Radio terminal, radio communication system, and radio communication method

• US 8,165,051 B2
• Filed: 04/15/2009
• Issued: 04/24/2012
• Est. Priority Date: 04/15/2008
• Status: Expired due to Fees

• Current Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Original Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Inventors: Loyola, Luis, Widmer, Joerg, Igarashi, Kei, Yamada, Akira, Aad, Imad
• Primary Examiner(s): Pwu, Jeffrey
• Assistant Examiner(s): Smarth, Gerald
• Application Number:
  US12/424,074
• Publication Number:
  US 20090257368A1
• Time in Patent Office: 1,105 Days
• Field of Search: 370/318, 370/311
• US Class Current: 370/311
• CPC Class Codes: H04W 52/0216 using a pre-established activity schedule, e.g. traffic indication frame
• CPC Class Codes: H04W 52/0235 where the received signal is a power saving command
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A radio terminal includes a radio interface configured to allow radio communication with a radio base station, and a controller configured to control switching between a wake-up state in which the radio interface is turned on and a sleep state in which the radio interface is turned off. The radio terminal acquires a reference wake-up timing scheduled as a wake-up timing for switching from the sleep state to the wake-up state. The controller shifts the wake-up timing from the reference wake-up timing.

Claims

1. A radio terminal comprising:

a radio interface configured to enable radio communication with a radio base station by using a predetermined radio band;

a controller configured to control switching between a wake-up state in which the radio interface is turned on and a sleep state in which the radio interface is turned off; and

an acquiring unit configured to acquire a reference wake-up timing scheduled as a wake-up timing for switching from the sleep state to the wake-up state, wherein

the controller shifts the wake-up timing from the reference wake-up timing to a different reference wake-up timing, and

the controller shifts the wake-up timing from the different reference wake-up timing back to the reference wake-up timing, when the predetermined radio band at the different wake-up timing is occupied by a different radio terminal.

2. The radio terminal according to claim 1, wherein

the acquiring unit acquires the reference wake-up timing from the radio base station.

3. The radio terminal according to claim 1, wherein

the acquiring unit acquires the reference wake-up timing from another radio terminal.

4. The radio terminal according to claim 1, wherein

the acquiring unit autonomously acquires the reference wake-up timing.

5. The radio terminal according to any one of claims 2 to 4, wherein

the reference wake-up timing is determined based on a usage state of the predetermined radio band.

6. The radio terminal according to any one of claims 2 to 4, wherein

the reference wake-up timing is determined based on a length of time used for radio communication.

7. The radio terminal according to claim 1, further comprising a monitor configured to monitor a usage state of the predetermined radio band in the wake-up state, wherein

the controller shifts the wake-up timing from the reference wake-up timing, based on the usage state of the predetermined radio band.

8. The radio terminal according to claim 1, wherein

the controller shifts the wake-up timing from the reference wake-up timing, based on QoS information set for the radio communication performed by the radio terminal.

9. The radio terminal according to claim 1, wherein

the controller shifts the wake-up timing from the reference wake-up timing, based on an error rate of the radio communication performed by the radio terminal.

10. The radio terminal according to claim 1, further comprising a battery configured to provide electric power to the radio interface, wherein

the controller shifts the wake-up timing from the reference wake-up timing, based on a remaining amount of electric power of the battery.

11. The radio terminal according to any one of claims 8 to 10, wherein

an upper limit is defined for a shift amount by which the wake-up timing is shifted from the reference wake-up timing, and

the controller shifts the wake-up timing from the reference wake-up timing without exceeding the upper limit for the shift amount.

12. The radio terminal according to any one of claims 8 to 10, wherein

the controller shifts the wake-up timing from the reference wake-up timing when a different radio terminal performs radio communication immediately before the radio terminal has shifted the wake-up timing from the reference wake-up timing.

13. The radio terminal according to claim 1, wherein

the controller controls a current shift amount by which the wake-up timing is shifted from the reference wake-up timing in a current shift, and

the controller controls a shift amount of a next shift, based on the current shift amount of the current shift.

14. The radio terminal according to claim 1, wherein

the controller shifts the wake-up timing from the reference wake-up timing to the different reference wake-up timing that identifies an earlier time slot relative to the reference wake-up timing, and

the controller shifts the wake-up timing from the different reference wake-up timing back to the reference wake-up timing, when the earlier time slot is occupied by the different radio terminal.

15. A radio communication system comprising:

a radio base station; and

a plurality of radio terminals each having a radio interface configured to allow radio communication with the radio base station by using a predetermined radio band;

a controller configured to control switching between a wake-up state in which the radio interface is turned on and a sleep-state in which the radio interface is turned off; and

a setter configured to set a reference wake-up timing scheduled as a wake-up timing for switching from the sleep state to the wake-up state, wherein

the controller shifts the wake-up timing from the reference wake-up timing to a different reference wake-up timing, and

the controller shifts the wake-up timing from the different reference wake-up timing back to the reference wake-up timing, when the predetermined radio band at the different wake-up timing is occupied by a different radio terminal.

16. A radio communication method for performing radio communication by using a predetermined radio band in a radio communication system including a radio base station and a plurality of radio terminals each having a radio interface configured to allow radio communication with the radio base station, the radio communication method comprising:

controlling switching between a wake-up state in which the radio interface is turned on and a sleep-state in which the radio interface is turned off;

setting a reference wake-up timing scheduled as a wake-up timing for switching from the sleep state to the wake-up state;

shifting the wake-up timing from the reference wake-up timing to a different reference wake-up timing, and

shifting the wake-up timing from the different reference wake-up timing back to the reference wake-up timing, when the predetermined radio band at the different wake-up timing is occupied by a different radio terminal.