Radio communication system, radio communication control method, radio communication apparatus, control method for radio communication apparatus, and computer program

• US 20030091019A1
• Filed: 11/12/2002
• Published: 05/15/2003
• Est. Priority Date: 11/12/2001
• Status: Active Grant

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Takano, Hiroaki
• Granted Patent: US 7,586,893 B2
• Time in Patent Office: Days
• US Class Current: 370/345
• CPC Class Codes: H04L 27/2601 Multicarrier modulation systems
• CPC Class Codes: H04W 16/24 Cell structures
• CPC Class Codes: H04W 72/542 using measured or perceived quality

Abstract

A radio communication system, a radio communication control method, a radio communication apparatus, a control method for a radio communication apparatus, and a computer program make it possible to minimize the chance of co-channel interference in a multi-cell environment, and also permit free adjustment of an uplink/downlink ratio. The carrier sense region of a terminal wanting an uplink shares the region used as a directional busy tone region for a terminal wanting an uplink, and the region used as a reference signal transmission region of a terminal wanting a downlink. Furthermore, the carrier sense region of a terminal wanting a downlink shares the region used as a directional busy tone region for a terminal wanting a downlink, and the region used as a reference signal transmission region of a terminal wanting an uplink. If a result of the carrier sense indicates an idle mode, then a reference signal is transmitted.

Claims

1. A radio communication system comprising:

a base station equipped with a sector antenna; and

a mobile station equipped with an omnidirectional antenna,

wherein a transmission frame is divided into slots to perform multiple access, and

each of the slots comprises;

region 1 in which the base station transmits a directional busy tone through a sector antenna used for a mobile station in an uplink mode;

region 2 in which a mobile station in a downlink mode transmits a reference signal through an omnidirectional antenna to the base station;

region 3 in which the base station transmits a directional busy tone through a sector antenna used for a mobile station in the downlink mode; and

region 4 in which a mobile station in the uplink mode transmits a reference signal through an omnidirectional antenna to the base station.

2. The radio communication system according to claim 1, wherein a mobile station wanting an uplink performs carrier sense in region 1 and region 2 of a desired slot, and transmits a reference signal through an omnidirectional antenna in region 4 of the slot in response to a result indicating no carriers sensed in any of the regions.

3. The radio communication system according to claim 1, wherein a mobile station continues to transmit a reference signal through an omnidirectional antenna in region 4 of the slot during an uplink.

4. The radio communication system according to claim 1, wherein a mobile station wanting an uplink performs carrier sense in region 1 and region 2 of a desired slot, and gives up the uplink if a carrier is sensed at least in one of the two regions.

5. The radio communication system according to claim 1, wherein the base station that has received an omnidirectional reference signal in region 4 of the slot selects a sector antenna having a most desirable ratio of a desired signal to an interference signal, and transmits a directional busy tone in region 1 of a relevant slot by using the sector antenna.

6. The radio communication system according to claim 1, wherein a mobile station wanting a downlink performs carrier sense in region 3 and region 4 of a desired slot, and transmits a reference signal through an omnidirectional antenna in region 2 of the same slot in response to a result indicating no carriers sensed in any of the regions.

7. The radio communication system according to claim 1, wherein a mobile station continues to transmit a reference signal through an omnidirectional antenna in region 2 of a relevant slot during a downlink.

8. The radio communication system according to claim 1, wherein a mobile station wanting a downlink performs carrier sense in region 3 and region 4 of a desired slot, and gives up the downlink if a carrier is sensed at least in one of the two regions.

9. The radio communication system according to claim 1, wherein the base station that has received an omnidirectional reference signal in region 2 of a slot selects a sector antenna having a most desirable ratio of a desired signal to an interference signal, and transmits a directional busy tone in region 3 of a relevant slot by using the sector antenna.

10. The radio communication system according to claim 1, wherein the base station transmits a broadcast slot that includes information regarding whether each slot is currently in the uplink mode or the downlink mode, information for notifying a mobile station that has a downlink waiting of the presence of downlink data, and information for granting a mobile station wanting an uplink to perform the uplink.

11. A radio communication control method for carrying out multiple access by dividing a transmission frame into slots in a radio cell having a base station equipped with a sector antenna and a mobile station equipped with an omnidirectional antenna, comprising:

a step in which the base station transmits a directional busy tone in region 1 of a relevant slot through a sector antenna used for a mobile station in an uplink mode;

a step in which a mobile station in a downlink mode transmits a reference signal in region 2 of a relevant slot through an omnidirectional antenna to the base station;

a step in which the base station transmits a directional busy tone in region 3 of a relevant slot through a sector antenna used for a mobile station in the downlink mode; and

a step in which a mobile station in an uplink mode transmits a reference signal in region 4 of a relevant slot through an omnidirectional antenna to the base station.

12. The radio communication control method according to claim 11, wherein a mobile station wanting the uplink performs carrier sense in region 1 and region 2 of a desired slot, and transmits a reference signal through the omnidirectional antenna in region 4 of the slot in response to a result indicating no carriers sensed in any of the regions.

13. The radio communication control method according to claim 11, wherein the mobile station in the uplink mode continues to transmit a reference signal through the omnidirectional antenna in region 4 of the relevant slot.

14. The radio communication control method according to claim 11, wherein a mobile station wanting an uplink performs carrier sense in region 1 and region 2 of a desired slot, and avoids entry if a carrier is sensed at least in one of the two regions.

15. The radio communication control method according to claim 11, wherein the base station that has received an omnidirectional reference signal in region 4 of the slot selects a sector antenna having a most desirable ratio of a desired signal to an interference signal, and transmits a directional busy tone in region 1 of a relevant slot by using the sector antenna.

16. The radio communication control method according to claim 11, wherein the mobile station wanting the downlink performs carrier sense in region 3 and region 4 of a desired slot, and transmits a reference signal in region 2 of the same slot through the omnidirectional antenna in response to a result indicating no carriers sensed in any of the regions.

17. The radio communication control method according to claim 11, further comprises a step in which the mobile station in the downlink mode continues to transmit a reference signal through the omnidirectional antenna in region 2 of a relevant slot.

18. The radio communication control method according to claim 11, further comprising a step in which the mobile station wanting the downlink performs carrier sense in region 3 and region 4 of a desired slot, and gives up the downlink if a carrier is sensed at least in one of the two regions.

19. The radio communication control method according to claim 11, wherein the base station that has received an omnidirectional reference signal in region 2 of a slot selects a sector antenna having a most desirable ratio of a desired signal to an interference signal, and transmits a directional busy tone in region 3 of a relevant slot by using the sector antenna.

20. The radio communication control method according to claim 11, further comprising a step in which the base station transmits a broadcast slot that includes information regarding whether each slot is currently in the uplink mode or the downlink mode, information for notifying a mobile station that has a downlink waiting of the presence of downlink data, and information for granting a mobile station wanting an uplink to perform the uplink.

21. A radio communication apparatus comprising:

a plurality of directional sector antennas;

means for transmitting a directional busy tone by using region 1 of a slot through a sector antenna used for a mobile station in an uplink mode; and

means for transmitting a directional busy tone by using region 3 of a slot through a sector antenna used for a mobile station in a downlink mode,

wherein the radio communication apparatus acts as a base station in a radio cell,

a transmission frame is divided into slots to perform multiple access, and

each of the slots comprises;

region 1 in which a base station transmits a directional busy tone through a sector antenna used for a mobile station in an uplink mode;

region 2 in which a mobile station in a downlink mode transmits a reference signal through an omnidirectional antenna to the base station;

region 3 in which the base station transmits a directional busy tone through a sector antenna used for a mobile station in the downlink mode; and

region 4 in which a mobile station in an uplink mode transmits a reference signal through an omnidirectional antenna to the base station.

22. The radio communication apparatus according to claim 21, further comprising:

means for selecting a sector antenna that has a most desirable ratio of a desired signal to an interference signal and for transmitting a directional busy tone in region 1 of a relevant slot by using the sector antenna when an omnidirectional reference signal is received in region 4 of the slot.

23. The radio communication apparatus according to claim 21, further comprising:

means for selecting a sector antenna that has a most desirable ratio of a desired signal to an interference signal and for transmitting a directional busy tone in region 3 of a relevant slot by using the sector antenna when an omnidirectional reference signal is received in region 2 of the slot.

24. The radio communication apparatus according to claim 21, further comprising:

means for transmitting a broadcast slot that includes information regarding whether each slot is currently in the uplink mode or the downlink mode, information for notifying a mobile station that has a downlink waiting of the presence of downlink data, and information for granting a mobile station wanting an uplink to perform the uplink.

25. A control method for a radio communication apparatus that has a plurality of directional sector antennas and acts as a base station in a radio cell, a transmission frame being divided into slots to perform multiple access,

each of the slots comprising:

region 1 in which the base station transmits a directional busy tone through a sector antenna used for a mobile station in an uplink mode;

region 2 in which a mobile station in a downlink mode transmits a reference signal through an omnidirectional antenna to the base station;

region 3 in which the base station transmits a directional busy tone through a sector antenna used for a mobile station in the downlink mode; and

region 4 in which a mobile station in an uplink mode transmits a reference signal through an omnidirectional antenna to the base station,

the control method comprising;

a step for transmitting a directional busy tone by using region 1 of a slot through the sector antenna used for the mobile station in the uplink mode; and

a step for transmitting a directional busy tone by using region 3 of a slot through the sector antenna used for the mobile station in the downlink mode.

26. The control method for a radio communication apparatus according to claim 25, further comprising:

a step for selecting a sector antenna that has a most desirable ratio of a desired signal to an interference signal and transmitting a directional busy tone in region 1 of a relevant slot by using the sector antenna when an omnidirectional reference signal is received in region 4 of the slot.

27. The control method for a radio communication apparatus according to claim 25, further comprising:

a step for selecting a sector antenna that has a most desirable ratio of a desired signal to an interference signal and transmitting a directional busy tone in region 3 of a relevant slot by using the sector antenna when an omnidirectional reference signal is received in region 2 of the slot.

28. The control method for a radio communication apparatus according to claim 25, further comprising:

a step for transmitting a broadcast slot that includes information regarding whether each slot is currently in the uplink mode or the downlink mode, information for notifying a mobile station that has a downlink waiting of the presence of downlink data, and information for granting a mobile station wanting an uplink to perform the uplink.

29. A radio communication apparatus comprising:

an omnidirectional antenna;

means for transmitting an omnidirectional reference signal by using region 2 of a slot in the downlink mode;

means for transmitting an omnidirectional reference signal by using region 4 of a slot in the uplink mode;

means for sensing carriers in region 1 and region 2 of a desired slot when an uplink is required; and

means for sensing carriers in region 3 and region 4 of a desired slot when a downlink is required,

wherein the radio communication apparatus acts as a mobile station in a radio cell,

a transmission frame is divided into slots to perform multiple access, and

each of the slots comprises;

region 1 in which a base station transmits a directional busy tone through a sector antenna used for a mobile station in an uplink mode;

region 2 in which a mobile station in a downlink mode transmits a reference signal through an omnidirectional antenna to the base station;

region 3 in which the base station transmits a directional busy tone through a sector antenna used for a mobile station in the downlink mode; and

region 4 in which a mobile station in the uplink mode transmits a reference signal through an omnidirectional antenna to the base station.

30. The radio communication apparatus according to claim 29, further comprising:

means for performing an uplink if no carriers are detected in region 1 and region 2 of the slot wanting an uplink, while avoiding the uplink if any carriers are detected.

31. The radio communication apparatus according to claim 29, further comprising:

means for performing a downlink if no carriers are detected in region 3 and region 4 of the slot wanting a downlink, while avoiding the downlink if any carriers are detected.

32. A control method for a radio communication apparatus that has an omnidirectional antenna and acts as a mobile station in a radio cell, a transmission frame being divided into slots to perform multiple access,

each of the slots comprising:

region 1 in which a base station transmits a directional busy tone through a sector antenna used for a mobile station in an uplink mode;

region 2 in which a mobile station in a downlink mode transmits a reference signal through an omnidirectional antenna to the base station;

region 3 in which the base station transmits a directional busy tone through a sector antenna used for a mobile station in the downlink mode; and

region 4 in which the mobile station in the uplink mode transmits a reference signal through an omnidirectional antenna to the base station,

the control method for a radio communication apparatus comprising;

a step for transmitting an omnidirectional reference signal by using region 2 of a slot in the downlink mode;

a step for transmitting an omnidirectional reference signal by using region 4 of a slot in the uplink mode;

a step for sensing carriers in region 1 and region 2 of a desired slot when an uplink is required; and

a step for sensing carriers in region 3 and region 4 of a desired slot when a downlink is required.

33. The control method for a radio communication apparatus according to claim 32, further comprising:

a step for performing an uplink if no carriers are detected in region 1 and region 2 of the slot wanting an uplink, while avoiding the uplink if any carriers are detected.

34. The control method for a radio communication apparatus according to claim 32, further comprising:

a step for performing a downlink if no carriers are detected in region 3 and region 4 of the slot wanting a downlink, while avoiding the downlink if any carriers are detected.

35. A computer program described to carry out, on a computer system, the control of a radio communication apparatus that has a plurality of directional sector antennas and acts as a base station in a radio cell, a transmission frame being divided into slots to perform multiple access,

each of the slots comprising:

region 1 in which a base station transmits a directional busy tone through a sector antenna used for a mobile station in an uplink mode;

region 2 in which a mobile station in a downlink mode transmits a reference signal through an omnidirectional antenna to the base station;

region 3 in which the base station transmits a directional busy tone through a sector antenna used for a mobile station in the downlink mode; and

region 4 in which the mobile station in the uplink mode transmits a reference signal through an omnidirectional antenna to the base station,

the computer program comprising;

a step for transmitting a directional busy tone by using region 1 of a slot through a sector antenna used for a mobile station in the uplink mode; and

a step for transmitting a directional busy tone by using region 3 of a slot through a sector antenna used for a mobile station in the downlink mode.

36. A computer program described to carry out, on a computer system, the control of a radio communication apparatus that has an omnidirectional antenna and acts as a mobile station in a radio cell, a transmission frame being divided into slots to perform multiple access,

each of the slots comprising:

region 1 in which a base station transmits a directional busy tone through a sector antenna used for a mobile station in an uplink mode;

region 2 in which a mobile station in a downlink mode transmits a reference signal through an omnidirectional antenna to the base station;

region 3 in which the base station transmits a directional busy tone through a sector antenna used for a mobile station in the downlink mode; and

region 4 in which a mobile station in an uplink mode transmits a reference signal through an omnidirectional antenna to the base station,

the computer program comprising;

a step for transmitting an omnidirectional reference signal by using region 2 of a slot in the downlink mode;

a step for transmitting an omnidirectional reference signal by using region 4 of a slot in the uplink mode;

a step for sensing carriers in region 1 and region 2 of a desired slot when requiring an uplink; and

a step for sensing carriers in region 3 and region 4 of a desired slot when requiring a downlink.