M-Sequence Secondary Synchronization Signal Generation and Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current wireless communication systems face inefficiencies in generating and detecting synchronization signals, particularly in multiple-access systems like CDMA, TDMA, FDMA, OFDMA, and SC-FDMA, where UEs need to quickly and accurately identify base stations, which is challenging due to the overhead and complexity of synchronization signals.
Innovation Solution
The generation of a secondary synchronization signal based on maximum length sequences (M-sequences) with specific cyclic shifts, combined and scrambled to optimize detection performance, allowing UEs to efficiently identify cells and obtain timing information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional synchronization signals are used, then base stations can transmit synchronization information, but UE detection performance is poor and cell search is inefficient
Solution Approach 1:
The patent changes the fundamental parameters of synchronization signals by using M-sequences with specific auto-correlation and cross-correlation properties. The signal structure is modified to include maximum length sequences with length 2^m-1, where m≥3, and cyclic shifts are applied to create distinguishable signals for different cells. This parameter change enables both high detection precision and efficient cell search.
Solution Approach 2:
The patent creates composite synchronization signals by combining M-sequences with different cyclic shifts and applying scrambling sequences. The composite signal structure includes the base M-sequence, cyclically shifted versions, and scrambling sequences, which together provide both good correlation properties for detection and sufficient diversity for efficient cell search.
2Loss of information
If synchronization signals are transmitted with high overhead, then more information can be conveyed, but transmission efficiency decreases
Solution Approach 1:
The patent segments the synchronization information by using different cyclic shifts of the M-sequence to represent different cell identities. Instead of transmitting all information explicitly, the system divides the information into parts encoded in the sequence structure (cyclic shifts) and parts transmitted through the signal content, reducing overall overhead while maintaining full information conveyance.
Solution Approach 2:
The M-sequence-based synchronization signal serves multiple functions simultaneously: it provides timing synchronization, frequency synchronization, cell identification, and channel estimation. This multi-functionality reduces the need for separate signals for each purpose, thereby reducing overall overhead and improving transmission efficiency.
3Measurement precision
If complex synchronization signal structures are used, then detection accuracy improves, but system complexity increases
Solution Approach 1:
The M-sequences have inherent self-correlation properties that enable automatic detection and synchronization. The auto-correlation peak provides automatic timing alignment, and the cross-correlation properties enable automatic cell identification. This self-service capability reduces the complexity of detection algorithms while maintaining high detection accuracy.
Solution Approach 2:
The patent replaces complex mechanical signal processing systems with mathematical sequence properties. Instead of using complex filtering and correlation hardware, the system utilizes the mathematical properties of M-sequences (auto-correlation and cross-correlation) to achieve detection, simplifying the overall system architecture while maintaining or improving detection accuracy.
4Loss of time
If synchronization signals are transmitted frequently, then UEs can quickly acquire timing information, but overhead increases
Solution Approach 1:
The patent applies preliminary action by pre-defining M-sequences with optimal correlation properties before transmission. The sequences are pre-processed with cyclic shifts and scrambling to encode cell information, so that upon reception, UEs can quickly decode timing and cell identity without requiring multiple transmissions or complex processing iterations, thus reducing both time and overhead.
Data Source
AI summary
Techniques for generating a synchronization signal (e.g., a secondary synchronization signal) based on an M-sequence are described. In one design, first and second sequences for a secondary synchronization signal may be generated based on different cyclic shifts of the M-sequence. The cyclic shifts may be determined based on cell ID and/or other information to send in the secondary synchronization signal. An output sequence may be generated based on the first and second sequences, e.g., by combining the first and second sequences and scrambling the combined first and second sequences with at least one scrambling sequence. The secondary synchronization signal may then be generated based on the output sequence, e.g., by mapping samples in the output sequence to subcarriers and generating an OFDM symbol with the mapped samples. Detection for the secondary synchronization signal may be efficiently performed using fast M-sequence transform (FMT).