Wireless communication system and system using same

• US 10,153,824 B2
• Filed: 11/13/2014
• Issued: 12/11/2018
• Est. Priority Date: 11/13/2014
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Takei, Ken
• Primary Examiner(s): Chu, Wutchung
• Application Number:
  US15/526,189
• Publication Number:
  US 20170310379A1
• Time in Patent Office: 1,489 Days
• CPC Class Codes: H04B 7/10 Polarisation diversity; Directional diversity
• CPC Class Codes: H04W 56/001 Synchronization between nodes

Abstract

Provided is a wireless communication system that achieves high-reliability communication between a transmitter and a receiver. Specifically, the wireless communication system includes: a transmitter that transmits a carrier wave with rotational polarization on which a strongly correlated code is superimposed; and a receiver that uses the strongly correlated code in the reception polarized wave from the transmitter to establish synchronization between the transmitter and the receiver, wherein the receiver receives signals in a plurality of different polarized waves, establishes synchronization between the transmitter and the receiver for the plurality of reception polarized waves using correlation values between the received signals and the strongly correlated code corresponding to the reception polarized waves, compares the correlation values to a threshold to extract a specific reception polarized wave and a received signal corresponding to the polarized wave, calculates transmission polarization angles from shifts in synchronization timing, and separates or selects the signals transmitted in different propagation paths using specific reception polarized waves corresponding to the plurality of transmission polarization angles and the received signals corresponding to the polarized waves.

Claims

1. A wireless communication system comprising:

a transmitter that transmits a carrier wave with rotational polarization on which a strongly correlated code is superimposed; and

a receiver that uses the strongly correlated code in the reception polarized wave from the transmitter to establish synchronization between the transmitter and the receiver, wherein

the receiver receives signals in a plurality of different polarized waves, establishes synchronization between the transmitter and the receiver for the plurality of reception polarized waves using correlation values between the received signals and the strongly correlated code corresponding to the reception polarized waves, compares the correlation values to a threshold to extract a specific reception polarized wave and a received signal corresponding to the polarized wave, calculates transmission polarization angles from shifts in synchronization timing, and separates or selects the signals transmitted in different propagation paths using specific reception polarized waves corresponding to the plurality of transmission polarization angles and the received signals corresponding to the polarized waves.

2. The wireless communication system according to claim 1, wherein the transmitter includes a plurality of different strongly correlated codes and performs communications while switching between the strongly correlated codes at different transmission timings.

3. The wireless communication system according to claim 1, wherein the strongly correlated code in the transmitter has periodicity, and the period and the rotational period of polarization of the carrier wave are identical.

4. The wireless communication system according to claim 1, wherein the strongly correlated code in the transmitter is divided at equal time intervals and partial codes of the divided strongly correlated code have mutually strong correlation.

5. The wireless communication system according to claim 1, wherein the transmitter divides the rotational period of polarization of the carrier wave and transmits divisional information at different time intervals in the same direction of polarization.

6. The wireless communication system according to claim 1, wherein the transmitter adds up carrier waves of two different frequencies to form a beat signal, and emits the same to the space in a spatially orthogonal manner with a shift of ¼

from a beat period.

7. The wireless communication system according to claim 1, wherein the transmitter uses total four carrier waves including sine waves and cosine waves of two different frequencies to composite cosine waves of different frequencies in phase and emit the composite wave from a first transmission antenna, and composite sine waves of different frequencies in opposite phase and emit the composite wave from a second transmission antenna spatially orthogonal to the first transmission antenna.

8. The wireless communication system according to claim 6, wherein the transmitter communicates different information at two different frequencies.

9. The wireless communication system according to claim 1, wherein there is a relation in monotonic decrease among the frequency of the carrier wave, the frequency of rotation of polarization, and the frequency of information to be transmitted.

10. An elevator control system to which the wireless communication system according to claim 1 is applied.

11. An electric substation system to which the wireless communication system according to claim 1 is applied.

12. The wireless communication system according to claim 7, wherein the transmitter communicates different information at two different frequencies.

13. The wireless communication system according to claim 7, wherein the transmitter communicates different information at two different frequencies.

14. A wireless communication system comprising:

a transmitter that transmits a carrier wave with rotational polarization on which a strongly correlated code is superimposed; and

a receiver that uses the strongly correlated code in the reception polarized wave from the transmitter to establish synchronization between the transmitter and the receiver, wherein,

the receiver receives signals in a plurality of different polarized waves, establishes synchronization for the plurality of reception polarized waves between the transmitter and the receiver using correlation values between the received signals and the strongly correlated code corresponding to the reception polarized waves, compares the quality of the received signals corresponding to the reception polarized waves to a threshold to extract a specific reception polarized wave and a received signal corresponding to the polarized wave, calculates transmission polarization angles from shifts in synchronization timing, and separates or selects the signals transmitted in different propagation paths using specific reception polarized waves corresponding to the plurality of transmission polarization angles and the received signals corresponding to the polarized waves.

15. The wireless communication system according to claim 14, wherein the transmitter includes a plurality of different strongly correlated codes and performs communications while switching between the strongly correlated codes at different transmission timings.

16. The wireless communication system according to claim 14, wherein the strongly correlated code in the transmitter has periodicity, and the period and the rotational period of polarization of the carrier wave are identical.

17. The wireless communication system according to claim 14, wherein the strongly correlated code in the transmitter is divided at equal time intervals and partial codes of the divided strongly correlated code have mutually strong correlation.

18. The wireless communication system according to claim 14, wherein the transmitter divides the rotational period of polarization of the carrier wave and transmits divisional information at different time intervals in the same direction of polarization.

19. The wireless communication system according to claim 14, wherein the transmitter adds up carrier waves of two different frequencies to form a beat signal, and emits the same to the space in a spatially orthogonal manner with a shift of ¼

from a beat period.

20. The wireless communication system according to claim 14, wherein the transmitter uses total four carrier waves including sine waves and cosine waves of two different frequencies to composite cosine waves of different frequencies in phase and emit the composite wave from a first transmission antenna, and composite sine waves of different frequencies in opposite phase and emit the composite wave from a second transmission antenna spatially orthogonal to the first transmission antenna.

21. The wireless communication system according to claim 14, wherein there is a relation in monotonic decrease among the frequency of the carrier wave, the frequency of rotation of polarization, and the frequency of information to be transmitted.

22. A wireless communication system comprising:

a transmitter that transmits a carrier wave with rotational polarization on which a strongly correlated code is superimposed; and

a receiver that uses the strongly correlated code in the reception polarized wave from the transmitter to establish synchronization between the transmitter and the receiver, wherein,

the receiver includes a plurality of reception circuits and a processing circuit that performs signal processing using detection signals from the plurality of reception circuits,

the plurality of reception circuits includes reception units that receive reception polarized waves at different polarization angles and delay time holding units that have a plurality of different delay times, and

the processing circuit performs signal processing using information on the synchronization, the delay time, and the polarization angle obtained from the plurality of reception circuits.