NB-IoT Synchronization Sequence Pairs for Frequency Offset Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In narrowband IoT (NB-IoT) systems, the large crystal oscillator error leads to significant carrier frequency offsets, degrading the correlation characteristic of synchronization sequences, which can result in the disappearance of correlation peaks during correlation processing, making it difficult for terminal devices to determine timing positions accurately.
Innovation Solution
A signal sending method that generates a first signal with sequence pairs, where each pair consists of two sequences with element values calculated based on a specific calculation rule, ensuring strong correlation and resistance to frequency offsets, allowing terminal devices to eliminate the impact of channel noise and carrier frequency offsets, thereby improving anti-frequency offset performance and retaining the autocorrelation characteristic.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a ZC sequence from LTE is directly used in NB-IoT system, then the sequence design is simple and easy to implement, but the anti-frequency offset performance is poor and correlation peak disappears under frequency offset
Solution Approach 1:
The patent divides the synchronization signal into multiple sequence pairs, where each sequence pair consists of two sequences that are correlated with each other. This segmentation allows the receiver to process multiple sequence pairs and identify the correct timing position even when frequency offset causes phase rotation, thereby improving anti-frequency offset performance while maintaining implementation simplicity.
Solution Approach 2:
The patent introduces a correlation sequence as an intermediary element. The correlation sequence is generated by correlating two sequences in a sequence pair, and this correlation sequence serves as a mediator to eliminate the impact of frequency offset. The correlation sequence retains the autocorrelation characteristic even when frequency offset is present, enabling accurate timing position determination.
2Measurement precision
If frequency offset compensation is performed to maintain correlation characteristic, then timing position determination accuracy is improved, but the system complexity increases
Solution Approach 1:
The patent employs self-service by utilizing the inherent correlation property of the sequence pairs. The receiver automatically generates correlation sequences by correlating the received sequence pairs, and this process self-compensates for frequency offset effects. The correlation sequence naturally retains the autocorrelation characteristic without requiring external frequency offset compensation mechanisms, thereby improving timing accuracy while avoiding additional system complexity.
Data Source
AI summary
Embodiments of the present invention disclose a signal sending method and apparatus and a signal receiving method and apparatus. The signal sending method includes: generating, by a network device, a first signal, where the first signal includes at least one sequence pair, each of the at least one sequence pair includes two sequences, and an element value of one sequence of the two sequences is a value obtained by calculating, according to a first calculation rule, an element value of the other sequence of the two sequences and an element value of a first sequence corresponding to the other sequence, where each sequence in the at least one sequence pair and the first sequence are complex sequences with lengths greater than 1; and sending, by the network device, the first signal to a terminal device.