WLAN Timeslot Synchronization for Deterministic TDMA Access
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Solution Overview
Problem
Current wireless LAN systems face challenges in meeting the network delay performance requirements of time-sensitive networks due to contention-based channel access, leading to variable data transmission times and potential transmission failures, which are not suitable for industrial applications.
Innovation Solution
Implementing a method and apparatus for synchronizing timeslots in a wireless LAN system using a time synchronization function (TSF) value to enable time-division multiple access (TDMA) communication, allowing for efficient timeslot synchronization across multiple links.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If contention-based channel access (CSMA/CA) is used in wireless LAN, then all communication nodes can share the wireless channel equally, but data transmission time becomes variable and network delay performance deteriorates
Solution Approach 1:
The patent changes the fundamental parameter of channel access mechanism from contention-based (CSMA/CA) to schedule-based (TDMA). By introducing a deterministic time slot structure where each node is assigned specific transmission time slots, the system transforms random access into scheduled access, eliminating transmission time variability while maintaining fair channel sharing through systematic time allocation
Solution Approach 2:
The patent implements periodic time slot allocation where communication nodes transmit data at predetermined intervals rather than contending for channel access continuously. The medium access controller schedules transmissions in periodic cycles, with each node having designated time slots within each cycle, creating a rhythmic and predictable transmission pattern that eliminates random access delays
2Reliability
If random back-off counter is used for channel access, then collision avoidance is achieved, but transmission delay becomes unpredictable and cannot be known in advance
Solution Approach 1:
The patent performs preliminary scheduling of transmission time slots before actual data transmission occurs. The medium access controller pre-calculates and assigns specific time slots to each communication node based on their transmission requirements, allowing the system to know in advance when each node will transmit without relying on random back-off counters during the actual transmission process
Solution Approach 2:
The patent introduces a medium access controller as an intermediary between the communication nodes and the wireless channel. This controller acts as a central coordinator that manages channel access by assigning time slots to nodes, replacing the distributed random back-off mechanism with a centralized scheduling approach that provides deterministic delay while maintaining collision-free transmission
3Reliability
If channel access is granted to one node at a time, then collision is avoided, but other nodes must wait and channel utilization efficiency decreases
Solution Approach 1:
The patent segments the channel access time into distinct time slots, allowing multiple nodes to transmit simultaneously in different segments of time rather than one node monopolizing the entire channel. By dividing the transmission medium into time-divided segments assigned to different nodes, the system achieves both collision-free transmission and improved channel utilization through parallel transmission opportunities
Data Source
AI summary
Disclosed herein is a method and apparatus for synchronizing timeslots in a wireless LAN system. The timeslot synchronization method includes: setting, by a first node, a timeslot synchronization reference based on a time synchronization function (TSF) value, followed by transmitting information about a reference of synchronization to a second node; and setting, by the second node, a timeslot synchronization reference based on a TSF value corresponding to the reference of synchronization based on the information transmitted from the first node.