Single OFDM Symbol Preamble for Low Latency Wireless Packet Detection
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Solution Overview
Problem
Current industrial wireless standards, such as IEEE 802.11g, suffer from high latency due to long preamble sequences required for packet detection and timing synchronization, which is inefficient for short packet sizes in power grid control applications, limiting achievable latency and reliability in wireless communication networks.
Innovation Solution
A method and packet receiver that utilize a single OFDM symbol preamble and a packet detection window for efficient packet detection and timing synchronization, reducing preamble duration and enabling low latency communications by performing packet detection only on samples received within the window.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If long preamble sequences are used for packet detection and timing synchronization, then reliability of message delivery is improved, but transmission time increases
Solution Approach 1:
The patent extracts and separates the packet detection function from the timing synchronization function. Instead of using a single long preamble for both purposes, the invention uses a short preamble solely for packet detection, and employs correlation of repeated packet portions (after detection) for timing synchronization. This extraction allows the system to achieve reliable message delivery without the time penalty of a long preamble.
Solution Approach 2:
The patent segments the traditional unified preamble function into two distinct phases: (1) packet detection using a short initial preamble, and (2) timing synchronization using correlation of repeated portions of the packet that follow detection. This segmentation resolves the contradiction by allowing each function to be optimized independently - the short preamble minimizes detection time while the post-detection correlation ensures precise synchronization.
2Reliability
If long preamble sequences are used for packet detection and timing synchronization, then robust packet detection is achieved, but latency increases
Solution Approach 1:
The invention extracts the packet detection function from the timing synchronization function, using a short preamble exclusively for detection. This extraction enables robust packet detection to be achieved with minimal latency, as the short preamble provides sufficient signal for reliable detection without the time overhead of longer sequences designed for both detection and synchronization.
Solution Approach 2:
The patent performs packet detection as a preliminary action using a short preamble before proceeding to timing synchronization. By detecting the packet presence first with minimal time investment, the system can then apply correlation-based synchronization only to the repeated portions that follow, thereby achieving robust detection while minimizing overall latency.
3Measurement precision
If long repeated sequences are used in packet preamble for correlation-based synchronization, then precise sample-level synchronization is achieved, but device complexity increases
Solution Approach 1:
The patent segments the synchronization process into two stages: (1) coarse packet detection using a short preamble, and (2) fine sample-level synchronization using correlation of repeated portions that occur after the short preamble. This segmentation allows precise sample-level synchronization to be achieved without requiring a complex long preamble structure, as the correlation is applied to packet content that naturally contains repeated sequences.
Solution Approach 2:
Instead of embedding all synchronization functionality in the preamble, the patent applies correlation-based synchronization partially - only to the repeated portions of the packet that follow the short preamble. This partial action approach achieves precise sample-level synchronization while keeping the preamble structure simple and minimal.
Data Source
AI summary
A method for packet detection in a wireless communication network employing time based scheduling of packets. The method is performed by a packet receiver in the wireless communication network. The method includes receiving a packet from a packet transmitter. The packet includes a preamble that is composed of a single orthogonal frequency-division multiplexing (OFDM) symbol and represented by a sequence of samples. T least part of the preamble is received within a packet detection window. Packet detection is performed in order to find a start of the packet only on those samples received within the packet detection window.