# US 10,873,489 B2 · Method of transmitting and receiving device-to-device UE signal in wireless communication system and apparatus therefor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,873,489 B2 - Document ID: US10873489B2 - Status: Granted - Kind: B2 - Application number: 15/126,973 - Filed: 2015-03-19 - Published: 2017-04-06 - Granted: 2020-12-22 - Earliest claimed: 2014-03-19 - Assignees: LG Electronics Inc. - Applicants: LG Electronics Inc. - Inventors: Kijun Kim; Hanbyul Seo; Hakseong Kim - Web page: https://patentgrep.com/patent/US10873489B2 ## CPC - H04L 27/2613: {Structure of the reference signals} - H04L 27/2607: {Cyclic extensions} - H04W 76/14: Direct-mode setup - H04L 5/0051: {of dedicated pilots, i.e. pilots destined for a single user or terminal} - H04W 84/042: {Public Land Mobile systems, e.g. cellular systems} - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) ## Abstract According to one embodiment of the present invention, a method of transmitting a D2D (device-to-device) signal, which is transmitted by a user equipment in a wireless communication system, comprising the steps of determining a sequence group, determining a base sequence in the sequence group, generating a reference signal sequence by applying cyclic shift to the base sequence, generating a demodulation reference signal sequence from the reference signal sequence and transmitting a subframe to which the demodulation reference signal sequence is mapped, wherein ID information, which is used for at least one selected from the group consisting of determination of the sequence group, determination of the base sequence and application of the cyclic shift, corresponds to one of an SSID (synchronization ID) and an L1 ID (layer 1 ID) changing according to time. ## Claims ### Claim 1 A method for transmitting a demodulation reference signal (DMRS), by a user equipment (UE) in a wireless communication system, the method comprising: receiving information related with a resource pool for device-to-device (D2D) transmission; determining a sequence for the DMRS based on an identifier (ID) and an index of a slot; and transmitting the DMRS based on the sequence, wherein the resource pool is composed of one or more subframes used for the D2D transmission, wherein the ID is used, by the UE within a D2D cluster, for performing group hopping for the sequence, wherein the one or more subframes are part of consecutive radio frames, and are discontinuous on time resources within the consecutive radio frames, and wherein the index of the slot is determined only within the one or more subframes included in the resource pool. ### Claim 2 (depends on 1) The method of claim 1, wherein the ID is received via scheduling assignment channel. ### Claim 3 (depends on 1) The method of claim 1, wherein the slot index is initialized at a start point of a D2D control channel transmission period. ### Claim 4 (depends on 1) The method of claim 1, wherein based on the DMRS being related to a D2D shared channel and the UE being related to an in-coverage UE, the ID is related to one designated by an eNB among an SSID (synchronization ID) and an L1 ID (layer 1 ID). ### Claim 5 (depends on 1) The method of claim 1, wherein if the DMRS is related to with a D2D shared channel and the UE is related to an out of coverage UE, the ID is related to one designated by a UE transmitting a synchronization signal among an SSID (synchronization ID) and an L1 ID (layer 1 ID). ### Claim 6 (depends on 5) The method of claim 5, wherein the L1 ID is received via a D2D control channel. ### Claim 7 (depends on 5) The method of claim 5, wherein based on the user equipment being related to the out of coverage UE, the L1 ID hops in every D2D control channel period. ### Claim 8 (depends on 1) The method of claim 1, wherein based on the DMRS being related to with a D2D control channel, the ID is related to an SSID (synchronization ID). ### Claim 9 (depends on 1) The method of claim 1, wherein based on group hopping being applied when a sequence group is determined, a group hopping pattern is determined according to the ID. ### Claim 10 (depends on 9) The method of claim 9, wherein the sequence group is determined by u=(fgh (ns)+fss)mod 30, wherein if the group hopping is not applied, fgh(ns) is related to 0, wherein if the group hopping is applied, the fgh(ns) is related to (Σi=07c(8ns+i)·2i)mod 30, wherein c(i) is related to a scrambling sequence initialized by c init = ⌊ N ID 30 ⌋ + offset , wherein NID is related to the ID, wherein fss corresponds to (NID+ΔSS)mod 30 and wherein Δss ∈{0, 1, . . . , 29}. ### Claim 11 (depends on 1) The method of claim 1, wherein based on a reference signal sequence generated by applying cyclic shift to the sequence being used for resource blocks equal to or less than 5, the sequence is related to a first sequence of a sequence group. ### Claim 12 (depends on 11) The method of claim 11, wherein based on the reference signal sequence being used for resource blocks equal to or greater than 6 and sequence hopping is used instead of group hopping, the sequence is selected according to the ID. ### Claim 13 (depends on 12) The method of claim 12, wherein the sequence is selected by a scrambling sequence c(i) initialized by c init = ⌊ N ID 30 ⌋ · 2 5 + ( N ID + Δ ss ) ⁢ mod ⁢ ⁢ 30 and wherein NID is related to the ID and Δss ∈{0, 1, . . . , 29}. ### Claim 14 (depends on 11) The method of claim 11, wherein the cyclic shift is determined by a scrambling sequence c(i) initialized by c init = ⌊ N ID 30 ⌋ · 2 5 + ( N ID ) ⁢ mod ⁢ ⁢ 30 and wherein NID is related to the ID. ### Claim 15 (depends on 1) The method of claim 1, wherein the ID is L1 ID (layer 1 ID), and the L1 ID is changed over time. ### Claim 16 (depends on 1) The method of claim 1, wherein the ID is an SSID (synchronization ID). ### Claim 17 A user equipment (UE) for transmitting a demodulation reference signal (DMRS), the UE comprising: a transceiver; and a processor operatively connected to the transceiver and configured to: receive information related with a resource pool for device-to-device (D2D) transmission, determine a sequence for the DMRS based on an identifier (ID) and an index of a slot, and transmit the DMRS based on the sequence, wherein the resource pool is composed of one or more subframes used for the D2D transmission, wherein the ID is used, by the UE within a D2D cluster, for performing group hopping for the sequence, wherein the one or more subframes are part of consecutive radio frames, and are discontinuous on time resources within the consecutive radio frames, and wherein the index of the slot is determined only within the one or more subframes included in the resource pool. ### Claim 18 (depends on 17) The UE of claim 17, wherein the ID is L1 ID (layer 1 ID), and the L1 ID is changed over time. ### Claim 19 (depends on 17) The UE of claim 17, wherein the ID is an SSID (synchronization ID).