Channel Access Timer Management for Multi-BSS Collision Avoidance
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Solution Overview
Problem
In wireless local area networks (WLANs) utilizing orthogonal frequency division multiplexing (OFDM), existing technologies face challenges in efficiently managing contention free periods across multiple basic service sets (BSSs), leading to potential collisions and inefficiencies in channel access.
Innovation Solution
A communication device sets a channel access timer based on duration indications in received data units and records contention free period durations in multiple BSSs, allowing it to track and manage these periods effectively, preventing collisions by resetting the timer based on received contention free end data units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a communication device uses a single channel access timer for a single BSS, then the timer management is simple, but the device cannot effectively track contention free periods in multiple BSSs, leading to potential collisions
Solution Approach 1:
The patent segments the timer management by creating multiple channel access timers, with each timer dedicated to tracking contention free periods in a specific BSS. This segmentation allows the device to independently manage timing for each BSS without interference, enabling effective tracking of multiple BSSs while maintaining relatively simple individual timer operations.
Solution Approach 2:
Each channel access timer is designed with multi-functionality to handle various operations including setting the timer based on duration indications in received data units, counting down the timer, recording contention free period durations in BSS records, and resetting the timer based on contention free end data units. This universal design allows a single timer structure to perform all necessary functions for managing contention free periods across multiple BSSs.
2Reliability
If the communication device records detailed contention free period information for multiple BSSs, then collision prevention improves, but the memory and processing requirements increase
Solution Approach 1:
The patent extracts only the essential information needed for collision prevention by recording specifically the contention free period duration and the offset value in BSS records. Rather than storing complete BSS information, the device extracts and stores only the critical timing parameters (duration and offset) that are necessary for tracking contention free periods and preventing collisions, thereby reducing memory requirements while maintaining reliability.
3Measurement precision
If the channel access timer is frequently reset based on received data units, then channel access accuracy improves, but the processing overhead increases
Solution Approach 1:
The patent applies preliminary action by setting the channel access timer based on duration indications received in data units before the actual channel access is needed. The timer is configured in advance with the expected busy duration, and the device prepares BSS records with contention free period information beforehand. This preliminary setup reduces the need for frequent mid-process adjustments and resets, thereby improving timing accuracy while reducing processing overhead during critical channel access moments.
Data Source
AI summary
A channel access timer at a communication device is set to a duration for which a shared communication medium is expected to be busy in a basic service set (BSS) heard by the communication device. The channel access timer is counted down. Before the channel access timer reaches zero, respective indications of respective contention free period durations in multiple basic service sets (BSSs) heard by the communication device are recorded in a BSS record maintained by the communication device. Recording the respective indications includes recording, for each particular BSS of the multiple BSSs, (i) an identifier of the particular BSS and (ii) an offset value corresponding to an offset of an end of a contention free period in the particular BSS from an end of a contention free period in the BSS based on which the channel access timer is currently set at the communication device.