Relay apparatus, terminal apparatus and relay method

• US 20050058104A1
• Filed: 09/16/2004
• Published: 03/17/2005
• Est. Priority Date: 09/16/2003
• Status: Active Grant

• Current Assignee: InterDigital Patent Holdings, Inc. (InterDigital, Inc.)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Kunieda, Yoshinori, Yomo, Hidekuni, Yamamoto, Yuuri, Kawai, Yoshihito
• Granted Patent: US 7,577,124 B2
• Time in Patent Office: Days
• US Class Current: 370/335
• CPC Class Codes: H04B 7/15528 Control of operation parameters of a relay station to exploit the physical medium
• CPC Class Codes: H04L 27/2602 Signal structure

Abstract

A relay apparatus, terminal apparatus and relay method for relaying signals with a reduced scale of the apparatus, without temporally switching between transmission and reception and with reduced waste of time when relay is performed at the same frequency on a radio communication network on which bidirectional communication is performed. A radio reception section 202 outputs information signals to a switch 208, outputs relay control signals to a demodulation section 204 after subjecting predetermined radio reception processing. The demodulation section 204 demodulates a relay control signal. A relay control signal processing section 206 decides the possibility of relay of information signals and inquires, when the relay is possible, whether the terminal apparatus on the receiving side can receive this information signal or not. Furthermore, the relay control signal processing section 206 connects a switch 208 during the stored relay time. The switch 208 is connected only the information signals to be relayed are received under the control of a relay control section 2063.

Claims

1. A relay apparatus for relaying information signals transmitted by radio at the same frequency, comprising:

a reception section that receives a relay control signal which notifies a relay time for relaying said information signal prior to said information signals; and

a relay section that relays the information signal during the relay time notified by said relay control signal.

2. The relay apparatus according to claim 1, further comprising a decision section that decides whether a relay operation on an information signal is possible or not within the relay time notified by said relay control signal,

wherein, when said decision result by said decision section shows that the relay operation is possible, said relay section relays the information signal during said relay time.

3. The relay apparatus according to claim 2, wherein said reception section receives a relay possibility inquiry signal for inquiring whether relay of an information signal is possible or not as a relay control signal,

said decision section decides, when relay of information signals other than said information signal during a relay time notified by said relay possibility inquiry signal is not scheduled and the relay destination of said information signal is not scheduled to receive any information signal other than said information signal, that the relay operation of said information signal is possible during said relay time.

4. The relay apparatus according to claim 3, wherein said decision section includes a reservation table that stores the relay time notified by said relay possibility inquiry signal in association with the possibility of relay operation during said relay time and decides whether other information signals are scheduled to be relayed or not during a newly notified relay time with reference to said reservation table.

5. The relay apparatus according to claim 3, wherein said decision section decides whether the other information signal is scheduled to be received or not according to a relay control signal indicating the possibility of reception transmitted from the relay destination of said information signal.

6. The relay apparatus according to claim 1, wherein said reception section receives a relay control signal assigned a frequency band which is different from that of said information signal and is a frequency band narrower than the frequency band assigned to said information signal.

7. The relay apparatus according to claim 1, wherein said reception section receives an OFDM signal with a relay control signal superimposed on a specific subcarrier of a plurality of subcarriers, and

said relay section relays the information signals superimposed on the subcarriers other than said specific subcarrier.

8. The relay apparatus according to claim 7, wherein said relay section includes a notch filter that attenuates only said specific subcarrier of said OFDM signal and relays the information signal obtained by attenuating said specific subcarrier.

9. The relay apparatus according to claim 7, wherein said reception section receives an OFCDM signal with a relay control signal spread using a predetermined spreading code superimposed on said specific subcarrier.

10. The relay apparatus according to claim 1, wherein said reception section receives a CDM signal with relay control signals spread using a predetermined spreading code, and

said relay section relays an OFDM signal with information signals superimposed on a plurality of subcarriers.

11. The relay apparatus according to claim 10, wherein said reception section receives said CDM signal transmitted simultaneously with said OFDM signal at the same frequency.

12. The relay apparatus according to claim 10, wherein said reception section receives said CDM signal transmitted by being time-division multiplexed with said OFDM signal.

13. The relay apparatus according to claim 1, wherein said relay section comprises an auto gain control section that controls gains so that transmit power of said information signal is fixed.

14. The relay apparatus according to claim 1, wherein said relay section comprises an echo canceller that removes echo generated when a signal relayed by said relay apparatus returns to from a signal to be relayed.

15. The relay apparatus according to claim 14, wherein said echo canceller comprises:

an FIR filter that inputs a signal relayed by said relay apparatus;

a coefficient control section that controls the filter coefficient of said FIR filter; and

a subtractor that subtracts the output from said FIR filter from the signal to be relayed.

16. The relay apparatus according to claim 15, wherein said coefficient control section comprises:

an FFT section that fast Fourier transforms signals relayed by said relay apparatus;

an error calculation section that compares the result of the fast Fourier transform with an ideal frequency characteristic and calculates an error;

an IFFT section that inverse fast Fourier transforms the calculated error; and

a coefficient updating section that updates the filter coefficient of said FIR filter so that the result of the inverse fast Fourier transform is reduced.

17. The relay apparatus according to claim 16, wherein said coefficient control section further comprises a storage section that stores the transmission source and relay destination of the information signal to be relayed in association with the filter coefficient of said FIR filter during relay of said information signal;

and

said coefficient updating section sets, when the transmission source and relay destination of the information signal to be relayed are the same, the filter coefficient stored in said storage section as an initial value.

18. The relay apparatus according to claim 15, wherein said coefficient control section decides the filter coefficient of said FIR filter using a known signal for setting a filter coefficient included in the information signal.

19. The relay apparatus according to claim 1, wherein the reception section receives an RTS signal used for a DCF on a radio local area network as a relay control signal.

20. A terminal apparatus comprising the relay apparatus according to any one of claims 1 to 19.

21. A terminal apparatus used in a radio communication system in which information signals transmitted by radio are relayed at the same frequency by a relay apparatus, comprising:

a generation section that generates a relay control signal including information on the relay time for relaying said information signals; and

a transmission section that transmits said relay control signal prior to said information signal,

wherein said transmission section transmits said information signal during said relay time.

22. The terminal apparatus according to claim 21, further comprising a reception section that receives a relay control signal indicating whether a relay operation is possible or not during said relay time as a response to the relay control signal transmitted by said transmission section,

wherein, when the relay control signal received by said reception section indicates that the relay operation is possible, said transmission section transmits said information signal during said relay time.

23. The terminal apparatus according to claim 21, wherein said transmission section transmits relay control signals assigned a frequency band which is different from that of information signals and narrower than the frequency band assigned to said information signal.

24. The terminal apparatus according to claim 21, wherein said transmission section transmits an OFDM signal with relay control signals superimposed on a specific subcarrier of a plurality of subcarriers and with information signals superimposed on subcarriers other than said specific subcarrier.

25. The terminal apparatus according to claim 24, wherein said transmission section transmits an OFCDM signal with relay control signals spread using a predetermined spreading code superimposed on said specific subcarrier.

26. The terminal apparatus according to claim 21, wherein said transmission section transmits a CDM signal obtained by spreading relay control signals using a predetermined spreading code and an OFDM signal with information signals superimposed on a plurality of subcarriers.

27. The terminal apparatus according to claim 26, wherein said transmission section transmits said OFDM signal and said CDM signal simultaneously at the same frequency.

28. The terminal apparatus according to claim 26, wherein said transmission section transmits said OFDM signal and said CDM signal time-division multiplexed.

29. The terminal apparatus according to claim 21, wherein said generation section generates an RTS signal used for DCF of a radio local area network.

30. A relay method for a relay apparatus relaying information signals transmitted from a terminal apparatus, comprising:

a step of said terminal apparatus transmitting a first relay control signal to reserve a path for transmitting said information signals;

a step of said relay apparatus receiving said first relay control signal;

a step of deciding whether the relay operation of said information signal is possible or not during the relay time notified by said first relay control signal;

a step of transmitting a second relay control signal indicating whether the relay operation is possible or not during said relay time as a result of the decision;

a step of said terminal apparatus receiving said second relay control signal;

a step of transmitting said information signals during said relay time when said second relay control signal indicates that the relay operation is possible; and

a step of said relay apparatus relaying said information signal during said relay time.