# US 12,004,102 B2 · Apparatus and method for configuring synchronization signal for communication between user devices > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,004,102 B2 - Document ID: US12004102B2 - Status: Granted - Kind: B2 - Application number: 17/885,518 - Filed: 2022-08-10 - Published: 2022-12-08 - Granted: 2024-06-04 - Earliest claimed: 2014-11-05 - Assignees: Innovative Technology Lab Co., Ltd. - Applicants: Innovative Technology Lab Co., Ltd. - Inventors: Sung Jun Yoon - Web page: https://patentgrep.com/patent/US12004102B2 ## CPC - H04W 56/001: {Synchronization between nodes} - H04L 27/2613: {Structure of the reference signals} - H04L 27/2692: {with preamble design, i.e. with negotiation of the synchronisation sequence with transmitter or sequence linked to the algorithm used at the receiver} - H04W 4/70: Services for machine-to-machine communication [M2M] or machine type communication [MTC] - 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 Exemplary embodiments provide a method and apparatus for transmitting a synchronization signal for Device-to-Device (D2D) communication in a wireless communication system. The method includes: receiving, at a first UE, a D2D synchronization signal transmitted from a second UE, the D2D synchronization signal comprising a primary D2D synchronization signal (PD2DSS) and a secondary D2D synchronization signal (SD2DSS); determining a root index based on the received PD2DSS; and determining a type of a synchronization source based on the root index. The root index corresponds to an integer value X when the type of synchronization source is associated with D2DSSue_net. The root index corresponds to an integer value Y when the type of synchronization source is associated with D2DSSue_oon. Each of the integer value X and integer value Y is not an element of a set {25, 29, 34}. ## Claims ### Claim 1 A first wireless user device comprising: at least one processor; and memory storing instructions that, when executed by the at least one processor, cause the first wireless user device to: receive, from a second wireless user device, one or more wireless signals for direct communication between wireless user devices, wherein the one or more wireless signals comprises a primary synchronization signal and a secondary synchronization signal; determine, based on the primary synchronization signal, a root index associated with the primary synchronization signal, wherein the root index associated with the primary synchronization signal corresponds to one of a plurality of integer values, wherein each of the plurality of integer values is different from root index values associated with synchronization signals transmitted from one or more base stations, and wherein a type of a synchronization source is associated with the one of the plurality of integer values; and decode the secondary synchronization signal that is mapped in two symbols in a same subframe by: determining, based on one of two different conditions, whether a first m-sequence of the secondary synchronization signal is mapped to first sub-carriers of the two symbols or mapped to second sub-carriers of the two symbols, wherein indexes of the first sub-carriers are even numbers and indexes of the second sub-carriers are odd numbers. ### Claim 2 (depends on 1) The first wireless user device of claim 1, wherein the instructions, when executed by the at least one processor, cause the first wireless user device to decode the primary synchronization signal mapped in second two symbols in the same subframe. ### Claim 3 (depends on 1) The first wireless user device of claim 1, wherein the instructions, when executed by the at least one processor, cause the first wireless user device to: determine, based on the root index corresponding to a first value of the plurality of integer values, that the second wireless user device has a synchronization timing originated from a base station. ### Claim 4 (depends on 3) The first wireless user device of claim 3, wherein NID(1) and NID(2) are associated with the secondary synchronization signal, where NID(1) is an integer selected from {0, 1, . . . , 167}, and NID(2) is 0 when the root index associated with the primary synchronization signal corresponds to the first value. ### Claim 5 (depends on 1) The first wireless user device of claim 1, wherein the instructions, when executed by the at least one processor, cause the first wireless user device to: determine, based on the root index corresponding to a second value of the plurality of integer values, that the second wireless user device has a synchronization timing of an independent synchronization source. ### Claim 6 (depends on 5) The first wireless user device of claim 5, wherein NID(1) and NID(2) are associated with the secondary synchronization signal, where NID(1) is an integer selected from {0, 1, . . . , 167}, and NID(2) when the root index associated with the primary synchronization signal corresponds to the second value. ### Claim 7 (depends on 1) The first wireless user device of claim 1, wherein the instructions, when executed by the at least one processor, cause the first wireless user device to determine whether the first m-sequence of the secondary synchronization signal is mapped to the first sub-carriers of the two symbols or mapped to the second sub-carriers of the two symbols by determining, based on a first communication mode of the two different conditions, that the first m-sequence of the secondary synchronization signal is mapped to the first sub-carriers. ### Claim 8 (depends on 1) The first wireless user device of claim 1, wherein the instructions, when executed by the at least one processor, cause the first wireless user device to determine whether the first m-sequence of the secondary synchronization signal is mapped to the first sub-carriers of the two symbols or mapped to the second sub-carriers of the two symbols by determining, based on a second communication mode of the two different conditions, that the first m-sequence of the secondary synchronization signal is mapped to the second sub-carriers. ### Claim 9 (depends on 1) The first wireless user device of claim 1, wherein the one or more wireless signals for direct communication is a device-to-device (D2D) communication signal. ### Claim 10 A method performed by a first wireless user device, the method comprising: receiving, from a second wireless user device, one or more wireless signals for direct communication between wireless user devices, wherein the one or more wireless signals comprises a primary synchronization signal and a secondary synchronization signal; determining, based on the primary synchronization signal, a root index associated with the primary synchronization signal, wherein the root index associated with the primary synchronization signal corresponds to one of a plurality of integer values, wherein each of the plurality of integer values is different from root index values associated with synchronization signals transmitted from one or more base stations, and wherein a type of a synchronization source is associated with the one of the plurality of integer values; and decoding the secondary synchronization signal that is mapped in two symbols in a same subframe by: determining, based on one of two different conditions, whether a first m-sequence of the secondary synchronization signal is mapped to first sub-carriers of the two symbols or mapped to second sub-carriers of the two symbols, wherein indexes of the first sub-carriers are even numbers and indexes of the second sub-carriers are odd numbers. ### Claim 11 (depends on 10) The method of claim 10, further comprising decoding the primary synchronization signal mapped in second two symbols in the same subframe. ### Claim 12 (depends on 10) The method of claim 10, further comprising: determining, based on the root index corresponding to a first value of the plurality of integer values, that the second wireless user device has a synchronization timing originated from a base station. ### Claim 13 (depends on 12) The method of claim 12, wherein NID(1) and NID(2) are associated with the secondary synchronization signal, where NID(1) is an integer selected from {0, 1, . . . , 167}, and NID(2) is 0 when the root index associated with the primary synchronization signal corresponds to the first value. ### Claim 14 (depends on 10) The method of claim 10, further comprising: determining, based on the root index corresponding to a second value of the plurality of integer values, that the second wireless user device has a synchronization timing of an independent synchronization source. ### Claim 15 (depends on 14) The method of claim 14, wherein NID(1) and NID(2) are associated with the secondary synchronization signal, where NID(1) is an integer selected from {0, 1, . . . , 167}, and NID(2) when the root index associated with the primary synchronization signal corresponds to the second value. ### Claim 16 (depends on 10) The method of claim 10, further comprising: determining whether the first m-sequence of the secondary synchronization signal is mapped to the first sub-carriers of the two symbols or mapped to the second sub-carriers of the two symbols by determining, based on a first communication mode of the two different conditions, that the first m-sequence of the secondary synchronization signal is mapped to the first sub-carriers. ### Claim 17 (depends on 10) The method of claim 10, further comprising: determining whether the first m-sequence of the secondary synchronization signal is mapped to the first sub-carriers of the two symbols or mapped to the second sub-carriers of the two symbols by determining, based on a second communication mode of the two different conditions, that the first m-sequence of the secondary synchronization signal is mapped to the second sub-carriers. ### Claim 18 (depends on 10) The method of claim 10, wherein the one or more wireless signals for direct communication is a device-to-device (D2D) communication signal.