Method for maintaining uplink timing synchronization in a mobile communication system and user equipment apparatus for the same

• US 8,031,692 B2
• Filed: 06/21/2007
• Issued: 10/04/2011
• Est. Priority Date: 06/22/2006
• Status: Active Grant

• Current Assignee: Nokia Solutions and Networks US LLC (Nokia Corporation)
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: van der Velde, Himke, Van Lieshout, Gert Jan, Song, O-Sok, Choi, Sung-Ho, Kwak, Yong-Jun, Lee, Ju-Ho, Jeong, Kyeong-In
• Primary Examiner(s): Kincaid, Lester
• Assistant Examiner(s): WOO, KUO-KONG
• Application Number:
  US11/766,498
• Publication Number:
  US 20080002660A1
• Time in Patent Office: 1,566 Days
• Field of Search: 370/516, 370/350, 370/389, 370/329, 375/371
• US Class Current: 370/350
• CPC Class Codes: H04B 7/2681 Synchronisation of a mobile station with one base station
• CPC Class Codes: H04L 27/2655 Synchronisation arrangements
• CPC Class Codes: H04L 27/2675 Pilot or known symbols
• CPC Class Codes: H04L 5/023 Multiplexing of multicarrier modulation signals multicarrier modulation H04L27/2601
• CPC Class Codes: H04L 7/033 using the transitions of the received signal to control the phase of the synchronising-signal-generating means, e.g. using a phase-locked loop
• CPC Class Codes: H04W 56/0005 synchronizing of arrival of multiple uplinks

Abstract

Disclosed is a method for maintaining uplink timing synchronization by a User Equipment (UE) in a mobile communication system, without uplink transmission of a preamble from a UE or without transmission of uplink timing difference information from an Evolved Node B (E-NB) to solve the inefficient use problem of radio resources, occurring due to periodic transmission of uplink signaling and downlink signaling during maintenance of the uplink timing synchronization, and a UE apparatus for the same.

Claims

1. A method for maintaining uplink timing synchronization (sync) in a mobile communication system, comprising:

transmitting from a User Equipment (UE) to a Node B an uplink sync request message including a preamble code;

receiving at the UE from the Node B an uplink sync response message in response to the request message;

adjusting, at the UE, uplink timing according to uplink timing adjustment information included in the response message, and storing the adjusted uplink timing as reference uplink timing for uplink signaling or data transmission at the UE;

periodically measuring downlink timing at the UE after storing the reference uplink timing, and calculating a difference between the measured downlink timing and previously stored reference downlink timing at the UE;

periodically re-determining the uplink timing at the UE by applying the calculated difference between the measured downlink timing and the previously stored reference downlink timing to the reference uplink timing after each periodically measured downlink timing;

receiving a request message for readjustment of the uplink timing at the UE from a Node B that has detected a discrepancy of the uplink timing;

readjusting the uplink timing at the UE using uplink timing adjustment information included in the uplink timing readjustment request message, updating the reference uplink timing with the readjusted uplink timing at the UE, and storing the updated reference uplink timing at the UE; and

updating a last measured downlink timing as the reference downlink timing at the UE when updating the reference uplink timing, and storing the updated reference downlink timing at the UE.

2. The method of claim 1, wherein the uplink timing information indicates a timing difference between the preamble code and a candidate preamble code that has a highest correlation with the preamble code and is available for uplink timing sync during a specific interval.

3. The method of claim 1, wherein downlink timing for when the uplink timing is adjusted is set as the reference downlink timing, and then stored.

4. The method of claim 1, wherein downlink timing for when the uplink sync response message is received is set as the reference downlink timing, and then stored.

5. The method of claim 1, wherein the calculation of the difference further comprises calculating a difference between an average value of downlink timing measured for a specific time and the previously stored reference downlink timing.

6. A user equipment apparatus for maintaining uplink timing synchronization (sync), comprising:

a message transceiver for receiving a message including uplink timing adjustment information from a Node B, and transmitting uplink data and signaling to the Node B according to uplink timing;

a message decrypter for decrypting a message received from the message transceiver to acquire the uplink timing adjustment information;

a reference timing manager for setting reference uplink timing according to the acquired uplink timing adjustment information, and setting the reference downlink timing according to the downlink timing;

an uplink timing adjuster for calculating a difference between a periodically measured downlink timing and the reference downlink timing and periodically adjusting the uplink timing by applying the calculated difference to the reference uplink timing after each periodically measured downlink timing and difference calculation;

a timer for counting a period for which the uplink timing is adjusted; and

a downlink measurer for measuring the downlink timing according to the period, and providing the measured downlink timing to the uplink timing adjuster and the reference timing manager.

7. The user equipment apparatus of claim 6, wherein the message transceiver receives from the Node B a readjustment request message for requesting readjustment of the uplink timing;

wherein the uplink timing adjuster readjusts the uplink timing using the uplink timing adjustment information included in the readjustment request message; and

further

wherein the reference timing manager updates and stores a last measured downlink timing as the reference downlink timing, and updates and stores the readjusted uplink timing as the reference uplink timing.

8. The user equipment apparatus of claim 6, wherein the reference timing manager sets, as the reference downlink timing, downlink timing for when the uplink timing adjuster adjusts the uplink timing, and stores the reference downlink timing.

9. The user equipment apparatus of claim 6, wherein the reference timing manager sets, as the reference downlink timing, downlink timing for when the message transceiver receives the message, and stores the reference downlink timing.

10. The user equipment apparatus of claim 6, wherein the reference timing manager calculates a difference between an average value of downlink timing measured for the period by the downlink measurer and previously stored reference downlink timing, and transmits the calculated timing difference information to the uplink timing adjuster so as to adjust the uplink timing.