Method and apparatus for sending hybrid automatic repeat request feedback for component carrier aggregation
Techniques for sending hybrid automatic repeat request (HARQ) feedback for stransmissions received via a plurality of aggregated component carriers are disclosed. A wireless transmit/receive unit (WTRU) receive a plurality of codewords via a plurality of component carriers and decodes the codewords. The component carriers are grouped into a plurality of groups, and the WTRU may generate a bundled positive/negative acknowledgement (ACK/NACK) for each group of component carriers. The WTRU may be assigned a plurality of uplink control channel resources and may implement a channel selection scheme for indicating the ACK/NACKs. The WTRU selects one of the uplink control channel resources, and sets the HARQ feedback based the ACK/NACKs or bundled ACK/NACKs in a way that a different uplink control channel resource is selected and HARQ feedback bits are set differently based on the ACK/NACKs or bundled ACK/NACKs. Each physical uplink control channel (PUCCHs) may be mapped to a particular antenna.
1. A method for sending hybrid automatic repeat request (HARQ) feedback for a plurality of codewords, the method comprising:
receiving and decoding downlink control channels;
determining physical uplink control channel (PUCCH) resources for sending the HARQ feedback using PUCCH format 1b and channel selection;
receiving a plurality of codewords based on information on the decoded downlink control channels;
decoding the codewords;
determining positive/negative acknowledgements (ACK/NACKs) for the codewords based on decoding results of the codewords;
grouping the ACK/NACKs into a plurality of groups;
generating a bundled ACK/NACK for each group of ACK/NACKs, wherein a bundled ACK is generated on a condition that all codewords belonging to the group are successfully decoded and a bundled NACK is generated on a condition that at least one codeword belonging to the group is not successfully decoded;
for each group of the plurality of groups, selecting one of the PUCCH format 1b resources and antenna combination, and setting the HARQ feedback, based on bundled ACK/NACKs, wherein a different PUCCH format 1b resource and antenna combination is selected based on the bundled ACK/NACKs; and
transmitting the HARQ feedback bits via the selected PUCCH format 1b resource and antenna combination.
2. The method of claim 1 wherein the ACK/NACKs are grouped into two groups and the HARQ feedback is transmitted using a single PUCCH format 1b resource.
3. The method of claim 1 further comprising:
receiving an indication of a number of downlink control channels being transmitted for each group of ACK/NACKs, wherein a bundled NACK is generated for an ACK/NACK group on a condition that a number of decoded downlink control channels of the ACK/NACK group is not equal to the indication for the ACK/NACK group.
4. The method of claim 1 further comprising:
sending an indication of a number of decoded downlink control channels for each ACK/NACK group.
5. The method of claim 1 further comprising:
grouping the bundled ACK/NACKs into a plurality of bundled ACK/NACK groups, wherein the PUCCH format 1b resources are selected for each bundled ACK/NACK group, and the PUCCH format 1b resource is selected and the HARQ feedback bits are set differently for each bundled ACK/NACK group based on bundled ACK/NACKs belonging to the bundled ACK/NACK group.
6. A wireless transmit/receive unit (WTRU) for sending hybrid automatic repeat request (HARQ) feedback for a plurality of codewords, the WTRU comprising:
a plurality of antennas;
a transceiver configured to receive a plurality of codewords based on control information on downlink control channels, and decode the codewords; and
a processor configured to determine positive/negative acknowledgements (ACK/NACKs) for the codewords based on decoding results of the codewords, group the ACK/NACKs into a plurality of groups, generate a bundled ACK/NACK for each group of ACK/NACKs, wherein a bundled ACK is generated on a condition that all codewords belonging to the group are successfully decoded and a bundled NACK is generated on a condition that at least one codeword belonging to the group is not successfully decoded, select a PUCCH format 1b resource and an antenna, and set the HARQ feedback, based on bundled ACK/NACKs, wherein a different PUCCH format 1b resource and antenna is selected based on the bundled ACK/NACKs, and transmit the HARQ feedback bits via the selected PUCCH format 1b resource and antenna.
7. The WTRU of claim 6 wherein the processor is configured to group the ACK/NACKs into two groups and send the HARQ feedback using a single PUCCH format 1b resource and a particular antenna.
8. The WTRU of claim 6 wherein the processor is configured to receive an indication of a number of downlink control channels being transmitted for each group of ACK/NACKs, and generate a bundled NACK for an ACK/NACK group on a condition that a number of decoded downlink control channels of the ACK/NACK group is not equal to the indication for the ACK/NACK group.
9. The WTRU of claim 6 wherein the processor is configured to send an indication of a number of decoded downlink control channels for each ACK/NACK group.
10. The WTRU of claim 6 wherein the processor is configured to group the bundled ACK/NACKs into a plurality of bundled ACK/NACK groups, and select the PUCCH format 1b resource and set the HARQ feedback bits differently for each bundled ACK/NACK group based on bundled ACK/NACKs belonging to the bundled ACK/NACK group, wherein PUCCH format 1b resources are received for each bundled ACK/NACK group.