METHOD AND APPARATUS FOR MANAGING UPLINK TIME ALIGNMENT

• US 20130294424A1
• Filed: 03/08/2012
• Published: 11/07/2013
• Est. Priority Date: 03/29/2011
• Status: Active Grant

• Current Assignee: LG Electronics, Inc. (LG Corporation)
• Original Assignee: LG Electronics, Inc. (LG Corporation)
• Inventors: Yi, Seung June, Chun, Sung Duck, Jung, Sung Hoon, Lee, Young Dae, Park, Sung Jun
• Granted Patent: US 9,681,403 B2
• Time in Patent Office: Days
• US Class Current: 370/336
• CPC Class Codes: H04W 56/00 Synchronisation arrangements
• CPC Class Codes: H04W 56/0005 synchronizing of arrival of multiple uplinks
• CPC Class Codes: H04W 56/0045 compensating for timing error by altering transmission time
• CPC Class Codes: H04W 74/004 in the uplink, i.e. towards network
• CPC Class Codes: H04W 74/006 in the downlink, i.e. towards the terminal
• CPC Class Codes: H04W 74/0833 Random access procedures, e.g. with 4-step access
• CPC Class Codes: H04W 74/0838 using contention-free random access [CFRA]
• CPC Class Codes: H04W 92/10 between terminal device and access point, i.e. wireless air interface

Abstract

A method and apparatus of managing uplink time alignment in a wireless communication system is provided. A user equipment starts a time alignment timer which is used to control how long the user equipment is considered uplink time aligned and receives an expiry request message from a base station while the time alignment timer is running. Upon receiving the expiry request, the user equipment expires the time alignment timer and releasing uplink resources.

Claims

1. A method of managing uplink time alignment in a wireless communication system, performed by a user equipment, the method comprising:

starting a time alignment timer which is used to control how long the user equipment is considered uplink time aligned;

receiving an expiry request message from a base station while the time alignment timer is running; and

upon receiving the expiry request, expiring the time alignment timer and releasing uplink resources.

2. The method of claim 1, wherein the expiry request message includes expiry information indicating when the time alignment timer is expired.

3. The method of claim 1, further comprising:

transmitting a request message for requesting the expiry of uplink time alignment to the base station.

4. The method of claim 3, wherein the request message includes request information indicating how long the user equipment wants to run the time alignment timer.

5. The method of claim 1, wherein the expiry request message is received as a medium access control (MAC) control element (CE) or in a Radio Resource Control (RRC) message.

6. A user equipment for managing uplink time alignment in a wireless communication system, comprising:

a radio frequency unit for receiving a radio signal; and

a processor, operatively coupled with the radio frequency unit, configured to;

start a time alignment timer which is used to control how long the user equipment is considered uplink time aligned;

receive an expiry request message from a base station while the time alignment timer is running; and

upon receiving the expiry request, expire the time alignment timer and release uplink resources.

7. The user equipment of claim 6, wherein the expiry request message includes expiry information indicating when the time alignment timer is expired.

8. The user equipment of claim 6, wherein the processor is configured to transmit a request message for requesting the expiry of uplink time alignment to the base station.

9. The user equipment of claim 8, wherein the request message includes request information indicating how long the user equipment wants to run the time alignment timer.

10. A user equipment for managing uplink time alignment in a wireless communication system, comprising:

a radio frequency unit configured to receive and transmit a radio signal; and

a processor, operatively coupled with the radio frequency unit, configured to;

start a time alignment timer which is used to control how long the user equipment is considered uplink time aligned; and

transmit a request message for requesting an extension or an expiry of uplink time alignment to a base station while the time alignment timer is running.

11. The user equipment of claim 10, wherein the processor is configured to receive a response message for indicating the extension or the expiry of uplink time alignment from the base station while the time alignment timer is running.

12. The user equipment of claim 10, wherein the processor is configured to transmit another request message to the base station when no response message is received from the base station within a predefined time interval.

13. The user equipment of claim 10, wherein the request message includes at least one of a type of an application that needs extension of uplink time alignment, a required extension time and a suggested value of the time alignment timer.

14. The user equipment of claim 10, wherein the response message includes expiry information indicating when the time alignment timer is expired.

15. The user equipment of claim 10, wherein the response message includes extension information indicating a value of the time alignment timer.