Communication device and communication method

• US 20080008276A1
• Filed: 09/14/2007
• Published: 01/10/2008
• Est. Priority Date: 03/15/2005
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Yokoyama, Hitoshi
• Granted Patent: US 7,684,527 B2
• Time in Patent Office: Days
• US Class Current: 375/347
• CPC Class Codes: H04B 7/063 Parameters other than those covered in groups H04B7/0623 - H04B7/0634, e.g. channel matrix rank or transmit mode selection
• CPC Class Codes: H04B 7/0669 using different channel coding between antennas space-time coding H04L1/0618
• CPC Class Codes: H04B 7/0689 using different transmission schemes, at least one of them being a diversity transmission scheme
• CPC Class Codes: H04L 7/08 the synchronisation signals recurring cyclically

Abstract

There is provided a radio communication device having a high quality and accuracy regardless of fluctuation degree of the transmission path characteristic. The radio communication device estimates the fluctuation speed of the transmission path characteristic from the time correlation of the reception signal, judges the diversity technique used between the communication devices from the estimated value, and feeds back the judgment information so as to switch the diversity between the communication devices, thereby increasing the diversity gain. The feedback information is minimized by defining a correspondence table. Moreover, diversity switching is performed at a timing considering a control delay and a propagation path delay so as to prevent an instantaneous disconnection of the communication.

Claims

1. A communication device comprising:

a receiving unit receiving radio signals from a partner communication device;

a unit stored with the received signals received for a predetermined period;

a unit calculating a time correlation defined as a correlation between the received signal received from a first reference point of time onward within the predetermined period and the received signal received from a second reference point of time onward within the predetermined period;

a unit obtaining a time difference between the first reference point of time and a second reference point of time when the time correlation takes a value of a predetermined range;

a selecting unit selecting a wireless communication procedure designated corresponding to the time difference; and

an instructing unit instructing said partner communication device about the selected wireless communication procedure.

2. A communication device according to claim 1, further comprising a unit calculating the time correlation with one received signal in the plurality of radio signals received from said partner communication device.

3. A communication device according to claim 1, further comprising:

a unit calculating a plurality of time correlations from the plurality of radio signals received from said partner communication device; and

a unit generating a combined time correlation weighted with a magnitude of a value of electric power of each of the plural received signals, from the plurality of time correlations and the plurality of received signals.

4. A communication device according to claim 1, further comprising a unit calculating the time correlation with respect to a combination of the plural received signals from the plurality of radio signals received from said partner communication device.

5. A communication device according to claim 1, further comprising a unit determining whether or not a communication procedure selected by said selecting unit is the same as a communication procedure used before the selection,

wherein said instructing unit includes a unit, if the pre-selection communication procedure is the same as the post-selection communication procedure, instructing said partner communication device about none of the selected communication procedure.

6. A communication device according to claim 1, further comprising:

a unit measuring a predetermined period of stopping time when selecting the communication procedure;

a unit stopping the calculation of the time correlation during the period of stopping time; and

a unit resuming the process of calculating the time correlation after the period of stopping time.

7. A communication device according to claim 1, further comprising a changeover control unit changing over a receiving procedure in said receiving unit to the selected wireless communication procedure after an elapse of a predetermined period of time since the wireless communication procedure has been selected.

8. A communication device according to claim 7, further comprising:

a unit determining whether or not the communication procedure selected by said selecting unit is the same as the communication procedure used before the selection; and

a unit changing over, if the pre-selection communication procedure is the same as the post-selection communication procedure, none of the communication procedure.

9. A communication device according to claim 1, wherein said unit instructing said partner communication device about the selected wireless communication procedure gives the instruction in a way that associates the selected wireless communication procedure with a bit sequence to be fed back.

10. A communication device comprising:

a unit receiving an instruction of changing over a communication procedure from a partner communication device; and

a unit changing over the communication procedure to the selected wireless communication procedure after an elapse of a predetermined period.

11. A communication method comprising

receiving radio signals from a partner communication device;

the received signals received for a predetermined period;

calculating a time correlation defined as a correlation between the received signal received from a first reference point of time onward within the predetermined period and the received signal received from a second reference point of time onward within the predetermined period;

obtaining a time difference between the first reference point of time and a second reference point of time when the time correlation takes a value of a predetermined range;

selecting a wireless communication procedure designated corresponding to the time difference; and

instructing said partner communication device about the selected wireless communication procedure.

12. A communication method according to claim 11, further comprising:

calculating the time correlation with one received signal in the plurality of radio signals received from said partner communication device.

13. A communication method according to claim 11, further comprising:

calculating a plurality of time correlations from the plurality of radio signals received from said partner communication device; and

generating a combined time correlation weighted with a magnitude of a value of electric power of each of the plural received signals, from the plurality of time correlations and the plurality of received signals.

14. A communication method according to claim 11, further comprising:

calculating the time correlation with respect to a combination of the plural received signals from the plurality of radio signals received from said partner communication device.

15. A communication method according to claim 11, further comprising:

determining whether or not a communication procedure selected in said selecting is the same as a communication procedure used before the selection,

wherein said instructing of instructing said partner communication device includes, if the pre-selection communication procedure is the same as the post-selection communication procedure, instructing said partner communication device about none of the selected communication procedure.

16. A communication method according to claim 11, further comprising:

measuring a predetermined period of stopping time when selecting the communication procedure;

stopping the calculation of the time correlation during the period of stopping time; and

resuming the process of calculating the time correlation after the period of stopping time.

17. A communication method according to claim 11, further comprising:

changing over a receiving procedure in said receiving of receiving the radio signals from said partner communication device to the selected wireless communication procedure after an elapse of a predetermined period of time since the wireless communication procedure has been selected.

18. A communication method according to claim 17, further comprising:

determining whether or not the communication procedure selected in said communication procedure selecting is the same as the communication procedure used before the selection; and

changing over, if the pre-selection communication procedure is the same as the post-selection communication procedure, none of the communication procedure.

19. A communication method according to claim 11, wherein said instructing said partner communication device about the selected wireless communication procedure includes giving the instruction in a way that associates the selected wireless communication procedure with a bit sequence to be fed back.