Synchronization Signal Sequence Generation for Dense Small Cell Deployments
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Solution Overview
Problem
Current synchronization signal designs for 5G wireless communication systems face challenges in supporting a large number of cell IDs, especially with dense small cell deployments, due to limited cross-correlation performance of short-length sequences and interference issues in high-frequency bands, which affect channel estimation and cell detection accuracy.
Innovation Solution
The method involves generating synchronization signal sequences through element-wise multiplication of cyclically shifted base sequences, allowing for the creation of a large number of sequences with enhanced cross-correlation performance, supporting multi-antenna port transmission, and enabling cell detection via interleaving or concatenation of sequences, thereby improving timing and frequency synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If short-length Zadoff-Chu sequences are used for synchronization signals, then the sequence length is reduced and transmission is simplified, but the number of sequences with good cross-correlation is limited and cell ID hypotheses cannot be sufficiently supported
Solution Approach 1:
The synchronization signal sequence is segmented into multiple parts: a base sequence (e.g., Zadoff-Chu sequence) is cyclically shifted to generate multiple distinct sequences. Each cyclic shift produces a new sequence with maintained correlation properties, enabling support for many cell ID hypotheses (e.g., 1000+) while using a relatively short base sequence length.
Solution Approach 2:
The patent changes the parameter of cyclic shift value to generate multiple sequences from a single base sequence. By varying the cyclic shift parameter, the system creates a large number of sequences with good cross-correlation properties without increasing the fundamental sequence length, thus supporting dense small cell deployments.
2Power
If power boosting is applied to synchronization signal transmission, then transmission power is increased, but SS SINR observed at UE receiver does not improve
Solution Approach 1:
The patent extracts and addresses the root cause of poor SINR: co-channel interference from dense cell deployments. Instead of simply boosting power, the solution uses specially designed sequences with optimized correlation properties that inherently reject interference, allowing UEs to distinguish desired signals from interfering signals even at lower power levels.
Solution Approach 2:
The patent changes the sequence design parameters (using specific base sequences and cyclic shifts) to improve signal distinguishability. This parameter optimization allows the system to achieve better SINR without relying solely on power boosting, as the sequences are designed to minimize interference from neighboring cells.
3Productivity
If dense small cell deployment is implemented, then system capacity is increased, but the number of cell ID hypotheses must be increased and cell ID confusion occurs
Solution Approach 1:
The patent segments the cell ID space by using different base sequences and cyclic shifts to uniquely identify different cells. This segmentation approach allows the system to support a large number of cell ID hypotheses (e.g., 1000+) without confusion, as each cell can be assigned a unique sequence identity derived from the segmented structure.
Solution Approach 2:
The patent uses parameter changes in cyclic shift values to create unique sequence identities for different cells. By systematically varying the cyclic shift parameter across cells, the network can support dense deployments with many cell IDs while maintaining clear distinction between cells, preventing cell ID confusion.
4Reliability
If Cyclic Prefix overhead is increased to avoid inter-symbol interference, then timing synchronization margin is improved, but transmission efficiency is reduced
Solution Approach 1:
The patent optimizes the Cyclic Prefix length parameter based on channel conditions. By carefully selecting the CP length parameter, the system achieves sufficient timing synchronization margin to prevent inter-symbol interference while minimizing the overhead proportion, thus maintaining transmission efficiency in dense small cell environments with varying delay spreads.
Data Source
AI summary
A first Synchronization Signal (SS) associated with a first identifier and a second SS associated with a second identifier can be stored. A first SS sequence can be defined by at least an element-wise multiplication of a first sequence with a second sequence. The first sequence can be a first base sequence cyclically shifted with a first cyclic shift value and the second sequence is a second base sequence cyclically shifted with a second cyclic shift value. A second SS sequence can be defined by at least an element-wise multiplication of a third sequence with a fourth sequence. The third sequence can be the first base sequence cyclically shifted with a third cyclic shift value and the fourth sequence is the second base sequence cyclically shifted with a fourth cyclic shift value. The first SS associated with the first identifier and the second SS associated with the second identifier can be output.