Method and apparatus for maintaining uplink synchronization and reducing battery power consumption

• US 9,900,857 B2
• Filed: 09/09/2015
• Issued: 02/20/2018
• Est. Priority Date: 03/24/2006
• Status: Active Grant

• Current Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Original Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Inventors: Wang, Jin, Chen, John S., Sammour, Mohammed, Terry, Stephen E., Chandra, Arty, Zhang, Guodong
• Primary Examiner(s): Nguyen, Anh Ngoc
• Application Number:
  US14/848,507
• Publication Number:
  US 20150382317A1
• Time in Patent Office: 895 Days
• Field of Search: None
• CPC Class Codes: H04J 11/0069 Cell search, i.e. determining cell identity [cell-ID] design of multiplexing codes H04J13/00; processing access restriction or access information H04W48/16; discovery of network devices for network data management H04W8/005; sounding signals for channel estimation H04L25/0226; structure of reference signals in multicarrier modulation systems H04L27/2613; frame, time or carrier synchronisation in multicarrier modulation systems H04L27/2655
• CPC Class Codes: H04W 52/0216 using a pre-established activity schedule, e.g. traffic indication frame
• CPC Class Codes: H04W 56/0045 compensating for timing error by altering transmission time
• CPC Class Codes: H04W 72/21 in the uplink direction of a wireless link, i.e. towards the network
• CPC Class Codes: H04W 92/10 between terminal device and access point, i.e. wireless air interface
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A Node-B sends a polling message to a wireless transmit/receive unit (WTRU). The WTRU sends an uplink synchronization burst in response to the polling message without contention. The Node-B estimates an uplink timing shift based on the synchronization burst and sends an uplink timing adjustment command to the WTRU. The WTRU then adjusts uplink timing based on the uplink timing adjustment command. Alternatively, the Node-B may send a scheduling message for uplink synchronization to the WTRU. The WTRU may send a synchronization burst based on the scheduling message. Alternatively, the WTRU may perform contention-based uplink synchronization after receiving a synchronization request from the Node-B. The WTRU may enter an idle state instead of performing a handover to a new cell when the WTRU moves to the new cell. A discontinuous reception (DRX) interval for the WTRU may be set based on activity of the WTRU.

Claims

1. A method performed by a wireless transmit/receive unit (WTRU), the method comprising:

receiving discontinuous reception (DRX) control information from a wireless network for DRX operation while the WTRU is operating in an active state, the DRX control information indicating predetermined time intervals that the WTRU checks a physical downlink control channel for an identifier associated with the WTRU;

entering a DRX mode such that the WTRU periodically wakes up according to the predetermined time intervals to check the physical downlink control channel for the identifier associated with the WTRU;

receiving at least one polling message on the physical downlink control channel while the WTRU is awake during the predetermined time intervals;

transmitting an uplink synchronization message based on receiving the polling message; and

receiving an uplink timing command in response to the uplink synchronization message.

3. The method of claim 1, wherein the at least one polling message received on the physical downlink control channel indicates a resource to be used by the WTRU to send the uplink synchronization message.

4. The method of claim 3, wherein the resource includes a subframe to be used by the WTRU to send the uplink synchronization message.

5. The method of claim 3, wherein the uplink synchronization message is transmitted using the resource indicated in the at least one polling message.

6. The method of claim 1, wherein the uplink synchronization message includes a preamble transmitted on a random access channel (RACH).

7. The method of claim 1, further comprising adjusting uplink timing based on the received uplink timing command.

2. A wireless transmit/receive unit (WTRU) comprising:

a receiver configured to receive discontinuous reception (DRX) control information from a wireless network for DRX operation while the WTRU is operating in an active state, the DRX control information indicating predetermined time intervals that the WTRU checks a physical downlink control channel for an identifier associated with the WTRU;

circuitry configured to enter a DRX mode such that the WTRU periodically wakes up according to the predetermined time intervals to check the physical downlink control channel for the identifier associated with the WTRU, the receiver further configured to receive at least one polling message on the physical downlink control channel while the WTRU is awake during the predetermined time intervals; and

a transmitter configured to transmit an uplink synchronization message based on the receiver receiving the polling message, the receiver further configured to receive an uplink timing command in response to the transmitter sending the uplink synchronization message.

8. The WTRU of claim 2, wherein the at least one polling message received on the physical downlink control channel indicates a resource to be used by the transmitter to send the uplink synchronization message.

9. The WTRU of claim 8, wherein the resource includes a subframe to be used by the transmitter to send the uplink synchronization message.

10. The WTRU of claim 8, wherein the uplink synchronization message is transmitted using the resource indicated in the at least one polling message.

11. The WTRU of claim 2, wherein the uplink synchronization message includes a preamble transmitted on a random access channel (RACH).

12. The WTRU of claim 2, wherein the circuitry is further configured to adjust uplink timing based on the received uplink timing command.