# US 2026/0075554 A1 · Channel usage indication and synchronization for lte operation in unlicensed bands > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2026/0075554 A1 - Document ID: US20260075554A1 - Status: Published application - Kind: A1 - Application number: 19/392,526 - Filed: 2025-11-18 - Published: 2026-03-12 - Earliest claimed: 2014-09-24 - Assignees: InterDigital Patent Holdings, Inc. - Applicants: InterDigital Patent Holdings, Inc. - Inventors: Pouriya Sadeghi; Janet A. Stern-Berkowitz; Moon-il Lee; J. Patrick Tooher; Marian Rudolf - Web page: https://patentgrep.com/patent/US20260075554A1 ## CPC - H04W 56/001: {Synchronization between nodes} - 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 5/0053: {Allocation of signalling, i.e. of overhead other than pilot signals} - H04W 56/00: Synchronisation arrangements - H04W 72/0453: Resources in frequency domain, e.g. a carrier in FDMA - H04W 72/23: in the downlink direction of a wireless link, i.e. towards a terminal - H04W 76/27: Transitions between radio resource control [RRC] states - 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 Systems, methods, and instrumentalities are disclosed for LTE operation in an unlicensed spectrum (LTE-U). A wireless transmit/receive unit (WTRU) may establish a connection with a first cell on a licensed frequency band. The WTRU may receive a first downlink transmission from a second cell operating on an unlicensed frequency band. The WTRU may determine that a synchronization signal transmission from a third cell operating on the unlicensed frequency band is transmitted using one or more resource elements. The WTRU may perform frequency and/or timing estimation based on the synchronization signal transmission. The WTRU may perform rate matching around the one or more resource elements that correspond to the synchronization signal transmission. The WTRU may perform rate matching around the one or more resource elements by de-mapping symbols of the downlink transmission. ## Claims ### Claim 1 A method of coordinating transmissions, the method comprising: establishing a connection with a first cell on a licensed frequency band; receiving, from a second cell operating on an unlicensed frequency band, a downlink transmission; determining that a synchronization signal transmission from a third cell operating on the unlicensed frequency band is transmitted using one or more resource elements, wherein the one or more resource elements correspond to a portion of at least one resource block of the downlink transmission from the second cell; and performing rate matching around the one or more resource elements that correspond to the synchronization signal transmission when receiving the downlink transmission from the second cell. ### Claim 2 (depends on 1) The method of claim 1, wherein performing rate matching around the one or more resource elements comprises: de-mapping symbols of the downlink transmission, wherein the one or more resource elements that correspond to the synchronization signal transmission are skipped during de-mapping. ### Claim 3 (depends on 1) The method of claim 1, wherein the synchronization signal transmission comprises at least one of a primary synchronization signal (PSS), a secondary synchronization signal (SSS), a physical broadcast channel (PBCH), a cell-specific reference signal (CRS), a channel state information reference signal (CSI-RS), or a demodulation reference signal (DMRS). ### Claim 4 (depends on 1) The method of claim 1, further comprising receiving a configuration from the first cell on the licensed frequency band, wherein the configuration indicates which resource elements will be used by the third cell for transmission of the synchronization signal. ### Claim 5 (depends on 4) The method of claim 4, wherein the configuration is received in a radio resource control (RRC) message. ### Claim 6 (depends on 1) The method of claim 1, further comprising performing frequency or timing estimation based on the synchronization signal transmission. ### Claim 7 (depends on 1) The method of claim 1, further comprising performing demodulation or resource symbol scaling based on the synchronization signal transmission. ### Claim 8 (depends on 1) The method of claim 1, wherein the downlink transmission is a first downlink transmission, the method further comprising: determining a power offset between the synchronization signal transmission and one or more other downlink transmissions; and determining a power level of a second downlink transmission based on the determined power offset. ### Claim 9 (depends on 1) The method of claim 1, wherein determining that the synchronization signal transmission from the third cell operating on the unlicensed frequency band is transmitted using the one or more resource elements comprises receiving downlink control information (DCI) on a downlink physical channel that indicates which resource elements are used for the synchronization signal. ### Claim 10 A wireless transmit/receive unit (WTRU) comprising: a processor configured to: establish a connection with a first cell on a licensed frequency band; receive, from a second cell operating on an unlicensed frequency band, a downlink transmission; determine that a synchronization signal transmission from a third cell operating on the unlicensed frequency band is transmitted using one or more resource elements, wherein the one or more resource elements correspond to a portion of at least one resource block of the downlink transmission from the second cell; and perform rate matching around the one or more resource elements that correspond to the synchronization signal transmission when receiving the downlink transmission from the second cell. ### Claim 11 (depends on 10) The WTRU of claim 10, wherein the processor being configured to perform rate matching around the one or more resource elements comprises being further configured to de-map symbols of the downlink transmission, wherein the one or more resource elements that correspond to the synchronization signal transmission are skipped during de-mapping. ### Claim 12 (depends on 10) The WTRU of claim 10, wherein the synchronization signal transmission comprises at least one of a primary synchronization signal (PSS), a secondary synchronization signal (SSS), a physical broadcast channel (PBCH), a cell-specific reference signal (CRS), a channel state information reference signal (CSI-RS), or a demodulation reference signal (DMRS). ### Claim 13 (depends on 10) The WTRU of claim 10, wherein the processor is further configured to receive a configuration from the first cell on the licensed frequency band, wherein the configuration indicates which resource elements will be used by the third cell for transmission of the synchronization signal transmission. ### Claim 14 (depends on 13) The WTRU of claim 13, wherein the configuration is received in a radio resource control (RRC) message. ### Claim 15 (depends on 10) The WTRU of claim 10, wherein the processor is further configured to perform frequency or timing estimation based on the synchronization signal transmission. ### Claim 16 (depends on 10) The WTRU of claim 10, wherein the processor is further configured to perform demodulation or resource symbol scaling based on the synchronization signal transmission. ### Claim 17 (depends on 10) The WTRU of claim 10, wherein the downlink transmission is a first downlink transmission, and wherein the processor is further configured to: determine a power offset between the synchronization signal transmission and one or more other downlink transmissions; and determine a power level of a second downlink transmission based on the determined power offset. ### Claim 18 (depends on 10) The WTRU of claim 10, wherein being configured to determine that the synchronization signal transmission from the third cell operating on the unlicensed frequency band is transmitted using the one or more resource elements comprises being configured to receive downlink control information (DCI) on a downlink physical channel that indicates which resource elements are used for the synchronization signal transmission.