Faster Than Nyquist Receiver Trellis Pruning
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Solution Overview
Problem
Current wireless communication systems face limitations in data transmission rates due to inter-symbol interference (ISI), which restricts bandwidth and decoding accuracy, especially when transmitting at faster than Nyquist rates.
Innovation Solution
The method involves a receiving device that determines reliability ratings for undecoded data streams, selects streams with the highest ratings for decoding using a trellis, updates the trellis with decoded symbols, and prunes trellis states to reduce uncertainty, thereby enhancing decoding accuracy and increasing data transmission rates by exploiting already decoded symbols to assist in decoding undecoded portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If transmission rate is increased beyond Nyquist rate, then data transmission rate increases, but inter-symbol interference increases and decoding accuracy deteriorates
Solution Approach 1:
The patent applies preliminary action by using successfully decoded symbols from previously decoded streams to prune the trellis states before decoding subsequent streams. This pre-processing step eliminates impossible states in advance, reducing the complexity and improving accuracy of decoding faster-than-Nyquist transmitted signals without requiring slower transmission rates.
2Productivity
If more data streams are transmitted to increase bandwidth utilization, then data transmission rate increases, but inter-symbol interference increases and reliability of individual streams deteriorates
Solution Approach 1:
The patent implements feedback by using the output from successfully decoded streams to inform and improve the decoding of remaining streams. The decoded symbols from high-reliability streams are fed back into the trellis decoding process for other streams, pruning impossible states and enhancing the reliability of decoding multiple simultaneously transmitted streams.
3Productivity
If trellis decoding is performed on all streams simultaneously, then all streams are decoded, but computational complexity increases and decoding accuracy decreases due to uncertainty
Solution Approach 1:
The patent applies segmentation by dividing the decoding process into sequential stages based on stream reliability rankings. Instead of decoding all streams simultaneously with full computational complexity, the system processes streams in order of their reliability, using results from earlier stages to simplify subsequent decoding operations, thereby reducing overall computational complexity while maintaining throughput.
Data Source
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AI summary
A method for operating a receiving device includes determining reliability ratings for undecoded data streams in a received transmission, selecting an undecoded data stream in the received transmission in accordance with the determined reliability ratings, thereby producing a selected data stream, and decoding the selected data stream with a decoding trellis, thereby producing a data symbol. The method also includes updating the decoding trellis in accordance with the data symbol, and repeating the selecting, the decoding, and the updating for remaining undecoded data streams in the received transmission.