Regenerative Interference Cancellation Using Dynamic Regeneration Factors
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Solution Overview
Problem
Existing DS/CDMA communication systems face challenges in maintaining high Quality of Service (QoS) due to increasing demand, with known interference cancellation techniques like HD-PIC and P-PIC degrading receiver performance when symbol decisions are unreliable.
Innovation Solution
The implementation of a soft-decision based regenerative interference cancellation method that adjusts regeneration factors for each user and stage, using a value between 0 and 1, to weight reliable and unreliable decisions differently, improving the accuracy of interference cancellation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If hard-decision PIC or partial PIC schemes are used, then implementation simplicity is improved, but receiver performance degrades when symbol decisions are unreliable
Solution Approach 1:
The patent changes the parameter of regeneration factor from fixed (0 or predetermined value) to variable based on decision reliability. The regeneration factor is dynamically adjusted according to the reliability of symbol decisions, allowing the system to adaptively weight the contribution of regenerated signals. This resolves the contradiction by maintaining implementation simplicity while improving receiver performance through parameter adaptation.
Solution Approach 2:
The patent introduces dynamic adjustment of regeneration factors based on the reliability of symbol decisions. Instead of using fixed regeneration factors as in conventional PIC schemes, the system dynamically modifies the regeneration factor for each user based on their decision reliability. This dynamic approach allows the system to optimize performance while maintaining simplicity in the overall architecture.
2Device complexity
If fixed regeneration factors are used for all users, then device complexity is reduced, but interference cancellation accuracy deteriorates
Solution Approach 1:
The patent applies local quality by assigning different regeneration factors to different users based on their individual decision reliability. Instead of using a uniform regeneration factor for all users, the system tailors the regeneration factor to each user's specific characteristics and reliability level. This localized approach improves interference cancellation accuracy without significantly increasing overall system complexity.
Solution Approach 2:
The patent changes the regeneration factor parameter from fixed and uniform to variable and user-specific. By adjusting the regeneration factor based on decision reliability, the system achieves more accurate interference cancellation. The parameter change is implemented in a way that maintains manageable complexity through efficient calculation methods.
3Productivity
If unreliable symbol decisions are fully subtracted, then interference cancellation is aggressive, but receiver performance significantly degrades
Solution Approach 1:
The patent applies partial action by using regeneration factors that can be less than 1.0, thereby applying only a portion of the regenerated signal to the interference cancellation. This partial subtraction approach prevents the system from being overly aggressive in canceling interference, thus avoiding the degradation that would result from fully subtracting unreliable decisions. The regeneration factor acts as a control parameter to balance cancellation aggressiveness with performance preservation.
Solution Approach 2:
The patent implements beforehand cushioning by using regeneration factors that dampen the impact of unreliable decisions before they can harm receiver performance. The regeneration factor acts as a cushioning mechanism that prevents full subtraction of potentially incorrect signals, thereby protecting the receiver performance from significant degradation while still achieving interference cancellation.
Data Source
AI summary
Interference cancellation is performed in a communication system. A signal associated with the users is received to produce a received signal. A set of regeneration factors associated with the users is determined based on the received signal. A frequency range associated with a first user from the users has at least a portion overlapping with at least a portion of a frequency range associated with a second user from the users. A time range associated with the first user from the users has at least a portion overlapping with at least a portion of a time range associated with the second user from the users. A regenerated signal associated with each user from the users is modified based on the determined regenerated factor associated with that user to produce a modified regenerated signal for each user.