# US 2017/0289935 A1 · Method and apparatus for synchronization for vehicle-to-x communication > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2017/0289935 A1 - Document ID: US20170289935A1 - Status: Published application - Kind: A1 - Application number: 15/475,933 - Filed: 2017-03-31 - Published: 2017-10-05 - Earliest claimed: 2016-04-01 - Assignees: Innovative Technology Lab Co., Ltd. - Applicants: Innovative Technology Lab Co., Ltd. - Inventors: Sung Jun YOON - Web page: https://patentgrep.com/patent/US20170289935A1 ## CPC - H04W 56/001: {Synchronization between nodes} - G01S 19/13: Receivers - H04B 1/3822: specially adapted for use in vehicles (H04B1/3827 takes precedence) - H04L 5/0051: {of dedicated pilots, i.e. pilots destined for a single user or terminal} - H04L 5/0053: {Allocation of signalling, i.e. of overhead other than pilot signals} - 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} - H04L 67/12: specially adapted for proprietary or special-purpose networking environments, e.g. medical networks, sensor networks, networks in vehicles or remote metering networks - H04L 27/2636: {with FFT or DFT modulators, e.g. standard single-carrier frequency-division multiple access [SC-FDMA] transmitter or DFT spread orthogonal frequency division multiplexing [DFT-SOFDM]} - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) - G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES - H04B: TRANSMISSION - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract Provided is a synchronization method and apparatus in a wireless communication system. A synchronization method according to an aspect of the present disclosure may include: receiving a first synchronization signal and a second synchronization signal; determining a priority order of the first synchronization signal and the second synchronization signal; and performing synchronization based on a synchronization signal having a higher priority between the first synchronization signal and the second synchronization signal. ## Claims ### Claim 1 A method of generating a synchronization signal, the method comprising: synchronizing, by a first device, a timing of a synchronization signal received from a synchronization source, the timing of the synchronization signal being associated with a synchronization timing of a Global Navigational Satellite System (GNSS); determining a subframe to transmit a primary sidelink synchronization signal (PSSS) and a secondary sidelink synchronization signal (SSSS); mapping the SSSS to two consecutive single frequency-frequency division multiple access (SC-FDMA) symbols in the determined subframe; and transmitting, from the first device to a second device, the PSSS and the SSSS in the determined subframe, wherein the mapping the SSSS comprises: generating a first length-31 sequence based on m1; generating a second length-31 sequence based on m0, where m1 is greater than m0; and mapping the first length-31 sequence and the second length-31 sequence to 62 consecutive subcarriers in the two consecutive SC-FDMA symbols in the determined subframe, wherein a portion of the first length-31 sequence is mapped to a subcarrier having a lowest index among the 62 consecutive subcarriers and a portion of the second length-31 sequence is mapped to a subcarrier having a highest index among the 62 consecutive subcarriers. ### Claim 2 (depends on 1) The method of claim 1, wherein the mapped first length-31 sequence and the second length-31 sequence are interleaved with each other. ### Claim 3 (depends on 1) The method of claim 1, further comprising: determining a different synchronization signal transmitted from a user equipment synchronized with an evolved NodeB, wherein the different synchronization signal comprises a different SSSS mapped to different 62 subcarriers in a different subframe, and wherein the different SSSS comprises a different first length-31 sequence generated based on a first value and a different second length-31 sequence generated based on a second value, wherein the second value is greater than the first value, and wherein a portion of the different first length-31 sequence is mapped to a subcarrier having a lowest index among the different 62 consecutive subcarriers and a portion of the different second length-31 sequence is mapped to a subcarrier having a highest index among the different 62 consecutive subcarriers. ### Claim 4 (depends on 1) The method of claim 1, further comprising: selecting, based on a priority, the synchronization signal among different synchronization signals, wherein a synchronization signal of a device directly synchronized to a GNSS is prioritized over a synchronization signal of a device indirectly synchronized to a GNSS or over a synchronization signal of a device indirectly synchronized to an evolved NodeB (eNB). ### Claim 5 (depends on 4) The method of claim 4, wherein a synchronization signal of a device directly synchronized to an eNB is prioritized over a synchronization signal of a device indirectly synchronized to a GNSS. ### Claim 6 (depends on 1) The method of claim 1, further comprising generating the PSSS based on root index 26 or root index 37. ### Claim 7 A method of generating a synchronization signal, the method comprising: determining, by a first device, at least one of synchronization signals transmitted from a plurality of synchronization sources, wherein the plurality of synchronization sources comprise an evolved NodeB (eNB), a Global Navigational Satellite System (GNSS), and a device capable of synchronizing with a GNSS; synchronizing, by the first device, a timing of a synchronization signal selected from the determined synchronization signals, the timing of the selected synchronization signal being associated with a synchronization timing of the GNSS; determining a subframe to transmit a primary sidelink synchronization signal (PSSS) and a secondary sidelink synchronization signal (SSSS); mapping the PSSS to first two consecutive single carrier-frequency division multiple access (SC-FDMA) symbols in the determined subframe; mapping the SSSS to second two consecutive SC-FDMA symbols in the determined subframe; and transmitting, from the first device to a second device, the PSSS and SSSS mapped in the determined subframe, wherein the mapping the SSSS comprises: determining two integers m0 and m1, where m1 is greater than m0; generating a first length-31 sequence based on mi; generating a second length-31 sequence based on m0; and mapping the first length-31 sequence and the second length-31 sequence to 62 consecutive subcarriers in the second two consecutive SC-FDMA symbols in the determined subframe, wherein a portion of the first length-31 sequence is mapped to a subcarrier having the lowest index among the 62 consecutive subcarriers and a portion of the second length-31 sequence is mapped to a subcarrier having the highest index among the 62 consecutive subcarriers. ### Claim 8 (depends on 7) The method of claim 7, wherein the mapped first length-31 sequence and the second length-31 sequence are interleaved with each other. ### Claim 9 (depends on 7) The method of claim 7, wherein the determining the at least one of synchronization signals comprises: determining a different synchronization signal transmitted from a user equipment synchronized with an evolved NodeB, wherein the different synchronization signal comprises a different SSSS mapped to different 62 subcarriers in a different subframe, and wherein the different SSSS comprises a different first length-31 sequence generated based on a first value and a different second length-31 sequence generated based on a second value, wherein the second value is greater than the first value, and wherein a portion of the different first length-31 sequence is mapped to a subcarrier having the lowest index among the different 62 consecutive subcarriers and a portion of the different second length-31 sequence is mapped to a subcarrier having the highest index among the different 62 consecutive subcarriers. ### Claim 10 (depends on 7) The method of claim 7, further comprising: selecting, based on a priority, the timing of the synchronization signal selected from the determined synchronization signals, wherein a synchronization signal of a device directly synchronized to a GNSS is prioritized over a synchronization signal of a device indirectly synchronized to a GNSS or over a synchronization signal of a device indirectly synchronized to an eNB. ### Claim 11 (depends on 10) The method of claim 10, wherein a synchronization signal of a device directly synchronized to an eNB is prioritized over a synchronization signal of a device indirectly synchronized to a GNSS. ### Claim 12 (depends on 7) The method of claim 7, further comprising generating the PSSS based on root index 26 or root index 37. ### Claim 13 A method of selecting a synchronization signal, the method comprising: determining, by a first device, at least one of synchronization signals transmitted from a plurality of synchronization sources, wherein the plurality of synchronization sources comprise an evolved NodeB (eNB), a Global Navigational Satellite System (GNSS), and a device capable of synchronizing with a GNSS; and synchronizing, by the first device, a timing of a synchronization signal selected from the determined synchronization signals, the timing of the selected synchronization signal being associated with a synchronization timing of the GNSS, wherein the synchronizing the timing of the synchronization signal comprises: determining a subframe to which a primary sidelink synchronization signal (PSSS) of the synchronization signal is mapped; and determining a secondary sidelink synchronization signal (SSSS) of the synchronization signal from 62 consecutive subcarriers of two consecutive single frequency-frequency division multiple access (SC-FDMA) symbols in the determined subframe, wherein the SSSS comprises a first length-31 sequence generated based on m1 and a second length-31 sequence generated based on m0, where m1 is greater than m0, and wherein a portion of the first length-31 sequence is mapped to a subcarrier having a lowest index among the 62 consecutive subcarriers and a portion of the second length-31 sequence is mapped to a subcarrier having a highest index among the 62 consecutive subcarriers. ### Claim 14 (depends on 13) The method of claim 13, wherein the mapped first length-31 sequence and the second length-31 sequence are interleaved with each other. ### Claim 15 (depends on 13) The method of claim 13, further comprising: determining a different synchronization signal transmitted from a user equipment synchronized with an evolved NodeB, wherein the different synchronization signal comprises a different SSSS mapped to different 62 subcarriers in a different subframe, and wherein the different SSSS comprises a different first length-31 sequence generated based on a first value and a different second length-31 sequence generated based on a second value, wherein the second value is greater than the first value, and wherein a portion of the different first length-31 sequence is mapped to a subcarrier having a lowest index among the different 62 consecutive subcarriers and a portion of the different second length-31 sequence is mapped to a subcarrier having a highest index among the different 62 consecutive subcarriers. ### Claim 16 (depends on 13) The method of claim 13, further comprising: selecting, based on a priority, the synchronization signal among different synchronization signals, wherein a synchronization signal of a device directly synchronized to a GNSS is prioritized over a synchronization signal of a device indirectly synchronized to a GNSS or over a synchronization signal of a device indirectly synchronized to an evolved NodeB (eNB). ### Claim 17 (depends on 16) The method of claim 16, wherein a synchronization signal of a device directly synchronized to an eNB is prioritized over a synchronization signal of a device indirectly synchronized to a GNSS. ### Claim 18 (depends on 13) The method of claim 13, further comprising determining, based on the PSSS, root index 26 or root index 37.