A PIM Interference Cancellation Method Based on Pilot Signal

Abstract

The invention discloses a passive intermodulation interference cancellation method based on a pilot signal, belonging to the field of anti-interference technologies of wireless communication, satellite communication and ground communication systems. The method comprises the following steps of adopting two time slot mechanisms of a pilot time slot and a data transmission time slot to carry out real-time estimation and suppression on a PIM (Passive Intermodulation) interference signal; during the pilot time slot, quickly estimating PIM model parameters and storing a result; and during the data transmission slot, utilizing a known emission pilot signal and the PIM model parameters to reconstruct the PIM interference signal, and removing the PIM interference signal from a receiving signal to complete PIM interference cancellation. According to the method based on digital signal processing, the passive intermodulation interference cancellation is quickly achieved, and the method has the advantages of simplicity, low computation complexity, small resource computation and easiness in hardware implementation.

Description

technical field [0001] The invention relates to a method for suppressing passive intermodulation interference of a radio frequency module, in particular to a method for canceling passive intermodulation interference based on pilot signals, and belongs to the technical field of anti-interference of wireless communication, satellite communication and ground communication systems. Background technique [0002] Passive intermodulation refers to the generation of new frequencies other than harmonics when a signal containing two or more frequency components passes through passive devices (such as duplexers, isolators, coaxial cables, connectors, antennas, loads, etc.) A phenomenon of composition. Although linearity is a basic characteristic exhibited by passive devices, research and experiments have shown that passive devices also have weak nonlinearities, especially at high power. [0003] As the input power increases, the passive intermodulation interference generated becomes m...

AI Technical Summary

Problems solved by technology

[0005] However, through the high-demand control of materials and processing technology, the current demand for PIM indicators cannot be fully met, and the difficulty of development has also increased.

At the same time, the PIM problem may be aggravated by factors such as temperature changes, aging and loosening of mechanical connectors, contamination or corrosion of the contact surface during system use, and affect the normal operation of the system.

Therefore, it is difficult to adapt to the subsequent development requirements

[0006] In 2008, Dr. Henrie used the point-source model to study passive intermodulation distortion in microwave networks, and proposed a cancellation algorithm and verified it through experiments, but the results have certain limitations.

This method needs to destroy the original communication system, periodically or suddenly interrupt the communication

[0008] In 2013, Ericsson continued to apply for a patent, and proposed an adaptive PIM interference cancellation method without a test mode. This method consumes a lot of resources, and the convergence speed of parameter estimation cannot be guaranteed. At the same time, test signals are required to determine the number of parameters.

In 2014, Beijing Institute of Technology, Ericsson and Huawei all applied for patents and proposed an adaptive PIM interference cancellation method based on digital signal processing, which also did not solve the problem of difficult convergence of parameter estimation.

[0010] To sum up, the current passive intermodulation interference cancellation method is relatively complicated, and the convergence speed and real-time cancellation effect are not very good

The present invention intends to propose an interference cancellation algorithm based on the existing pilot frequency, without modifying the existing communication system, and quickly estimating PIM. No similar research results have been seen so far.

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