Reference signal design for wireless communication systems

1. A wireless transmit receive unit (WTRU), comprising:

a memory; and

a processor configured to:

receive downlink control information (DCI) that includes an indication of a set of downlink resources and an indication of a modulation coding scheme, the set of downlink resources corresponding to a plurality of resource block (RBs) associated with a physical downlink shared channel (PDSCH) transmission;

determine a phase noise reference signal density associated with the PDSCH transmission, wherein the phase noise reference signal density is determined based at least on the indicated modulation coding scheme; and

receive the PDSCH transmission via the set of downlink resources, wherein the set of downlink resources comprises a first subset of the set of downlink resources that is used for reception of one or more phase noise reference signals, the first subset of the set of uplink resources is comprised in a subset of the plurality of RBs, and the subset of the plurality of RBs that comprise the first subset of the set of uplink resources is determined based on at least a WTRU-ID.

2. The WTRU of claim 1 , wherein the phase noise reference signal (PNRS) density is a time density.

3. The WTRU of claim 1 , wherein, if the modulation coding scheme is a first modulation coding scheme, the phase noise reference signal density is a first density, and if the modulation coding scheme is a second modulation coding scheme, the phase noise reference signal density is a second density, and wherein the first density is a higher density than the second density.

4. A method comprising:

receiving downlink control information (DCI) that includes an indication of a set of downlink resources and an indication of a modulation coding scheme, the set of downlink resources corresponding to a plurality of resource block (RBs) associated with a physical downlink shared channel (PDSCH) transmission;

determining a phase noise reference signal density associated with the PDSCH transmission, wherein the phase noise reference signal density is determined based at least on the indicated modulation coding scheme; and

receiving the PDSCH transmission via the set of downlink resources, wherein the set of downlink resources comprises a first subset of the set of downlink resources that is used for reception of one or more phase noise reference signals, the first subset of the set of uplink resources is comprised in a subset of the plurality of RBs, and the subset of the plurality of RBs that comprise the first subset of the set of uplink resources is determined based on at least a WTRU-ID.

5. The method of claim 4 , wherein the phase noise reference signal (PNRS) density is a time density.

6. The method of claim 4 , wherein, if the modulation coding scheme is a first modulation coding scheme, the phase noise reference signal density is a first density, and if the modulation coding scheme is a second modulation coding scheme, the phase noise reference signal density is a second density, and wherein the first density is a higher density than the second density.

7. A wireless transmit receive unit (WTRU), comprising:

a memory; and

a processor configured to:

receive an indication of a set of resources and an indication of a modulation coding scheme, the set of resources corresponding to a plurality of resource block (RBs);

determine a phase noise reference signal density, wherein the phase noise reference signal density is determined based at least on the indicated modulation coding scheme; and

determine a first subset of the set of resources, wherein the first subset of the set of resources are associated with one or more phase noise reference signals, wherein the first subset of the set of resources is comprised in a subset of the plurality of RBs, and the subset of the plurality of RBs that comprise the first subset of the set of resources is determined based on at least a WTRU-ID.

8. The WTRU of claim 7 , wherein the phase noise reference signal (PNRS) density is a time density.

9. The WTRU of claim 7 , wherein, if the modulation coding scheme is a first modulation coding scheme, the phase noise reference signal density is a first density, and if the modulation coding scheme is a second modulation coding scheme, the phase noise reference signal density is a second density, and wherein the first density is a higher density than the second density.

10. The WTRU of claim 7 , wherein the indication of the set of resources and the indication of the modulation coding scheme are received via downlink control information.

11. The WTRU of claim 10 , wherein the first subset of the set of resources are associated with a physical downlink control channel (PDCCH) transmission.

12. The WTRU of claim 7 , wherein the indication of the set of resources and the indication of the modulation coding scheme are received via scheduling information, and wherein the processor is further configured to:

determine a second subset of the set of resources, wherein the second subset of the set of resources is used for transmission of data associated with an uplink transmission; and

send an uplink transmission using the first subset of the set of resources and the second subset of the set of resources.

13. The WTRU of claim 7 , wherein the uplink transmission is a physical uplink shared channel (PUSCH) transmission.

14. The WTRU of claim 13 , wherein the indicated modulation coding scheme is associated with the PUSCH transmission.