FREQUENCY SELECTION METHOD AND COGNITIVE WIRELESS SYSTEM

• US 20140315565A1
• Filed: 11/07/2012
• Published: 10/23/2014
• Est. Priority Date: 11/11/2011
• Status: Active Grant

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Altintas, Onur, Ihara, Yutaka
• Granted Patent: US 9,313,778 B2
• Time in Patent Office: Days
• US Class Current: 455/452.1
• CPC Class Codes: G08G 1/056 with provision for distinguishing direction of travel
• CPC Class Codes: G08G 1/094 Hardware aspects; Signal processing or signal properties, e.g. frequency bands
• CPC Class Codes: H04L 5/0066 Requirements on out-of-channel emissions
• CPC Class Codes: H04W 16/14 Spectrum sharing arrangements between different networks
• CPC Class Codes: H04W 4/029 Location-based management or tracking services
• CPC Class Codes: H04W 64/006 with additional information processing, e.g. for direction or speed determination
• CPC Class Codes: H04W 72/20 Control channels or signalling for resource management
• CPC Class Codes: H04W 72/56 based on priority criteria

Abstract

A frequency to be used in a cognitive wireless system is determined appropriately. A DB apparatus manages white spaces (WS) for each frequency, and calculates and reports, to a mobile terminal, WS vectors (distances from a mobile terminal location to an interference area in the four directions, north, south, east and west) for each frequency. The mobile terminal refers to the WS vectors and uses a frequency providing the longest available distance in a direction of movement. The available distance is calculated by interpolation (triangular interpolation, elliptical interpolation, rectangular interpolation) of WS boundaries using various methods. Desirably, the mobile terminal reports a direction of movement to the DB apparatus, and the DB apparatus reports the distance to an interference area only in the two directions near to the direction of movement. Furthermore, desirably, information indicating whether the interference areas in the two directions are the same area or different areas is added to the WS vectors, and the interpolation method employed by the mobile terminal is changed in accordance with this information.

Claims

1. A frequency determination method for determining a frequency to be used for communication by a mobile communication apparatus, in a wireless communications system including a database apparatus which stores, for each frequency, a prohibited area which is an area where a licensed user is using radio waves, and the mobile communication apparatus which is capable of wireless communications with the database apparatus;

the method comprising;

a step in which the mobile communication apparatus acquires location information of the mobile communication apparatus;

a step in which the mobile communication apparatus reports the location information to the database apparatus;

a step in which the database apparatus determines, for each frequency, a first distance, which is a distance in a first direction to the prohibited area from the location indicated by the reported location information, and a second distance, which is a distance in a second direction to the prohibited area from the location indicated by the reported location information, and generating distance information including the first distance and the second distance;

a step in which the database apparatus reports the distance information for each frequency, to the mobile communication apparatus; and

a step in which the mobile communication apparatus determines a frequency to be used for communication, on the basis of the reported distance information and a direction of movement of the mobile communication apparatus.

2. The frequency determination method according to claim 1,

wherein the step in which a frequency to be used for communication is determined includes:

an available distance calculation step of determining, for each frequency, a distance to the prohibited area in the direction of movement of the mobile communication apparatus, by interpolation on the basis of the first distance and the second distance included in the distance information; and

a frequency selection step of determining, as a frequency to be used for communication, a frequency providing the longest distance, of the distances determined by the available distance calculation step.

3. The frequency determination method according to claim 2, wherein, in the available distance calculation step, the distance to the prohibited area in the direction of movement of the mobile communication apparatus is determined by assuming that a boundary of the prohibited area is a straight line linking a point distanced by the first distance in the first direction from a current location of the mobile communication apparatus, and a point distanced by the second distance in the second direction from the current location of the mobile communication apparatus.

4. The frequency determination method according to claim 2, wherein, in the available distance calculation step, the distance to the prohibited area in the direction of movement of the mobile communication apparatus is determined by assuming that a boundary of the prohibited area is an ellipse passing through a point distanced by the first distance in the first direction from a current location of the mobile communication apparatus, and a point distanced by the second distance in the second direction from the current location of the mobile communication apparatus.

5. The frequency determination method according to claim 2, wherein, in the available distance calculation step, the distance to the prohibited area in the direction of movement of the mobile communication apparatus is determined by assuming that a boundary of the prohibited area is a rectangle passing through a point distanced by the first distance in the first direction from a current location of the mobile communication apparatus, and a point distanced by the second distance in the second direction from the current location of the mobile communication apparatus.

6. The frequency determination method according to claim 2,

wherein the distance information includes information indicating whether the prohibited area in the first direction from the location indicated by the location information reported from the mobile communication apparatus and the prohibited area in the second direction from the location indicated by the location information reported from the mobile communication apparatus are the same area or different areas;

and

in the available distance calculation step,

if the prohibited area in the first direction and the prohibited area in the second direction are the same area, the distance to the prohibited area in the direction of movement of the mobile communication apparatus is determined by assuming that a boundary of the prohibited area is an ellipse passing through a point distanced by the first distance in the first direction from a current location of the mobile communication apparatus, and a point distanced by the second distance in the second direction from the current location of the mobile communication apparatus, and

if the prohibited area in the first direction and the prohibited area in the second direction are different areas, the distance to the prohibited area in the direction of movement of the mobile communication apparatus is determined by assuming that the boundary of the prohibited area is a rectangle passing through a point distanced by the first distance in the first direction from the current location of the mobile communication apparatus, and a point distanced by the second distance in the second direction from the current location of the mobile communication apparatus.

7. The frequency determination method according to claim 1,

further comprising a step in which the mobile communication apparatus reports a direction of movement of the mobile communication apparatus, to the database apparatus, wherein

two directions nearest to the direction of movement of the mobile communication apparatus are selected as the first direction and the second direction from among a previously predetermined plurality of directions.

8. The frequency determination method according to claim 7, wherein the first direction and the second direction are perpendicular to each other.

9. The frequency determination method according to claim 8, wherein the first direction and the second direction are selected from among four predetermined directions 90°

apart from each other.

10. The frequency determination method according to claim 1, wherein, in the step in which distance information is generated, a distance, for each frequency, from the location indicated by the location information reported from the mobile communication apparatus to an area where the frequency is unavailable, is determined for predetermined first to fourth directions 90°

apart from each other, and distance information is generated so as to include these distances.

11. The frequency determination method according to claim 1, wherein, in the step in which a frequency to be used for communication is determined, the mobile communication apparatus determines the frequency to be used for communication by also taking account of a predicted path of travel of the mobile communication apparatus.

12. The frequency determination method according to claim 11,

wherein the step in which a frequency to be used for communication is determined includes:

a step of acquiring a predicted path of movement of the mobile communication apparatus;

a step of setting an intermediate point on the predicted path of movement;

a step of acquiring distance information at the intermediate point, from the database apparatus;

a step of determining, for each frequency, a distance to a prohibited area in the direction of movement from the current location on the basis of the distance information at the current location, and if the distance exceeds a distance to a next intermediate point on the predicted path of movement, determining a distance to the prohibited area in the direction of movement from the next intermediate point on the basis of the distance information at the next intermediate point and the direction of movement at the next intermediate point, and calculating the sum of the distance from the current location of the mobile communication apparatus to the next intermediate point and the distance to the prohibited area determined at the next intermediate point, as the available distance for the frequency; and

a frequency selection step of determining, as a frequency to be used for communication, a frequency providing the longest distance, of the distances determined by the available distance calculation step.

13. A wireless communications system comprising a database apparatus and a mobile communication apparatus, the mobile communication apparatus performing communications by selecting a frequency from among available frequencies,

wherein the database apparatus includes:

prohibited area storage means for storing, for each frequency, a prohibited area which is an area where a licensed user is using radio waves; and

distance information generating means for determining, for each frequency and on the basis of location information reported from the mobile communication apparatus, a first distance, which is a distance in a first direction to the prohibited area from a location indicated by the reported location information, and a second distance, which is a distance in a second direction to the prohibited area from the location indicated by the reported location information, and generating distance information including the first distance and the second distance, and

the mobile communication apparatus includes;

location information acquisition means for acquiring location information;

distance information requesting means for reporting the location information to the database apparatus and acquiring the distance information; and

use frequency determining means for determining a frequency to be used for communication, on the basis of the reported distance information and a direction of movement of the mobile communication apparatus.

14. The wireless communications system according to claim 13,

wherein the use frequency determining means:

determines, for each frequency, a distance to the prohibited area in the direction of movement of the mobile communication apparatus, by interpolation on the basis of the first distance and the second distance included in the distance information; and

determines, as a frequency to be used for communication, a frequency providing the longest distance, of the determined distances.

15. A mobile communication apparatus which performs communication by determining a frequency to use on the basis of distance information reported from a database apparatus storing, for each frequency, a prohibited area which is an area where a licensed user is using radio waves, the mobile communication apparatus comprising:

location information acquisition means for acquiring location information;

distance information requesting means for reporting the location information to the database apparatus and acquiring distance information including a first distance, which is a distance in a first direction to the prohibited area from a location indicated by the location information, and a second distance, which is a distance in a second direction to the prohibited area from the location indicated by the location information; and

use frequency determining means for determining a frequency to be used for communication, on the basis of the reported distance information and a direction of movement of the mobile communication apparatus.

16. The mobile communication apparatus according to claim 15,

wherein the use frequency determining means:

determines, for each frequency, a distance to the prohibited area in the direction of movement of the mobile communication apparatus, by interpolation on the basis of the first distance and the second distance included in the distance information; and

determines, as a frequency to be used for communication, a frequency providing the longest distance, of the determined distances.

17. A database apparatus, comprising:

prohibited area storage means for storing, for each frequency, a prohibited area which is an area where a licensed user is using radio waves; and

distance information generating means for determining, for each frequency and on the basis of location information reported from a mobile communication apparatus, a first distance, which is a distance in a first direction to the prohibited area from a location indicated by the reported location information, and a second distance, which is a distance in a second direction to the prohibited area from the location indicated by the reported location information, and generating distance information including the first distance and the second distance.

18. The database apparatus according to claim 17, wherein the distance information generating means selects, as the first direction and the second direction, two directions nearest to a direction of movement of the mobile communication apparatus, from among a predetermined plurality of directions, on the basis of the direction of movement reported from the mobile communication apparatus.

19. The database apparatus according to claim 18, wherein the first direction and the second direction are perpendicular to each other.

20. The database apparatus according to claim 17, wherein the distance information generating means includes, in the distance information, information indicating whether the prohibited area in the first direction and the prohibited area in the second direction are the same area or different areas.