OFDM communication system and OFDM communication method

• US 20070297323A1
• Filed: 08/31/2007
• Published: 12/27/2007
• Est. Priority Date: 03/02/2005
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Seki, Hiroyuki
• Granted Patent: US 7,839,880 B2
• Time in Patent Office: Days
• US Class Current: 370/208
• CPC Class Codes: H04L 27/2602 Signal structure
• CPC Class Codes: H04L 5/023 Multiplexing of multicarrier modulation signals multicarrier modulation H04L27/2601

Abstract

In an OFDM communication system that performs OFDM data communication by dividing a band region into a plurality of bands and assigning each band to a mobile station, a base station monitors transmission characteristics of the bands and state of use of adjacent bands, then sets whether to use or not use guard band regions between bands for data transmission based upon the transmission characteristics, and the state of use of the adjacent bands.

Claims

1. An OFDM communication method that performs OFDM data communication by dividing a band region into a plurality of bands and assigning each band to a mobile station, comprising steps of:

monitoring the transmission characteristics of the bands and the state of use of the adjacent bands, and setting whether to use or not use a guard band region on the boundary between bands for data transmission, based on the transmission characteristics of the bands and the state of use of the adjacent bands.

2. An OFDM communication method that performs OFDM data communication by dividing a band region into a plurality of bands and assigning each band to a mobile station, comprising steps of:

monitoring the DOWN transmission characteristics reported from the mobile stations and the state of use of the adjacent bands, and setting whether to use or not use a guard band region on the boundary between bands for downlink data transmission, based on the transmission characteristics of the bands and the state of use of the adjacent bands.

3. The OFDM communication method of claim 2 wherein, a base station sends control data to the mobile stations and notifies mobile stations of how to use the guard band regions in downlink communication using the control data.

6. The OFDM communication method of claim 2, wherein;

when there is no mobile station assigned to a band, the base station sets to use the guard band regions on both ends of that band for data transmission of the respective adjacent bands.

7. The OFDM communication method of claim 2, wherein;

when data transmission of a band is performed at a high transmission rate, the base station sets to not use the guard band regions on both ends of that band for data transmission.

8. The OFDM communication method of claim 2, wherein;

when the difference in reception power between adjacent bands is large, the base station sets not to use the guard band region on the boundary between the adjacent bands for data transmission.

9. The OFDM communication method of claim 2, wherein;

when the reception SIR of subcarriers near a guard band region is small, the base station sets not to use that guard band region for data transmission.

4. An OFDM communication method that performs OFDM data communication by dividing a band region into a plurality of bands and assigning each band to a mobile station, comprising steps of:

monitoring the transmission characteristics in uplink communication of each band and the state of use of the adjacent bands,

setting whether to use or not use a guard band region on the boundary between bands for uplink data transmission, based on the transmission characteristics of the bands and the state of use of the adjacent bands,

and notifying the mobile stations of how to use the guard band region in that uplink communication.

5. The OFDM communication method of claim 4, wherein;

a mobile station transmits data to a base station according to an instruction regarding how to use the guard band region.

10. The OFDM communication method of claim 4, wherein;

when the difference in reception timing of adjacent bands is large, the base station sets not to use the guard band on the boundary between the adjacent bands for data transmission.

11. The OFDM communication method of claim 4, wherein;

when the difference in frequency offset between adjacent bands is large, the base station sets not to use the guard band region on the boundary between the adjacent bands for data transmission.

12. A base station in an OFDM communication system that performs OFDM data communication by dividing a band region into a plurality of bands and assigning each band to a mobile station, comprising:

an information receiving unit that receives feedback information related to transmission characteristics in downlink communication from the mobile stations;

a monitoring unit that monitors the state of use of the adjacent bands;

a measurement unit that measures the transmission characteristics of each band in uplink communication, and

a control unit that sets whether to used or not use guard band regions on the boundaries between bands for data transmission, based on feedback information from said mobile stations, the state of use of adjacent bands, and the transmission characteristics of bands.

13. The base station of claim 12 that further comprises an OFDM transmission unit that performs OFDM transmission by distributing data to be transmitted in each of said bands to subcarriers based on whether or not said guard band regions is used when performing downlink transmission.

14. The base station of claim 13, wherein;

said OFDM transmission unit sends control data to the mobile station and notifies the mobile stations of how to use the guard band regions in downlink communication using the control data.

15. The base station of claim 12, wherein;

said OFDM transmission unit sends control data to the mobile station and notifies the mobile stations of how to use the guard band regions in uplink communication using the control data.

16. A mobile station in an OFDM communication system that performs OFDM data communication by dividing a band region into a plurality of bands and assigning each band to a mobile station;

comprising;

an OFDM receiving unit that receives DOWN transmission data and control information from a base station using a specified band,

a measurement unit that measures the transmission characteristic in downlink communication;

an OFDM transmission unit that transmits the measured transmission characteristic to the base station;

a control information demodulation unit that demodulates the control information that is transmitted from the base station; and

a data demodulation unit that demodulates the DOWN transmission data based on an instruction of control information regarding whether or not to use guard band regions in downlink communication for data transmission.

17. The mobile station of claim 16, wherein;

said OFDM transmission unit includes means for distributing UP transmission data to subcarriers of a specified band and performing transmission based on an instruction of control information of whether or not to use guard band regions in uplink communication for data transmission.