Multi-AP TDMA Access Method for Industrial Wireless Reliability
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Solution Overview
Problem
Factory automation wireless networks using TDMA face challenges in reliability and resource utilization due to electromagnetic interference and the limitations of single access point star network topologies, which are inadequate for large-scale, high-speed, and real-time communication demands.
Innovation Solution
A TDMA access method and device utilizing multiple access points, where APs are grouped to cover the entire network, with beacon frames for time synchronization and ACK replies based on communication link quality, ensuring data reliability and resource efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single AP star network topology is used, then the network structure is simple and easy to manage, but the network reliability deteriorates because once a single AP is broken, the network collapses
Solution Approach 1:
The patent divides the single AP into multiple APs (AP1, AP2, AP3, etc.), segmenting the network into multiple access points that can independently operate. This segmentation allows the network to continue functioning even if one AP fails, thus improving reliability while maintaining manageable complexity through modular deployment
Solution Approach 2:
The patent changes the network topology parameter from a single-point star structure to a multi-point distributed structure. By introducing multiple APs with different coverage areas and introducing mobility parameters for both APs and STA, the system achieves enhanced reliability without excessive complexity
2Reliability
If pre-assigning a fixed number of retransmission time slots is used, then the end-to-end reliability requirement is satisfied, but the resource utilization rate deteriorates because most retransmission time slots cannot be utilized
Solution Approach 1:
The patent introduces dynamic time slot allocation where the number of retransmission slots is not fixed but adapts based on actual communication conditions. Multiple APs can dynamically assign different time slots (TS1, TS2, TS3, etc.) based on channel quality, traffic load, and interference conditions, allowing the system to maintain reliability while minimizing wasted resources
Solution Approach 2:
The system implements feedback mechanisms where APs monitor transmission success rates and channel conditions, then adjust retransmission slot allocation accordingly. This feedback-driven dynamic allocation ensures reliability requirements are met while avoiding the waste of pre-allocated but unused time slots
3Reliability
If multiple APs are distributed in the network, then the network reliability and coverage are improved, but the device complexity increases due to coordination and time synchronization requirements
Solution Approach 1:
The patent implements periodic super-frame structures with designated beacon transmission times for each AP. This periodic organization creates predictable patterns in the multi-AP system, making synchronization and coordination more manageable despite the increased number of access points
Solution Approach 2:
The patent introduces a gateway as an intermediary that coordinates between multiple APs and the upper network layers. The gateway manages the complexity of multi-AP coordination, handling tasks such as centralized scheduling, interference management, and resource allocation, thereby isolating the complexity from individual APs and STAs
4Device complexity
If a single AP serves the entire network, then the device complexity is low, but the network capacity deteriorates making it a bottleneck for large-scale networks
Solution Approach 1:
The patent segments the single AP into multiple APs, each capable of serving different spatial regions and different groups of STAs. This segmentation directly increases the network's node capacity by distributing the access load across multiple access points while keeping each individual AP relatively simple
Solution Approach 2:
The patent transitions from a single-dimensional (single AP) to a multi-dimensional (multiple APs in space) architecture. By adding the spatial dimension with multiple distributed APs, the network capacity scales up to support hundreds or thousands of nodes while maintaining manageable device complexity through standardized AP designs
Data Source
AI summary
The present invention relates to a TDMA access method and device based on multiple access points. According to the problems that the existing method cannot simultaneously satisfy the demands of timeliness and reliability in actual industrial application and has low resource utilization rate, the present invention takes full consideration of the transmission characteristics and industrial automation application characteristics of wireless networks, and provides a TDMA access method and device based on multiple access points. The main ideas of the method in the present invention are: the multi-access point redundant communication manner is adopted to improve system reliability, beacon frames of multiple access points are utilized to perform time synchronization so as to improve synchronization precision, confirmation messages are fed back with regard to reliable access points to reduce the number of retransmissions, and a modularized multi-access point device design method is adopted to lower the difficulties of device maintenance and management.