One Bit Per Symbol Timing Recovery Phase Detector
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Solution Overview
Problem
Existing one bit per symbol timing recovery phase detectors, such as the Mueller and Muller phase detector, degrade in performance when channels have narrower bandwidths and higher modulation orders, like PAM-4, due to the requirement for correct decisions and the introduction of delay from equalization processes.
Innovation Solution
A method and apparatus for timing recovery in communication systems that utilize a combination of analog to digital conversion, interpolation filters, non-linear devices, and mathematical operations to generate phase information, independent of equalization mechanisms, allowing for improved timing recovery without the need for higher sampling rates and reducing delay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional phase detectors (e.g., Mueller and Muller) are used for timing recovery, then the system can operate with one bit per symbol, but performance degrades when channels have narrower bandwidths and higher modulation orders
Solution Approach 1:
The patent changes the fundamental parameters of phase detection by using multiple sampling points per symbol instead of one bit per symbol, and by applying non-linear processing (absolute value, square root) to the sampled signals. This transforms the detection approach to work effectively with narrower bandwidths and higher modulation orders where traditional methods fail
2Measurement precision
If equalization processes are used to improve signal recovery, then detection accuracy improves, but delay is introduced that degrades timing recovery
Solution Approach 1:
The patent extracts the timing recovery function from the equalization process. By using multiple sampling points and non-linear processing to directly generate phase information, the system achieves accurate timing recovery without requiring equalization, thereby eliminating the delay that equalization introduces
3Measurement precision
If higher sampling rates are used to improve timing recovery accuracy, then phase detection precision improves, but power consumption increases
Solution Approach 1:
Instead of using excessively high sampling rates, the patent uses a moderate sampling rate with multiple samples per symbol and applies non-linear processing. This partial action approach achieves high phase detection accuracy without the prohibitive power consumption of much higher sampling rates
Data Source
AI summary
Embodiments are disclosed for timing recovery used in conjunction with a phase detector embedded in a receiver of a communication system. An example method includes receiving, via a receiver of a communication system, an input signal. The input signal encodes a plurality of bits in a number of amplitude levels. The method further includes using an analog to digital converter to generate a sampled signal based on the input signal. The method further includes using a first interpolation filter to filter the sampled signal. The method further includes using a second interpolation filter to filter the sampled signal. The method further includes using a first non-linear device to process an output of the first interpolation filter. The method further includes using a second non-linear device to process an output of the second interpolation filter. The method further includes performing a mathematical operation on an output of the first non-linear device with an output of the second non-linear device to generate phase information.