Decision-Feedback Differential Demodulation for Lower BER
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Solution Overview
Problem
Conventional differential detection in radio signal receivers suffers from poor noise performance and bit error rate (BER) due to the use of single output signals, lacking the efficiency of coherent detection while maintaining lower complexity.
Innovation Solution
A receiver device employing differential detector circuitry that utilizes decision feedback to generate multiple output signals for each symbol interval, combining these signals to reduce noise power and improve signal-to-noise ratio (SNR), thereby enhancing BER performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional differential detection is used to avoid complex carrier recovery circuits, then device complexity is reduced, but noise performance and bit error rate deteriorate
Solution Approach 1:
The differential detection process is segmented into multiple parallel paths, each producing a separate output signal. Instead of using a single differential output, the invention divides the detection into multiple segments (first output signal, second output signal, etc.) that are subsequently combined. This segmentation allows each path to process the signal differently, and when combined, they provide diversity gain that improves noise performance while maintaining the simple differential detection architecture.
Solution Approach 2:
Multiple output signals from different differential detection paths are merged/combined to form a final decision. The invention combines the first output signal (from direct differential detection) with the second output signal (from phase-adjusted differential detection) to make the final phase decision. This combining process provides signal diversity and improves the signal-to-noise ratio, thereby improving bit error rate performance while avoiding complex carrier recovery circuits.
2Device complexity
If single output signal from differential detector is used to maintain simplicity, then device complexity remains low, but noise performance deteriorates
Solution Approach 1:
The invention employs feedback from previous phase decisions to adjust the phase of reference signals in subsequent differential detection operations. The phase decision from one symbol interval is fed back to adjust the phase of the reference signal for the next symbol interval. This feedback mechanism enables the detector to compensate for phase rotations accumulated over time, reducing the impact of noise and improving detection accuracy without significantly increasing device complexity.
Data Source
AI summary
A receiver device comprises receiving circuitry configured to receive a radio signal modulated using frequency shift keying or phase shift keying, the radio signal comprising a plurality of successive symbol intervals, differential detector circuitry configured to multiply a signal for a current symbol interval with a first reference signal and output a first output signal for the current symbol interval, wherein the first reference signal corresponds to a conjugate of a signal for a first symbol interval preceding the current symbol interval and multiply the signal for the current symbol interval with a second reference signal and output a second output signal for the current symbol interval, wherein the second reference signal corresponds to a conjugate of a signal for a second symbol interval preceding the first symbol interval, in which the conjugate of the signal for the second symbol interval has been phase adjusted in dependence on a previous phase decision for the first symbol interval preceding the current symbol interval, combining circuitry configured to combine the first output signal for the current symbol interval and the second output signal for the current symbol interval to obtain a combined signal for the current symbol interval, and decision circuitry configured to output a phase decision for the current symbol interval in dependence upon the combined signal.