Wireless Preamble Sequence Design for Time-Frequency Synchronization
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Solution Overview
Problem
Conventional wireless communication preambles face challenges in enhancing automatic gain control, signal detection, and time and frequency synchronization performances, leading to increased complexity and peak-to-average-power ratio (PAPR), and constraints on synchronization estimation performance.
Innovation Solution
A method and apparatus for generating a frame that includes a modified sequence using a first base sequence for synchronization estimation, assigning it and its complex conjugate or sign-different sequence to the frequency domain, and incorporating a TD sequence for automatic gain control and signal detection, along with NRP/RP sequences for robust synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional IEEE preamble structure with two OFDM symbols and repetition pattern sequences is used, then the basic synchronization function is provided, but the automatic gain control, signal detection, and synchronization estimation performances are insufficient
Solution Approach 1:
The preamble is divided into multiple OFDM symbols (first, second, and third symbols) with distinct functions. The first symbol contains the base sequence for synchronization estimation, the second symbol contains the complex conjugate sequence for enhanced correlation, and the third symbol provides additional synchronization information. This segmentation allows each part to be optimized for specific purposes, improving overall synchronization performance while maintaining manageable complexity.
Solution Approach 2:
The preamble structure combines multiple sequence types (base sequence, complex conjugate sequence, and their combinations) within a unified framework. By composite these different sequence elements with complementary properties, the invention achieves enhanced automatic gain control, signal detection, and synchronization estimation performances that exceed what any single sequence type could provide alone.
2Reliability
If the preamble uses complex conjugate sequences and multiple OFDM symbols, then synchronization performance is improved, but the peak-to-average-power ratio increases
Solution Approach 1:
The invention employs dynamic sequence selection where the second OFDM symbol uses the complex conjugate of the base sequence from the first symbol. This dynamic relationship between symbols allows the system to adapt the preamble structure for optimal correlation properties while controlling the peak-to-average-power ratio through the mathematical properties of complex conjugation.
Solution Approach 2:
By changing the parameter of the sequence from the base sequence to its complex conjugate in the second symbol, the invention modifies the correlation properties without fundamentally changing the overall energy distribution. This parameter change enables improved synchronization robustness while maintaining acceptable peak-to-average-power ratio characteristics.
3Ease of manufacture
If a single base sequence is used for synchronization, then the preamble structure is simple, but the automatic gain control and signal detection performances are limited
Solution Approach 1:
The invention creates a copy of the base sequence in the second OFDM symbol but transforms it into its complex conjugate form. This copying approach with transformation maintains the simplicity of generation (since it's derived from the same base sequence) while significantly improving signal detection performance through the enhanced correlation properties of the complex conjugate relationship.
Data Source
AI summary
Disclosed is a technique related to a method and apparatus for generating a preamble and a data frame for wireless communication, and to a synchronization estimation method using the preamble. According to the technique, a method for generating a frame for wireless communication is disclosed, wherein the method comprises: a step of generating a modified sequence using a first base sequence for synchronization estimation; and a step of allocating the first base sequence and the modified sequence to the frequency domain of a first timeslot to generate a preamble. The modified sequence includes a complex conjugated sequence of the first base sequence or a sequence having a code different from that of the first base sequence.