Apparatus and method for receiving/transmitting data in wireless communication system

1. An apparatus for receiving data, comprising:

a receiving unit configured to receive a beacon packet from at least one of a plurality of base stations included in a wireless network having a plurality of stations;

a searching unit configured to search for an index of a subchannel including an optimal channel state among subchannels allocated to a plurality of sectors determined through spatial multiplexing based on the at least one base station using the beacon packet;

a calculating unit configured to calculate a final back off time by adding a random time to a slot time corresponding to the index of the subchannel, the random time being generated randomly; and

a transmitting unit configured to include information about the index of the subchannel in a beacon response packet and transmit the beacon response packet after the final back off time.

2. The apparatus of claim 1 , wherein the beacon packet includes information about a first training symbol, a second training symbol, and data.

3. The apparatus of claim 2 , wherein the first training symbol is a symbol transmitted in omni-directions without different beamforming weights applied to the subchannels allocated to the plurality of sectors.

4. The apparatus of claim 2 , wherein the second training symbol is a symbol transmitted in a predetermined direction with different beamforming weights applied to the subchannels allocated to the plurality of sectors.

5. The apparatus of claim 2 , wherein the searching unit is configured to compare a beamforming weight applied channel state with a beamforming weight not applied channel state using the first and second training symbols.

6. The apparatus of claim 1 , wherein the calculating unit randomly generates an integer number not greater than a predetermined maximum value and calculates the final back off time using a slot time corresponding to the generated integer number.

7. An apparatus for transmitting data, comprising:

a receiving unit configured to receive beacon response packets from a plurality of stations in a wireless network having a plurality of base stations;

a deciding unit configured to decide directions of the plurality of stations using the received beacon response packets;

a weight unit configured to apply beamforming weights in the decided directions to subchannels allocated to a plurality of sectors determined through spatial multiplexing;

a transmitting unit configured to load data on the weight applied subchannels and transmit the data to the plurality of stations in the decided directions,

wherein the receiving unit receives the beacon response packets respectively from the plurality of stations after final back off times corresponding to the plurality of stations, and each of the final back off times is acquired by adding a random time to a slot time corresponding to an index of one of the subchannels.

8. The apparatus of claim 7 , wherein each of the beacon response packets includes information about the index of the one subchannel, the one subchannel having an optimal channel state.

9. The apparatus of claim 7 , wherein, if one station is located in each of the decided directions, the weight unit applies a beamforming weight to subchannels of a sector for transmitting data to said station in each of the decided directions.

10. The apparatus of claim 7 , wherein, if plural stations are located in one of the decided directions, the weight unit applies beamforming weights to corresponding subchannels of a sector for transmitting data to the plural stations.

11. The apparatus of claim 7 , wherein the weight unit applies different beamforming weights to different data to be transmitted to the plurality of stations.

12. A method for receiving data, comprising:

receiving a beacon packet from at least one of a plurality of base stations in a wireless network having a plurality of stations;

searching for an index of a subchannel having an optimal state among subchannels allocated to a sector determined through spatial multiplexing based on the at least one base station using the beacon packet;

calculating a final back off time by adding a slot time corresponding to the index of the subchannel and a random time randomly generated; and

including information about the index of the subchannel in a beacon response packet and transmitting the beacon response packet after the final back off time.

13. The method of claim 12 , wherein the beacon packet includes a first training symbol, a second training symbol, and data information.

14. The method of claim 13 , wherein searching for the index comprises comparing a beamforming weight applied channel state with a beamforming weight not applied channel state using the first and second training symbols.

15. The method of claim 12 , wherein calculating the final back off time comprises:

randomly generating an integer number not greater than a predetermined maximum value; and

calculating the final back off time using a slot time corresponding to the generated integer number.

16. A method for transmitting data, comprising:

transmitting a beacon packet to a plurality of stations;

receiving beacon response packets from the plurality of stations in a wireless network having a plurality of base stations;

deciding directions to the plurality of stations using the received beacon response packets;

applying beamforming weights in the decided directions to subchannels allocated to a plurality of sectors determined through spatial multiplexing; and

loading data on the weight applied subchannels and transmitting the data to the at least one station in the decided directions,

wherein the beacon response packets are respectively received from the plurality of stations after final back off times corresponding to the plurality of stations, and each of the final back off times is acquired by adding a random time to a slot time corresponding to an index of one of the subchannels.

17. The method of claim 16 , wherein each of the beacon response packets includes information about the index of the one subchannel, the one subchannel having an optimal channel state.

18. The method of claim 16 , wherein in applying the beamforming weights,

if one station is located in each of the decided directions, a beamforming weight is applied to subchannels of a sector for transmitting data to said station in each of the decided directions.

19. The method of claim 16 , wherein in applying the beamforming weights,

if plural stations are located in one of the decided directions, beamforming weights are applied to corresponding subchannels of a sector for transmitting data to the plural stations.

20. The method of claim 16 , wherein applying the beamforming weights comprises

applying different beamforming weights to different data to be transmitted to the plurality of stations.