Coordinated uplink transmission in LTE DRX operations for a wireless transmit receive unit
A method and apparatus for discontinuous reception (DRX) operation in a wireless transmit receive unit aligns uplink and downlink transmissions with a DRX cycle. The transmission may be a channel quality indicator report, a sounding reference signal, or a silence descriptor among other downlink and uplink transmissions.
1. A method implemented by a wireless transmit receive unit (WTRU) for aligning uplink transmissions with a discontinuous reception (DRX) cycle, comprising:
determining that the DRX cycle is a DRX cycle of a first length;
receiving an uplink channel allocation for a periodic uplink transmission, the uplink channel allocation having timing aligned with at least one of a DRX on-duration period or a DRX active time period of the DRX cycle of the first length; and
sending the periodic uplink transmission during at least one of the DRX on-duration period or the DRX active time period.
2. The method as in claim 1 , wherein the periodic uplink transmission is a channel quality indicator (CQI) report.
3. The method as in claim 2 , further comprising receiving an allocation of a physical uplink shared channel (PUSCH) for the CQI report for the DRX cycle of the first length, on the condition that the DRX cycle of the first length is shorter than a configured threshold.
4. The method as in claim 2 , further comprising receiving a CQI request from an eNB and starting an inactivity timer.
5. The method as in claim 2 , further comprising setting the DRX active time period to a length sufficient for transmitting the CQI report.
6. The method as in claim 1 , wherein the uplink transmission is a sounding reference symbol (SRS) transmission.
7. The method as in claim 6 , further comprising comparing the length of the DRX cycle of the first length to a SRS transmission period and sending the SRS transmission on a condition that the SRS transmission period is greater than or equal to the length of the DRX cycle of the first length.
8. The method as in claim 6 , further comprising configuring a DRX cycle of a second length that is longer than the first length, determining a SRS transmission period and aligning the SRS with the DRX cycle of the second length, and sending the SRS transmission during a DRX active time period on a condition that the SRS transmission period equals an integer multiple of the length of the DRX cycle of the second length.
9. A wireless transmit/receive unit (WTRU), comprising:
a processor configured, at least in part, to:
determine that a discontinuous reception (DRX) cycle is a DRX cycle of a first length;
receive an uplink channel allocation for a periodic uplink transmission, the uplink channel allocation having timing aligned with at least one of a DRX on-duration period or a DRX active time period of the DRX cycle of the first length; and
send the periodic uplink transmission during at least one of the DRX on-duration period or the DRX active time period.
10. The WTRU as in claim 9 , wherein the periodic uplink transmission is a channel quality indicator (CQI) report.
11. The WTRU as in claim 10 , further comprising receiving an allocation of a physical uplink shared channel (PUSCH) for the CQI report for the DRX cycle of the first length, on the condition that the DRX cycle of the first length is shorter than a configured threshold.
12. The WTRU as in claim 10 , further comprising receiving a CQI request from an eNB and starting an inactivity timer.
13. The WTRU as in claim 10 , further comprising setting the DRX active time period to a length sufficient for transmitting the CQI report.
14. The WTRU as in claim 9 , wherein the uplink transmission is a sounding reference symbol (SRS) transmission.
15. The WTRU as in claim 14 , wherein the processor is further configured to configure a DRX cycle of a second length, determine a SRS transmission period and align the SRS with the DRX cycle of the second length, and transmit the SRS during a DRX active time period on a condition that the SRS transmission period equals an integer multiple of the length of the DRX cycle of the second length.
16. The WTRU as in claim 14 , wherein the processor is further configured to determine a SRS transmission period, compare the DRX cycle of the first length to the SRS transmission period, and send the SRS transmission on a condition that the DRX cycle of the first length is greater than or equal to the SRS transmission period.