Base Station Gain Control for Passive Intermodulation Suppression
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Solution Overview
Problem
The increasing number of frequency bands and carriers in wireless communications leads to a significant problem of passive intermodulation (PIM), causing interference that can render receivers unusable, and existing solutions require complex station designs and costly tower reinforcements or feeder additions to mitigate this issue.
Innovation Solution
A passive intermodulation suppression method and system that uses uplink controllable gain modules to adjust the gain of base stations, allowing multiple frequency bands to share a feeder without the need for remote radio unit (RRU) mounting on towers or additional feeder installations, by dynamically controlling the gain to maintain constant attenuation and reduce PIM requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple frequency bands are transmitted on a single feeder, then traffic density and coverage requirements are met, but passive intermodulation interference increases exponentially
Solution Approach 1:
The patent extracts the harmful PIM interference from the mixed frequency band transmission by introducing a dedicated PIM cancellation signal path. The cancellation signal is generated separately and then combined with the received signal to remove the PIM components, allowing multiple frequency bands to share feeders without suffering from exponential PIM interference increase.
Solution Approach 2:
The patent changes the parameter of signal processing by introducing active PIM cancellation techniques. By dynamically adjusting cancellation signal parameters (amplitude, phase, frequency) based on detected PIM characteristics, the system can suppress PIM interference while maintaining high traffic density on shared feeders.
2Object-affected harmful factors
If feeders are not shared between low and high frequency bands, then PIM interference is avoided, but station design becomes complicated and costs increase
Solution Approach 1:
The patent merges previously separate frequency band transmissions into shared feeders by implementing PIM cancellation functionality within the base station. This allows low and high frequency bands to coexist on the same physical infrastructure without requiring separate feeder paths, thereby simplifying station design while maintaining PIM suppression.
Solution Approach 2:
The patent introduces an intermediary PIM cancellation mechanism that mediates between multiple frequency bands sharing the same feeder. This intermediary processing stage detects and removes PIM components, enabling feeder sharing without the need for complex physical separation or reinforcement structures.
3Object-affected harmful factors
If tower reinforcement or feeder addition is performed, then PIM problems are resolved, but costs increase significantly
Solution Approach 1:
The patent replaces mechanical solutions (tower reinforcement, feeder addition) with an electronic/software-based PIM cancellation system. By using signal processing algorithms and digital signal manipulation, the system achieves PIM suppression without requiring expensive physical infrastructure modifications.
Solution Approach 2:
The patent changes the approach from physical parameter changes (adding infrastructure) to signal parameter changes (adjusting cancellation signal characteristics). This allows PIM problems to be resolved through software-controlled parameter adjustments rather than costly hardware modifications.
Data Source
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AI summary
Embodiments of the present invention disclose a passive intermodulation suppression method and a passive intermodulation suppression system. The method in the embodiments of the present invention includes: obtaining, by using a target uplink controllable gain module, a first power Pt of an uplink signal sent by an antenna; obtaining a second power Pb of a signal that is output from an output port of a base station; configuring a target attenuation of the base station; and adjusting the initial gain value based on the target attenuation to keep a gain of the base station constant. According to the method described in the embodiments, the base station can maintain the target attenuation constant in a process of adjusting a gain of the target uplink controllable gain module, thereby reducing a PIM requirement of a passive intermodulation suppression system.