# US 2018/0027418 A1 · Channel reservation method for unlicensed band communication, base station, and user terminal > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2018/0027418 A1 - Document ID: US20180027418A1 - Status: Published application - Kind: A1 - Application number: 15/541,927 - Filed: 2015-12-28 - Published: 2018-01-25 - Earliest claimed: 2015-01-09 - Assignees: Sharp Kabushiki Kaisha - Applicants: Sharp Kabushiki Kaisha - Inventors: BO LI; QI JIANG; RENMAO LIU - Web page: https://patentgrep.com/patent/US20180027418A1 ## CPC - H04W 16/14: Spectrum sharing arrangements {between different networks} - H04L 5/001: {the frequencies being arranged in component carriers} - H04L 5/0048: {Allocation of pilot signals, i.e. of signals known to the receiver (allocation of control signalling H04L5/0053; use of control signalling H04L5/0091)} - H04L 27/0006: {Assessment of spectral gaps suitable for allocating digitally modulated signals, e.g. for carrier allocation in cognitive radio (for spectrum sharing between different networks H04W16/14)} - H04W 72/04: Wireless resource allocation - H04W 72/12: Wireless traffic scheduling - H04W 74/0808: using carrier sensing, e.g. carrier sense multiple access [CSMA] - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract The present invention provides an uplink channel reservation method used in a mobile communication system supporting an unlicensed carrier, as well as a base station and a user terminal that execute the method. The method includes: assessing whether an unlicensed carrier resource is free; and sending a channel reservation signal over the assessed free unlicensed carrier resource. According to embodiments of the present invention, it is ensured that an unlicensed carrier resource remains free during the period from the time when an unlicensed carrier is assessed to be free to the time when an uplink license is issued and comes into effect. ## Claims ### Claim 1 An uplink channel reservation method used in a mobile communication system supporting an unlicensed carrier, comprising the steps of: assessing whether an unlicensed carrier resource is free; and sending a channel reservation signal over the assessed free unlicensed carrier resource. ### Claim 2 (depends on 1) The method according to claim 1, wherein the method is executed by a base station or a user terminal. ### Claim 3 (depends on 1) The method according to claim 1, wherein a signal format of the channel reservation signal comprises a signal format of one of the following signals: an assessment reference signal, a synchronizing signal, and a demodulation reference signal. ### Claim 4 (depends on 1) The method according to claim 1, wherein the mobile communication system comprises a Long Term Evolution (LTE) system and a Long Term Evolution Advanced (LTE-A) system. ### Claim 5 (depends on 1) The method according to claim 1, further comprising: setting a timer, the timer being indicative of a maximum time of duration for sending the channel reservation signal, wherein the channel reservation signal continues being sent until uplink transmission begins or until the timer expires. ### Claim 6 (depends on 1) The method according to claim 1, wherein the step of assessment is initiated randomly. ### Claim 7 (depends on 1) The method according to claim 1, wherein the step of assessment is initiated according to an uplink scheduling license. ### Claim 8 (depends on 1) The method according to claim 1, wherein the assessment is executed during the period of a Free Channel Assessment (CCA) symbol. ### Claim 9 (depends on 8) The method according to claim 8, wherein the step of sending comprises: starting to send the channel reservation signal over the assessed free unlicensed carrier resource from a first Orthogonal Frequency Division Multiplexing (OFDM) symbol after the CCA symbol. ### Claim 10 (depends on 1) The method according to claim 1, wherein the assessment is executed during the period of a CCA symbol of a current sub-frame that decides to perform uplink transmission over the unlicensed carrier resource. ### Claim 11 (depends on 1) The method according to claim 1, wherein the assessment is executed during the period of a CCA symbol of an Mth sub-frame after a corresponding sub-frame for sending the uplink scheduling license, M being a positive integer greater than or equal to 1. ### Claim 12 (depends on 7) The method according to claim 7, further comprising: performing uplink transmission over the assessed free unlicensed carrier resource, wherein a terminal for executing the uplink transmission is a user terminal for executing the step of assessment, or other user terminals accessing the present cell. ### Claim 13 A base station, comprising: an assessment module, configured to assess whether an unlicensed carrier resource is free; and a sending module, configured to send a channel reservation signal over the assessed free unlicensed carrier resource. ### Claim 14 (depends on 13) The base station according to claim 13, wherein the base station supports a Long Term Evolution (LTE) or Long Term Evolution Advanced (LTE-A) standard. ### Claim 15 (depends on 13) The base station according to claim 13, further comprising: a timer, the timer being indicative of a maximum time of duration for sending the channel reservation signal, wherein the sending module is further configured to continue sending the channel reservation signal until uplink transmission begins or until the timer expires. ### Claim 16 (depends on 13) The base station according to claim 13, wherein the assessment module is configured to randomly initiate the assessment. ### Claim 17 (depends on 13) The base station according to claim 13, wherein the assessment module is configured to make a decision according to an uplink scheduling license, and initiate the assessment at a specified time before or after a moment when the base station sends the uplink scheduling license. ### Claim 18 (depends on 13) The base station according to claim 13, wherein the assessment module is configured to execute the assessment during the period of a Free Channel Assessment (CCA) symbol. ### Claim 19 (depends on 18) The base station according to claim 18, wherein the sending module is further configured to start to send the channel reservation signal over the assessed free unlicensed carrier resource from a first Orthogonal Frequency Division Multiplexing (OFDM) symbol after the CCA symbol. ### Claim 20 (depends on 13) The base station according to claim 13, wherein the assessment module is further configured to execute the assessment during the period of a CCA symbol of a current sub-frame that decides to perform uplink transmission over the unlicensed carrier resource. ### Claim 21 (depends on 13) The base station according to claim 13, wherein the assessment module is further configured to execute the assessment during the period of a CCA symbol of a next frame with respect to a sub-frame for sending the uplink scheduling license. ### Claim 22 A user terminal, comprising: an assessment module, configured to assess whether an unlicensed carrier resource is free; and a sending module, configured to send a channel reservation signal over the assessed free unlicensed carrier resource. ### Claim 23 (depends on 22) The user terminal according to claim 22, wherein a signal format of the channel reservation signal comprises a signal format of one of the following signals: an assessment reference signal, a synchronizing signal, and a demodulation reference signal. ### Claim 24 (depends on 22) The user terminal according to claim 22, wherein the user terminal supports a Long Term Evolution (LTE) or Long Term Evolution Advanced (LTE-A) standard. ### Claim 25 (depends on 22) The user terminal according to claim 22, wherein the sending module is further configured to: set a timer, the timer being indicative of a maximum time of duration for sending the channel reservation signal; and continue sending the channel reservation signal until uplink transmission begins or until the timer expires. ### Claim 26 (depends on 22) The user terminal according to claim 22, wherein the assessment module is configured to randomly initiate the assessment. ### Claim 27 (depends on 22) The user terminal according to claim 22, wherein the assessment module is configured to initiate, in response to an uplink scheduling license, the assessment. ### Claim 28 (depends on 22) The user terminal according to claim 22, wherein the assessment module is configured to execute the assessment during the period of a Free Channel Assessment (CCA) symbol. ### Claim 29 (depends on 28) The user terminal according to claim 28, wherein the sending module is further configured to start to send the channel reservation signal over the assessed free unlicensed carrier resource from a first Orthogonal Frequency Division Multiplexing (OFDM) symbol after the CCA symbol. ### Claim 30 (depends on 22) The user terminal according to claim 22, wherein the assessment module is further configured to execute the assessment during the period of a CCA symbol of a current sub-frame that decides to perform uplink transmission over the unlicensed carrier resource. ### Claim 31 (depends on 22) The user terminal according to claim 22, wherein the assessment module is further configured to execute the assessment during the period of a CCA symbol of an Mth sub-frame after a corresponding sub-frame for sending the uplink scheduling license, M being a positive integer greater than or equal to 1. ### Claim 32 (depends on 31) The user terminal according to claim 31, further comprising: a data sending module, configured to start to perform uplink transmission over an unlicensed carrier channel through an M+1th sub-frame after a corresponding sub-frame for sending the uplink scheduling license.