OFDM Packet Detector Using Re-quantized Cross-correlation
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Solution Overview
Problem
Conventional Digital Signal Processors (DSPs) are inadequate to handle the high arithmetic calculation demands of Orthogonal Frequency Division Multiplexing (OFDM) communication systems, leading to the need for more efficient packet detection methods that require less circuitry.
Innovation Solution
A method for packet detection in OFDM systems involving signal quantization, cross-correlation using a reference template, and partial results accumulation, implemented using a cross-correlator with re-quantization, sub-correlators, and accumulators to reduce circuitry requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional Digital Signal Processors (DSPs) are used to handle OFDM arithmetic calculations, then calculation capability is sufficient, but circuitry complexity and cost increase significantly
Solution Approach 1:
The patent divides the cross-correlation computation into multiple processing elements (PEs), where each PE handles a portion of the correlation calculation. The sequence of samples is divided into portions, and each PE processes a specific portion using sub-correlators. This segmentation allows the system to achieve the required calculation capability while distributing the computational load across simpler, modular units rather than requiring a single complex DSP.
2Measurement precision
If full-precision arithmetic operations are performed for cross-correlation, then measurement precision is maintained, but circuitry requirements and operational complexity increase
Solution Approach 1:
The patent applies re-quantization to the sequence of samples, transforming them into a quantized form with reduced precision requirements. By changing the parameter of sample representation from full-precision to quantized values, the system maintains sufficient measurement precision for packet detection while significantly reducing the circuitry requirements for arithmetic operations. The re-quantized samples can be processed using simpler logic circuits rather than full-precision arithmetic units.
Data Source
AI summary
Method and apparatus for packet detection is described. More particularly, a signal having sub-signals is received. The signal is quantized (“re-quantized”) to provide a quantized signal to processing units, where the quantized signal is a sequence of samples. A cross-correlation is done between the sequence of samples and a reference template, including totaling partial results from the processing units to provide a result. The result is a symbol timing synchronization responsive to the cross-correlation, which is provided in part by combining by addition or subtraction a regression vector obtained from the sequence of samples and a coefficient term vector obtained from the reference template.