Optical-fiber wireless system for full-duplex communication

Abstract

The invention relates to an optical-fiber wireless system for full-duplex communication, which consists of a central station and a base station, wherein the central station and the base station are connected through an optical-fiber transmission links; the central station generates subcarrier signals by mixing baseband signals with radio frequency sine-wave signals, generates optical double-sideband differential phase-shift keying signals through the modulation of an optical phase modulator, performs power amplification, and then transmits the signals to the base station; the base station separates the signals transmitted by the central station; the signals are divided into an upper way and a lower way through an optical splitter; the upper way generates carrier-suppressed differential phase-shift keying optical-carried millimeter waves which are converted into downlink millimeter wave signals through photoelectric conversion and then sent to wireless terminals through antennas; the lower way generates reference local oscillator signals through photoelectric conversion, mixes the reference local oscillator signals with uplink millimeter wave signals, and generates uplink baseband signals through down conversion; and central carrier waves are re-modulated by the uplink baseband signals and then transmitted back to the central station. The system has the advantages of simplifying generation devices for optical-carried millimeter waves and reducing cost, along with simple flexible structure, strong extensibility, more compact structure and easiness for integration.

Description

technical field [0001] The present invention relates to a kind of optical fiber-wireless (Radio-Over-Fiber, abbreviated as ROF) communication technology, especially a kind of generation of carrier suppression-differential phase shift keying optical carrier millimeter wave signal, and realize the full duplex of optical fiber wireless system communication. technical background [0002] Optical fiber-wireless communication technology uses optical fiber links to transmit radio signals, and organically combines the characteristics of broadband wireless communication such as mobility and point-to-multipoint access with the ultra-bandwidth and high reliability of optical fiber communication to provide large-capacity, low-cost Wired transmission of radio signals and ultra-broadband wireless access exceeding Gbit / s provide an ideal solution. For fiber-optic wireless systems, the generation of high-quality optical-borne millimeter waves is one of the key technologies for realizing co...

AI Technical Summary

Problems solved by technology

However, since the two-electrode M-Z modulator used in this system is based on carrier suppression modulation, it is necessary to load a pair of anti-phase subcarrier drive signals on the upper and lower arms of the two-electrode M-Z modulator; and it is also necessary to configure complex peripherals Control Circuits to Eliminate DC Bias Drift Problems of Two-Electrode M-Z Modulators

Therefore, the system requires a large number of electrical components, and the signal processing in the electrical domain is relatively complicated.

On the other hand, since the system uses the first-order upper sideband for wavelength reuse, it is necessary to configure a tunable optical band-pass filter to filter out the first-order upper sideband. The center wavelength and passband range of the optical band-pass filter must be able to It is adjusted according to the change of the repetition frequency of the optical carrier millimeter wave, which leads to a complex structure of the base station, lack of flexibility and scalability

In addition, in this system, the higher power center carrier has not been fully utilized, resulting in waste of signal power

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