COMMUNICATION APPARATUS AND COMMUNICATION METHOD

• US 20090116572A1
• Filed: 11/10/2006
• Published: 05/07/2009
• Est. Priority Date: 11/29/2005
• Status: Active Grant

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Fujita, Suguru, Takahashi, Kazuaki, Matsuoka, Akihiko
• Granted Patent: US 8,135,423 B2
• Time in Patent Office: Days
• US Class Current: 375/267
• CPC Class Codes: G01S 13/10 using transmission of interrupted, pulse modulated waves determination of distance by phase measurement G01S13/32
• CPC Class Codes: G01S 13/878 Combination of several spaced transmitters or receivers of known location for determining the position of a transponder or a reflector G01S13/874 takes precedence
• CPC Class Codes: G01S 7/40 Means for monitoring or calibrating
• CPC Class Codes: G07B 15/063 using wireless information transmission between the vehicle and a fixed station identification of vehicles G08G
• CPC Class Codes: H04L 27/02 Amplitude-modulated carrier systems, e.g. using on-off keying; Single sideband or vestigial sideband modulation H04L27/32 takes precedence
• CPC Class Codes: H04L 7/0033 Correction by delay
• CPC Class Codes: H04L 7/0091 Transmitter details

Abstract

A communication apparatus in which only a terminal having a specific positional relationship can perform communication through a relatively simple arrangement. When initial setting is performed or communication is started, a timing calculating section (104) calculates a time difference corresponding to the difference between a path from an antenna (101) to a terminal (200) and a path from an antenna (102) to the terminal (200), based on a transmission signal from the antenna (101) and a reflection signal provided by having the transmission signal reflected from the antenna (102) or a communication partner, i.e. the terminal (200), and returned back to the antenna (101). Based on the time difference thus calculated, the timing calculating section (104) outputs a signal for regulating the transmission timing of transmission data from the antenna (101) to a variable delay unit (105). The variable delay unit (105) delays transmission timing of the transmission data depending on the timing regulation signal and outputs the delayed transmission data to a modulating/demodulating section (106).

Claims

1. A communication apparatus comprising:

a first generating section that generates a first transmission signal based on an information data stream;

a second generating section that generates a second transmission signal that enables demodulation of the information data stream by being combined with the first transmission signal at a specified timing;

a first antenna that transmits the first transmission signal;

a second antenna that transmits the second transmission signal; and

an adjusting section that adjusts a transmission timing of at least one of the first transmission signal and the second transmission signal such that the first transmission signal and the second transmission signal arrive in a specific area at specified timings.

2. The communication apparatus according to claim 1, further comprising a time difference calculating section that calculates a time difference between a time the first transmission signal arrives in the specific area and a time the second transmission signal arrives in the specific area,

wherein the adjusting section adjusts a transmission timing of at least one of the first transmission signal and the second transmission signal based on the time difference such that the first transmission signal and the second transmission signal arrive in the specific area at the specified timings.

3. The communication apparatus according to claim 2, wherein the time difference calculating section calculates the time difference from a round-trip time T1 of a signal on a transmission path between the first antenna and the second antenna, and a round-trip time T2 of a signal on a transmission path between one of the first antenna and the second antenna and the specific area.

4. The communication apparatus according to claim 3, wherein the time difference calculating section calculates the round-trip time T1 using the second transmission signal which is reflected by the first antenna and received by the second antenna or the first transmission signal which is reflected by the second antenna and received by the first antenna and calculates the round-trip time T2 using one of the first transmission signal which is reflected in the specific area and received by the first antenna and the second transmission signal which is reflected in the specific area and received by the second antenna.

5. The communication apparatus according to claim 2, wherein the time difference calculating section calculates the time difference from a round-trip time T3 of a signal on a transmission path between the first antenna and the specific area and a round-trip time T4 of a signal on a transmission path between the second antenna and the specific area.

6. The communication apparatus according to claim 5, wherein the time difference calculating section calculates the round-trip time T3 using the first transmission signal which is reflected in the specific area and received by the first antenna and calculates the round-trip time T4 using the second transmission signal which is reflected in the specific area and received by the second antenna.

7. The communication apparatus according to claim 1, wherein:

the second generating section generates a reference signal for the first transmission signal as the second transmission signal; and

the adjusting section adjusts transmission timings such that the first transmission signal and part of the second transmission signal arrive in the specific area at the same time.

8. The communication apparatus according to claim 7, wherein the reference signal comprises symbol synchronization information showing a phase timing of the first transmission signal, frame synchronization information showing a frame timing of a communication frame or authentication information.

9. The communication apparatus according to claim 1, wherein:

the first and second generating sections generate pulse signals as the first and second transmission signals; and

the adjusting section adjusts transmission timings such that the first transmission signal and the second transmission signal arrive in the specific area alternately.

10. The communication apparatus according to claim 1, wherein:

the second generating section generates a timing signal of the first transmission signal as the second transmission signal; and

the adjusting section adjusts transmission timings such that the first transmission signal and part of the second transmission signal arrive in the specific area at the same time.

11. The communication apparatus according to claim 10, wherein the timing signal comprises a clock signal for synchronization.

12. The communication apparatus according to claim 1, wherein the time difference calculating section measures the time difference at predetermined time intervals.

13. The communication apparatus according to claim 1, further comprising a reporting section that reports a command to move a position, to a communicating party located in the specific area, wherein:

the time difference calculating section calculates the time difference again from a time the first transmission signal arrives in an area the communicating party after a move is located, and a time the second transmission signal arrives in an area the communicating party after the move is located; and

the adjusting section adjusts transmission timings based on the time difference calculated again.

14. The communication apparatus according to claim 1, wherein at least one of the first antenna and the second antenna performs transmission to a specific fixture fixed in a direction different from the specific area.

15. The communication apparatus according to claim 1, further comprising a frequency converting section that converts a frequency of at least one of the first transmission signal and the second transmission signal to a signal in a different carrier frequency band.

16. The communication apparatus according to claim 1, further comprising a measuring section that measures a first delay signal and a second delay time it takes a first delay signal and a second delay signal of the first transmission signal and the second transmission signal, produced by influence of multipath, to arrive in the specific area after the first transmission signal and the second transmission signal arrive,

wherein the first and the second generating sections generate the first and second transmission signals based on the first and second delay times.

17. The communication apparatus according to claim 1, wherein the specific area is a predetermined location.

18. The communication apparatus according to claim 1, wherein the first transmission signal and the second transmission signal are differentially coded signals.

19. A communication method comprising the steps of:

generating a first transmission signal based on an information data stream;

generating a second transmission signal that enables demodulation of the information data stream by being combined with the first transmission signal at a specified timing;

transmitting the first transmission signal;

transmitting the second transmission signal; and

adjusting a transmission timing of at least one of the first transmission signal and the second transmission signal such that the first transmission signal and the second transmission signal arrive in a specific area at specified timings.