Methods and apparatus related to demodulation reference signal design and related signaling

1. A method of wireless communication of an apparatus, comprising:

determining locations for a plurality of Demodulation Reference Signal (DM-RS) symbols to be transmitted in frequency hops within a scheduling unit of a channel included in a slot or mini-slot, wherein the determined locations of the DM-RS symbols in each frequency hop are based on a duration of the scheduling unit and on one or more of a number of control symbols in the slot or mini-slot, or a number of symbols carrying scheduled data, and wherein a last DM-RS symbol of the plurality of DM-RS symbols is determined to be positioned one symbol prior to a last symbol carrying scheduled data; and

transmitting the plurality of DM-RS symbols in the scheduling unit based on the determined locations.

2. The method of claim 1 , wherein determining the locations comprises determining that a first DM-RS symbol be positioned at a front load position within the scheduling unit, and

wherein transmitting the plurality of DM-RS symbols comprises transmitting the first DM-RS symbol at the front load position based on the determined locations.

3. The method of claim 2 , wherein determining the locations further comprises determining that a third DM-RS symbol be positioned between the first DM-RS symbol and the last DM-RS symbol within the scheduling unit, and

wherein transmitting the plurality of DM-RS symbols comprises transmitting the third DM-RS symbol at a symbol location between the first DM-RS symbol and the last DM-RS symbol within the scheduling unit.

4. The method of claim 2 , wherein determining the locations further comprises determining that a third DM-RS symbol be positioned within the scheduling unit at an equal distance from the first DM-RS symbol and the last DM-RS symbol.

5. The method of claim 2 , wherein determining the locations further comprises determining that a third DM-RS symbol be positioned between the first DM-RS symbol and the last DM-RS symbol within the scheduling unit such that a first spacing between the first DM-RS symbol and the third DM-RS symbol and a second spacing between the third DM-RS symbol and the last DM-RS symbol differ by one symbol.

6. The method of claim 2 , wherein determining the locations further comprises determining that a third DM-RS symbol and a fourth DM-RS symbol be positioned midway between the first DM-RS symbol and the last DM-RS symbol within the scheduling unit, and wherein a spacing between any two consecutive DM-RS symbols within the scheduling unit is the same or different by a maximum of one symbol.

7. The method of claim 1 , wherein the determined locations are further based on one or more of a number of guard symbols in the slot or mini-slot.

8. The method of claim 1 , wherein a same pattern of DM-RS positions is determined for each frequency hop within the scheduling unit.

9. The method of claim 1 , wherein the apparatus comprises a base station.

10. The method of claim 1 , wherein the channel is a physical downlink shared channel (PDSCH).

11. The method of claim 1 , wherein the duration of the scheduling unit is smaller than 14 symbols.

12. An apparatus for wireless communication, comprising:

a memory; and

at least one processor coupled to the memory and configured to:

determine locations for a plurality of Demodulation Reference Signal (DM-RS) symbols to be transmitted in frequency hops within a scheduling unit of a channel included in a slot or mini-slot, wherein the determined locations of the DM-RS symbols in each frequency hop are based on a duration of the scheduling unit and on one or more of a number of control symbols in the slot or mini-slot, or a number of symbols carrying scheduled data, and wherein a last DM-RS symbol of the plurality of DM-RS symbols is determined to be positioned one symbol prior to a last symbol carrying scheduled data; and

transmit the plurality of DM-RS symbols in the scheduling unit based on the determined locations.

13. The apparatus of claim 12 , wherein the at least one processor is further configured, as part of being configured to determine the locations for the plurality of DM-RS symbols, to determine that a first DM-RS symbol be positioned at a front load position within the scheduling unit, and

wherein the at least one processor is further configured, as part of being configured to transmit the plurality of DM-RS symbols, to transmit the first DM-RS symbol at the front load position within the scheduling unit based on the determined locations.

14. The apparatus of claim 13 , wherein the at least one processor is further configured, as part of being configured to determine the locations for the plurality of DM-RS symbols, to determine that a third DM-RS symbol be positioned between the first DM-RS symbol and the last DM-RS symbol within the scheduling unit, and

wherein the at least one processor is further configured, as part of being configured to transmit the plurality of DM-RS symbols, to transmit the third DM-RS symbol at a symbol location between the first DM-RS symbol and the last DM-RS symbol within the scheduling unit.

15. The apparatus of claim 13 , wherein the at least one processor is further configured, as part of being configured to determine the locations for the plurality of DM-RS symbols, to determine that a third DM-RS symbol be positioned within the scheduling unit at an equal distance from the first DM-RS symbol and the last DM-RS symbol.

16. The apparatus of claim 12 , wherein the at least one processor is configured to determine the locations further based on one or more of a number of guard symbols in the slot or mini-slot.

17. The apparatus of claim 12 , wherein the at least one processor is configured to determine a pattern of DM-RS positions for each frequency hop within the scheduling unit, wherein the determined pattern is a same pattern for each frequency hop within the scheduling unit.

18. The apparatus of claim 12 , wherein the apparatus comprises a base station.

19. An apparatus for wireless communication, comprising:

means for determining locations for a plurality of Demodulation Reference Signal (DM-RS) symbols to be transmitted in frequency hops within a scheduling unit of a channel included in a slot or mini-slot, wherein the determined locations of the DM-RS symbols in each frequency hop are based on a duration of the scheduling unit and on one or more of a number of control symbols in the slot or mini-slot, or a number of symbols carrying scheduled data, and wherein a last DM-RS symbol is determined to be positioned one symbol prior to a last symbol carrying scheduled data; and

means for transmitting the plurality of DM-RS symbols in the scheduling unit based on the determined locations.

20. The apparatus of claim 19 , wherein the means for determining the locations is configured to determine that a first DM-RS symbol be positioned at a front load position within the scheduling unit, and

wherein the means for transmitting the plurality of DM-RS symbols is configured to transmit the first DM-RS symbol at the front load position based on the determined locations.

21. The apparatus of claim 20 , wherein the means for determining the locations is configured to determine that a third DM-RS symbol be positioned between the first DM-RS symbol and the last DM-RS symbol within the scheduling unit, and

wherein the means for transmitting the plurality of DM-RS symbols is configured to transmit the third DM-RS symbol at a symbol location between the first DM-RS symbol and the last DM-RS symbol within the scheduling unit.

22. The apparatus of claim 19 , wherein the determined locations are further based on one or more of a number of guard symbols in the slot or mini-slot.

23. A non-transitory computer-readable medium storing computer executable code, the code when executed by at least one processor of an apparatus, causes the at least one processor to:

determine locations for a plurality of Demodulation Reference Signal (DM-RS) symbols to be transmitted in frequency hops within a scheduling unit of a channel included in a slot or mini-slot, wherein the determined locations of the DM-RS symbols in each frequency hop are based on a duration of the scheduling unit and on one or more of a number of control symbols in the slot or mini-slot, or a number of symbols carrying scheduled data, and wherein a last DM-RS symbol is determined to be positioned one symbol prior to a last symbol carrying scheduled data; and

transmit the plurality of DM-RS symbols in the scheduling unit based on the determined locations.

24. The non-transitory computer-readable medium of claim 23 , wherein the at least one processor is further caused, as part of being caused to determine the locations for the plurality of DM-RS symbols, to determine that a first DM-RS symbol be positioned at a front load position within the scheduling unit, and

wherein the at least one processor is further caused, as part of being caused to transmit the plurality of DM-RS symbols, to transmit the first DM-RS symbol at the front load position within the scheduling unit.

25. The non-transitory computer-readable medium of claim 24 , wherein the at least one processor is further caused, as part of being caused to determine the locations for the plurality of DM-RS symbols, to determine that a third DM-RS symbol be positioned between the first DM-RS symbol and the last DM-RS symbol within the scheduling unit, and

wherein the at least one processor is further caused, as part of being caused to transmit the plurality of DM-RS symbols, to transmit the third DM-RS symbol at a symbol location between the first DM-RS symbol and the last DM-RS symbol within the scheduling unit.

26. The non-transitory computer-readable medium of claim 23 , wherein the at least one processor is caused to determine the locations further based on one or more of a number of guard symbols in the slot or mini-slot.

27. The method of claim 1 , wherein the apparatus comprises a user equipment.

28. The method of claim 1 , wherein the channel is a physical uplink shared channel (PUSCH).

29. The apparatus of claim 13 , wherein the at least one processor is further configured, as part of being configured to determine the locations for the plurality of DM-RS symbols, to determine that a third DM-RS symbol be positioned between the first DM-RS symbol and the last DM-RS symbol within the scheduling unit such that a first spacing between the first DM-RS symbol and the third DM-RS symbol and a second spacing between the third DM-RS symbol and the last DM-RS symbol differ by one symbol.

30. The apparatus of claim 13 , wherein the at least one processor is further configured, as part of being configured to determine the locations for the plurality of DM-RS symbols, to determine that a third DM-RS symbol and a fourth DM-RS symbol be positioned midway between the first DM-RS symbol and a fourth DM-RS symbol be positioned midway between the first DM-RS symbol and the last DM-RS symbol within the scheduling unit, and wherein a spacing between any two consecutive DM-RS symbols within the scheduling unit is the same or different by a maximum of one symbol.

31. The apparatus of claim 12 , wherein the channel is a physical downlink shared channel (PDSCH).

32. The apparatus of claim 12 , wherein the channel is a physical uplink shared channel (PUSCH).

33. The apparatus of claim 12 , wherein the duration of the scheduling unit is smaller than 14 symbols.

34. The apparatus of claim 12 , wherein the apparatus comprises a user equipment.