Optimal operation method of high-frequency phase dithering technique for compensating for interference noise in analog-optical transmission-based mobile fronthaul network, and transmitter using same
Proposed are an optimal operation method of a high-frequency dithering technique for compensating for interference noise in an analog optical transmission-based mobile fronthaul network, and a transmitter using same. An interference noise compensation method using high-frequency phase dithering performed in an analog optical transmission-based mobile fronthaul network may include the steps in which: a frequency-multiplexed wireless signal is converted in an optical transmitter to an intensity-modulated optical signal; and the phase of the optical signal intensity-modulated in the optical transmitter is dithered with an Orthogonal Frequency-Division Multiplexing (OFDM) signal.
1. An interference noise compensation method using a high-frequency phase dithering performed in an analog optical transmission-based mobile fronthaul network, the interference noise compensation method comprising:
converting, by an optical transmitter, a frequency-multiplexed wireless signal to an intensity-modulated optical signal;
dithering, by the optical transmitter, a phase of the intensity-modulated optical signal to an orthogonal frequency division multiplexing (OFDM) signal, wherein a modulation index of the OFDM signal is set to 2 to 4 and a bandwidth thereof is set to 100 megahertz (MHz) or more.
2. The interference noise compensation method of claim 1 , further comprising:
receiving the optical signal transmitted from the optical transmitter through an optical transmission link that includes optical elements of an optical fiber and an optical connector; and
converting, by an optical receiver, the received optical signal to an electrical signal.
3. The interference noise compensation method of claim 2 , wherein the converting, by the optical receiver, the received optical signal to the electrical signal comprises:
measuring intensity of an electric field of the received optical signal through a direct detector and, when connection of at least two optical connectors is poor in the optical transmission link, generating interference noise that includes a beating component of an electric field of a signal and an electric field of an interference signal in the received optical signal.
4. The interference noise compensation method of claim 1 , wherein the dithering, by the optical transmitter, the phase of the intensity-modulated optical signal to the OFDM signal comprises suppressing interference noise using a high-frequency phase dithering that uses a single frequency sinusoidal wave for the phase of the intensity-modulated optical signal.
5. The interference noise compensation method of claim 1 , wherein the dithering, by the optical transmitter, the phase of the intensity-modulated optical signal to the OFDM signal comprises suppressing interference noise using a high-frequency phase dithering that uses Gaussian noise having a desired bandwidth for the phase of the intensity-modulated optical signal.
6. The interference noise compensation method of claim 1 , wherein a carrier frequency of the frequency-multiplexed wireless signal is set to 1.5 gigahertz (GHz) or more to suppress a performance degradation by interference noise.
7. An interference noise compensation apparatus using a high-frequency phase dithering performed in an analog optical transmission-based mobile fronthaul network, the interference noise compensation apparatus comprising:
an optical intensity modulator configured to convert a frequency-multiplexed wireless signal to an intensity-modulated optical signal in an optical transmitter;
an optical phase modulator configured to dither a phase of the intensity-modulated optical signal with an orthogonal frequency division multiplexing (OFDM) signal in the optical transmitter, wherein a modulation index of the OFDM signal is set to 2 to 4 and a bandwidth thereof is set to 100 megahertz (MHz) or more.
8. The interference noise compensation apparatus of claim 7 , further comprising:
an optical transmission link configured to transmit the optical signal transmitted from the optical transmitter and to include optical elements of an optical fiber and an optical connector; and
a direct detector configured to convert the received optical signal to an electrical signal in an optical receiver.
9. The interference noise compensation apparatus of claim 8 , wherein the direct detector is configured to measure intensity of an electric field of the received optical signal and, when connection of at least two optical connectors is poor in the optical transmission link, to generate interference noise that includes a beating component of an electric field of a signal and an electric field of an interference signal in the received optical signal.
10. The interference noise compensation apparatus of claim 7 , wherein the optical phase modulator is configured to suppress interference noise using a high-frequency phase dithering that uses a single frequency sinusoidal wave for the phase of the intensity-modulated optical signal.
11. The interference noise compensation apparatus of claim 7 , wherein the optical phase modulator is configured to suppress interference noise using a high-frequency phase dithering that uses Gaussian noise having a desired bandwidth for the phase of the intensity-modulated optical signal.
12. The interference noise compensation apparatus of claim 7 , wherein a carrier frequency of the frequency-multiplexed wireless signal is set to 1.5 gigahertz (GHz) or more to suppress a performance degradation by interference noise.
13. An optical transmitter for compensating for interference noise using a high-frequency phase dithering performed in an analog optical transmission-based mobile fronthaul network, the interference noise compensation device comprising:
an optical intensity modulator configured to convert a frequency-multiplexed wireless signal to an intensity-modulated optical signal; and
an optical phase modulator configured to dither a phase of the intensity-modulated optical signal to an orthogonal frequency division multiplexing (OFDM) signal,
wherein a modulation index of the OFDM signal is set to 2 to 4 and a bandwidth thereof is set to 100 megahertz (MHz) or more, and
a carrier frequency of the frequency-multiplexed wireless signal is set to 1.5 gigahertz (GHz) or more to suppress a performance degradation by interference noise.