Block Boundary Detection Using XOR Cross-Correlation
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Solution Overview
Problem
Conventional OFDM/OFDMA communication systems require extensive circuitry for block boundary detection, which is costly and exceeds the capacity of conventional Digital Signal Processors, especially in terms of arithmetic calculations that demand billions of operations per second.
Innovation Solution
A method for block boundary detection that employs less circuitry by quantizing the received OFDM signal, cross-correlating the sequence of samples with a reference template using exclusive-OR operations, and utilizing a cross-correlator with re-quantizer, sub-correlators, and an array of exclusive-OR gates to achieve symbol timing synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional Digital Signal Processors are used for OFDM block boundary detection, then arithmetic calculation capacity is sufficient, but circuit cost and complexity become excessive
Solution Approach 1:
The patent replaces complex arithmetic multiplication operations with simpler exclusive-OR (XOR) logic operations for cross-correlation in block boundary detection. Instead of using conventional multipliers and adders that demand billions of operations per second, the invention uses XOR gates to compute correlations between received signals and reference templates, dramatically reducing computational complexity while maintaining detection accuracy
Solution Approach 2:
The patent changes the operational parameters of the correlation computation by using quantized signal representations and XOR-based arithmetic instead of full-precision floating-point or fixed-point arithmetic. This parameter change allows the system to achieve the same block boundary detection function with significantly reduced computational requirements, making it suitable for implementation in cost-effective circuitry
2Measurement precision
If billions of arithmetic operations per second are performed for block boundary detection, then detection accuracy is maintained, but power consumption increases
Solution Approach 1:
The patent substitutes energy-intensive arithmetic multiplication and addition operations with low-power XOR logic operations. The XOR-based cross-correlation method maintains detection precision by accurately identifying block boundaries while consuming significantly less power, as logic XOR operations require far less energy than conventional arithmetic computations at high speeds
Solution Approach 2:
The patent employs simplified computational models that use quantized signal representations instead of full-precision data. By processing quantized versions of the received signals through XOR operations, the system achieves adequate detection accuracy with much lower power consumption, effectively using simplified computational 'objects' that consume less energy
Data Source
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AI summary
Method and apparatus for block boundary detection is described. A signal is received. The signal is quantized to provide a quantized signal to at least one correlator (310, 400, 500, 610) the quantized signal being a sequence of samples. The sequence of samples and a reference template including totaling partial results from the at least one correlator (310, 400, 500, 610) are cross-correlated to provide a result, the result being a symbol timing synchronization responsive to the cross-correlation also known as block boundary detection. The cross-correlation is provided in part by combining by exclusive-ORing a regression vector obtained from the sequence of samples and a coefficient term vector obtained from the reference template.