Iterative Channel Estimator for DTMB Signal Demodulation
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Solution Overview
Problem
Conventional channel estimation methods in Digital Terrestrial Multimedia Broadcast (DTMB) systems face performance issues due to data interference from multipath channels, non-ideal auto-correlation properties of pseudo-random noise codes, and mirrored paths, requiring different estimation methods for varying time delay paths.
Innovation Solution
A channel estimator comprising a receiver, a convolution circuit, a subtractor, and an updating circuit that iteratively processes a time-domain training sequence to generate and refine channel estimation values, using techniques like least mean squares or recurrence least squares algorithms to improve accuracy and adaptability across different frame structures and delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional channel estimation methods using auto-correlation of PN sequence are used in DTMB system, then the estimation process is simple, but the performance is undesirable due to data interference, non-ideal auto-correlation property, and mirrored path issues
Solution Approach 1:
The patent implements an iterative feedback mechanism where the channel estimator continuously refines channel estimates by comparing received training sequences with expected sequences, updating channel impulse response values across multiple iterations to converge on accurate estimates, thereby resolving the performance limitations of conventional single-pass methods
Solution Approach 2:
The patent performs preliminary channel estimation using available training sequences before actual data reception, establishing initial channel impulse response values that are then refined iteratively. This preliminary action enables the system to compensate for multipath effects and non-ideal auto-correlation properties before critical data transmission begins
2Measurement precision
If different channel estimation methods are used for different time delay paths to address mirrored path issues, then the estimation accuracy improves, but the device complexity increases
Solution Approach 1:
The patent employs a universal iterative channel estimation algorithm that handles multiple time delay paths and mirrored paths through a single unified framework. The method uses consistent mathematical operations (convolution, correlation, iterative updating) that automatically adapt to different path conditions, eliminating the need for separate specialized methods for each path type while maintaining high accuracy
3Measurement precision
If iterative channel estimation is performed to improve accuracy and reduce interference, then the channel estimation performance improves, but the processing time and computational complexity increase
Solution Approach 1:
The patent implements a controlled iterative process that performs channel estimation to a predetermined number of iterations or until convergence criteria are met, rather than attempting exhaustive refinement. This partial action approach achieves sufficient accuracy for practical applications while limiting computational overhead and processing time, balancing performance improvement with time constraints
Data Source
AI summary
A channel estimator, comprises: a receiver receives a first time-domain training sequence; a first convolution circuit generates an estimated value for the first time-domain training sequence by convoluting a second time-domain training sequence with a current channel estimation value; a first subtractor generates an error by subtracting the estimated value for the first time-domain training sequence from the value of the first time-domain training sequence; an updating circuit generates an updated channel estimation value by updating the current channel estimation value with the error; the receiver iteratively receives a next symbol of the first time-domain training sequence, the first convolution circuit, the subtractor and the updating circuit repeat their operation until completion of receipt of a last symbol of the first time-domain training sequence. The updating circuit outputs the current updated channel estimation value upon completion of receipt of a last first time-domain training sequence.