Methods for enhanced HARQ mechanism
Apparatus and methods are provided to enhance HARQ mechanism. In one novel aspect, the UE decodes resource blocks in a HARQ indicator channel and detects a single-state HARQ indicator encoded with a UE ID of the UE. The UE determines a HARQ acknowledgment status for the data transmission based on the HARQ indicator. In one embodiment, the HARQ indicator channel is either a UE-specific channel, a group-specific channel or a cell-specific channel. In another novel aspect, the UE increases a HARQ count upon decoding the HARQ indicator channel. The UE retransmits the data transmission if the HARQ count is smaller than a predefined maximum HARQ count and the HARQ acknowledgement status is determined to be negative. Otherwise, the UE stops the data transmission. In another embodiment, the UE terminates the data transmission is the total repetition number is greater than a predefined maximum data transmission number.
1. A method comprising:
decoding one or more resource blocks in a HARQ indicator channel by a user equipment (UE) in a wireless communication system;
detecting a hybrid automatic repeat request (HARQ) indicator for a data transmission, wherein the HARQ indicator is a single-state indicator encoded with a UE identity (ID) of the UE, and wherein the HARQ indicator is encoded in one of resource blocks of the HARQ indicator channel;
determining a HARQ acknowledgment status for the data transmission based on the detection of the HARQ indicator, wherein the data transmission repeatedly transmits a data block for a first repetition number N 1 times, wherein N 1 is an integer greater than zero;
increasing a data transmission count by N 1 upon performing the data transmission;
retransmitting the data block with a second repetition number N 2 if the HARQ acknowledgement status is determined to be negative;
increasing the data transmission count by N 2 upon retransmitting the data block; and
stopping transmitting or retransmitting the data block if the data transmission count is greater than a predefined maximum transmission number.
2. The method of claim 1 , wherein the UE ID is an identity sequence configured at a Mobility Management Entity (MME).
3. The method of claim 1 , wherein the UE ID is configured by a higher layer.
4. The method of claim 1 , wherein the HARQ indicator is generated by scrambling a sequence of coded CRC bits with a subset of the UE ID sequence.
5. The method of claim 4 , wherein the HARQ indicator is a common signal for NACK/ACK.
6. The method of claim 1 , wherein the HARQ acknowledgment status is determined to be positive if the HARQ indicator is detected.
7. The method of claim 1 , wherein the HARQ acknowledgment status is determined to be negative if the HARQ indicator is detected.
8. The method of claim 1 , wherein the HARQ indicator is not detected, and wherein one or more of the resource blocks in the HARQ indicator channel is allocated to non-HARQ data transmission.
9. The method of claim 1 , wherein the HARQ indicator channel is a UE-specific channel that contains only HARQ indicator resource blocks for the UE.
10. The method of claim 1 , wherein the HARQ indicator channel is a group-specific channel that contains HARQ indicator resource blocks for a plurality of UEs.
11. The method of claim 1 , wherein the HARQ indicator channel is a cell-specific channel that contains HARQ indicator resource blocks for multiple UEs belonging to the same cell.
12. The method of claim 1 , further comprising:
increasing a HARQ count upon decoding the HARQ indicator channel;
retransmitting the data transmission if the HARQ count is smaller than a predefined maximum HARQ count and the HARQ acknowledgement status is determined to be negative, and;
stopping decoding the HARQ indicator channel if the HARQ count is greater than a predefined maximum HARQ count.
13. The method of claim 1 , further comprising:
increasing a HARQ count upon decoding the HARQ indicator channel;
stopping transmitting or retransmitting the data block if the HARQ count is determined to be greater than a predefined maximum HARQ count.
14. The method of claim 1 , wherein the HARQ indicator channel spans over multiple subframes.
15. The method of claim 1 , wherein the HARQ indicator channel spans over one subframe.
16. An user equipment (UE) comprising:
a transceiver that transmits an uplink data transmission to a base station and receives a downlink data transmission from the base station;
an HAQR decoder that decodes one or more resource blocks of a HARQ indicator channel;
a HARQ detector that detects a hybrid automatic repeat request (HARQ) indicator for the uplink data transmission, wherein the HARQ indicator is a single-state indicator encoded with a UE identity (ID) of the UE, and wherein the HARQ indicator is encoded in one of resource blocks of the HARQ indicator channel;
a HARQ handler that determines a HARQ acknowledgment status for the uplink data transmission based on the detection of the HARQ indicator; and
a transmission counter that increases an transmission count by a repetition number of corresponding data transmission and data retransmissions, wherein each data transmission or retransmission retransmits a data block for a new repetition number of times triggered by a negative HARQ acknowledgment status; and wherein the transmission counter determines if the transmission count is greater than a predefined maximum transmission number after each data transmission or retransmission, and wherein the transmission counter informs the HARQ decoder when the maximum HARQ count is reached such that the HARQ decoder stops decoding the HARQ indicator channel.
17. The UE of claim 16 , wherein the HARQ indicator is generated by scrambling a sequence of coded CRC bits with a subset of the UE ID sequence, and wherein the coded CRC bits are common signal for NACK/ACK.
18. The UE of claim 16 , wherein the HARQ indicator is a subset sequence of the UE ID sequence.
19. The UE of claim 16 , wherein the HARQ indicator is detected if the decoded resource blocks contain the UE ID.
20. The UE of claim 19 , wherein the HARQ acknowledgment status is determined to be positive if the HARQ indicator is detected.
21. The UE of claim 19 , wherein the HARQ acknowledgment status is determined to be negative if the HARQ indicator is detected.
22. The UE of claim 16 , wherein the HARQ indicator channel is selected from a channel group comprising a UE-specific channel that contains only HARQ indicator resource blocks for the UE, a group-specific channel that contains HARQ indicator resource blocks for a plurality of UEs, and a cell-specific channel that contains HARQ indicator resource blocks for multiple UEs of a cell.
23. The UE of claim 16 , further comprising:
a HARQ counter that increases a HARQ count upon detecting the HARQ indicator channel, determines if the HARQ count is greater than a predefined maximum HARQ number, and informs the HARQ decoder when the maximum HARQ count is reached such that the HARQ decoder stops decoding the HARQ indicator channel.