ARRIVAL ANGLE ESTIMATION SYSTEM, COMMUNICATION DEVICE, AND COMMUNICATION SYSTEM

• US 20080297401A1
• Filed: 05/28/2008
• Published: 12/04/2008
• Est. Priority Date: 05/29/2007
• Status: Active Grant

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: NISHIDA, Yoshifumi
• Granted Patent: US 8,681,048 B2
• Time in Patent Office: Days
• US Class Current: 342/147
• CPC Class Codes: G01S 1/10 using amplitude comparison of signals transmitted sequentially from antennas or antenna systems having differently-oriented overlapping directivity characteristics, e.g. equi-signal A-N type
• CPC Class Codes: G01S 1/14 using amplitude comparison of signals transmitted simultaneously from antennas or antenna systems having differently oriented overlapping directivity-characteristics
• CPC Class Codes: G01S 3/18 derived directly from separate directional antennas
• CPC Class Codes: H04B 7/0822 according to predefined selection scheme

Abstract

An arrival angle estimation system includes a transmitting device and a receiving device and estimates an arrival angle at which frames transmitted by radio from the transmitting device arrive at the receiving device. The transmitting device includes two directional antennas each arranged so that its directivity is tilted at ±θ degrees with respect to the front of the transmitting device. The receiving device includes a directional antenna having directivity toward the front of the receiving device. Frames are transmitted alternately from the respective directional antennas of the transmitting device, and received signal strengths of the frames on the receiving device side for the respective transmitting directional antennas are compared with each other to estimate the arrival angle.

Claims

1. An arrival angle estimation system comprising a transmitting device and a receiving device, the arrival angle estimation system estimating an arrival angle at which frames transmitted by radio from the transmitting device arrive at the receiving device, wherein:

the transmitting device includes two directional antennas each arranged so that its directivity is tilted at ±

θ

degrees with respect to the front of the transmitting device;

the receiving device includes a directional antenna having directivity toward the front of the receiving device; and

frames are transmitted alternately from the respective directional antennas of the transmitting device, and received signal strengths of the frames on the receiving device side for the respective transmitting directional antennas are compared with each other to estimate the arrival angle.

2. The arrival angle estimation system according to claim 1, wherein:

the transmitting device transmits frames to the receiving device by alternately switching the transmitting directional antennas while varying an angle between the transmitting device and the receiving device, the receiving device measures received signal strengths of the frames received from the respective transmitting directional antennas to obtain a difference Δ

S in received signal strength between the transmitting directional antennas, and a relationship between the difference Δ

S and an angle between the transmitting device and the receiving device is stored in advance; and

the transmitting device communicates with the receiving device while alternately switching the transmitting directional antennas and, simultaneously, the receiving device measures received signal strengths of frames received from the respective transmitting directional antennas of the transmitting device to obtain a difference Δ

S in received signal strength between the transmitting directional antennas, and the difference Δ

S currently obtained is compared against previously measured data to estimate an angle between the transmitting device and the receiving device.

3. The arrival angle estimation system according to claim 2, wherein:

by assuming that the transmitting device transmits frames from the transmitting directional antennas at the same transmission power, and that a propagation loss between each of the transmitting directional antennas and the receiving directional antenna is the same, a difference in gain between the transmitting directional antennas is regarded as a difference Δ

S in received signal strength between the transmitting directional antennas.

4. The arrival angle estimation system according to claim 2, wherein:

the transmitting device transfers data frames while alternately switching the directional antennas used for transmission at a fixed cycle, and the receiving device measures signal strengths of the transferred data frames.

5. The arrival angle estimation system according to claim 4, wherein:

if there is no transmit data to be transferred in an upper layer, the transmitting device generates and transmits data frames whose data size is 0.

6. The arrival angle estimation system according to claim 2, wherein:

the receiving device transmits data frames at fixed intervals, and the receiving device measures received signal strengths of acknowledgement frames that are returned in response to the data frames from the transmitting device while alternately switching the transmitting directional antennas.

7. The arrival angle estimation system according to claim 6, wherein:

if there is no data to be transferred in an upper layer, the receiving device generates and transmits data frames whose data size is 0.

8. An arrival angle estimation system comprising a transmitting device and a receiving device, the arrival angle estimation system estimating an arrival angle at which frames transmitted by radio from the transmitting device arrive at the receiving device, wherein:

the transmitting device includes a directional antenna having directivity toward the front of the transmitting device;

the receiving device includes two directional antennas each arranged so that its directivity is tilted at ±

θ

degrees with respect to the front of the receiving device; and

frames transmitted from the transmitting device are received by using the directional antennas alternately, and received signal strengths of the frames at the respective receiving directional antennas are compared with each other to estimate the arrival angle.

9. The arrival angle estimation system according to claim 8, wherein:

the receiving device receives frames from the transmitting device by alternately switching the receiving directional antennas while varying an angle between the transmitting device and the receiving device, and measures received signal strengths of the frames at the respective receiving directional antennas to obtain a difference Δ

S between the received signal strengths, and a relationship between the difference Δ

S and an angle between the transmitting device and the receiving device is stored in advance; and

the transmitting device and the receiving device communicate with each other and, simultaneously, the receiving device switches the receiving directional antennas alternately and measures signal strengths of frames received at the respective receiving directional antennas to obtain a difference Δ

S in received signal strength between the receiving directional antennas, and the difference Δ

S currently obtained is compared against previously measured data to estimate an angle between the transmitting device and the receiving device.

10. The arrival angle estimation system according to claim 9, wherein:

the transmitting device transfers data frames that are to be transferred; and

the receiving device measures signal strengths of the transferred data frames while switching the directional antennas used for reception at a fixed cycle.

11. The arrival angle estimation system according to claim 10, wherein:

if there is no transmit data to be transferred in an upper layer, the transmitting device generates and transmits data frames whose data size is 0.

12. The arrival angle estimation system according to claim 9, wherein:

the receiving device transmits data frames from one of the directional antennas at fixed intervals, and the receiving device receives acknowledgement frames, which are returned from the transmitting device in response to the data frames, while alternately switching the receiving directional antennas and measures signal strengths of the acknowledgement frames.

13. The arrival angle estimation system according to claim 12, wherein:

if there is no data to be transferred in an upper layer, the receiving device generates and transmits data frames whose data size is 0.

14. An arrival angle estimation system comprising a transmitting device and a receiving device, the arrival angle estimation system estimating an arrival angle at which frames transmitted by radio from the transmitting device arrive at the receiving device, wherein:

the transmitting device includes two directional antennas each arranged so that its directivity is tilted at ±

θ

degrees with respect to the front of the transmitting device;

the receiving device includes two directional antennas each arranged so that its directivity is tilted at ±

θ

degrees with respect to the front of the receiving device; and

frames transmitted from the transmitting device are received by using the directional antennas alternately, and received signal strengths of the frames at the respective receiving directional antennas are compared with each other to estimate the arrival angle.

15. The arrival angle estimation system according to claim 14, wherein:

the transmitting device transmits frames to the receiving device by alternately switching the transmitting directional antennas while varying an angle between the transmitting device and the receiving device, the receiving device receives the frames while alternately switching the receiving directional antennas and measures received signal strengths of the frames at the respective receiving directional antennas from the respective transmitting directional antennas to obtain a difference Δ

S in received signal strength between the transmitting directional antennas, and a relationship between the difference Δ

S and an angle between the transmitting device and the receiving device is stored in advance with respect to each of the receiving directional antennas; and

the transmitting device communicates with the receiving device while alternately switching the transmitting directional antennas and, simultaneously, the receiving device receives frames from the transmitting device by alternately switching the receiving directional antennas and measures received signal strengths of the frames at the respective receiving directional antennas to obtain a difference Δ

S in received signal strength between the transmitting directional antennas, and the difference Δ

S currently obtained is compared against previously measured data for each of the receiving directional antennas to estimate an angle between the transmitting device and the receiving device.

16. The arrival angle estimation system according to claim 15, wherein:

the transmitting device transfers data frames while alternately switching the transmitting directional antennas, and the receiving device measures signal strengths of the data frames transferred from the transmitting device while alternately switching the receiving directional antennas.

17. The arrival angle estimation system according to claim 16, wherein:

if there is no transmit data to be transferred in an upper layer, the transmitting device generates and transmits data frames whose data size is 0.

18. The arrival angle estimation system according to claim 15, wherein:

the receiving device transmits data frames at fixed intervals, and the receiving device measures received signal strengths of acknowledgement frames that are returned in response to the data frames from the transmitting device while alternately switching the transmitting directional antennas.

19. The arrival angle estimation system according to claim 18, wherein:

if there is no transmit data to be transferred in an upper layer, the receiving device generates and transmits data frames whose data size is 0.

20. A communication device comprising:

two directional antennas each arranged so that its directivity is tilted at ±

θ

degrees with respect to the front;

an antenna switching mechanism that alternately switches the directional antennas used for transmission or reception of frames;

an RF section that processes an RF transmit/receive signal;

a signal processing section that processes the RF transmit/receive signal; and

a transfer control section that controls an antenna switching operation of the antenna switching mechanism in accordance with a transfer operation.

21. The communication device according to claim 20, wherein:

when transmitting frames to a predetermined communication party, the frames are transmitted while alternately switching the directional antennas used for transmission.

22. The communication device according to claim 20, wherein:

when receiving frames from a predetermined communication party, the frames are received while alternately switching the directional antennas used for reception, and received signal strengths of the frames at the respective directional antennas used for reception are compared with each other to estimate the arrival angle.

23. The communication device according to claim 22, wherein:

frames are received from the communication party by alternately switching the directional antennas used for reception while varying an angle relative to the communication party, received signal strengths of the frames at the respective directional antennas are measured to obtain a difference Δ

S between the received signal strengths, and a relationship between the difference Δ

S and an angle between the transmitting device and the receiving device is stored in advance; and

while performing communication with the communication party, frames are received by alternately switching the directional antennas used for reception, received strengths of the received frames at the respective directional antennas are measured to obtain a difference Δ

S in received signal strength between the directional antennas, and the difference Δ

S currently obtained is compared against previously measured data to estimate an angle relative to the communication party.

24. The communication device according to claim 22, wherein:

data frames transferred from the communication party are received while switching the directional antennas used for reception at a fixed cycle, and signal strengths of the transferred data frames are measured.

25. The communication device according to claim 22, wherein:

data frames are transmitted from one of the directional antennas at fixed intervals and acknowledgement frames, which are returned from the communication party in response to the data frames, are received while alternately switching the directional antennas used for reception, and signal strengths of the acknowledgement frames are measured.

26. The communication device according to claim 22, wherein:

if there is no transmit data to be transferred in an upper layer, data frames whose data size is 0 are generated and transmitted.

27. A communication device which performs communication with a transmitting device including two directional antennas that are each arranged so that its directivity is tilted at ±

θ

degrees with respect to the front, comprising;

an antenna used for transmission/reception;

an RF section that processes an RF transmit/receive signal;

a signal processing section that processes the RF transmit/receive signal; and

a transfer control section that controls a transfer operation,

wherein frames are transmitted alternately from the respective directional antennas of the transmitting device, and received signal strengths of the frames received at the respective transmitting directional antennas are compared with each other to estimate a tilt of the transmitting device with respect to the receiving device.

28. The communication device according to claim 27, wherein:

received signal strengths of data frames transferred from the transmitting device while alternately switching the transmitting directional antennas at a fixed cycle are measured.

29. The communication device according to claim 27, wherein:

data frames are transmitted at fixed intervals, and received signal strengths of acknowledgement frames, which are returned in response to the data frames from the transmitting device while alternately switching the transmitting directional antennas, are measured.

30. The communication device according to claim 29, wherein:

if there is no transmit data to be transferred in an upper layer, data frames whose data size is 0 are generated and transmitted.

31. A communication system comprising:

a transmitting device including two directional antennas having vertical polarization that are attached to the front so that polarization directions of the directional antennas are tilted at substantially 90 degrees with respect to each other; and

a receiving device including a directional antenna having directivity toward the front, wherein

frames are transmitted alternately from the respective directional antennas of the transmitting device, and received signal strengths of the frames on the receiving device side for the respective transmitting directional antennas are compared with each other to estimate a tilt of the transmitting device with respect to the receiving device.

32. The communication system according to claim 31, wherein:

the transmitting device transmits frames to the receiving device by alternately switching the transmitting directional antennas while varying a tilt of the transmitting device with respect to a horizontal direction, the receiving device measures received signal strengths of the frames received from the respective transmitting directional antennas to obtain a difference Δ

P in received signal strength between the transmitting directional antennas, and a relationship between the difference Δ

P and an angle between the transmitting device and the receiving device is stored in advance; and

the transmitting device communicates with the receiving device while alternately switching the transmitting directional antennas and, simultaneously, the receiving measures received signal strengths of frames received from the respective transmitting directional antennas of the transmitting device to obtain a difference Δ

P in received signal strength between the transmitting directional antennas, and the difference Δ

P currently obtained is compared against previously measured data to estimate a tilt of the transmitting device with respect to the horizontal direction.

33. The communication system according to claim 31, wherein:

each of the transmitting antennas is a microstrip antenna having a plurality of feeding points; and

a combination of polarizations of the two directional antennas is changed by switching the feeding points.