using the same transmission advancement timing, the timing advance sequence and the contention-resolving identity to the recipient radio node on the one or more radio resources;

responsive to said transmitting, receiving from the recipient radio node a response signal that indicates a contention-resolving identity as well as a timing advance derived from a timing advance sequence received by the recipient radio node;

resolving the contention in favor of the contending radio node when the contention-resolving identity indicated by the response signal corresponds to the contention-resolving identity that the contending radio node transmitted; and

responsive to resolving the contention in favor of the contending radio node, adjusting the transmission advancement timing that governs the timing advancement of transmissions from the contending radio node to the recipient radio node, according to the timing advance indicated by the response signal.

91. The method of claim 90, further comprising determining that the one or more radio resources are deemed clear of transmission activity, and wherein said transmitting is performed responsive to determining that the one or more radio resources are deemed clear of transmission activity.

92. The method of claim 90, further comprising performing a clear channel assessment on the one or more radio resources for a defined duration, and wherein said transmitting is performed responsive to the clear channel assessment indicating that the one or more radio resources are clear of transmission activity, wherein any amount of time between transmitting the timing advance sequence and transmitting the contention-resolving identity is less than the defined duration.

93. The method of claim 90, wherein said transmitting comprises maintaining control of the one or more radio resources throughout transmission of the timing advance sequence and the contention-resolving identity.

94. A method implemented by a recipient radio node for facilitating contention-based random access over one or more radio resources, the method comprising:

receiving, from a contending radio node and on the one or more radio resources, a timing advance sequence and a contention-resolving identity of the contending radio node that have been transmitted using the same transmission advancement timing, wherein the timing advance sequence is susceptible to contention;

responsive to said receiving and based on the received timing advance sequence, deriving a timing advance for transmission from the contending radio node to the recipient radio node; and

responsive to said deriving, transmitting from the recipient radio node to the contending radio node a response signal that indicates the derived timing advance as well as a contention-resolving identity that corresponds to the contention-resolving identity received from the contending radio node.

95. The method of claim 94, further comprising determining that one or more radio resources are deemed clear of transmission activity, and wherein said transmitting is performed responsive to said determining.

96. The method of claim 94, further comprising performing a clear channel assessment on one or more radio resources for a defined duration, and wherein said transmitting is performed responsive to the clear channel assessment indicating that the one or more radio resources are clear of transmission activity, wherein any amount of time between transmitting the timing advance and transmitting the contention-resolving identity is less than the defined duration.

97. The method of claim 94, wherein said transmitting comprises transmitting the response signal on one or more radio resources, and maintaining control of those one or more radio resources throughout transmission of the response signal.