Remote Radio Head Power Switching for Inter-Band Interference
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Solution Overview
Problem
Inter-band interference occurs between collocated transmitters of different cellular networks, particularly when their radio bands are nearly spectrally adjacent, leading to passive intermodulation interference, which existing multi-band remote radio heads do not effectively alleviate despite cost savings from serving multiple networks with the same equipment.
Innovation Solution
A remote radio head system that switches power between two power amplifier systems based on alternating duty cycles, ensuring that only one frequency band is transmitted at a time to prevent simultaneous transmission and thus mitigate inter-band interference, utilizing control data from a baseband unit to dynamically adjust and balance load between different RF bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a multi-band remote radio head transmits for multiple cellular networks simultaneously, then cost savings are achieved by serving multiple networks with the same equipment, but inter-band interference occurs between collocated transmitters with adjacent bands
Solution Approach 1:
The patent implements alternating transmission periods where the remote radio head transmits on different frequency bands at different times rather than simultaneously. The baseband unit schedules transmission time slots for different cellular networks, ensuring that transmitters with adjacent bands do not operate at the same time, thereby eliminating inter-band interference while maintaining cost-effective multi-band operation
Solution Approach 2:
The system dynamically adjusts transmission scheduling between different frequency bands based on traffic demands and interference conditions. The baseband unit can flexibly allocate transmission time slots to different cellular networks, allowing the system to adapt to changing network conditions while preventing simultaneous transmission on adjacent bands
2Productivity
If both transmitters transmit simultaneously to maintain high productivity, then service quality is improved, but inter-band interference occurs leading to degraded signal quality
Solution Approach 1:
The system uses periodic time-division multiplexing where different cellular networks are assigned alternating transmission time slots. This ensures that transmitters on adjacent frequency bands never operate simultaneously, eliminating inter-band interference and maintaining high signal quality while still providing continuous service through coordinated scheduling
Data Source
AI summary
A remote radio head system (RRH) transmits first Radio-Frequency-signals (signals) at a first frequency-band (band) and second signals at a second band. The RRH receives and processes first control-data (data) to determine a first duty-cycle (cycle). In response to the first data and based on the first cycle, the RRH switches power between a first power amplifier system (PA) and a second PA and transmits the first signals at the first band through the first PA and transmits the second signals at the second band through the second PA. The RRH receives and processes second data to determine a second cycle. Responding to the second data and based on the second cycle, the RRH switches power between the first PA and the second PA and transmits the first signals at the first band through the first PA and transmits the second signals at the second band through the second PA.