Multi-Band Signal Filtering and Combining for Low-PIM RRUs
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Solution Overview
Problem
Current radio remote units (RRUs) supporting multiple frequency bands face challenges in avoiding passive intermodulation (PIM) issues while also minimizing the number of antenna ports used.
Innovation Solution
A signal processing apparatus comprising a power amplification module with multiple power amplifiers and filter units, along with a combiner unit, which separates and combines signals across different frequency bands based on specific conditions to reduce the number of antenna ports required, thereby avoiding PIM problems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple antenna ports are used to support multiple frequency bands, then the signal transmission capability is improved, but the device complexity and PIM problems increase
Solution Approach 1:
The signal processing is segmented into distinct stages: power amplification for each frequency band, followed by filtering to separate frequency components, and then combination of filtered signals. This segmentation allows each component to handle specific frequency ranges independently, reducing overall system complexity while maintaining multi-band capability
Solution Approach 2:
Filtered signals from different frequency bands are merged into a single combined signal that can be transmitted through one antenna port. The combiner unit integrates multiple processed signals while the frequency separation prevents PIM interference, achieving both signal transmission capability and reduced device complexity
2Reliability
If multiple antenna ports are used to avoid PIM problems, then the signal quality is improved, but the quantity of antenna ports increases
Solution Approach 1:
Filter units are introduced as intermediary components between power amplifiers and the combiner. These filters act as mediators that separate frequency components, allowing multiple signals to be combined without causing PIM interference. This intermediary filtering mechanism enables signal quality maintenance while using fewer antenna ports
Solution Approach 2:
The system changes the frequency parameter of signals through filtering operations. By transforming signals into different frequency ranges through filtering before combination, the system prevents PIM interference that would otherwise require separate antenna ports, thus maintaining signal quality with reduced port quantity
3Quantity of substance
If signals from different frequency bands are combined, then the quantity of antenna ports is reduced, but PIM problems may occur
Solution Approach 1:
The system converts the potential harmful PIM interference into a beneficial frequency separation mechanism. By filtering signals into distinct frequency ranges before combination, the system ensures that even when multiple signals are combined in one port, their frequency separation prevents PIM interference, thus reducing antenna port quantity without sacrificing signal quality
4Reliability
If separate processing is used for each frequency band, then the signal quality is maintained, but the device complexity increases
Solution Approach 1:
The filter units serve multiple functions: they separate frequency components from different power amplifiers, prepare signals for combination, and prevent PIM interference. This multi-functionality allows separate processing of each frequency band while using shared filtering and combining resources, maintaining signal quality without proportionally increasing device complexity
Data Source
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AI summary
Embodiments of this application disclose a signal processing apparatus and method, and an access network device, and relate to the field of communication technologies. The signal processing apparatus includes a first power amplifier, a second power amplifier, a first filter unit, a second filter unit, and a combiner unit. The first filter unit filters a second signal obtained by the first power amplifier, to obtain a first sub-signal belonging to a first frequency band and a second sub-signal belonging to a second frequency band. The second filter unit filters a fourth signal obtained by the second power amplifier, to obtain n sub-signals, where the n sub-signals include at least a third sub-signal belonging to a third frequency band. The combiner unit combines the first sub-signal and i sub-signals in the n sub-signals based on a preset condition, to obtain a first combined signal. The communication module sends the first combined signal by using a first port, and sends the second sub-signal by using a second port. The signal processing apparatus effectively avoids PIM and reduces a quantity of ports used.