Far-end true time delay beamforming implementation method based on few-mode fiber

Abstract

The invention discloses a far-end true time delay beamforming implementation method based on a few-mode fiber, and the method comprises the steps: 1), adjusting the bandwidth of an ASE light source according to the signal-to-noise ratio of a to-be-transmitted radio frequency signal, and taking the adjusted ASE light source as an optical carrier; 2) modulating the optical carrier through the radio frequency signal to be transmitted to obtain an optical carrier radio frequency signal, dividing the optical carrier radio frequency signal into N paths of time delay copy signals, and injecting the N paths of time delay copy signals into a few-mode optical fiber link through a mode multiplexer in a corresponding mode and transmitting the N paths of time delay copy signals to a far-end mode demultiplexer; (3) a mode demultiplexer carries out demultiplexing on the N paths of time delay copy signals and couples the N paths of time delay copy signals to N paths of single-mode tail fibers; wherein the demultiplexed ith-path time delay copy signal is input into the ith-path single-mode tail fiber, and the length of the ith-path single-mode tail fiber meets the condition that the time delay difference between the ith-path time delay copy signal and the inter-mode crosstalk is far greater than the coherence time of the ASE light source; and 4) converting and amplifying the N paths of single-mode tail fiber output signals, and injecting the signals into N units of the antenna array for emission.

Description

technical field [0001] The invention relates to the field of microwave photonics, in particular to a method of amplifying a spontaneous emission light source (hereinafter referred to as an ASE light source) as an optical carrier, eliminating the coherence between a signal and inter-mode crosstalk, and avoiding the influence of inter-mode interference on time delay jitter, Thus, a remote true-delay beamforming method based on few-mode fiber is realized. Background technique [0002] Beamforming is a key technology in 5G mobile communications, which can effectively reduce electromagnetic interference in wireless links and greatly improve radiation gain in specific directions. The beamformer realized by optical true delay can avoid the problem of beam squint, thus supporting the access of broadband radio frequency signals. Due to this advantage, a large number of local beamforming schemes have been proposed in recent years. However, in the 5G mobile communication system, the ...

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Problems solved by technology

[0005] In order to overcome the time delay jitter caused by inter-mode interference, the present invention provides a solution using an ASE light source as an optical carrier

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