# US 10,772,135 B2 · Two-step contention-based random access over radio resources in LAA > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,772,135 B2 - Document ID: US10772135B2 - Status: Granted - Kind: B2 - Application number: 15/576,082 - Filed: 2016-10-28 - Published: 2018-05-24 - Granted: 2020-09-08 - Earliest claimed: 2015-10-30 - Assignees: Telefonaktiebolaget LM Ericsson (publ) - Applicants: Telefonaktiebolaget LM Ericsson (publ) - Inventors: Henrik Sahlin; Amitav Mukherjee - Web page: https://patentgrep.com/patent/US10772135B2 ## CPC - H04W 74/0841: {with collision treatment} - H04W 56/0005: {synchronizing of arrival of multiple uplinks} - H04W 56/0045: {compensating for timing error by altering transmission time} - H04W 16/14: Spectrum sharing arrangements {between different networks} - H04W 74/002: {Transmission of channel access control information} - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) ## 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 ### Claim 1 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. ### Claim 2 (depends on 1) The contending radio node of claim 1, 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. ### Claim 3 (depends on 1) The contending radio node of claim 1, 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. ### Claim 4 (depends on 1) The contending radio node of claim 1, 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. ### Claim 5 (depends on 1) The contending radio node of claim 1, 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. ### Claim 6 (depends on 1) The contending radio node of claim 1, 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. ### Claim 7 (depends on 1) The contending radio node of claim 1, 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. ### Claim 8 (depends on 1) The contending radio node of claim 1, 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. ### Claim 9 (depends on 1) The contending radio node of claim 1, 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. ### Claim 10 (depends on 1) The contending radio node of claim 1, 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. ### Claim 11 (depends on 1) The contending radio node of claim 1, 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. ### Claim 12 (depends on 1) The contending radio node of claim 1, 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. ### Claim 13 (depends on 1) The contending radio node of claim 1, 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. ### Claim 14 (depends on 1) The contending radio node of claim 1, 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. ### Claim 15 (depends on 1) The contending radio node of claim 1, wherein the contending radio node and the recipient radio node communicate using Orthogonal Frequency Division Multiplexing (OFDM). ### Claim 16 (depends on 1) The contending radio node of claim 1, 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). ### Claim 17 (depends on 1) The contending radio node of claim 1, 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. ### Claim 18 (depends on 1) The contending radio node of claim 1, wherein the one or more radio resources comprise unlicensed radio resources. ### Claim 19 (depends on 1) The contending radio node of claim 1, wherein the contending radio node is a user equipment and the recipient radio node is a base station. ### Claim 20 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. ### Claim 21 (depends on 20) The recipient radio node of claim 20, 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. ### Claim 22 (depends on 20) The recipient radio node of claim 20, 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. ### Claim 23 (depends on 20) The recipient radio node of claim 20, 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. ### Claim 24 (depends on 20) The recipient radio node of claim 20, 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. ### Claim 25 (depends on 20) The recipient radio node of claim 20, 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. ### Claim 26 (depends on 20) The recipient radio node of claim 20, 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. ### Claim 27 (depends on 20) The recipient radio node of claim 20, wherein the response signal is transmitted on one or more unlicensed radio resources. ### Claim 28 (depends on 20) The recipient radio node of claim 20, wherein the response signal further indicates a random access sequence to which the response signal is responsive. ### Claim 29 (depends on 20) The recipient radio node of claim 20, 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. ### Claim 30 (depends on 20) The recipient radio node of claim 20, 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. ### Claim 31 (depends on 20) The recipient radio node of claim 20, 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. ### Claim 32 (depends on 20) The recipient radio node of claim 20, 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. ### Claim 33 (depends on 20) The recipient radio node of claim 20, 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. ### Claim 34 (depends on 20) The recipient radio node of claim 20, wherein the contending radio node and the recipient radio node communicate using Orthogonal Frequency Division Multiplexing (OFDM). ### Claim 35 (depends on 20) The recipient radio node of claim 20, 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). ### Claim 36 (depends on 20) The recipient radio node of claim 20, 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. ### Claim 37 (depends on 20) The recipient radio node of claim 20, wherein the one or more radio resources comprise unlicensed radio resources. ### Claim 38 (depends on 20) The recipient radio node of claim 20, wherein the contending radio node is a user equipment and the recipient radio node is a base station. ### Claim 39 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. ### Claim 40 (depends on 39) The method of claim 39, 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. ### Claim 41 (depends on 39) The method of claim 39, 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. ### Claim 42 (depends on 39) The method of claim 39, 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. ### Claim 43 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. ### Claim 44 (depends on 43) The method of claim 43, 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. ### Claim 45 (depends on 43) The method of claim 43, 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. ### Claim 46 (depends on 43) The method of claim 43, 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.