Antenna port indication based on maximum number of transmission layers

1. A method comprising:

receiving, by a wireless device, configuration parameters indicating:

a bandwidth part (BWP), of a cell, associated with a maximum number of transmission layers; and

a plurality of demodulation reference signal (DMRS) ports;

receiving a downlink control information comprising an antenna port indication value;

determining a subset of DMRS ports, from the plurality of DMRS ports, based on the maximum number of transmission layers associated with the BWP;

selecting, based on the antenna port indication value, one or more DMRS ports from the subset of DMRS ports; and

receiving, via the BWP, a transport block with the one or more selected DMRS ports and with a number of transmission layers, wherein the number is less than or equal to the maximum number in response to the BWP being associated with the maximum number of transmission layers.

2. The method of claim 1 , further comprising receiving one or more radio resource control (RRC) messages comprising the configuration parameters of the cell, wherein the one or more RRC messages further comprise a DMRS type associated with the plurality of DMRS ports.

3. The method of claim 2 , wherein the DMRS type comprises at least one of:

a first DMRS type; and

a second DMRS type.

4. The method of claim 2 , wherein the one or more RRC messages further comprise a position indication for the plurality of DMRS ports.

5. The method of claim 4 , wherein the position indication indicates one or more symbol indexes of one or more DMRS symbols for the plurality of DMRS ports in a slot.

6. The method of claim 1 , wherein the number is indicated in the downlink control information.

7. The method of claim 1 , wherein the downlink control information is received via the BWP, and wherein the downlink control information comprises downlink assignment parameters of a physical downlink shared channel resource for reception of the transport block.

8. The method of claim 2 , wherein the one or more RRC messages further comprise a maximum length of a DMRS.

9. The method of claim 8 , wherein the one or more RRC messages further comprise a position indication for the plurality of DMRS ports, and the method further comprises determining the subset of DMRS ports from the plurality of DMRS ports based on the position indication and the maximum length of the DMRS.

10. A wireless device comprising:

one or more processors; and

memory storing instructions that, when executed by the one or more processors, cause the wireless device to:

receive configuration parameters indicating:

a bandwidth part (BWP), of a cell, associated with a maximum number of transmission layers; and

a plurality of demodulation reference signal (DMRS) ports;

receive a downlink control information comprising an antenna port indication value;

determine a subset of DMRS ports, from the plurality of DMRS ports, based on the maximum number of transmission layers associated with the BWP;

select, based on the antenna port indication value, one or more DMRS ports from the subset of DMRS ports; and

receive, via the BWP, a transport block with the one or more selected DMRS ports and with a number of transmission layers, wherein the number is less than or equal to the maximum number in response to the BWP being associated with the maximum number of transmission layers.

11. The wireless device of claim 10 , wherein the instructions, when executed by the one or more processors, further cause the wireless device to receive one or more radio resource control (RRC) messages comprising the configuration parameters of the cell, wherein the one or more RRC messages further comprise a DMRS type associated with the plurality of DMRS ports.

12. The wireless device of claim 11 , wherein the DMRS type comprises at least one of:

a first DMRS type; and

a second DMRS type.

13. The wireless device of claim 11 , wherein the one or more RRC messages further comprise a position indication for the plurality of DMRS ports.

14. The wireless device of claim 13 , wherein the position indication indicates one or more symbol indexes of one or more DMRS symbols for the plurality of DMRS ports in a slot.

15. The wireless device of claim 10 , wherein the number is indicated in the downlink control information.

16. The wireless device of claim 10 , wherein the downlink control information is received via the BWP, and wherein the downlink control information comprises downlink assignment parameters of a physical downlink shared channel resource for reception of the transport block.

17. The wireless device of claim 11 , wherein the one or more RRC messages further comprise a maximum length of a DMRS.

18. A system comprising:

a base station comprising:

one or more first processors; and

memory storing first instructions that, when executed by the one or more first processors, cause the base station to:

transmit configuration parameters indicating:

a bandwidth part (BWP), of a cell, associated with a maximum number of transmission layers; and

a plurality of demodulation reference signal (DMRS) ports; and

transmit a downlink control information comprising an antenna port indication value; and

a wireless device comprising:

one or more second processors; and

memory storing second instructions that, when executed by the one or more second processors, cause the wireless device to:

receive the configuration parameters;

receive the downlink control information;

determine a subset of DMRS ports, from the plurality of DMRS ports, based on the maximum number of transmission layers associated with the BWP;

select, based on the antenna port indication value, one or more DMRS ports from the subset of DMRS ports; and

receive, via the BWP, a transport block with the one or more selected DMRS ports and with a number of transmission layers, wherein the number is less than or equal to the maximum number in response to the BWP being associated with the maximum number of transmission layers.