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 determining radio link failure (RLF) in a wireless transmit receive unit (WTRU), the method comprising:
performing a series of radio link measurements in 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 using an evaluation period corresponding to non-DRX mode until an expiry or a stop of the timer, wherein the timer is stopped upon detecting a predetermined number of consecutive in-synch conditions based on the continued series of radio link measurements.
2. The method as in claim 1 , further comprising:
determining that the timer has expired; and
determining that a radio link failure has been detected.
3. The method as in claim 1 further comprising:
determining a number of measurements for the series of radio link measurements.
4. The method as in claim 1 , further comprising
determining a number of measurements during the sleep-time based on a duration of the measurements, a duration of an in-synch measurement, a counter value and a constant.
5. The method as in claim 1 further comprising the WTRU determining reference signal quality to determine a radio link failure.
6. The method as in claim 1 further comprising the WTRU determining a block error rate of a downlink channel to determine a radio link failure.
7. The method as in claim 6 further comprising the WTRU decoding a radio network temporary identifier (RNTI).
8. The method of claim 1 , further comprising:
determining that a radio link failure has occurred when the timer expires prior to being stopped.
9. 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 in 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 using an evaluation period corresponding to non-DRX mode until an expiry or a stop of the timer, 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.
10. The WTRU as in claim 9 , wherein the processor is further configured to:
determine whether the timer has expired; and
determine that a radio link failure has been detected.
11. The WTRU as in claim 9 wherein the processor is further configured to determine a number of measurements for the series of radio link measurements.
12. The WTRU as in claim 11 wherein the processor is further configured to determine a number of measurements during the sleep-time based on a duration of the measurements, a duration of an in-synch measurement, a counter value and a constant.
13. The WTRU as in claim 9 wherein the processor is further configured to determine a reference signal quality to determine a radio link failure.
14. The WTRU as in claim 9 further comprising the WTRU determining a block error rate of a downlink channel to determine a radio link failure.
15. The WTRU as in claim 14 further comprising the WTRU decoding a radio network temporary identifier (RNTI).
16. The WTRU in claim 9 , wherein the processor is further configured to determine that a radio link failure has occurred when the timer expires prior to being stopped.