# US 12,192,038 B2 · Systems and methods of phase-tracking reference signal transmission for OFDM > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,192,038 B2 - Document ID: US12192038B2 - Status: Granted - Kind: B2 - Application number: 17/418,150 - Filed: 2020-03-13 - Published: 2022-02-24 - Granted: 2025-01-07 - Earliest claimed: 2019-03-14 - Assignees: Apple Inc. - Applicants: Apple Inc. - Inventors: Yushu Zhang; Alexei Davydov; Gregory Morozov; Guotong Wang; Dae Won Lee; Gang Xiong; Sameer Pawar; Jie Zhu - Web page: https://patentgrep.com/patent/US12192038B2 ## CPC - H04L 27/2613: {Structure of the reference signals} - H04J 13/0062: {Zadoff-Chu} - H04L 5/0007: {the frequencies being orthogonal, e.g. OFDM(A) or DMT} - 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 27/2607: {Cyclic extensions} - H04J 11/0053: {using co-ordinated multipoint transmission/reception (co-ordinated antenna or beam-forming aspects H04B7/022)} - H04L 27/2602: {Signal structure} - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) - H04J: MULTIPLEX COMMUNICATION (transmission in general H04B; peculiar to transmission of digital information H04L5/00; systems for the simultaneous or sequential transmission of more than one television signal H04N7/08; in exchanges H04Q11/00; stereophonic systems H04S) ## Abstract Communication in a wireless network using a phase-tracking reference signal (PT-RS) for orthogonal frequency division multiplexing (OFDM) includes determining one or more PT-RS groups of adjacent subcarriers in a resource allocation for a physical uplink shared channel (PUSCH) or a physical downlink shared channel (PDSCH), encoding data to be transmitted by the PUSCH or the PDSCH in data subcarriers within the resource allocation for the PUSCH or the PDSCH, and encoding phase-tracking reference signals within the one or more PT-RS groups of adjacent subcarriers. ## Claims ### Claim 1 An apparatus for communicating a phase-tracking reference signal (PT-RS) for orthogonal frequency division multiplexing (OFDM) in a wireless communication system, the apparatus comprising: a processor; and a memory storing instructions that, when executed by the processor, configure the apparatus to: determine one or more PT-RS groups of adjacent subcarriers in a resource allocation for a physical uplink shared channel (PUSCH), wherein to determine the one or more PT-RS groups of adjacent subcarriers in the resource allocation is in response to a determination that a modulation and code scheme (MCS) indicated by downlink control information (DCI) is above an MCS threshold; modulate PT-RS subcarriers within the one or more PT-RS groups of adjacent subcarriers with a predetermined PT-RS modulation sequence, wherein the predetermined PT-RS modulation sequence is based on a Zadoff-Chu sequence; cyclically extend the Zadoff-Chu sequence to zero-power guard subcarriers, wherein the predetermined PT-RS modulation sequence comprises: s ⁡ ( n ) = x q ( { n + N 0 } ⁢ mod ⁢ N ZC ) , x q = e - j ⁢ π ⁢ qm ⁡ ( m + 1 ) N ZC , n = 0 , 1 , … , N - 1 , where q is a root of the Zadoff-Chu sequence, Nzc is a length of the Zadoff-Chu sequence, N is a number of non-zero subcarriers in a PT-RS group, m is an integer between zero and Nzc, and N0 determines a length of a cyclic extension; encode data to be transmitted by the PUSCH in data subcarriers within the resource allocation for the PUSCH; and encode phase-tracking reference signals within the one or more PT-RS groups of adjacent subcarriers. ### Claim 2 (depends on 1) The apparatus of claim 1, wherein the apparatus is configured for a user equipment (UE) or a base station, and wherein the one or more PT-RS groups of adjacent subcarriers comprise at least two PT-RS groups separated from one another by one or more of the data subcarriers. ### Claim 3 (depends on 1) The apparatus of claim 1, wherein the instructions further configure the apparatus to configure a guard subcarrier within the one or more PT-RS groups of adjacent subcarriers to protect from inter-carrier interference created by the PUSCH. ### Claim 4 (depends on 3) The apparatus of claim 3, wherein the instructions further configure the apparatus to configure the guard subcarrier with zero power at a boundary of the one or more PT-RS groups of adjacent subcarriers. ### Claim 5 (depends on 4) The apparatus of claim 4, wherein the instructions further configure the apparatus to use unused power of the guard subcarrier configured with zero power to power boost non-zero power PT-RS subcarriers within the one or more PT-RS groups of adjacent subcarriers. ### Claim 6 (depends on 1) The apparatus of claim 1, wherein to determine the one or more PT-RS groups of adjacent subcarriers in the resource allocation comprises to determine a total number of the adjacent subcarriers in the one or more PT-RS groups or a number of non-zero power subcarriers within the one or more PT-RS groups based on at least one of a radio resource control (RRC) signal, the DCI, a cell identifier (ID), a virtual cell ID, a PT-RS port index, a radio network temporary identifier (RNTI), a symbol index, a slot index, a subcarrier spacing, the MCS, and a number of physical resource blocks (PRBs). ### Claim 7 (depends on 1) The apparatus of claim 1, wherein to determine the one or more PT-RS groups of adjacent subcarriers in the resource allocation comprises to determine a frequency offset of the PT-RS group based on at least one of a radio resource control (RRC) signal, the DCI, a cell identifier (ID), a virtual cell ID, a PT-RS port index, a radio network temporary identifier (RNTI), a symbol index, a slot index, a subcarrier spacing, the MCS, and a number of physical resource blocks (PRBs). ### Claim 8 (depends on 1) The apparatus of claim 1, wherein to determine the one or more PT-RS groups of adjacent subcarriers in the resource allocation is in response to a determination that an allocated bandwidth is above an allocated bandwidth threshold. ### Claim 9 (depends on 1) The apparatus of claim 1, wherein the instructions further configure the apparatus to generate, at a user equipment (UE), UE capability signaling for a base station comprising at least one of the MCS threshold and an allocated bandwidth threshold. ### Claim 10 (depends on 1) The apparatus of claim 1, wherein the instructions further configure the apparatus to, in response to determining that at least a subset of non-zero power PT-RS subcarriers within a particular PT-RS group of the one or more PT-RS groups are punctured due to a collision with another downlink signal, use PT-RS subcarriers within the PT-RS group for data channel transmission. ### Claim 11 A method for transmitting a phase-tracking reference signal (PT-RS) for orthogonal frequency division multiplexing (OFDM) in a wireless communication system, the method comprising: determining one or more PT-RS groups of adjacent subcarriers in a resource allocation for a physical uplink shared channel (PUSCH), wherein determining the one or more PT-RS groups of adjacent subcarriers in the resource allocation is in response to a determination that a modulation and code scheme (MCS) indicated by downlink control information (DCI) is above an MCS threshold; modulating PT-RS subcarriers within the one or more PT-RS groups of adjacent subcarriers with a predetermined PT-RS modulation sequence, wherein the predetermined PT-RS modulation sequence is based on a Zadoff-Chu sequence; cyclically extending the Zadoff-Chu sequence to zero-power guard subcarriers, wherein the predetermined PT-RS modulation sequence comprises: s ⁡ ( n ) = x q ( { n + N 0 } ⁢ mod ⁢ N ZC ) , x q = e - j ⁢ π ⁢ qm ⁡ ( m + 1 ) N ZC , n = 0 , 1 , … , N - 1 , where q is a root of the Zadoff-Chu sequence, Nzc is a length of the Zadoff-Chu sequence, N is a number of non-zero subcarriers in a PT-RS group, m is an integer between zero and Nzc, and N0 determines a length of a cyclic extension; transmitting data in data subcarriers within the resource allocation for the PUSCH; and transmitting phase-tracking reference signals within the one or more PT-RS groups of adjacent subcarriers. ### Claim 12 (depends on 11) The method of claim 11, further comprising configuring a guard subcarrier with zero power at a boundary of the one or more PT-RS groups of adjacent subcarriers. ### Claim 13 (depends on 12) The method of claim 12, further comprising using unused power of the guard subcarrier configured with zero power to power boost non-zero power PT-RS subcarriers within the one or more PT-RS groups of adjacent subcarriers.