Radio terminal

• US 20070042733A1
• Filed: 08/07/2006
• Published: 02/22/2007
• Est. Priority Date: 08/17/2005
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Tomioka, Tazuko
• Granted Patent: US 7,715,343 B2
• Time in Patent Office: Days
• US Class Current: 455/179.100
• CPC Class Codes: H04W 48/18 Selecting a network or a communication service

Abstract

There is provided with a radio terminal which carries out data transmission using frequency bands licensed to other licensed radio terminals, including: a judging section configured to carry out a modulation analysis on a radio signal for each frequency band to judge whether the radio signal is a radio signal from a licensed radio terminal or not; a selection section configured to select a plurality of frequency bands; a schedule generation section configured to generate a schedule for intermittent data transmission; a data transmission section configured to transmit data according to the schedule; a carrier sensing section configured to carry out carrier sensing on a frequency band in which data is transmitted before data transmission for each the intermittent data transmission; and a control section configured to stop, when a radio signal from a licensed radio terminal is detected in a certain frequency band, data transmission using at least the certain frequency band.

Claims

1. A radio terminal which carries out data transmission using a plurality of frequency bands including frequency bands licensed to other licensed radio terminals, comprising:

a detection section configured to detect a radio signal for each frequency band;

a judging section configured to carry out a modulation analysis on the detected radio signal to judge whether the radio signal is a radio signal from a licensed radio terminal or not;

a selection section configured to select a plurality of frequency bands to be used for data transmission based on the judgment result;

a schedule generation section configured to generate a schedule for intermittent data transmission using the plurality of selected frequency bands;

a data generation section configured to generate data for the intermittent data transmission;

a data transmission section configured to transmit the generated data according to the schedule;

a carrier sensing section configured to carry out carrier sensing on a frequency band in which data is transmitted before data transmission for each the intermittent data transmission; and

a control section configured to stop, when the carrier sensing result shows that a radio signal from a licensed radio terminal is detected in a certain frequency band, data transmission using at least the certain frequency band.

2. The radio terminal according to claim 1, wherein the selection section selects frequency bands in which periods during which no radio signal from licensed radio terminals are detected equal or exceed first threshold.

3. The radio terminal according to claim 1, wherein the selection section selects frequency bands in which no radio signals from licensed terminals are detected and periods during which no radio signals from other unlicensed radio terminals are detected equal or exceed a second threshold.

4. The radio terminal according to claim 1, wherein the selection section selects frequency bands based on frequency band utilization rates by unlicensed radio terminals.

5. The radio terminal according to claim 1, wherein the selection section selects frequency bands in which frequency band utilization rates by unlicensed radio terminals are equal to or lower than a third threshold, and

the schedule generation section determines a continuous data transmission time per one time in each intermittent data transmission such that the utilization rate falls to or below the third threshold for each the selected frequency band.

6. The radio terminal according to claim 5, wherein a third threshold corresponding to the utilization rate is determined for each the frequency band.

7. The radio terminal according to claim 5, wherein a third threshold corresponding to the utilization rate is determined based on interference tolerance of the licensed radio terminals in the each frequency band.

8. The radio terminal according to claim 5, wherein a third threshold corresponding to the utilization rate is determined based on a frequency of usage of the frequency band by the licensed radio terminals in the each frequency band.

9. The radio terminal according to claim 1, wherein the schedule generation section determines a continuous data transmission time in the intermittent data transmission for each the selected frequency band.

10. The radio terminal according to claim 1, wherein the schedule generation section generates a data transmission schedule in each frequency band so that periodical data transmission is carried out for each the selected frequency band.

11. The radio terminal according to claim 10, wherein the schedule generation section determines a data transmission period in the periodical data transmission for each the selected frequency band.

12. The radio terminal according to claim 1, wherein for a frequency band of the selected frequency bands for which the licensed radio terminals have carrier sensing functions, the schedule generation section generates a data transmission schedule of the frequency band so that data transmission is performed in a period longer than the carrier sensing time of the licensed radio terminals.

13. The radio terminal according to claim 1, wherein for a frequency band in which an unlicensed radio terminal is periodically transmitting radio signal, the schedule generation section generates a data transmission schedule in the frequency band so that data transmission is performed in synchronization with the period.

14. The radio terminal according to claim 13, wherein the data transmission synchronized with the unlicensed radio terminal is performed after the transmission of the radio signal by the unlicensed radio terminal and before carrier sensing by the unlicensed radio terminal.

15. The radio terminal according to claim 1, wherein the schedule generation section generates a data transmission schedule of each frequency band so as to perform intermittent data transmission through frequency hopping using the plurality of selected frequency bands, and

the carrier sensing section carries out carrier sensing to be carried out before data transmission in each frequency band during data transmission scheduled for a time immediately preceding the data transmission in the frequency band.

16. The radio terminal according to claim 15, wherein the schedule generation section generates a data transmission schedule in each frequency band so that an interval between two temporally adjacent frequency bands to be used is wider than an input bandwidth of an analog/digital converter of the detection section for detecting the radio signal.

17. The radio terminal according to claim 15, wherein the schedule generation section generates a data transmission schedule in each frequency band so that for two temporally adjacent frequency bands to be used, the frequency band to be used later does not include a second harmonic wave, third harmonic wave, third-order intermodulation distortion and fifth-order intermodulation distortion of a frequency included in the frequency band to be used first.

18. The radio terminal according to claim 16, wherein based on frequency differences between at least two predetermined frequencies and the plurality of selected frequency bands, the schedule generation section performs grouping by selecting frequency bands from the selected frequency bands for each of the at least two predetermined frequencies, and the two temporally adjacent frequency bands to be used are selected from frequency bands of different groups respectively.

19. The radio terminal according to claim 1, wherein the bandwidth of the frequency band in which the radio signal is detected is narrower than the input bandwidth of an analog/digital converter of the detection section for detecting the radio signal.

20. The radio terminal according to claim 1, wherein when data transmission using a certain frequency band is stopped by the control section, the schedule generation section uses another frequency band selected by the selection section instead of the certain frequency band and generates a data transmission schedule in each frequency band over again.

21. The radio terminal according to claim 1, wherein when data transmission using a certain frequency band is stopped by the control section, the data generation section generates notification data for notifying a reception radio terminal of the frequency band in which data transmission is stopped, and

the data transmission section transmits the notification data generated.

22. The radio terminal according to claim 21, wherein the data transmission section transmits the notification data in different frequency bands a plurality of times.