METHOD AND SYSTEM FOR RECOVERING FROM DRX TIMING DE-SYNCHRONIZATION IN LTE _ACTIVE

• US 20080192703A1
• Filed: 02/14/2007
• Published: 08/14/2008
• Est. Priority Date: 02/14/2007
• Status: Active Grant

• Current Assignee: Guangdong OPPO Mobile Telecommunications Corporation Limited
• Original Assignee: Research In Motion Limited (Blackberry Limited)
• Inventors: SUZUKI, Takashi
• Granted Patent: US 8,072,963 B2
• Time in Patent Office: Days
• US Class Current: 370/335
• CPC Class Codes: H04W 56/00 Synchronisation arrangements
• CPC Class Codes: H04W 76/28 Discontinuous transmission [DTX]; Discontinuous reception [DRX]

Abstract

A method for recovering from discontinuous reception (DRX) timing de-synchronization between the UE and the eNB in an LTE_ACTIVE state having the steps of: the eNB detecting DRX timing de-synchronization; transmitting an indicator to a User Equipment (UE) to resume continuous reception; and waiting for an indication from the UE of whether a Continuous Reception Response or Continuous Reception Notification was received.

Claims

1. A method for recovering from discontinuous reception (DRX) timing de-synchronization in an LTE_ACTIVE state comprising the steps of:

a. detecting DRX timing de-synchronization;

b. transmitting an indicator to a User Equipment (UE) to resume continuous reception; and

c. waiting for an indication of whether a Continuous Reception Response or Continuous Reception Notification was received.

2. The method of claim 1, wherein the transmitting step includes adding a radio network temporarily identifier (RNTI) for the User Equipment to a predefined system information block.

3. The method of claim 2, wherein said detecting step comprises:

sending or retransmitting a medium access control protocol data unit (MAC-PDU) to the UE; and

failing to receive a hybrid automatic repeat request (HARQ) feedback signal within a predetermined time.

4. The method of claim 3, further comprising the steps of:

receiving the indication of the Continuous Reception Notification; and

retransmitting the MAC-PDU.

5. The method of claim 4, further comprising the step of:

removing the RNTI for the User Equipment from the predefined system information block upon confirmation that the MAC-PDU was received.

6. The method of claim 1, wherein the transmitting step comprises:

waiting from an absolute wake-up time; and

sending a Continuous Reception Command.

7. The method of claim 6, wherein said detecting step comprises:

sending or retransmitting a medium access control protocol data unit (MAC-PDU) to the UE; and

failing to receive a hybrid automatic repeat request (HARQ) feedback signal within a predetermined time.

8. The method of claim 7, further comprising the steps of:

receiving the indication of the Continuous Reception Response; and

retransmitting the MAC-PDU.

9. The method of claim 8, further comprising the steps of:

if the indication of the Continuous Reception Response is not received, or if the retransmission of the MAC-PDU is unsuccessful, checking whether a handover has occurred or if an RRC connection has been released, and if yes, ending the process.

10. The method of claim 9, wherein if a handover has not occurred and if an RRC connection has been not been released, checking whether a retry period is over, and

if yes, releasing the RRC connection;

and

if no, repeating the waiting and sending steps.

11. The method of claim 6, wherein absolute wake-up timing is defined by a radio frame offset to the system radio frame timing and DRX interval.

12. The method of claim 11, wherein the absolute wake-up timing is a radio frame defined by the radio frame offset, added to the DRX interval multiplied by a positive integer or zero.

13. The method of claim 12, wherein absolute wake-up timing is transmitted to the UE by RRC.

14. The method of claim 12, wherein the radio frame offset is calculated from a subscriber or UE identity.

15. The method of claim 12, wherein the identity is the International Mobile Station Identity.

16. A method for going to continuous reception in User Equipment due to a discontinuous reception (DRX) timing de-synchronization in an LTE_ACTIVE state comprising the steps of:

waking up from DRX;

checking an indicator to determine whether to go to continuous reception; and

if an indicator exists to go to continuous reception, deactivating DRX, going to continuous reception, and transmitting a Continuous Reception Response or Continuous Reception Notification.

17. The method of claim 16, wherein the checking step comprises:

reading a predefined system information block; and

determining whether a radio network temporarily identifier (RNTI) for the User Equipment is within the predefined system information block, wherein if the determining step finds the RNTI of the User Equipment in the predefined system information block, checking step finds the indicator exists.

18. The method of claim 16, wherein, if an indicator exists to go to continuous reception and to obtain uplink synchronization, obtaining an uplink synchronization and scheduling grant for sending a Continuous Reception Response.

19. The method of claim 16, wherein the checking step comprises:

determining whether a Continuous Reception Command is received at an absolute wake-up time,

wherein if the Continuous Reception Command is received at an absolute wake-up time the checking step find the indicator exists.

20. An enhanced Node B (eNB) adapted to recover from discontinuous reception (DRX) timing de-synchronization in an LTE_ACTIVE state, characterized by:

means for detecting DRX timing de-synchronization;

means for transmitting an indicator to a User Equipment (UE) to resume continuous reception; and

means for waiting for an indication of whether a Continuous Reception Response or Continuous Reception Notification was received.

21. The eNB of claim 20, wherein the means for transmitting an indicator to the UE is adapted to include, in the indicator, a need for uplink synchronization and radio resource to be used for a Continuous Command Response.

22. The eNB of claim 20, wherein the means for transmitting is adapted to add a radio network temporarily identifier (RNTI) for the User Equipment to a predefined system information block.

23. The eNB of claim 20, wherein the means for transmitting is adapted to:

wait from an absolute wake-up time; and

send a Continuous Reception Command.

24. A User Equipment (UE) adapted to go to continuous reception due to a discontinuous reception (DRX) timing de-synchronization in an LTE_ACTIVE state, characterized by:

means for waking up from DRX;

means for checking an indicator to determine whether to go to continuous reception; and

means for deactivating DRX, going to continuous reception and transmitting a Continuous Reception Response or Continuous Reception Notification if an indicator exists to go to continuous reception.

25. The UE of claim 24, wherein the means for checking is adapted to:

read a predefined system information block; and

determine whether a radio network temporarily identifier (RNTI) for the User Equipment is within the predefined system information block, wherein if the RNTI of the User Equipment in the predefined system information block, the means for checking step is adapted to find the indicator exists.

26. The UE of claim 24, wherein the means for checking is adapted to determine whether a Continuous Reception Command is received at an absolute wake-up time,

wherein if the Continuous Reception Command is received at an absolute wake-up time the means for checking is adapted to find the indicator exists.