Adaptive Modulation for Cross-Polarization Interference in Frequency Reuse
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Solution Overview
Problem
Existing frequency reuse systems in radio communication face challenges due to cross-polarization interference, which degrades system effectiveness and requires complex and costly cross-polarization interference cancellers (XPICs) that struggle with synchronization and signal exchange, especially in high-frequency bands and non-overlapping channel spectrums.
Innovation Solution
Implementing an adaptive modulation technique that dynamically changes modulation schemes in response to detected cross-polarization interference levels, allowing for independent operation of dual polarizations without the need for XPICs, thereby eliminating interference and simplifying system design and installation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If frequency reuse with orthogonal polarizations is implemented to double spectral efficiency, then spectral efficiency is improved, but cross-polarization interference ratio degrades due to fading or rain de-polarization
Solution Approach 1:
The patent implements adaptive modulation that dynamically changes modulation schemes based on detected cross-polarization interference levels. The system transitions from static modulation to dynamic adaptation, selecting robust modulation schemes when interference exceeds thresholds and using higher-order modulation when conditions permit, thereby resolving the contradiction between maintaining high spectral efficiency and ensuring reliable transmission under varying interference conditions
Solution Approach 2:
The patent changes the modulation scheme parameter in response to detected interference conditions. By monitoring cross-polarization interference levels and adjusting the modulation order accordingly, the system optimizes the trade-off between spectral efficiency and transmission reliability, using higher modulation orders when interference is low and more robust lower-order modulation when interference is high
2Reliability
If cross-polarization interference cancellers (XPICs) are used to cancel interference signals, then cross-polarization interference ratio is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts and eliminates the need for complex XPIC hardware by using adaptive modulation instead. Rather than adding interference cancellation equipment, the system removes the requirement for XPICs by adapting the modulation scheme to match channel conditions, thereby improving reliability without increasing device complexity
Solution Approach 2:
The patent replaces expensive, complex XPIC hardware with a simpler, software-based adaptive modulation approach. The solution uses standard modulation components that can be dynamically reconfigured rather than requiring dedicated interference cancellation equipment, reducing both cost and complexity while maintaining interference mitigation effectiveness
3Reliability
If adaptive modulation is implemented to change modulation schemes in response to interference, then cross-polarization interference management is improved, but device complexity increases due to detection and control mechanisms
Solution Approach 1:
The patent implements a self-service mechanism where the receiver detects cross-polarization interference levels and sends feedback to the transmitter, which automatically adjusts the modulation scheme. This closed-loop system manages interference through self-regulation rather than requiring complex external control mechanisms, improving reliability while keeping the control architecture relatively simple
Solution Approach 2:
The patent uses feedback from the receiver to the transmitter regarding detected interference conditions. The receiver measures cross-polarization interference and communicates this information back, enabling the transmitter to adaptively adjust modulation schemes. This feedback mechanism provides effective interference management through relatively simple detection and control compared to hardware-based cancellation approaches
Data Source
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AI summary
A method and a receiver for implementing frequency reuse in a radio communication system, wherein a first channel is transmitted using a first frequency, a first polarization and a first modulation scheme and at least and at least a second channel is transmitted using a second frequency, a second polarization and a second modulation scheme, the first modulation scheme and the second modulation scheme being adaptive and the first polarization being different from the second polarization. In case a level of co-channel interference is detected between the first channel and the second channel, at least one of said first modulation scheme and the second modulation scheme is changed.