Synchronization Signal Symmetric Mapping for Offset Robustness
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Solution Overview
Problem
In wireless communication systems, especially in 4G and 5G networks, the synchronization estimation performance is deteriorated due to high frequency offsets and terminal movement, leading to inter-channel interference and complex operations for synchronization signal processing.
Innovation Solution
The method involves generating a synchronization signal with a base sequence and its modified version, symmetrically mapped around a center subcarrier, and using an exclusive-OR operation between different binary sequences for the secondary synchronization signal, to enhance synchronization and cell ID estimation efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional synchronization signal methods are used, then the system can operate with simple structure, but synchronization estimation performance deteriorates under high frequency offsets and terminal movement
Solution Approach 1:
The synchronization signal is segmented into multiple sequences with different cyclic shifts. Each sequence is designed to handle specific frequency offset ranges, allowing the system to maintain reliable synchronization estimation even under high frequency offsets and terminal movement conditions without requiring overly complex processing for the entire signal range.
Solution Approach 2:
The patent changes key parameters of the synchronization signal including cyclic shift values, root indices, and sequence lengths. These parameter variations create multiple signal versions that are robust against different frequency offset conditions, improving synchronization performance while maintaining manageable processing complexity through systematic parameter selection.
2Reliability
If the base sequence and modified sequence are symmetrically mapped around the center subcarrier, then frequency offset robustness is improved, but the mapping complexity increases
Solution Approach 1:
While the overall mapping strategy uses symmetry around the center subcarrier for robustness, the patent introduces controlled asymmetry in the sequence design and cyclic shift patterns. This allows the system to achieve frequency offset robustness through symmetric mapping while managing complexity through asymmetric sequence properties that simplify correlation operations.
Solution Approach 2:
The symmetric mapping around the center subcarrier creates equipotential conditions in the frequency domain, where all frequency offsets are handled equally well. This approach improves frequency offset robustness by ensuring uniform performance across different offset conditions without requiring complex adaptive mapping strategies.
3Speed
If inter-channel interference occurs due to high carrier frequency offset, then terminal mobility is enabled, but synchronization estimation accuracy deteriorates
Solution Approach 1:
The patent converts the harmful effect of inter-channel interference caused by high carrier frequency offset into a beneficial feature. By designing sequences with specific cyclic shifts and orthogonality properties, the system allows terminals to move at high speeds while the interference patterns themselves become distinguishable, enabling accurate synchronization estimation even in the presence of ICI through correlation-based detection.
Data Source
AI summary
Disclosed are a method and an apparatus for transmitting and receiving a synchronization signal in a communication system. According to an exemplary embodiment of the present disclosure, a method of transmitting a first synchronization signal, performed by a base station in the communication system, may comprise generating a base sequence; generating a modified sequence by inverting polarity of the base sequence; mapping the base sequence and the modified sequence to a first frequency region having a frequency higher than a center subcarrier and a second frequency region having a frequency lower the center subcarrier, so that the base sequence and the modified sequence are symmetric centering the center subcarrier located at a center frequency of a frequency domain of the synchronization signal; and transmitting the synchronization signal comprising the base sequence and the modified sequence to a terminal. Therefore, performance of the communication system can be improved.