Sign-Based Synchronization Sequences Reduce OFDM Correlation Complexity
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Solution Overview
Problem
Current OFDM systems face complexity in correlation processes for synchronization, particularly in LTE/E-UTRA standards, due to the need for multi-bit correlation coefficients, which increases computational requirements and reduces efficiency in cell search and handover processes.
Innovation Solution
The use of sign-based synchronization sequences derived from Zadoff-Chu sequences, which eliminate the need for multiplication operations by utilizing only the signs of real and imaginary parts for correlation, transforming the process into a single-bit summation, thereby reducing correlation complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multi-bit correlation coefficients are used in the correlation process, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent extracts only the sign information (positive or negative) from the full multi-bit correlation coefficients, discarding the magnitude information. This extraction of essential sign data maintains sufficient detection accuracy for synchronization while dramatically reducing computational complexity by eliminating multiplication operations.
Solution Approach 2:
The patent replaces expensive multi-bit correlation calculations with inexpensive single-bit sign comparisons. The sign-based correlation uses only addition and comparison operations, which are computationally cheap and can be implemented efficiently in hardware, effectively substituting complex mathematical operations with simpler logical operations.
2Measurement precision
If multi-bit correlation coefficients are used in the correlation process, then measurement precision is improved, but productivity decreases
Solution Approach 1:
By extracting only the sign information from complete correlation coefficients, the patent enables faster processing that improves synchronization productivity. The sign-based approach allows parallel processing and simpler hardware implementation, significantly increasing the speed of cell search and handover operations while maintaining adequate detection precision.
Solution Approach 2:
The patent skips the computationally intensive multiplication and full coefficient calculation steps, rushing directly to sign-based comparison. This skipping of intermediate computational steps accelerates the correlation process, improving productivity in synchronization-critical operations where speed is essential.
3Device complexity
If sign-based synchronization sequences are used, then device complexity is reduced, but measurement precision may deteriorate
Solution Approach 1:
The patent creates a simplified copy of the correlation process that uses only sign information rather than full multi-bit coefficients. This sign-based copy maintains the essential correlation detection functionality while reducing complexity, effectively creating a lightweight version that suffices for synchronization applications where full precision is not critical.
Data Source
AI summary
A mobile device receives a signal, from a base station, comprising a primary synchronization signal (PSS) and a secondary synchronization signal (SSS). The received PSS and SSS are used to acquire cell-specific parameters so as to ensure communicates between the mobile device and the base station. The mobile device correlates the received signal in time domain using signs of each of a plurality of correlation reference sequences (reference PSSs). The mobile device generates sign based correlation reference PSSs using signs of the corresponding reference PSSs, which are generated based on a variety of Zadoff-Chu sequences. The received PSS is detected based on the correlation. No multiplication operations are used in the correlation process. Symbol timing is identified according to the detected PSS. The mobile device uses the identified symbol timing to baseband process the received signal. The received signal is an OFDM signal received over a 3GPP LTE/E-UTRA air interface.