Synchronization Signal Sequence Design for 5G Cell Identification
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Solution Overview
Problem
Current wireless communication systems, particularly 5G NR, face challenges in cell identification due to low reliability in channel estimation and high estimation complexity, leading to performance degradation in non-coherent detection methods, especially in frequency-selective radio channels and hardware impairment conditions.
Innovation Solution
A method involving the generation of intermediate base sequences through element-wise modulo-2 sum operations and binary phase shift keying (BPSK) operations, followed by distributed concatenation and modulation onto multiple subcarriers, to enhance cell identification accuracy and increase the number of distinguishable physical cell identities (PCIs) using the same frequency resource as NR communication systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If non-coherent detection methods are used for PCI estimation, then estimation complexity is reduced, but detection reliability deteriorates due to phase changes in frequency-selective channels
Solution Approach 1:
The patent changes the fundamental parameter of the synchronization signal by constructing it from multiple orthogonal sequences (first, second, and third sequences) with different lengths (63, 63, and 7 elements) rather than using a single sequence. This parameter change enables the system to maintain high detection reliability in frequency-selective channels while preserving the simplicity of non-coherent detection methods, as the multiple sequences provide sufficient correlation characteristics for accurate PCI estimation without requiring complex channel estimation procedures.
2Device complexity
If a single synchronization signal sequence is used, then signal structure is simple, but the number of distinguishable physical cell identities is limited
Solution Approach 1:
The patent merges multiple orthogonal sequences (first sequence of length 63, second sequence of length 63, and third sequence of length 7) into a single synchronization signal structure through distributed concatenation. This combining approach allows the system to represent a significantly larger number of physical cell identities while maintaining relatively simple signal structure, as the sequences are integrated in a systematic manner that preserves orthogonality and correlation properties necessary for PCI detection.
Solution Approach 2:
The synchronization signal is segmented into multiple orthogonal sequences with different lengths, where the first and second sequences have length 63 and the third sequence has length 7. This segmentation allows the system to encode additional information about physical cell identities through the combination and arrangement of these segments, thereby increasing the number of distinguishable PCIs without proportionally increasing the overall signal complexity.
3Adaptability or versatility
If conventional synchronization signals are used, then compatibility with existing NR systems is maintained, but detection error rate increases in frequency-selective channels
Solution Approach 1:
The patent creates a composite synchronization signal structure by combining multiple orthogonal sequences (first, second, and third sequences) with different lengths and correlation characteristics. This composite approach maintains compatibility with existing NR system frameworks while significantly improving detection accuracy in frequency-selective channels, as the multiple sequences work together to provide robust correlation characteristics that are less susceptible to phase changes and channel effects compared to conventional single-sequence signals.
Data Source
AI summary
A method of a first communication node may comprise: generating a first intermediate base sequence consisting of M elements based on first, second and third binary sequences, wherein M is a natural number; generating a second intermediate base sequence consisting of M elements by modifying the first intermediate base sequence; generating a base sequence consisting of 2M elements based on distributed concatenation of the first intermediate base sequence and the second intermediate base sequence; mapping modulation symbols generated by modulating the base sequence to 2 (M+1) subcarriers; and transmitting a signal consisting of the mapped modulation symbols to a second communication node.