Access Point Polling for Deterministic WLAN Client Communication
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Solution Overview
Problem
Mainstream WLAN technology struggles to meet the low delay and low jitter requirements of industrial communication due to the CSMA/CA mechanism, leading to indeterminate channel access and limited support for a large number of clients without hardware customization.
Innovation Solution
Implementing a broadcast/multicast IPCF mechanism where an access point sends a polling request message simultaneously to multiple clients, allowing them to send polling responses within predefined time windows, reducing channel access contention and jitter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If CSMA/CA mechanism is used for WLAN communication, then channel access is distributed and simple to implement, but channel access delay varies greatly and determinate communication cannot be provided
Solution Approach 1:
The patent implements periodic polling cycles where the access point sequentially polls each client in the service set. Each polling cycle includes a polling request from the access point and a polling response from the client, creating regular periodic intervals for channel access that eliminate random contention delays while maintaining system simplicity
Solution Approach 2:
The patent establishes a feedback mechanism where clients send polling response messages to confirm receipt and status to the access point. The access point uses this feedback to track which clients have been served and manages the polling sequence, enabling deterministic communication while keeping the access mechanism straightforward
2Quantity of substance
If more clients are connected to the same WLAN channel, then network coverage and connectivity are improved, but channel access contention time increases and jitter increases
Solution Approach 1:
The patent segments the channel access process by creating separate polling slots for each client within a service set. Instead of allowing all clients to contend simultaneously for channel access, the access point divides access opportunities into distinct time slots assigned to individual clients through sequential polling, eliminating contention even as client numbers increase
Solution Approach 2:
The patent implements periodic polling cycles where the access point sequentially polls each client in the service set. Each polling cycle includes a polling request from the access point and a polling response from the client, creating regular periodic intervals for channel access that eliminate random contention delays while maintaining system simplicity
3Loss of time
If sequential polling is used to reduce contention, then channel access delay is reduced, but support for large number of clients is limited
Solution Approach 1:
The patent merges multiple client polling operations into a unified service set managed by a single access point. By combining the polling requests and responses of multiple clients into coordinated sequential operations under one access point's control, the system reduces overall channel access delay while supporting a large number of clients through efficient resource management
Data Source
AI summary
Various embodiments of the teachings herein include WLAN communication methods. An example includes: sending a polling request message from an access point simultaneously to a client among clients associated therewith; receiving a polling response message sent by the one or more client to the access point; upon receiving each polling response message, sending an ACK acknowledgement message to the corresponding client from the access point; and when the access point has received the polling response messages of all of the clients or a preset latest response time of the last client is reached, repeating the above operations, starting with sending a polling request message to a client.