Symbol Sequence Estimation With Reduced Trellis Complexity
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Solution Overview
Problem
The increasing symbol multi-level degree in communication systems leads to a significant increase in the amount of computation required for symbol determination, particularly in algorithms like the Viterbi algorithm, which becomes computationally expensive as the number of branches in the trellis diagram grows exponentially.
Innovation Solution
A symbol determination device that includes a provisional determination unit for adaptive equalization, a transmission line estimation unit for generating estimation reception symbol sequences, and a sequence estimation algorithm processing unit that calculates metrics and selects the most likely estimation reception symbol sequence using a predetermined algorithm, such as the Viterbi or BCJR algorithm, while narrowing down the range of symbol sequences to reduce computational complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the symbol multi-level degree is increased to achieve higher transmission capacity, then the transmission capacity is improved, but the amount of computation required for symbol determination increases exponentially
Solution Approach 1:
The patent segments the symbol determination process into two distinct stages: (1) a provisional determination stage that performs adaptive equalization to generate initial symbol estimates, and (2) a sequence estimation stage that applies the Viterbi algorithm to determine the final symbol sequence. This segmentation allows the computationally intensive Viterbi algorithm to operate on a reduced search space defined by the provisional estimates, thereby managing computation complexity while maintaining high transmission capacity support
Solution Approach 2:
The patent performs preliminary adaptive equalization to generate provisional symbol estimates before applying the Viterbi algorithm. This preliminary action narrows down the possible symbol sequences that need to be evaluated, transforming the exponential search problem into a manageable computation by pre-processing the reception signal to produce likely candidate symbols that guide the subsequent sequence estimation
2Measurement precision
If the Viterbi algorithm is applied to determine symbol sequences with high multi-level degrees, then the measurement precision of symbol determination is improved, but the processing time increases due to the exponential number of branches
Solution Approach 1:
The patent applies local quality by using the provisional symbol estimates to define a localized search space around the most likely symbol values. Instead of evaluating all possible symbol sequences globally, the Viterbi algorithm is applied locally to sequences that are consistent with the provisional estimates, thereby maintaining measurement precision while dramatically reducing the number of branches that need to be processed
3Reliability
If adaptive equalization is performed to compensate for transmission line effects, then the reliability of symbol determination is improved, but the computational load increases
Solution Approach 1:
The patent implements dynamic adaptation by using the provisional equalization results to dynamically adjust the search space for the Viterbi algorithm. The adaptive equalization is not performed in isolation but is dynamically coupled with the sequence estimation, where the equalization results directly influence the subsequent Viterbi processing by providing initial symbol estimates that guide the dynamic programming search
Data Source
AI summary
A device generates a symbol sequence by performing adaptive equalization by an estimation inverse transfer function of a transmission line on a reception signal sequence extracted from the transmission line, and performing provisional determination on the symbol sequence generated; generates a plurality of the symbol sequences indicating transmission line states in a range of a provisional determination symbol provisionally determined and nearby symbols of the provisional determination symbol; generates, based on the plurality of the symbol sequences indicating the transmission line states generated and an estimation transfer function of the transmission line, an estimation reception symbol sequence for each of the transmission line states; calculates a metric between the symbol sequence obtained from the reception signal sequence and each of a plurality of the estimation reception symbol sequences; selects a most likelihood estimation reception symbol sequence of the plurality of the estimation reception symbol sequences, based on the calculated metric, the provisional determination symbol, and the nearby symbols of the provisional determination symbol; and determines a transmission symbol sequence.