Multi-Carrier Superposition Gain Reduction for Signal Overflow Prevention
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Solution Overview
Problem
In multi-carrier superposition technology, the peak-to-average ratio (PAR) of signals increases with the number of carriers, leading to signal overflow and degradation of signal quality due to unscaled power and lack of saturation processing, affecting Adjacent Channel Power Ratio (ACPR) and Error Vector Magnitude (EVM).
Innovation Solution
The proposed solution involves dividing each downlink sub-frame into Control and Data Regions, applying non-linear phase rotation, and using gain reduction and multi-carrier filtering and frequency shifting to manage signal power, ensuring that the peak power does not exceed scaling thresholds, thereby preventing signal overflow and maintaining precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multi-carrier superposition is performed with high scaling to maintain signal precision, then manufacturing precision is improved, but signal overflow occurs leading to degraded signal quality
Solution Approach 1:
The patent applies preliminary action by performing gain reduction processing on carrier signals before they are superposed. This pre-scaling prevents the combined signal from exceeding the maximum representable value after superposition, thereby avoiding overflow and maintaining signal quality while preserving necessary precision through controlled amplitude adjustment.
Solution Approach 2:
The patent changes the amplitude parameter of carrier signals by applying gain reduction factors (e.g., 0.707 for two carriers, 0.577 for three carriers) before superposition. This parameter adjustment ensures that the combined signal remains within the representable range while maintaining optimal signal-to-noise ratio and preventing overflow that would degrade signal quality.
2Productivity
If the number of carriers is increased to enhance system capacity, then productivity is improved, but peak-to-average ratio increases causing signal overflow
Solution Approach 1:
The patent addresses the increased PAR from multiple carriers by dynamically adjusting the gain parameter of each carrier based on the number of superposed carriers. For example, using gain factors of 0.707 for two carriers, 0.577 for three carriers, and 0.5 for four or more carriers, the system maintains signal stability and prevents overflow while supporting higher system capacity through multi-carrier operation.
3Reliability
If direct truncation at peak amplitude is applied to prevent overflow, then signal overflow is avoided, but signal mutation occurs affecting EVM and ACPR
Solution Approach 1:
The patent avoids signal mutation by applying preliminary gain reduction before superposition rather than truncating after superposition. This proactive amplitude control prevents the combined signal from reaching overflow levels in the first place, eliminating the need for truncation and thereby preserving signal continuity and quality without causing EVM or ACPR degradation.
Data Source
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AI summary
Disclosed are a multi-carrier superposition method and device. First, input carrier signals are superposed, and gain reduction processing is conducted during the superposition process, and then CFR processing and increase processing are conducted on the superposed carrier signals. Thus, under the circumstance of multi-carrier superposition, it can be effectively ensured that signals cannot overflow, and meanwhile the requirement for precision of a system during processing is met.