OFDMA-based multiplexing of uplink control information
Methods and apparatus are described for transmitting uplink control information (UCI) over an OFDMA-based uplink. In some embodiments, UCI symbols are mapped to resource elements (REs) in the time/frequency resource grid to maximize frequency diversity. In some embodiments, UCI is mapped in a manner that takes into account channel estimation performance by mapping UCI symbols to those REs that are closest (in terms of OFDM subcarriers/symbols) to REs that carry reference signals.
1. An apparatus comprising:
at least one processor configured to cause a UE (user equipment) to:
multiplex uplink control information (UCI) with uplink shared channel (UL-SCH) data for transmission over orthogonal frequency division multiplexing (OFDM) symbols in the time domain and in physical resource blocks (PRBs) in the frequency domain, wherein the OFDM symbols and PRBs include a plurality of time-frequency resource elements (REs);
divide channel state information (CSI) bits into multiple segments; and
map UCI including modulated hybrid automatic request repeat acknowledgement (HARQ-ACK) bits and modulated CSI bits to REs of OFDM symbols that do not contain demodulation reference signal (DMRS) REs, wherein said mapping includes mapping the modulated CSI bits of the multiple segments to REs first in the frequency domain and then in the time domain, and map UL-SCH data to REs of the PRB first in the frequency domain and then in the time domain after mapping the modulated CSI bits.
2. The apparatus of claim 1 , wherein the HARK-ACK bits are mapped to REs reserved for HARQ-ACK bits after the mapping of the UL-SCH data.
3. The apparatus of claim 2 , wherein the REs reserved for HARQ-ACK bits puncture the mapped CSI.
4. The apparatus of claim 2 , wherein the REs reserved for HARQ-ACK bits puncture the mapped UL-SCH data.
5. The apparatus of claim 1 , wherein the UL-SCH data is mapped to remaining REs that do not contain CSI or DMRS.
6. The apparatus of claim 1 , wherein OFDM symbols to which the DMRS are mapped is changed dynamically based on signaling in downlink control information (DCI) that schedules a physical uplink shared channel (PUSCH) the carriers the UL-SCH.
7. The apparatus of claim 6 , wherein the OFDM symbols to which the DMRS are mapped are shifted according to the DCI.
8. The apparatus of claim 7 , wherein the mapping of the UCI dynamically changes based on the OFDM symbols to which the DMRS are mapped.
9. The apparatus of claim 7 , wherein the symbols to which the DMRS are mapped are shifted within the OFDM symbols of a subframe.
10. A non-transitory computer-readable medium storing program instructions executable by at least one processor of a user equipment (UE) to:
multiplex uplink control information (UCI) with uplink shared channel (UL-SCH) data for transmission over orthogonal frequency division multiplexing (OFDM) symbols in the time domain and in physical resource blocks (PRBs) in the frequency domain, wherein the OFDM symbols and PRBs include a plurality of time-frequency resource elements (REs); divide channel state information (CSI) bits into multiple segments;
map UCI including modulated hybrid automatic request repeat acknowledgement (HARQ-ACK) bits and modulated CSI bits to REs of OFDM symbols that do not contain demodulation reference signal (DMRS) REs, wherein said mapping includes mapping the modulated CSI bits of the multiple segments to REs first in the frequency domain and then in the time domain, and map UL-SCH data to REs of the PRB first in the frequency domain and then in the time domain after mapping the modulated CSI bits.
11. The non-transitory computer-readable medium of claim 10 , wherein the HARK-ACK bits are mapped to REs reserved for HARQ-ACK bits after the mapping of the UL-SCH data.
12. The non-transitory computer-readable medium of claim 11 , wherein the REs reserved for HARQ-ACK bits puncture the mapped CSI.
13. The non-transitory computer-readable medium of claim 11 , wherein the REs reserved for HARQ-ACK bits puncture the mapped UL-SCH data.
14. The non-transitory computer-readable medium of claim 10 , wherein the UL-SCH data is mapped to remaining REs that do not contain CSI or DMRS.
15. The non-transitory computer-readable medium of claim 10 , wherein OFDM symbols to which the DMRS are mapped is changed dynamically based on signaling in downlink control information (DCI) that schedules a physical uplink shared channel (PUSCH) the carriers the UL-SCH.
16. The non-transitory computer-readable medium of claim 15 , wherein the OFDM symbols to which the DMRS are mapped are shifted according to the DCI.
17. The non-transitory computer-readable medium of claim 16 , wherein the mapping of the UCI dynamically changes based on the OFDM symbols to which the DMRS are mapped.
18. The non-transitory computer-readable medium of claim 16 , wherein the symbols to which the DMRS are mapped are shifted within the OFDM symbols of a subframe.
19. A method comprising:
by a user equipment device (UE):
multiplexing uplink control information (UCI) with uplink shared channel (UL-SCH) data for transmission over orthogonal frequency division multiple access (OFDM) symbols in the time domain and in physical resource blocks (PRBs) in the frequency domain, wherein the OFDM symbols and PRBs include a plurality of time-frequency resource elements (REs);
dividing channel state information (CSI) bits into multiple segments;
mapping UCI including modulated hybrid automatic request repeat acknowledgement (HARQ-ACK) bits and modulated CSI bits to REs of OFDM symbols that do not contain demodulation reference signal (DMRS) REs, wherein said mapping includes mapping the modulated CSI bits of the multiple segments to REs first in the frequency domain and then in the time domain, and mapping UL-SCH data to REs of the PRB first in the frequency domain and then in the time domain after mapping the modulated CSI bits.
20. The method of claim 19 , wherein the HARK-ACK bits are mapped to REs reserved for HARQ-ACK bits after the mapping of the UL-SCH data.