Radio Cell Synchronization via Segmented Cross-Correlation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current radio communication cell synchronization methods in NB-IoT systems face challenges with high computational complexity and long synchronization times, especially in low SNR conditions, due to large memory allocation and sensitivity to noise, which affects battery life and power consumption.
Innovation Solution
A two-phase synchronization method involving symbol-length cross-correlations followed by segmented symbol-wise auto-correlations, with recursive calculations and weighted cost functions, is employed to quickly and accurately estimate coarse and fine synchronization points, reducing computational complexity and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If full-length cross-correlation method is used for synchronization, then detection accuracy is improved, but computational complexity and synchronization time increase significantly
Solution Approach 1:
The patent divides the synchronization signal into multiple segments and processes each segment separately through cross-correlation. Instead of performing one large full-length cross-correlation operation, the method segments the signal and performs multiple smaller correlations, reducing peak memory allocation and computational complexity while maintaining detection accuracy through coherent combination of segment results.
2Measurement precision
If full-length cross-correlation method is used for synchronization, then detection accuracy is improved, but synchronization time increases
Solution Approach 1:
By segmenting the correlation process, the patent enables parallel processing of multiple segments, significantly reducing the overall synchronization time. The segmented approach allows the UE to process smaller data blocks concurrently while maintaining the same detection accuracy as full-length cross-correlation, directly addressing the time complexity issue.
3Measurement precision
If UE keeps RF transceiver ON for long synchronization time, then synchronization accuracy is improved, but power consumption increases
Solution Approach 1:
The patent enables the synchronization process to be completed efficiently using self-contained segment processing that requires minimal RF-ON duration. By designing the correlation method to work effectively with segmented, shorter processing windows, the UE can achieve accurate synchronization while keeping the RF transceiver ON for minimal time, thereby reducing power consumption and extending battery life.
4Reliability
If large memory allocation is used for full-length cross-correlation, then synchronization performance is improved, but device resource requirements increase
Solution Approach 1:
The patent applies segmentation to divide the large memory allocation requirement into smaller, manageable segments. Each segment requires only a fraction of the total memory that would be needed for full-length cross-correlation, while the overall synchronization performance is maintained through coherent combination of segment correlation results. This directly reduces peak memory allocation requirements.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A system and method for cell synchronization suitable for a wireless signal including substantially identical synchronization signals that repeat in predetermined time intervals, the synchronization signals including a plurality of substantially identical symbols. For a plurality of candidate synchronization points: dividing the wireless signal into a plurality of signal segments, each equal or longer than the time interval, and each including a plurality of sub-segments having substantially same length as the symbol; performing symbol-length cross-correlations between an expected symbol and the sub-segments; performing segmented symbol-wise correlations between the cross-correlation results; calculating a cost function based on the results of the symbol-wise correlations; accumulating the cost functions across a plurality of signal segments; and selecting a coarse synchronization point from the plurality of candidate synchronization points based on the accumulated cost function; Estimating synchronization parameters e.g. time and frequency offset based on the selected synchronization point.