Wireless communication system and wireless station

Abstract

A station determines the presence/absence of directional beam control in an access point, on the basis of received power measured when data transmitted from the access point are received, and the type of the received data. In accordance with the result of this determination, the station controls transmitting power to transmit data to the access point.

1. A wireless communication system which exchanges data between an access point and plural stations, wherein said station comprises:
 a received data type detection unit which detects whether received data from said access point is a beacon frame; 
 a received power measurement unit which measures received power of the beacon frame, and measures received power of data sent from said access point to said station after the beacon frame; 
 a beam gain estimation unit which determines the presence/absence of directional beam control in said access point, on the basis of the received powers of the beacon frame and the data measured by said received power measurement unit; and 
 a transmitting power control unit which controls transmitting power for transmitting data to said access point, when said beam gain estimation unit determines that said access point is performing directional beam control. 
 
     
     
       2. A system according to  claim 1 , wherein the data is an authentication frame from the access point. 
     
     
       3. A system according to  claim 1 , wherein the data is an association response frame from the access point. 
     
     
       4. A system according to  claim 1 , wherein when said beam gain estimation unit determines that said access point is performing directional beam control, said transmitting power control unit sets the transmitting power to transmit data to said access point at the minimum necessary power receivable by said access point. 
     
     
       5. A system according to  claim 1 , wherein when determining that said access point is performing directional beam control, said beam gain estimation unit further checks whether space division multiple access is applicable at said access point, and
 when said beam gain estimation unit determines that said access point is performing directional beam control, and that space division multiple access is applicable at said access point, said transmitting power control unit sets the transmitting power to transmit data to said access point at the minimum necessary power receivable by said access point. 
 
     
     
       6. A system according to  claim 1 , further comprising:
 a transmitted power detection unit which detects transmitted power when said access point transmits a first data, and detects transmitted power when said access point transmits a second data. 
 
     
     
       7. A wireless communication system which exchanges data between an access point and plural stations by CSMA (Carrier Sense Multiple Access), wherein said station comprises:
 a received data type detection unit which detects whether received data from said access point is a beacon frame; 
 a received power measurement unit which measures the received power of the beacon frame, and measures the received power of data sent from said access point to said station after the beacon frame; 
 a beam gain estimation unit which determines the presence/absence of directional beam control in said access point, on the basis of the received powers of the beacon frame and the data measured by said received power measurement unit; 
 a transmitting power control unit which controls transmitting power to transmit data to said access point, when said beam gain estimation unit determines that said access point is performing directional beam control; and 
 a carrier sense control unit which controls the carrier sense level of said station in accordance with the result of the determination by said beam gain estimation unit. 
 
     
     
       8. A system according to  claim 7 , wherein the data is an authentication frame from the access point. 
     
     
       9. A system according to  claim 7 , wherein the data is an association response frame from the access point. 
     
     
       10. A system according to  claim 7 , wherein when said beam gain estimation unit determines that said access point is performing directional beam control, said carrier sense control unit raises the carrier sense level of said station to such an extent that the carrier sense function does not degrade. 
     
     
       11. A system according to  claim 7 , wherein
 when determining that said access point is performing directional beam control, said beam gain estimation unit further checks whether space division multiple access is applicable at said access point, and 
 when said beam gain estimation unit determines that said access point is performing directional beam control, and that space division multiple access is applicable at said access point, said carrier sense control unit raises the carrier sense level of said station to such an extent that the carrier sense function does not degrade. 
 
     
     
       12. A system according to  claim 7 , further comprising:
 a transmitted power detection unit which detects transmitted power when said access point transmits a first data, and detects transmitted power when said access point transmits a second data. 
 
     
     
       13. A wireless station which exchanges data with an access point, comprising:
 a received data type detection unit which detects whether received data from said access point is a beacon frame; 
 a received power measurement unit which measures the received power of the beacon frame, and measures the received power of the data sent from said access point to said station after the beacon frame; 
 a beam gain estimation unit which determines the presence/absence of directional beam control in said access point, on the basis of the received powers of the beacon frame and the data measured by said received power measurement unit; and 
 a transmitting power control unit which controls transmitting power for transmitting data to said access point, when said beam gain estimation unit determines that said access point is performing directional beam control. 
 
     
     
       14. A system according to  claim 13 , wherein the data is an authentication frame from the access point. 
     
     
       15. A system according to  claim 13 , wherein the data is an association response frame from the access point. 
     
     
       16. A station according to  claim 13 , wherein when said beam gain estimation unit determines that said access point is performing directional beam control, said transmitting power control unit sets the transmitting power to transmit data to said access point at the minimum necessary power receivable by said access point. 
     
     
       17. A station according to  claim 13 , wherein
 when determining that said access point is performing directional beam control, said beam gain estimation unit further checks whether space division multiple access is applicable at said access point, and 
 when said beam gain estimation unit determines that said access point is performing directional beam control, and that space division multiple access is applicable at said access point, said transmitting power control unit sets the transmitting power to transmit data to said access point at the minimum necessary power receivable by said access point. 
 
     
     
       18. A station according to  claim 13 , further comprising:
 a transmitted power detection unit which detects transmitted power when said access point transmits the beacon frame, and detects transmitted power when said access point transmits the data. 
 
     
     
       19. A wireless station which exchanges data with an access point by CSMA (Carrier Sense Multiple Access), comprising:
 a received data type detection unit which detects whether received data from said access point is a beacon frame; 
 a received power measurement unit which measures the received power of the beacon frame, and measures the received power of data sent from said access point to said station after the beacon frame; 
 a beam gain estimation unit which determines the presence/absence of directional beam control in said access point, on the basis of the received powers of the beacon frame and the data measured by said received power measurement unit; 
 a transmitting power control unit which controls transmitting power for transmitting data to said access point, when said beam gain estimation unit determines that said access point is performing directional beam control; and 
 a carrier sense control unit which controls the carrier sense level of said station in accordance with the result of the determination by said beam gain estimation unit. 
 
     
     
       20. A system according to  claim 19 , wherein the data is an authentication frame from the access point. 
     
     
       21. A system according to  claim 19 , wherein the data is an association response frame from the access point. 
     
     
       22. A wireless station according to  claim 19 , further comprising:
 a transmitted power detection unit which detects transmitted power when said access point transmits the beacon frame, and detects transmitted power when said access point transmits a second data. 
 
     
     
       23. A wireless communication method for a wireless terminal which exchanges data with another wireless terminal which transmits beacon frames, the method comprising:
 measuring received power when data are transmitted from the another wireless terminal;   detecting a type of the received data;   determining whether the another wireless terminal performs directional beam control based on the measured received power and the detected type of the received data; and   controlling transmitting power for transmitting data to the another wireless terminal in accordance with the result of the determination.    
     
     
       24. A method according to claim 23, wherein the detecting comprises detecting whether the received data are broadcast type data or unicast type data.  
     
     
       25. A method according to claim 23, wherein the determining comprises determining that SDMA (Space Division Multiple Access) is applicable at the another wireless terminal when a level of a directional beam is larger than a predetermined level.  
     
     
       26. A method according to claim 23, further comprising:
 detecting transmitting power of the received data.    
     
     
       27. A method according to claim 23, wherein when it is determined that the another wireless terminal performs directional beam control, the controlling sets the transmitting power at a minimum necessary power receivable by the another wireless terminal.  
     
     
       28. A method according to claim 23, wherein when it is determined that the another wireless terminal performs directional beam control, the determining further checks whether SDMA (Space Division Multiple Access) is applicable at the another wireless terminal, and when it is determined that the another wireless terminal performs directional beam control and that SDMA is applicable at the another wireless terminal, the controlling sets the transmitting power at a minimum necessary power receivable by the another wireless terminal.  
     
     
       29. A wireless terminal which exchanges data with another wireless terminal which transmits beacon frames, comprising:
 a measurement unit configured to measure received power when data are transmitted from the another wireless terminal;   a detector configured to detect a type of the received data;   a determining unit configured to determine whether the another wireless terminal performs directional beam control based on the received power measured by the measurement unit and the type of the received data detected by the detector; and   a controller configured to control transmitting power for transmitting data to the another wireless terminal in accordance with a result of determination by the determining unit.    
     
     
       30. A wireless communication method for a wireless terminal which exchanges with another wireless terminal which transmits beacon frames by CSMA (Carrier Sense Multiple Access), the method comprising:
 measuring received power when data are transmitted from the another wireless terminal;   detecting a type of the received data;   determining whether the another wireless terminal performs directional beam control based on the measured received power and the detected type of the received data; and   controlling a carrier sense level in accordance with the result of the determination.    
     
     
       31. A method according to claim 30, wherein the detecting comprises detecting whether the received data are broadcast type data or unicast type data.  
     
     
       32. A method according to claim 30, further comprising:
 detecting transmitting power of the received data.    
     
     
       33. A method according to claim 30, wherein when it is determined that the another wireless terminal performs directional beam control, the controlling raises the carrier sense level to such an extent that a carrier sense function does not degrade.  
     
     
       34. A method according to claim 30, wherein when it is determined that the another wireless terminal performs directional beam control, the determining further checks whether SDMA (Space Division Multiple Access) is applicable at the another wireless terminal, and
 when it is determined that the another wireless terminal performs directional beam control and that the SDMA is applicable at the another wireless terminal, the controlling raises the carrier sense level to such an extent that a carrier sense function does not degrade.    
     
     
       35. A wireless terminal which exchanges data with another wireless terminal which transmits beacon frames by CSMA (Carrier Sense Multiple Access), comprising:
 a measurement unit configured to measure received power when data are transmitted from the another wireless terminal;   a detector configured to detect a type of the received data;   a determining unit configured to determine whether the another wireless terminal performs directional beam control based on the received power measured by the measurement unit and the type of the received data detected by the detector; and   a controller configured to control a carrier sense level in accordance with a result of determination by the determining unit.