WLAN Trigger Frame Padding for Receiver Processing Time
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Solution Overview
Problem
Wireless Local-Area Network (WLAN) communication systems face challenges in ensuring simultaneous uplink transmissions from multiple client stations due to varying processing times required by receivers, where insufficient padding in the Trigger frame can lead to failed transmissions, while excessive padding reduces bandwidth efficiency.
Innovation Solution
A WLAN Access Point (AP) with a Medium Access Control (MAC) processor and physical layer (PHY) processor generates a Trigger frame with padding bits, determining the required number based on the longest processing-time constraint from client stations, and encodes it using Error Correction Codes (ECC) to meet the processing-time requirements, ensuring efficient transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If padding bits are added to the Trigger frame to meet minimum processing time requirement, then receiver processing time is improved, but bandwidth efficiency deteriorates
Solution Approach 1:
The patent dynamically adjusts the padding field length parameter in the Trigger frame based on the longest processing time requirement among multiple client stations. The MAC processor calculates the required padding length as a function of the longest processing time constraint and inserts accordingly many padding bits, thereby changing the frame parameter to meet the minimum processing time requirement while minimizing unnecessary padding that would waste bandwidth.
Solution Approach 2:
The patent makes the padding field length dynamic rather than fixed. The MAC processor determines the required padding length based on the specific processing time constraints received from different client stations, and adjusts the padding field size accordingly. This dynamic adjustment ensures that the Trigger frame provides sufficient processing time for all stations while avoiding excessive padding that would reduce bandwidth efficiency.
2Reliability
If padding field length is increased to ensure sufficient processing time for all client stations, then transmission reliability is improved, but frame complexity increases
Solution Approach 1:
The MAC processor performs preliminary calculation of the required padding length before generating the Trigger frame. It determines the longest processing time constraint among all client stations and calculates the minimum padding length needed to meet this requirement. This preliminary action ensures that the Trigger frame is constructed with the correct amount of padding from the outset, avoiding both insufficient padding (which would cause transmission failure) and excessive padding (which would increase complexity).
Solution Approach 2:
The patent changes the padding field length parameter dynamically based on the longest processing time constraint. By calculating the required padding length as a function of the longest processing time requirement and adjusting the frame parameter accordingly, the system achieves transmission reliability without unnecessarily increasing frame complexity.
Data Source
AI summary
A WLAN Access Point (AP) includes a MAC processor and a PHY processor. The MAC processor is configured to generate a trigger frame including user information fields destined to respective STAs, and a padding field including one or more padding bits, to determine a number of padding bits that, after the trigger frame including the padding bats being encoded for transmission, satisfy a processing-time constraint imposed by the STAs, and to insert the determined number of padding bits in the padding field. The PHY processor is configured to generate a packet from the trigger frame, including encoding the trigger frame in accordance with an ECC, into one or more code words whose length depends on a number of padding bits in the padding field, to generate multiple modulated symbols from the one or more code words of the packet, and to transmit the modulated symbols to the STAs.