Configuring a nominal number of resource elements in a data channel
Methods, systems, and devices for wireless communication are described. A base station may transmit a set of candidate resource element parameters to a wireless device. Each candidate resource element parameters may indicate a nominal number of physical resource block resource elements. The base station may then transmit downlink control information and a data transmission during a slot. The data transmission may include one or more transport blocks whose size is based on a nominal number of physical resource block resource elements. The wireless device may select one of the candidate resource element parameters from the set of candidate resource element parameters based at least in part on the downlink data, determine a transport block size for the data transmission, and decode the data transmission.
1. A method for wireless communication, comprising:
receiving, by a wireless device, downlink control information;
receiving a data transmission assigned by the downlink control information;
determining a number of resource elements per physical resource block based at least in part on the downlink control information, wherein the number of resource elements per physical resource block is determined based at least in part on a reference signal overhead indicated by the downlink control information or a number of physical downlink shared channel (PDSCH) symbols allocated by the downlink control information; and
processing the data transmission based at least in part on the determined number of resource elements per physical resource block.
2. The method of claim 1 , wherein:
determining the number of resource elements per physical resource block based at least in part on the downlink control information comprises: selecting a candidate resource element parameter from a set of candidate resource element parameters based at least in part on the downlink control information, wherein each candidate resource element parameter in the set of candidate resource element parameters indicates a respective number of resource elements per physical resource block.
3. The method of claim 1 , wherein:
processing the data transmission comprises: determining a transport block size for the data transmission based at least in part on the determined number of resource elements per physical resource block.
4. The method of claim 1 , wherein:
the downlink control information comprises an explicit indication of the number of resource elements per physical resource block, and wherein the number of resource elements per physical resource block is determined based at least in part on the explicit indication.
5. The method of claim 4 , wherein:
the explicit indication of the number of resource elements per physical resource block is included in a device-specific control search space.
6. The method of claim 1 , wherein:
determining the number of resource elements per physical resource block based at least in part on the downlink control information comprises: determining the number of resource elements based at least in part on a configuration of the downlink control information.
7. The method of claim 6 , wherein:
determining the number of resource elements per physical resource block based at least in part on the configuration of the downlink control information comprises: using a selection algorithm known to the wireless device and a base station to determine the number of resource elements per physical resource block.
8. The method of claim 7 , wherein:
the selection algorithm comprises at least one of an algorithm for determining the number of resource elements per physical resource block corresponding to a slot configuration of the downlink control information, an algorithm for determining the number of resource elements per physical resource block based at least in part on the reference signal overhead indicated by the downlink control information, and an algorithm for determining the number of resource elements per physical resource block based at least in part on the number of PDSCH symbols allocated by the downlink control information.
9. The method of claim 7 , wherein:
the selection algorithm comprises an algorithm for determining the number of resource elements per physical resource block closest to a number of resources for data transmission that are available in the slot.
10. The method of claim 4 , further comprising:
receiving, from a transmitting base station, an indication of whether aperiodic channel state information reference signals are to be taken into account when determining the number of resource elements per physical resource block.
11. The method of claim 4 , further comprising:
receiving, from a transmitting base station, an indication of which reference signals are to be taken into account when determining the number of resource elements per physical resource block.
12. The method of claim 6 , wherein:
the number of resource elements per physical resource block is determined based at least in part on the reference signal overhead indicated by the downlink control information and the number of PDSCH symbols allocated by the downlink control information.
13. The method of claim 2 , wherein:
the set of candidate resource element parameters is received in a radio resource control message.
14. The method of claim 2 , wherein:
the set of candidate resource element parameters comprises at least one candidate nominal number of resource elements per physical resource block.
15. The method of claim 2 , wherein:
the set of candidate resource element parameters comprises at least one indication of a candidate nominal number of resource elements per physical resource block.
16. A method for wireless communication, comprising:
receiving, by a wireless device, downlink control information;
determining a number of resource elements per physical resource block based at least in part on the downlink control information, wherein the number of resource elements per physical resource block is determined based at least in part on a reference signal overhead indicated by the downlink control information or a number of physical downlink shared channel (PDSCH) symbols allocated by the downlink control information; and
configuring an uplink data transmission based at least in part on the determined number of resource elements per physical resource block.
17. The method of claim 16 , wherein:
determining the number of resource elements per physical resource block based at least in part on the downlink control information comprises: selecting a candidate resource element parameter from a set of candidate resource element parameters based at least in part on the downlink control information, wherein each candidate resource element parameter in the set of candidate resource element parameters indicates a respective number of resource elements per physical resource block.
18. The method of claim 16 , wherein:
configuring the uplink data transmission comprises: determining a transport block size for the uplink data transmission based at least in part on the determined number of resource elements per physical resource block.
19. The method of claim 16 , wherein:
the downlink control information comprises an explicit indication of the number of resource elements per physical resource block, and wherein number of resource elements per physical resource block is determined based at least in part on the explicit indication.
20. The method of claim 19 , wherein:
the explicit indication of the number of resource elements per physical resource block is included in a device-specific control search space.
21. The method of claim 16 , wherein:
determining the number of resource elements per physical resource block based at least in part on the downlink control information comprises: determining the number of resource elements based at least in part on a configuration of the downlink control information.
22. The method of claim 21 , wherein:
determining the number of resource elements per physical resource block based at least in part on the configuration of the downlink control information comprises: using a selection algorithm known to the UE and a base station to determine the number of resource elements per physical resource block.
23. The method of claim 22 , wherein:
the selection algorithm comprises at least one of an algorithm for determining the number of resource elements per physical resource block corresponding to a slot configuration of the downlink control information, an algorithm for determining the number of resource elements per physical resource block based at least in part on the reference signal overhead indicated by the downlink control information, and an algorithm for determining the number of resource elements per physical resource block based at least in part on the number of PDSCH symbols allocated by the downlink control information.
24. The method of claim 22 , wherein:
the selection algorithm comprises an algorithm for determining the number of resource elements per physical resource block closest to a number of resources for data transmission that are available in the slot.
25. The method of claim 19 , further comprising:
receiving, from a transmitting base station, an indication of whether aperiodic channel state information reference signals are to be taken into account when determining the number of resource elements per physical resource block.
26. The method of claim 19 , further comprising:
receiving, from a transmitting base station, an indication of which reference signals are to be taken into account when determining the number of resource elements per physical resource block.
27. The method of claim 21 , wherein:
the number of resource elements per physical resource block is determined based at least in part on the reference signal overhead indicated by the downlink control information and the number of PDSCH symbols allocated by the downlink control information.
28. An apparatus for wireless communication, comprising:
means for receiving, by a wireless device, downlink control information;
means for receiving a data transmission assigned by the downlink control information;
means for determining a number of resource elements per physical resource block based at least in part on the downlink control information, wherein the number of resource elements per physical resource block is determined based at least in part on a reference signal overhead indicated by the downlink control information or a number of physical downlink shared channel (PDSCH) symbols allocated by the downlink control information; and
means for processing the data transmission based at least in part on the determined number of resource elements per physical resource block.
29. The apparatus of claim 28 , wherein:
processing the data transmission comprises: determining a transport block size for the data transmission based at least in part on the determined number of resource elements per physical resource block.
30. An apparatus for wireless communication, comprising:
means for receiving, by a wireless device, downlink control information;
means for determining a number of resource elements per physical resource block based at least in part on the downlink control information, wherein the number of resource elements per physical resource block is determined based at least in part on a reference signal overhead indicated by the downlink control information or a number of physical downlink shared channel (PDSCH) symbols allocated by the downlink control information; and
means for configuring an uplink data transmission based at least in part on the determined number of resource elements per physical resource block.