Method and apparatus for uplink timing synchronization with ranging signal in mobile communication system

• US 8,600,420 B2
• Filed: 12/08/2006
• Issued: 12/03/2013
• Est. Priority Date: 12/08/2005
• Status: Active Grant

• Current Assignee: Electronics and Telecommunications Research Institute, Hanaro Telecom., Inc., KT Corporation, Samsung Electronics Co. Ltd., SK Telecom Co., Ltd.
• Original Assignee: Electronics and Telecommunications Research Institute, Hanaro Telecom., Inc., KT Corporation, Samsung Electronics Co. Ltd., SK Telecom Co., Ltd.
• Inventors: Lee, Young-Ha, Yu, Chang-Wahn, Park, Youn-Ok
• Primary Examiner(s): Eng, George
• Assistant Examiner(s): HUYNH, NAM TRUNG
• Application Number:
  US12/094,763
• Publication Number:
  US 20080305804A1
• Time in Patent Office: 2,552 Days
• Field of Search: 370/350, 370329-330, 455/450, 455/455
• US Class Current: 455/517
• CPC Class Codes: H04L 27/2646 using feedback from receiver for adjusting OFDM transmission parameters, e.g. transmission timing or guard interval length
• CPC Class Codes: H04L 27/2655 Synchronisation arrangements

Abstract

When a base station of a time division duplex based mobile communication system receives an initial ranging request signal from a subscriber station, the base station generates initial ranging information including delay time information to the subscriber station, and receives uplink data delayed and transmitted using a delay time from the subscriber station. Also, when the subscriber station transmits an initial ranging request signal to the base station and receives initial ranging information including delay time information from the base station, the subscriber station establishes a transmission parameter value by using the transmission parameter value included in the initial ranging information and transmits uplink data by using the established delay time.

Claims

1. A method for a base station of a mobile communication system to synchronize a subscriber station and an uplink time, the method comprising:

performing an initial ranging with the subscriber station and establishing a fast fourier transform (FFT) interval based on delay time for delay transmission of uplink data caused by movement of the subscriber station, wherein a starting position of the FFT is prior to a starting position of a reference FFT interval as much as the delay time;

generating initial ranging information including the delay time information and transmitting the initial ranging information to the subscriber station; and

receiving the uplink data transmitted by using the delay time from the subscriber station,

wherein the uplink data transmitted by the subscriber station approaching the base station are transmitted faster than the uplink data transmitted by the subscriber station when not moving, and

the uplink data transmitted by the subscriber station leaving the base station are transmitted later than the uplink data transmitted by the subscriber station when not moving.

2. The method of claim 1, wherein in the establishing the FFT interval, a size of an area in which no interference in a cyclic prefix (CP) interval positioned prior to the FFT is greater than the delay time.

3. The method of claim 1, wherein in the receiving the uplink data, a starting position of the FFT interval to the uplink data transmitted from the subscriber station approaching the base station is positioned at the area in which no interference in the CP interval, and a starting position of the FFT interval to the uplink data transmitted from the subscriber station leaving the base station corresponds to the starting position of the reference FFT interval.

4. The method of claim 1, wherein the delay time is established in advance between the base station and the subscriber station according to mobile communication service types supported by the base station.

5. The method of claim 1, wherein the uplink data includes a periodic ranging code for periodic ranging or a bandwidth request code for bandwidth request ranging.

6. The method of claim 1, wherein the uplink data include data transmitted using the delay time when the bandwidth request ranging is performed with the subscriber station.

7. A method for a subscriber station of a mobile communication system to synchronize a base station and an uplink time, the method comprising:

transmitting an initial ranging request signal for initial ranging to the base station;

receiving initial ranging information including delay time for delay transmission of uplink data caused by movement of the subscriber station after initial ranging and time offset and frequency offset which are for synchronization, from the base station;

performing initial ranging by using transmission parameter values included in the initial ranging information; and

transmitting the uplink data by using a delay time established through the initial ranging,

wherein a starting point of a fast fourier transform (FFT) interval for data is prior to a starting position of a reference FFT interval as much as the delay time, and

wherein in the transmitting the uplink data, based on the delay time, transmitting uplink data is faster than a set timing when approaching the base station and transmitting uplink data is delayed than a set timing when leaving the base station.

8. The method of claim 7, wherein information on transmission power, time offset, frequency offset, and the delay time is checked from the initial ranging information, and the initial ranging is performed by establishing the transmission power, the time, the frequency offset, and the delay time, and the delay time information is determined based on a speed of a subscriber station which is supported by the base station.

9. The method of claim 7, wherein transmitting of uplink data comprises delaying a periodic ranging code for requesting to perform the periodic ranging by the delay time, and transmitting the delayed period ranging code to the base station when a timer established for the periodic ranging is finished.

10. The method of claim 7, wherein transmitting of uplink data comprises delaying a bandwidth request code for transmitting the uplink traffic by the delay time, and transmitting the delayed bandwidth request code to the base station when uplink traffic to be transmitted to the base station is generated.

11. The method of claim 7, wherein the uplink data include at least one of the periodic ranging code and the bandwidth request code, and

the method further comprises:

receiving a ranging response signal on the uplink data from the base station; and

controlling an initial ranging value established by the initial ranging by using the transmission parameter control values included in the ranging response signal.

12. The method of claim 11, further comprising delaying the uplink traffic by the delay time by using the controlled initial ranging value, and transmitting the delayed uplink traffic to the base station.

13. The method of claim 7,

wherein a size of an area in which no interference in a cyclic prefix (CP) interval positioned prior to the FFT is greater than the delay, and

wherein a starting position of the FFT interval to the uplink data transmitted from the subscriber station approaching the base station is positioned at the area in which no interference in the CP interval, and a starting position of the FFT interval to the uplink data transmitted from the subscriber station leaving the base station corresponds to the starting position of the reference FFT interval.

14. A device for synchronizing a subscriber station and an uplink time by using a delay time in a base station of a mobile communication system, the device comprising:

means for receiving an initial ranging request signal for initial ranging from the subscriber station;

means for establishing a fast fourier transform (FFT) interval based on delay time for delay transmission of uplink data caused by movement of the subscriber station, wherein a starting position of the FFT is prior to a starting position of a reference FFT interval as much as the delay time, and generating initial ranging information including the delay time, in response to the initial ranging request signal;

means for transmitting the generated initial ranging information to the subscriber station; and

means for receiving the uplink data delayed and transmitted by using the delay time from the subscriber station,

wherein the uplink data transmitted by the subscriber station approaching the base station are transmitted faster than the uplink data transmitted by the subscriber station when not moving and the uplink data transmitted by the subscriber station leaving the base station are transmitted later than the uplink data transmitted by the subscriber station when not moving.

15. The device of claim 14, wherein

a size of an area in which no interference in a cyclic prefix (CP) interval positioned prior to the FFT is greater than the delay time, and

wherein a starting position of the FFT interval to the uplink data transmitted from the subscriber station approaching the base station is positioned at the area in which no interference in the CP interval, and a starting position of the FFT interval to the uplink data transmitted from the subscriber station leaving the base station corresponds to the starting position of the reference FFT interval.

16. A subscriber station for synchronizing a base station of a mobile communication system and an uplink time, the subscriber station comprising:

means for transmitting an initial ranging request signal for initial ranging to the base station;

means for receiving initial ranging information including delay time established for delay transmission of uplink data caused by movement of the subscriber station after initial ranging and time offset and frequency offset which are for synchronization, from the base station;

means for performing initial ranging by using a transmission parameter value included in the initial ranging information; and

means for transmitting the uplink data by using a delay time established through the initial ranging,

wherein a starting point of a fast fourier transform (FFT) interval for data is prior to a starting position of a reference FFT interval as much as the delay time, and

wherein, based on the delay time, transmitting uplink data is faster than a set timing when approaching the base station and transmitting uplink data is delayed than a set timing when leaving the base station.

17. The subscriber station of claim 16, further comprising means for controlling a transmission parameter value established through the initial ranging according to a ranging response signal received from the base station in response to a periodic ranging code for periodic ranging or a bandwidth request code transmitted for band request ranging, the ranging response signal including a transmission parameter control value.

18. The subscriber station of claim 16, wherein a size of an area in which no interference in a cyclic prefix (CP) interval positioned prior to the FFT is greater than the delay, and

wherein a starting position of the FFT interval to the uplink data transmitted from the subscriber station approaching the base station is positioned at the area in which no interference in the CP interval, and a starting position of the FFT interval to the uplink data transmitted from the subscriber station leaving the base station corresponds to the starting position of the reference FFT interval.