Uplink PPDU Duration Field for Collision Avoidance
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Solution Overview
Problem
In wireless local area networks, especially in dense environments with multiple access points and stations, there is a need for an improved protection mechanism to prevent collisions due to simultaneous transmissions, which existing technologies have not adequately addressed.
Innovation Solution
A method and device for uplink transmission in a wireless local area network that involves establishing a connection with an access point, receiving information about a basic service set color, comparing it with a received physical layer protocol data unit (PPDU) to determine if it's from the access point, and transmitting a response PPDU with a duration field indicating the estimated time required for transmission, thereby preventing collisions by managing network allocation vectors (NAV) and resource unit allocations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple access points and stations transmit simultaneously in dense environments, then communication throughput increases, but collision probability increases
Solution Approach 1:
The patent applies preliminary action by having stations determine the duration of upcoming transmissions in advance and update their NAV (Network Allocation Vector) counters before the actual transmission occurs. This allows stations to proactively avoid collisions by knowing when the channel will be busy, rather than reacting after a collision has occurred. The duration field in the trigger frame and response frame enables this advance planning.
Solution Approach 2:
The patent implements feedback mechanisms where the access point provides duration information in trigger frames to stations, and stations respond with acknowledgment frames that confirm receipt and understanding of the transmission schedule. This feedback loop ensures all stations have consistent knowledge of channel occupancy timing, enabling coordinated transmission without collisions.
2Loss of time
If stations transmit response frames immediately upon receiving trigger frames, then response time decreases, but timing coordination becomes more difficult
Solution Approach 1:
The access point acts as an intermediary that mediates timing coordination between multiple stations. It sends trigger frames with duration fields that specify when transmissions should occur and how long they should last. Stations use this intermediary-provided timing information to synchronize their responses, eliminating the need for complex peer-to-peer timing coordination while maintaining fast response times.
Solution Approach 2:
The patent uses parameter changes by incorporating duration fields in the MAC headers of trigger and response frames. These duration parameters dynamically adjust the timing behavior of stations, allowing them to transmit immediately when needed while automatically coordinating with ongoing transmissions through the parameter-driven NAV update mechanism.
3Reliability
If stations update NAV based on received PPDU duration, then channel access coordination improves, but processing overhead increases
Solution Approach 1:
The patent extracts the essential timing information (duration field) from the complete PPDU structure and uses only this critical parameter for NAV updates. Stations extract the duration value from the MAC header without needing to process the entire frame payload, reducing processing overhead while maintaining accurate channel access coordination based on the extracted timing parameter.
Data Source
AI summary
Uplink transmission in a wireless local area network is provided. A station receives a trigger frame for requesting a transmission of an uplink physical layer protocol data unit (PPDU) from an access point (AP). The station determines a value of a second duration field of an uplink PPDU based on a first duration field of the trigger frame. The station transmits the uplink PPDU. The uplink PPDU does not include any frame that solicits a response frame from the AP when the value of the second duration field is set to zero.