Successive Interference Cancellation Phase Rotation Correction
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Solution Overview
Problem
Current successive interference cancellation methods in CDMA communication systems fail to consider the frequency shift caused by high-speed terminal movements, leading to errors and performance degradation, especially in neighbor cell channels, resulting in significant detection performance losses.
Innovation Solution
The method determines whether an interfering user channel is from a service cell or a neighbor cell, corrects and restores the phase rotation of the user signal using a CORDIC algorithm, and performs signal reconstruction to remove the reconstructed signal from the reception signal, enhancing accuracy and detection performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If successive interference cancellation is performed without considering frequency shift of neighbor cell channel, then device complexity is reduced, but detection precision deteriorates
Solution Approach 1:
The patent applies local quality by differentiating processing for service cell channels versus neighbor cell channels. For neighbor cell channels experiencing frequency shifts, the system performs phase rotation correction and signal reconstruction, while service cell channels undergo standard processing. This localized adaptation of processing quality resolves the contradiction by applying enhanced processing only where frequency shift effects occur.
Solution Approach 2:
The patent changes the frequency shift parameter from zero (ignored) to a non-zero value (compensated) for neighbor cell channels. By estimating and compensating for frequency shifts in the phase rotation correction process, the system maintains detection precision without uniformly increasing complexity across all channels, thus resolving the contradiction between simplicity and accuracy.
2Measurement precision
If phase rotation correction and signal reconstruction are performed for neighbor cell channels, then detection precision is improved, but device complexity increases
Solution Approach 1:
The patent segments the interference cancellation process into distinct stages: phase rotation correction, tentative ruling, phase rotation restoration, and signal reconstruction. By dividing the complex processing into modular segments that are applied selectively to neighbor cell channels, the system improves detection precision while managing complexity through structured, incremental processing steps.
3Reliability
If frequency shift compensation is implemented, then reliability is improved, but ease of operation deteriorates
Solution Approach 1:
The patent performs preliminary phase rotation correction before signal detection and reconstruction. By pre-compensating for frequency shifts in the phase domain before making tentative rulings, the system improves reliability of the subsequent detection steps without requiring complex real-time adjustments during the main detection process, thus maintaining operational simplicity.
Data Source
AI summary
A successive interference cancellation method includes: determining whether a current interfering user channel is a service cell channel of a service cell or a neighbor cell channel of a neighbor cell; correcting a phase rotation of a user signal of the neighbor channel when the interfering user channel is the neighbor cell channel; determining a tentative ruling for a user signal of the neighbor cell channel; restoring the phase rotation of the user signal of the neighbor cell channel; performing a signal reconstruction on the neighbor cell channel to obtain a reconstructed signal of the neighbor cell channel; removing the reconstructed signal of the neighbor cell channel from a reception signal to obtain a corrected signal, and completing successive interference cancellation on the current interfering user channel. With the above successive interference cancellation method, accuracy of successive interference cancellation as well as system detection performance is enhanced.