Decision Feedback Equalizer for Digital TV Receiver
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Solution Overview
Problem
Conventional digital television receivers using VSB signals face challenges in maintaining robustness against inter-symbol interference and thermal noise, leading to increased hardware complexity and power consumption due to higher system clock rates required for reliable decoding, which can introduce delays and performance degradation.
Innovation Solution
A receiver apparatus and method that includes a decoder and equalizer, where the decoder generates symbol decisions and a soft information signal, and the equalizer quantizes and filters the signal based on these decisions to improve reliability, using a soft information signal to select boundary levels for quantization and filter the signal, thereby reducing hardware complexity and maintaining performance without significant delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a higher system clock rate is used for TCM decoding, then decoding reliability is improved, but hardware complexity and power consumption increase
Solution Approach 1:
The patent implements a decision-feedback equalizer where the decoder's symbol decisions are fed back to the equalizer to compensate for inter-symbol interference. This feedback mechanism allows the system to achieve reliable decoding at lower clock rates by using the decoded information to correct previous decisions, thereby reducing the need for high-speed operation and complex hardware architectures.
Solution Approach 2:
The equalizer performs preliminary equalization of the received signal before the TCM decoding process. By pre-processing the signal to remove inter-symbol interference, the subsequent decoding operation can proceed at lower clock rates with reduced hardware complexity, as the signal is already prepared in an optimal state for decoding.
2Reliability
If a higher system clock rate is used for TCM decoding, then decoding reliability is improved, but power consumption increases
Solution Approach 1:
The decision-feedback equalizer uses feedback from the decoder to the equalizer to correct inter-symbol interference effects. This feedback loop enables the system to achieve reliable decoding at lower operating speeds, significantly reducing power consumption compared to high-speed approaches that would be required without feedback mechanisms.
Solution Approach 2:
By performing equalization as a preliminary action before decoding, the system prepares the signal in advance, reducing the computational burden and power consumption during the actual decoding process. This pre-processing approach allows the decoder to operate at lower clock rates with reduced power requirements.
3Device complexity
If delays are introduced in the decoding process, then hardware complexity is reduced, but performance degradation occurs
Solution Approach 1:
The feedback mechanism in the decision-feedback equalizer compensates for any delays introduced in the decoding process. By continuously monitoring and correcting symbol decisions based on feedback from the equalizer, the system maintains high performance even when delays are present, effectively neutralizing their harmful effects.
Solution Approach 2:
The equalizer performs preliminary equalization before decoding, preparing the signal in advance to compensate for potential delays in the decoding process. This pre-processing ensures that even if delays are introduced, the signal is already optimized for accurate decoding, maintaining performance while allowing for simpler, less complex hardware implementations.
Data Source
AI summary
A receiver and method for the same are provided. In the receiver, a decoder may decode an equalized signal to generate symbol decisions and a soft information signal. An equalizer may select boundary levels for non-uniform quantization using a soft information signal delayed by a symbol interval. The equalized signal may be generated from a feedback-filtered signal using the symbol decisions.