Phasor-Based Symbol Detection With Carrier Offset Estimation
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Solution Overview
Problem
Existing wireless communication systems face challenges in detecting signals with unknown carrier frequency offsets (CFO), leading to difficulties in recognizing received signals due to frequency deviations between transmitters and receivers, which complicates signal detection and increases circuit complexity, power consumption, and signal detection latency.
Innovation Solution
A phasor-based signal detector calculates a phasor indicating the phase difference between samples of symbol groups in a received signal, allowing for coherent accumulation and estimation of CFO, thereby improving sensitivity and enabling rapid detection of signals with unknown CFOs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional signal detection methods are used to handle unknown carrier frequency offset, then signal detection can be performed, but circuit complexity increases
Solution Approach 1:
The signal detection process is segmented into distinct phases: initial coarse CFO estimation using phase difference calculation between symbol groups, followed by refined detection only when needed. This segmentation allows the system to handle unknown CFO without maintaining complex circuitry continuously.
Solution Approach 2:
A phasor-based intermediate representation is introduced as a mediator between the received signal and the detection logic. The phasor captures phase information while discarding amplitude variations, simplifying the detection process and reducing circuit complexity while maintaining reliability.
2Reliability
If conventional signal detection methods are used to handle unknown carrier frequency offset, then signal detection can be performed, but power consumption increases
Solution Approach 1:
The system employs periodic phasor-based CFO estimation at predetermined intervals rather than continuous complex processing. This periodic action maintains signal detection capability while significantly reducing average power consumption by activating full processing only when necessary.
Solution Approach 2:
The invention extracts only the essential phase information from the received signal using phasor representation, discarding unnecessary amplitude and timing details. This extraction reduces the computational burden and power consumption while maintaining sufficient information for reliable detection.
3Reliability
If conventional signal detection methods are used to handle unknown carrier frequency offset, then signal detection can be performed, but signal detection latency increases
Solution Approach 1:
The system performs preliminary phasor-based CFO estimation using only phase information from symbol groups before committing to full signal detection. This preliminary action quickly identifies whether a signal is present and estimates CFO, reducing latency by avoiding unnecessary full-processing cycles.
Solution Approach 2:
The detection system dynamically adapts its processing level based on phasor analysis results. When CFO is within acceptable ranges, simplified detection paths are taken; when offset is large, more robust processing is activated. This dynamic approach minimizes average detection latency while maintaining reliability across varying conditions.
Data Source
AI summary
A phasor-based signal detector includes a signal processor to detect symbols in a received signal in the presence of an offset between the carrier frequency and an oscillator frequency of the signal processor. The signal processor calculates a phasor that indicates a phase difference between a first sample in a first symbol group and a second sample in a second symbol group. The first and second samples each include a real part and an imaginary part corresponding to a same sample position within the first and second symbol groups. Calculating the phasor includes a complex multiplication of one of the samples and a conjugate of the other one of the samples. A phase difference indicated by a phasor meeting a criteria may be used to estimate a carrier frequency offset (CFO). If the CFO is within a supported range, the signal processor may coherently accumulate symbols.