Primary Synchronization Signal Generation Using CAZAC Sequences
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Solution Overview
Problem
Current wireless communication systems face challenges in efficiently generating and detecting primary synchronization signals due to high computational complexity and peak-to-average power ratio (PAPR) issues in next-generation wireless networks, particularly in OFDM-based systems operating at high frequencies.
Innovation Solution
The technique involves generating binary sequences using maximum run length sequences (m-sequences) with discrete Fourier transform (DFT) precoding, which are then modulated using BPSK or QBPSK and mapped to frequency subcarriers, allowing for simpler detection algorithms and reduced PAPR through cyclic extension, padding, or truncation, and cyclic shift mapping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional synchronization signal generation methods are used in OFDM-based systems, then the signals can be transmitted, but the computational complexity of signal detection and the peak-to-average power ratio (PAPR) become excessively high
Solution Approach 1:
The patent changes the fundamental parameters of the synchronization signal by using constant amplitude zero autocorrelation (CAZAC) sequences instead of conventional sequences. This parameter change maintains detection reliability while reducing PAPR and computational complexity, as the special mathematical properties of CAZAC sequences enable simpler detection algorithms
Solution Approach 2:
The patent uses cyclic shifts of the base CAZAC sequence to generate multiple synchronization signal sequences. Instead of creating entirely new complex sequences, the system copies and transforms the base sequence through cyclic shifting, which preserves the favorable correlation properties while reducing the computational burden of generating and detecting multiple independent sequences
2Reliability
If conventional synchronization signal generation methods are used in OFDM-based systems, then the signals can be transmitted, but the peak-to-average power ratio (PAPR) becomes excessively high
Solution Approach 1:
The patent fundamentally changes the signal parameter by adopting CAZAC sequences with constant amplitude properties. This parameter change directly addresses the PAPR issue by ensuring the signal maintains constant amplitude, thereby eliminating peak power variations and reducing the harmful effects of high PAPR in power amplifier operation
Solution Approach 2:
The patent converts the mathematical structure of CAZAC sequences into a benefit by exploiting their constant amplitude property. What might appear as a restrictive constraint (constant amplitude) actually becomes advantageous by naturally reducing PAPR, turning a potential limitation into a solution for the high PAPR problem
3Measurement precision
If complex detection algorithms are used to maintain detection reliability, then synchronization accuracy is improved, but the computational complexity increases
Solution Approach 1:
The patent changes the signal structure to CAZAC sequences which possess optimal autocorrelation properties. This parameter change enables the use of simpler detection algorithms that exploit these properties, achieving high synchronization accuracy without requiring computationally intensive processing
Solution Approach 2:
The CAZAC sequences are designed to be self-detectable through their inherent mathematical properties. The sequences possess autocorrelation characteristics that allow the receiver to detect synchronization signals through simple correlation operations, making the signal itself serve the detection function without requiring complex external processing
Data Source
AI summary
Technology for a Next Generation NodeB (gNB) operable to encode a primary synchronization signal for transmission to a user equipment (UE) is disclosed. The gNB can identify a sequence d(n) for a primary synchronization signal. The sequence d(n) can be defined by: d(n)=1−2s(n), where s(n) is a maximum run length sequence (m-sequence) and s(n) is provided as s(n+7)=(s(n+4)+s(n))mod 2, where 0≤n≤127. The gNB can generate the primary synchronization signal based on the sequence d(n). The gNB can encode the primary synchronization signal for transmission to the UE.