WTSN Frame Structure Reducing Preamble Overhead for Short Periodicity
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Solution Overview
Problem
In industrial wireless communication systems, existing WiFi-based technologies face challenges in efficiently transmitting small amounts of data at very short periodicities due to the overhead of preambles, which is inadequate for real-time closed-loop controls in industrial automation and robot controls, such as ensuring deterministic data transmission/reception opportunities for multiple terminals within a short period.
Innovation Solution
The proposed solution involves a frame structure and synchronization method for Wireless Time Sensitive Networking (WTSN) that includes a reduced preamble and compensation indication information in the downlink frame, allowing terminals to perform pre-compensation for transmission power, timing, and frequency offsets, enabling efficient data transmission without the conventional preamble, and supporting multiple terminals at short periodicities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional preamble is used for data transmission in WiFi-based communication, then carrier frequency error and symbol timing error can be extracted and compensated, but data transmission efficiency is lowered when the data size is smaller than the preamble size
Solution Approach 1:
The patent extracts only the essential synchronization functions from the conventional preamble structure. Instead of using the full preamble for every transmission, the system uses a simplified preamble format that contains only the minimum necessary training fields for frequency and timing synchronization, separating these synchronization functions from the data transmission path.
Solution Approach 2:
The system performs frequency offset estimation and compensation in advance using the extracted preamble information before actual data transmission begins. This preliminary synchronization action allows the main data payload to be transmitted without the overhead of carrying the full preamble structure.
2Measurement precision
If a conventional preamble is used for data transmission, then symbol timing error can be compensated, but the short periodicity requirement (e.g., 125 us) for closed-loop control cannot be satisfied due to preamble transmission time
Solution Approach 1:
The patent extracts only the essential timing synchronization function from the conventional preamble. The simplified preamble structure contains minimal training fields sufficient for timing offset estimation, allowing the synchronization to be completed much faster than with full preambles, thus meeting the 125 us periodicity requirement.
Solution Approach 2:
The system changes the temporal parameters of the preamble structure by reducing its duration and optimizing the training field configuration. This parameter optimization allows timing synchronization to be achieved within the constrained 125 us period required for industrial closed-loop control applications.
3Productivity
If a reduced preamble structure is used to improve transmission efficiency, then data transmission efficiency increases, but the capability to estimate channel information may be insufficient
Solution Approach 1:
The system performs channel estimation and compensation in advance using the reduced preamble structure. By estimating frequency offset and channel characteristics before data transmission and applying pre-compensation, the system maintains accurate channel information extraction despite the reduced preamble size.
Solution Approach 2:
The system uses feedback mechanisms where the access point estimates channel information from the reduced preamble, generates compensation indication information, and transmits it back to the terminal. This feedback loop ensures that channel estimation accuracy is maintained even with the simplified preamble structure.
Data Source
AI summary
An operation method of an access point (AP) and a terminal, in a wireless time sensitive network (WTSN), may comprise: receiving, by an AP, an uplink frame from a first terminal; generating compensation indication information for compensation to be performed in the first terminal according to channel information between the first terminal and the AP estimated based on the uplink frame; transmitting the compensation indication information to the first terminal through a downlink frame; and performing, by the first terminal, the compensation based on the compensation indication message transmitted through the downlink frame.