METHODS AND SYSTEM FOR PERFORMING HANDOVER IN A WIRELESS COMMUNICATION SYSTEM

• US 20150319653A1
• Filed: 07/09/2015
• Published: 11/05/2015
• Est. Priority Date: 06/20/2006
• Status: Active Grant

• Current Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Original Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Inventors: Wang, Jin, Terry, Stephen E., Chandra, Arty
• Granted Patent: US 10,880,791 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H04W 36/0011 for data sessions of end-to-end connection
• CPC Class Codes: H04W 36/0055 Transmission or use of information for re-establishing the radio link
• CPC Class Codes: H04W 36/0058 Transmission of hand-off measurement information, e.g. measurement reports
• CPC Class Codes: H04W 36/0061 of neighbour cell information
• CPC Class Codes: H04W 36/0079 in case of hand-off failure or rejection
• CPC Class Codes: H04W 36/0085 Hand-off measurements
• CPC Class Codes: H04W 56/001 Synchronization between nodes
• CPC Class Codes: H04W 92/20 between access points

Abstract

A method and system for performing handover in a third generation (3G) long term evolution (LTE) system are disclosed. A source evolved Node-B (eNode-B) makes a handover decision based on measurements and sends a handover request to a target eNode-B. The target eNode-B sends a handover response to the source eNode-B indicating that a handover should commence. The source eNode-B then sends a handover command to a wireless transmit/receive unit (WTRU). The handover command includes at least one of reconfiguration information, information regarding timing adjustment, relative timing difference between the source eNode-B and the target eNode-B, information regarding an initial scheduling procedure at the target eNode-B, and measurement information for the target eNode-B. The WTRU then accesses the target eNode-B and exchanges layer 1/2 signaling to perform downlink synchronization, timing adjustment, and uplink and downlink resource assignment based on information included in the handover command.

Claims

1. A wireless transmit receive unit (WTRU) comprising a processor configured to:

determine that a radio link failure has occurred; and

transmit a message to an evolved Node-B (eNode-B) in response to determining that the radio link failure has occurred, wherein the message comprises a radio network temporary identifier (RNTI) of the WTRU and a cell identity of a cell previously utilized by the WTRU.

2. The WTRU as in claim 1, wherein the RNTI is a long term evolution (LTE) RNTI.

3. The WTRU as in claim 1, wherein the message is sent via a cell served by the eNode-B.

4. The WTRU as in claim 3, wherein the cell is selected by the WTRU based on a measurement result.

5. The WTRU as in claim 1, wherein the radio link failure is due to a handover failure.

6. The WTRU as in claim 1, wherein the RNTI and the cell identity of the WTRU are sent to the eNode-B in order to facilitate detection of the WTRU at the eNode-B.

7. A method implemented by wireless transmit receive unit (WTRU), the method comprising:

the WTRU determining that a radio link failure has occurred; and

the WTRU transmitting a message to an evolved Node-B (eNode-B) in response to determining that the radio link failure has occurred, wherein the message comprises a radio network temporary identifier (RNTI) of the WTRU and a cell identity of a cell previously utilized by the WTRU.

8. The method as in claim 7, wherein the RNTI is a long term evolution (LTE) RNTI.

9. The method as in claim 7, wherein the message is sent via a cell served by the eNode-B.

10. The method as in claim 9, wherein the cell is selected by the WTRU based on a measurement result.

11. The method as in claim 7, wherein the radio link failure is due to a handover failure.

12. The method as in claim 7, wherein the RNTI and the cell identity of the WTRU are sent to the eNode-B in order to facilitate detection of the WTRU at the eNode-B.

13. An evolved Node-B (eNode-B) comprising a processor configured to:

receive a message from a wireless transmit receive unit (WTRU), wherein the message indicates that a radio link failure has occurred for the WTRU and the message comprises a radio network temporary identifier (RNTI) of the WTRU and a cell identity of a cell previously utilized by the WTRU; and

detect a previous context for the WTRU based on the RNTI and the cell ID.

14. The eNode-B as in claim 13, wherein the eNode-B previous served the WTRU prior to a handover of the WTRU failing.

15. The eNode-B as in claim 14, wherein the eNode-B served the WTRU via a source cell prior to the handover of the WTRU failing.