Polarization-angle-division diversity wireless transmitter, wireless receiver, and wireless communication system

• US 9,407,349 B2
• Filed: 03/09/2011
• Issued: 08/02/2016
• Est. Priority Date: 03/09/2011
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Takei, Ken
• Primary Examiner(s): Huang, David S
• Application Number:
  US14/002,521
• Publication Number:
  US 20130336417A1
• Time in Patent Office: 1,973 Days
• Field of Search: 375/267
• US Class Current: 1/1
• CPC Class Codes: H04B 7/0613 using simultaneous transmission H04B7/0686 takes precedence
• CPC Class Codes: H04B 7/08 at the receiving station
• CPC Class Codes: H04B 7/0894 using different delays between antennas
• CPC Class Codes: H04B 7/10 Polarisation diversity; Directional diversity
• CPC Class Codes: H04L 27/18 Phase-modulated carrier systems, i.e. using phase-shift keying H04L27/32 takes precedence

Abstract

A wireless transmitter has a modulator modulating an information signal of a frequency f1 by a carrier wave of a frequency f2 to output a first modulated signal, a transmitting antenna transmitting the first modulated signal using a linearly polarized wave, and a motor rotating the transmitting antenna at a frequency f3 to rotate the outgoing linearly polarized wave at the frequency f3 thereby multiplexing the first modulated signal with a linearly polarized wave component and a horizontally polarized wave component, the two components being independent of each other. A wireless receiver has diversity receiving antennas receiving the signal on a plurality of polarization planes to obtain a plurality of input signals; a path difference phase shifter compensating each of the input signals for the phase shift stemming from path differences, and a composer composing the corrected received signals.

Claims

1. A polarization-angle-division diversity wireless communication system including a wireless receiver for receiving an electromagnetic wave transmitted from a polarization-angle-division diversity wireless transmitter, the receiver including:

a first receiving antenna which receives a first polarized wave from the polarization-angle-division diversity wireless transmitter to obtain a first input signal;

a second receiving antenna which receives a second polarized wave from the polarization-angle-division diversity wireless transmitter to obtain a second input signal;

a first rotational frequency detecting unit to block frequencies at least twice as high as a third frequency in the first signal to generate a first received signal;

a second rotational frequency detecting unit to block frequencies at least twice as high as the third frequency in the second input signal to generate a second received signal;

a multi-delay composer configured to delay and to compose the first received signal and the second received signal; and

the polarization-angle-division diversity wireless transmitter including;

an electromagnetic wave transmitting unit configured to transmit first and second independent circularly polarized waves,

wherein the electromagnetic wave transmitting unit comprises;

a first modulator configured to modulate an information signal having a first frequency by a second frequency to output a first modulated signal;

a second modulator configured to modulate the first modulated signal by the third frequency to obtain a first output signal;

a first transmitter which transmits the first output signal using the first circularly polarized wave;

a phase shift circuit configured to shift a phase of the third frequency by 90 degrees;

a third modulator configured to modulate the first modulated signal by the shifted phase of the third frequency to obtain a second output signal; and

a second transmitter which transmits the second output signal using the second circularly polarized wave.

2. The polarization-angle-division diversity wireless communication system according to claim 1,

wherein the first receiving antenna receives a first linearly polarized wave component from the first circularly polarized wave, and

wherein the second receiving antenna is set up at an angle between 85 and 95 degrees with the first receiving antenna and receives a second linearly polarized wave component from the second circularly polarized wave.

3. The polarization-angle-division diversity wireless communication system according to claim 1,

wherein the multi-delay composer performs polarization phase rotation on the first received signal and the second received signal and inputs the polarization phase rotation of the received signals to at least one adder and performs path difference phase correction on the first received signal and the second received signal and inputs the path difference phase correction to the at least one adder,

wherein the multi-delay composer composes the input polarization phase rotation and path difference phase correction to increase signal power.

4. The polarization-angle-division diversity wireless communication system according to claim 3,

wherein the polarization phase rotation and the path difference phase correction are determined so as to maximize the intensity of the composed first received signal and the second received signal.

5. The polarization-angle-division diversity wireless communication system according to claim 3,

wherein a polarization phase rotation and the path difference phase correction are determined so as to minimize error rate of the composed first received signal and the second received signal.