Method and apparatus for LTE radio link failure determination in DRX mode
A method and apparatus for detecting radio link failure (RLF) in a wireless transmit receive unit (WTRU) includes the WTRU performing a series of radio link measurements during a discontinuous reception (DRX) on-duration, comparing each of the series of radio link measurements to a threshold, and determining that the series of radio link measurements indicates an out-of-synch condition.
1. A method of detecting radio link failure (RLF) in a wireless transmit receive unit (WTRU), the method comprising:
performing a series of radio link measurements on a serving cell during discontinuous reception (DRX) mode;
detecting a predetermined number of consecutive out-of-synch conditions based on the series of radio link measurements;
starting a timer upon detecting the predetermined number of consecutive out-of-synch conditions; and
while operating in DRX mode, continuing the series of radio link measurements on the serving cell using an evaluation period corresponding to non-DRX mode until an expiry or a stop of the timer.
2. The method of claim 1 , wherein the timer is stopped upon detecting a predetermined number of consecutive in-synch conditions based on the continued series of radio link measurements.
3. The method of claim 1 , further comprising:
determining that the timer has expired; and
determining that a radio link failure has been detected.
4. The method of claim 1 , wherein the continued series of radio link measurements are performed during DRX on-duration and DRX sleep-time until an expiry or a stop of the timer.
5. The method of claim 4 , further comprising:
determining a number of measurements during the DRX sleep-time based on at least one of: a duration of the radio link measurements, a duration of an in-synch measurement, a counter value or a constant.
6. The method of claim 1 , wherein the series of radio link measurements are continued as if operating in a non-DRX mode until the expiry of the timer.
7. The method of claim 1 , further comprising:
determining that a radio link failure has occurred on a condition that the timer expires prior to being stopped.
8. The method of claim 1 , further comprising:
determining a block error rate of a downlink channel to determine a radio link failure.
9. The method of claim 1 , further comprising:
decoding a radio network temporary identifier (RNTI).
10. A wireless transmit receive unit (WTRU) configured to determine a radio link failure, the WTRU comprising:
a processor configured to:
perform a series of radio link measurements on a serving cell during discontinuous reception (DRX) mode;
detect a predetermined number of consecutive out-of-synch conditions based on the series of radio link measurements;
start a timer upon detecting the predetermined number of consecutive out-of-synch conditions; and
while operating in DRX mode, continue the series of radio link measurements on a serving cell using an evaluation period corresponding to non-DRX mode until an expiry or a stop of the timer.
11. The WTRU of claim 10 , wherein the timer is configured to stop upon detecting a predetermined number of consecutive in-synch conditions based on the continued series of radio link measurements.
12. The WTRU of claim 10 , wherein the processor is further configured to:
determine that the timer has expired; and
determine that a radio link failure has been detected.
13. The WTRU of claim 10 , wherein the processor is configured to continue the series of radio link measurements during DRX on-duration and DRX sleep-time until an expiry or a stop of the timer.
14. The WTRU of claim 13 , wherein the processor is further configured to:
determine a number of measurements during the DRX sleep-time based on at least one of: a duration of the radio link measurements, a duration of an in-synch measurement, a counter value or a constant.
15. The WTRU of claim 10 , wherein the series of radio link measurements are configured to continue as if operating in a non-DRX mode until the expiry of the timer.
16. The WTRU of claim 10 , wherein the processor is further configured to:
determine that a radio link failure has occurred on a condition that the timer expires prior to being stopped.
17. The WTRU of claim 10 , wherein the processor is further configured to:
determine a block error rate of a downlink channel to determine a radio link failure.
18. The WTRU of claim 10 , wherein the processor is further configured to:
decode a radio network temporary identifier (RNTI).