Method and apparatus for configuring DM-RS for V2X

1. A wireless user device comprising:

a wireless transceiver comprising an antenna and configured to receive one or more messages comprising one or more parameters associated with Vehicle-to-everything (V2X) communication; and

one or more processors configured to:

determine, based on a first group-hopping associated with a first time resource, a first Demodulation-Reference Signal (DM-RS) for V2X communication, and determine, based on a second group-hopping associated with the first time resource and with an offset, a second DM-RS for V2X communication, wherein the first group-hopping and the second group-hopping apply different inputs in a pseudo-random sequence;

map the first DM-RS for V2X communication in a first symbol in the first time resource, and map the second DM-RS for V2X communication in a second symbol in the time resource;

determine, based on a third group-hopping associated with a second time resource, a third DM-RS for V2X communication, and determine, based on a fourth group-hopping associated with the second time resource and with an offset, a fourth DM-RS for V2X communication, wherein the third group-hopping and the fourth group-hopping apply different inputs in the pseudo-random sequence; and

map the third DM-RS for V2X communication in a first symbol in the second time resource, and map the fourth DM-RS for V2X communication in a second symbol in the second time resource,

wherein the wireless transceiver transmits the mapped first DM-RS for V2X communication, the mapped second DM-RS for V2X communication, the mapped third DM-RS for V2X communication, and the mapped fourth DM-RS for V2X communication.

2. The wireless user device of claim 1 , wherein the first group-hopping and the third group-hopping are associated with (Σ i=0 7 c(16n ss PUSSCH +i)·2 i )mod 30, and

wherein the second group-hopping and the fourth group-hopping are associated with (Σ i=0 7 c(16n ss PSSCH +8+i)·2 i )mod 30,

where c(x) denotes the pseudo-random sequence that is defined as a length-31 Gold sequence and n ss PSSCH denotes a current slot number in a subframe pool for a sidelink, wherein the first time resource is a first slot of a subframe, and wherein the second time resource is a second slot of the subframe.

3. The wireless user device of claim 2 , wherein n ss PSSCH =k for the first slot of the subframe and n ss PSSCH =k+1 for the second slot of the subframe, where k is a non-negative integer.

4. The wireless user device of claim 1 , wherein the wireless transceiver is configured to transmit, using first orthogonal sequence [+1 +1 +1 +1] or second orthogonal sequence [+1 −1 +1 −1], the first, second, third, and fourth DM-RSs for V2X communication.

5. The wireless user device of claim 4 , wherein the one or more processors is configured to use the first orthogonal sequence [+1 +1 +1 +1] based on a modulo-2 operation of an identifier being equal to zero, or

wherein the one or more processors is configured to use the second orthogonal sequence [+1 −1 +1 −1] based on a modulo-2 operation of the identifier being equal to one.

6. The wireless user device of claim 1 , wherein the one or more processors is configured to:

determine to transmit, to a target wireless user device, a V2X data channel; and

determine, for mapping the first, second, third, and fourth DM-RSs, a plurality of symbols in the first time resource and a plurality of symbols in the second time resource,

wherein the first, second, third, and fourth DM-RSs are associated with the V2X data channel.

7. The wireless user device of claim 1 , wherein the one or more processors is configured to:

determine whether to enable a group-hopping for DM-RSs associated with a V2X data channel.

8. The wireless user device of claim 1 ,

wherein each of the first time resource and the second time resource consists of seven symbols, respectively,

wherein the first time resource precedes the second time resource in a time axis,

wherein the first symbol in the first time resource is symbol #2 and the second symbol in the first time resource is symbol #5, the seven symbols in the first time resource being arranged from symbol #0 to symbol #6, and

wherein the first symbol in the second time resource is symbol #1 and the second symbol in the second time resource is symbol #4, the seven symbols in the second time resource being arranged from symbol #0 to symbol #6.

9. A system comprising:

a base station configured to transmit one or more messages comprising one or more parameters associated with Vehicle-to-everything (V2X) communication; and

a wireless user device comprising:

a wireless transceiver comprising an antenna and configured to receive, from the base station, the one or more messages; and

one or more processors configured to:

determine, based on a first group-hopping associated with a first time resource, a first Demodulation-Reference Signal (DM-RS) for V2X communication, and determine, based on a second group-hopping associated with the first time resource and with an offset, a second DM-RS for V2X communication, wherein the first group-hopping and the second group-hopping apply different inputs in a pseudo-random sequence;

map the first DM-RS for V2X communication in a first symbol in the first time resource, and map the second DM-RS for V2X communication in a second symbol in the time resource;

determine, based on a third group-hopping associated with a second time resource, a third DM-RS for V2X communication, and determine, based on a fourth group-hopping associated with the second time resource and with an offset, a fourth DM-RS for V2X communication, wherein the third group-hopping and the fourth group-hopping apply different inputs in the pseudo-random sequence; and

map the third DM-RS for V2X communication in a first symbol in the second time resource, and map the fourth DM-RS for V2X communication in a second symbol in the second time resource,

wherein the wireless transceiver transmits the mapped first DM-RS for V2X communication, the mapped second DM-RS for V2X communication, the mapped third DM-RS for V2X communication, and the mapped fourth DM-RS for V2X communication.

10. The system of claim 9 , wherein the first group-hopping and the third group-hopping are associated with (Σ i=0 7 c(16n ss PSSCH +i)·2 i )mod 30, and

wherein the second group-hopping and the fourth group-hopping are associated with (Σ i=0 7 c(16n ss PSSCH +8+i)·2 i )mod 30,

where c(x) denotes the pseudo-random sequence that is defined as a length-31 Gold sequence and n ss PSSCH denotes a current slot number in a subframe pool for a sidelink, wherein the first time resource is a first slot of a subframe, and wherein the second time resource is a second slot of the subframe.

11. The system of claim 10 , wherein n ss PSSCH =k for the first slot of the subframe and n ss PSSCH =k+1 for the second slot of the subframe, where k is a non-negative integer.

12. The system of claim 9 , wherein the wireless transceiver is configured to transmit, using first orthogonal sequence [+1 +1 +1 +1] or second orthogonal sequence [+1 −1 +1 −1], the first, second, third, and fourth DM-RSs for V2X communication.

13. The system of claim 12 , wherein the one or more processors is configured to use the first orthogonal sequence [+1 +1 +1 +1] based on a modulo-2 operation of an identifier being equal to zero, or

wherein the one or more processors is configured to use the second orthogonal sequence [+1 −1 +1 −1] based on a modulo-2 operation of the identifier being equal to one.

14. The system of claim 9 , wherein the one or more processors is configured to:

determine to transmit, to a target wireless user device, a V2X data channel; and

determine, for mapping the first, second, third, and fourth DM-RSs, a plurality of symbols in the first time resource and a plurality of symbols in the second time resource,

wherein the first, second, third, and fourth DM-RSs are associated with the V2X data channel.

15. The system of claim 9 , wherein the one or more processors is configured to:

determine whether to enable a group-hopping for DM-RSs associated with a V2X data channel.

16. The system of claim 9 ,

wherein each of the first time resource and the second time resource consists of seven symbols, respectively,

wherein the first time resource precedes the second time resource in a time axis,

wherein the first symbol in the first time resource is symbol #2 and the second symbol in the first time resource is symbol #5, the seven symbols in the first time resource being arranged from symbol #0 to symbol #6, and

wherein the first symbol in the second time resource is symbol #1 and the second symbol in the second time resource is symbol #4, the seven symbols in the second time resource being arranged from symbol #0 to symbol #6.

17. A method comprising:

receiving, by a wireless transceiver of a wireless user device, one or more messages comprising one or more parameters associated with Vehicle-to-everything (V2X) communication;

determining, by the wireless user device and based on a first group-hopping associated with a first time resource, a first Demodulation-Reference Signal (DM-RS) for V2X communication, and determining, based on a second group-hopping associated with the first time resource and with an offset, a second DM-RS for V2X communication, wherein the first group-hopping and the second group-hopping apply different inputs in a pseudo-random sequence;

mapping the first DM-RS for V2X communication in a first symbol in the first time resource, and mapping the second DM-RS for V2X communication in a second symbol in the time resource;

determining, based on a third group-hopping associated with a second time resource, a third DM-RS for V2X communication, and determining, based on a fourth group-hopping associated with the second time resource and with an offset, a fourth DM-RS for V2X communication, wherein the third group-hopping and the fourth group-hopping apply different inputs in the pseudo-random sequence;

mapping the third DM-RS for V2X communication in a first symbol in the second time resource, and mapping the fourth DM-RS for V2X communication in a second symbol in the second time resource; and

transmitting the mapped first DM-RS for V2X communication, the mapped second DM-RS for V2X communication, the mapped third DM-RS for V2X communication, and the mapped fourth DM-RS for V2X communication.

18. The method of claim 17 , wherein the first group-hopping and the third group-hopping are associated with (Σ i=0 7 c(16n ss PSSCH +i)·2 i )mod 30, and

wherein the second group-hopping and the fourth group-hopping are associated with (Σ i=0 7 c(16n ss PSSCH +8+i)·2 i )mod 30,

where c(x) denotes the pseudo-random sequence that is defined as a length-31 Gold sequence and n ss PSSCH denotes a current slot number in a subframe pool for a sidelink, wherein the first time resource is a first slot of a subframe, and wherein the second time resource is a second slot of the subframe.

19. The method of claim 18 , wherein n ss PSSCH =k for the first slot of the subframe and n ss PSSCH =k+1 for the second slot of the subframe, where k is a non-negative integer.

20. The method of claim 17 , wherein the transmitting comprises transmitting, using first orthogonal sequence [+1 +1 +1 +1] or second orthogonal sequence [+1 −1 +1 −1], the first, second, third, and fourth DM-RSs for V2X communication.

21. The method of claim 20 , wherein the first orthogonal sequence [+1 +1 +1 +1] is used based on a modulo-2 operation of an identifier being equal to zero, or

wherein the second orthogonal sequence [+1 −1 +1 −1] is used based on a modulo-2 operation of the identifier being equal to one.

22. The method of claim 17 , further comprising:

determining to transmit, to a target wireless user device, a V2X data channel; and

determining, for mapping the first, second, third, and fourth DM-RSs, a plurality of symbols in the first time resource and a plurality of symbols in the second time resource,

wherein the first, second, third, and fourth DM-RSs are associated with the V2X data channel.

23. The method of claim 17 , further comprising:

determining whether to enable a group-hopping for DM-RSs associated with a V2X data channel.

24. The method of claim 17 ,

wherein each of the first time resource and the second time resource consists of seven symbols, respectively,

wherein the first time resource precedes the second time resource in a time axis,

wherein the first symbol in the first time resource is symbol #2 and the second symbol in the first time resource is symbol #5, the seven symbols in the first time resource being arranged from symbol #0 to symbol #6, and

wherein the first symbol in the second time resource is symbol #1 and the second symbol in the second time resource is symbol #4, the seven symbols in the second time resource being arranged from symbol #0 to symbol #6.