Latency reduction for wireless data transmission

1. An apparatus of a user equipment (UE), the apparatus comprising:

processing circuitry and memory, the processing circuitry to:

decode downlink control information that signals a shortened transmission time interval (xTTI) length configuration for a time division duplexing (TDD) component carrier (CC), the xTTI length configuration comprising a length in time or a length in orthogonal frequency division multiplexing (OFDM) symbols;

decode a physical downlink control channel (PDCCH) to identify scheduling timing and hybrid automatic repeat request (HARQ) timing of a physical downlink shared channel (PDSCH) and physical uplink shared channel (PUSCH) on the TDD CC based on the identified xTTI length configuration, the PDCCH scheduling a PDSCH in a single xTTI; and

encode a HARQ acknowledgement (HARQ-ACK) for transmission to an evolved NodeB (eNB) based at least on a HARQ-ACK timeline and based on the identified xTTI length configuration, the HARQ-ACK for the PDSCH being encoded for transmission in a next uplink xTTI,

wherein prior to receipt of the downlink control information signalling the xTTI length configuration, the UE was configured to use a legacy TTI length configuration, the xTTI length configuration being half the legacy TTI length configuration.

2. The apparatus of claim 1 , further comprising:

transceiver circuitry to transmit the HARQ-ACK to the eNB based at least on the HARQ-ACK timeline and based on the identified xTTI length configuration.

3. The apparatus of claim 2 , further comprising:

an antenna coupled with the transceiver circuitry.

4. The apparatus of claim 1 , wherein the identified xTTI length configuration is 0.5 milliseconds.

5. The apparatus of claim 1 , wherein the identified length configuration is one or two OFDM symbols.

6. The apparatus of claim 1 , wherein a single downlink control channel transmitted in a single xTTI schedules a single PDSCH transmission in the single xTTI.

7. The apparatus of claim 1 , wherein the scheduling timing comprises a downlink control information (DCI) format that includes an information element (IE) representing by a first number of bits and indicating a set of xTTI indexes for a corresponding downlink or uplink data transmission.

8. The apparatus of claim 1 , wherein the processing circuitry is further to:

signal for transmission of the HARQ acknowledgement (HARQ-ACK) to the evolved NodeB for a set of PDSCHs in a set of available xTTIs.

9. The apparatus of claim 8 , wherein the processing circuitry is further to:

encode for transmission of the HARQ-ACK for a PDSCH in a xTTI n in a first available uplink xTTI after n+k xTTIs, wherein a value of n is fixed, and wherein a value of k is fixed, indicated by a downlink control information (DCI) format, or configured by higher layers.

10. The apparatus of claim 8 , wherein the processing circuitry is further to:

encode for transmission of the HARQ-ACK for the set of PDSCHs in a set of available uplink xTTIs after k xTTIs, wherein a value of k is fixed, indicated by a downlink control information (DCI) format, or configured by higher layers.

11. The apparatus of claim 1 , wherein the processing circuitry is further to:

determine a self-contained HARQ-ACK window in xTTI, the self-contained window comprising a downlink transmission burst period, a guard period (GP), and an uplink transmission period; and

signal for transmission of HARQ-ACK bits for PDSCH in the downlink transmission burst period, the GP, or the uplink transmission period of the HARQ-ACK window.

12. The apparatus of claim 11 , wherein HARQ-ACK bits for one or more PDSCHs in the self-contained HARQ-ACK window are transmitted within a subset of the GP in the self-contained HARQ-ACK window.

13. The apparatus of claim 11 , wherein HARQ-ACK bits for one or more PDSCHs in the self-contained HARQ-ACK window are transmitted in a first available uplink xTTI after n+k xTTIs in the self-contained HARQ-ACK window, wherein a value of n is fixed, and wherein a value of k is fixed, indicated by a downlink control information (DCI) format, or configured by higher layers.

14. The apparatus of claim 11 , wherein HARQ-ACK bits for one or more PDSCHs in the self-contained HARQ-ACK window are transmitted in a set of available uplink xTTIs after k xTTIs in the self-contained HARQ-ACK window, wherein a value of k is fixed, indicated by a downlink control information (DCI) format, or configured by higher layers.

15. The apparatus of claim 1 , wherein the processing circuitry comprises a baseband processor.

16. An apparatus of a user equipment (UE), the apparatus comprising:

processing circuitry and memory, the processing circuitry to:

identify a shortened transmission time interval (xTTI) length configuration for a time division duplexing (TDD) component carrier (CC), the xTTI length configuration comprising a length in time or a length in orthogonal frequency division multiplexing (OFDM) symbols;

identify scheduling timing and hybrid automatic repeat request (HARQ) timing of a physical downlink shared channel (PDSCH) and physical uplink shared channel (PUSCH) on the TDD CC based on the identified xTTI length configuration;

signal for transmission of a HARQ acknowledgement (HARQ-ACK) to an evolved NodeB (eNB) based at least on a HARQ-ACK timeline and based on the identified xTTI length configuration;

determine a self-contained HARQ-ACK window in xTTI, the self-contained window comprising a downlink transmission burst period, a guard period (GP), and an uplink transmission period;

signal for transmission of HARQ-ACK bits for PDSCH in the downlink transmission burst period, the GP, or the uplink transmission period of the HARQ-ACK window; and

configure the self-contained window based on at least a time division duplex (TDD) uplink/downlink (UL/DL) configuration broadcasted by higher layers, wherein the xTTI length is configured by higher layers or indicated by a downlink control information (DCI) format.

17. The apparatus of claim 16 , wherein:

a DL transmission period comprises a duration reserved for downlink transmission between two consecutive uplink pilot time slots (UpPTS);

the GP is signaled based on the UL/DL configuration; and

an UL transmission period comprises a duration reserved for UL transmission between two consecutive downlink pilot time slots (DwPTS).

18. A non-transitory machine-readable medium comprising instructions that, when executed by one or more processors of a user equipment (UE), causes the one or more processors to:

decode downlink control information that signals a shortened transmission time interval (xTTI) length configuration for a time division duplexing (TDD) component carrier (CC), the xTTI length configuration comprising a length in time or a length in orthogonal frequency division multiplexing (OFDM) symbols;

decode a physical downlink control channel (PDCCH) to identify scheduling timing and hybrid automatic repeat request (HARQ) timing of physical downlink shared channel (PDSCH) and physical uplink shared channel (PUSCH) on the TDD CC based on the identified xTTI length configuration, the PDCCH scheduling a PDSCH in a single xTTI; and

encode a HARQ acknowledgement (HARQ-ACK) for transmission to an evolved NodeB (eNB) based at least on the identified xTTI length configuration, the HARQ-ACK for the PDSCH being encoded for transmission in a next uplink xTTI,

wherein prior to receipt of the downlink control information signalling the xTTI length configuration, the UE was configured to use a legacy TTI length configuration, the xTTI length configuration being half the legacy TTI length configuration.