Method of transmitting and receiving device-to-device UE signal in wireless communication system and apparatus therefor
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.
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.
2. The method of claim 1 , wherein the ID is received via scheduling assignment channel.
3. The method of claim 1 , wherein the slot index is initialized at a start point of a D2D control channel transmission period.
4. 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).
5. 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).
6. The method of claim 5 , wherein the L1 ID is received via a D2D control channel.
7. 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.
8. 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).
9. 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.
10. The method of claim 9 , wherein the sequence group is determined by u=(f gh (n s )+f ss )mod 30, wherein if the group hopping is not applied, f gh (n s ) is related to 0, wherein if the group hopping is applied, the f gh (n s ) is related to (Σ i=0 7 c(8n s +i)·2 i )mod 30, wherein c(i) is related to a scrambling sequence initialized by
c
init
=
⌊
N
ID
30
⌋
+
offset
,
wherein N ID is related to the ID, wherein f ss corresponds to (N ID +Δ SS )mod 30 and wherein Δ ss ∈{0, 1, . . . , 29}.
11. 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.
12. 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.
13. 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 N ID is related to the ID and Δ ss ∈{0, 1, . . . , 29}.
14. 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 N ID is related to the ID.
15. The method of claim 1 , wherein the ID is L1 ID (layer 1 ID), and the L1 ID is changed over time.
16. The method of claim 1 , wherein the ID is an SSID (synchronization ID).
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.
18. The UE of claim 17 , wherein the ID is L1 ID (layer 1 ID), and the L1 ID is changed over time.
19. The UE of claim 17 , wherein the ID is an SSID (synchronization ID).