Receiving uplink data starting at a starting position in a subframe and ending before an ending symbol

1. A method comprising:

transmitting, by a base station to a wireless device, a downlink control information (DCI) comprising:

an allocation of resource blocks for wireless device transmission of uplink data via a subframe of an unlicensed cell;

a first field comprising an index indicating a starting position for the wireless device transmission of the uplink data, the index identifying one of pre-configured starting positions; and

a second field indicating an ending symbol for the wireless device transmission of the uplink data, the ending symbol being one of pre-configured ending symbols; and

receiving the uplink data, based on the DCI and via the unlicensed cell, starting at the starting position in the subframe and ending before the ending symbol, wherein:

the receiving is based on a listen-before-talk procedure indicating a clear channel before the starting position of the subframe; and

the uplink data is mapped, based at least on the starting position and the ending symbol, to resource elements corresponding to the resource blocks.

2. The method of claim 1 , wherein the subframe is a starting subframe of a multi-subframe burst.

3. The method of claim 1 , wherein the receiving the uplink data further comprises:

receiving a reservation signal until an allowed symbol for a physical uplink shared channel transmission; and

receiving data symbols starting from the allowed symbol.

4. The method of claim 3 , wherein a duration of the reservation signal is less than one symbol.

5. The method of claim 1 , wherein the starting position is based on a value of an uplink timing advance calculated by a wireless device.

6. The method of claim 1 , wherein the downlink control information comprises a listen-before-talk parameter.

7. The method of claim 1 , wherein the downlink control information comprises a transmit power control command.

8. The method of claim 1 , further comprising transmitting uplink transmission parameters for the unlicensed cell.

9. The method of claim 1 , wherein the downlink control information indicates a starting time for the listen-before-talk procedure.

10. The method of claim 1 , wherein a starting time for the listen-before-talk procedure is at a pre-determined time before the starting position.

11. A base station comprising:

one or more processors; and

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

transmit, to a wireless device, a downlink control information (DCI) comprising:

an allocation of resource blocks for wireless device transmission of uplink data via a subframe of an unlicensed cell;

a first field comprising an index indicating a starting position for the wireless device transmission of the uplink data, the index identifying one of pre-configured starting positions; and

a second field indicating an ending symbol for the wireless device transmission of the uplink data, the ending symbol being one of pre-configured ending symbols; and

receive the uplink data, based on the DCI and via the unlicensed cell, starting at the starting position in the subframe and ending before the ending symbol, wherein:

the reception is based on a listen-before-talk procedure indicating a clear channel before the starting position of the subframe; and

the uplink data is mapped, based at least on the starting position and the ending symbol, to resource elements corresponding to the resource blocks.

12. The base station of claim 11 , wherein the subframe is a starting subframe of a multi-subframe burst.

13. The base station of claim 11 , wherein the reception of the uplink data further comprise instructions that cause the base station to:

receive a reservation signal until an allowed symbol for a physical uplink shared channel transmission; and

receive data symbols starting from the allowed symbol.

14. The base station of claim 13 , wherein a duration of the reservation signal is less than one symbol.

15. The base station of claim 11 , wherein the starting position is based on a value of an uplink timing advance calculated by a wireless device.

16. The base station of claim 11 , wherein the downlink control information comprises a listen-before-talk parameter.

17. The base station of claim 11 , wherein the downlink control information comprises a transmit power control command.

18. The base station of claim 11 , further comprising instructions that cause the base station to transmit uplink transmission parameters for the unlicensed cell.

19. The base station of claim 11 , wherein the downlink control information indicates a starting time for the listen-before-talk procedure.

20. A system comprising:

a wireless device; and

a base station comprising:

one or more processors; and

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

transmit, to the wireless device, a downlink control information (DCI) comprising:

an allocation of resource blocks for wireless device transmission of uplink data via a subframe of an unlicensed cell;

a first field comprising an index indicating a starting position for the wireless device transmission of the uplink data, the index identifying one of pre-configured starting positions; and

a second field indicating an ending symbol for the wireless device transmission of the uplink data, the ending symbol being one of pre-configured ending symbols; and

receive the uplink data, based on the DCI and via the unlicensed cell, starting at the starting position in the subframe and ending before the ending symbol, wherein:

the receiving is based on a listen-before-talk procedure indicating a clear channel before the starting position of the subframe; and

the uplink data is mapped, based at least on the starting position and the ending symbol, to resource elements corresponding to the resource blocks.